MSK Conditions for USMLE PDF

MEHLMANMEDICAL.COM USMLE wants “triamcinolone injection into carpal tunnel” (not IV steroids) as next answer. Surgery is always wrong answer for carpal tunnel on USMLE. - 2CK wants “electrophysiological testing” and “electromyogra...

MEHLMANMEDICAL.COM USMLE wants “triamcinolone injection into carpal tunnel” (not IV steroids) as next answer. Surgery is always wrong answer for carpal tunnel on USMLE. - 2CK wants “electrophysiological testing” and “electromyography and nerve conduction studies” as next best step in diagnosis for carpal tunnel. - Main innervation of medial “1 and a half” fingers, and medial forearm. - Ulnar nerve also does finger abduction and adduction (i.e., interosseous muscles). - USMLE loves Froment sign for ulnar nerve injury, which is inability to pinch a piece of paper between the thumb and index finger (ulnar nerve needed for thumb adduction against index finger, despite thumb being most lateral digit). - Distal compression (i.e., of wrist and hand only, not forearm) is aka Guyon canal syndrome and is caused by hook of hamate fracture; this can sometimes be seen in cyclists due to handlebar compression; presents as paresthesias / numbness of 4th and Ulnar 5th fingers + hypothenar eminence. - Proximal compression (i.e., medial forearm + wrist/hand) is aka cubital tunnel syndrome and is one of the most underrated diagnoses on USMLE, since its yieldness, especially on 2CK, is comparable to carpal tunnel syndrome, but students often haven’t heard of it. Essentially, patient will get paresthesias of medial forearm + hand, where it “sounds like carpal tunnel but on the ulnar side instead” à answer = cubital tunnel syndrome. - Tx for cubital tunnel syndrome is “overnight elbow splint.” Surgery is wrong answer on USMLE. - Main innervation for finger, wrist, and elbow extension. - Innervates BEST à Brachioradialis, Extensors, Supinator, Triceps. - Palsy occurs as a result of midshaft fracture of the humerus, or as a result of fracture at the radial groove (latter is obvious). Radial - Retired Step 1 NBME Q says construction worker sustains “comminuted spiral fracture of humerus” (unusual, since spiral fracture classically = child abuse), and they ask for the resulting defect à answer = “loss of radial nerve function.” - Highest yield point is that injury results in pronated forearm + wrist drop. - Main innervation of the biceps. - Just need to know injury results in loss of sensation over lateral forearm + decreased Musculocutaneous biceps function. - USMLE doesn’t give a fuck about what kind of injury causes palsy. Frequently confused shoulder conditions - In NBME vignettes, I’ve seen both can give Hx of patient doing frequent overhead movement (i.e., painting a fence) + pain with palpation + pain that’s worse when lying on one’s shoulder in bed at night, making differentiating these Subacromial bursitis vs difficult. rotator cuff tendonitis - Subacromial bursitis will only present with above findings, which collectively are known as impingement syndrome. - Rotator cuff tendonitis will present with weakness when performing exam maneuvers (as described in prior table). - Presents as anterior shoulder pain with focal tenderness over the biceps tendon Biceps tendonitis (i.e., when pressing on anterior shoulder). - Aka “frozen shoulder,” or arthrofibrosis. - Decreased passive and active motion of shoulder in all directions. Adhesive capsulitis - Idiopathic, but increased risk in diabetes. - Tx = range of motion exercises / physiotherapy. - This is a Dx that is LY on Step 1, but for whatever reason, becomes HY on 2CK. MEHLMANMEDICAL.COM210  MEHLMANMEDICAL.COM Winged scapula - Long thoracic nerve injury, which innervates serratus anterior. - Can occur post-mastectomy. Brachial plexus injuries - Both can be caused in neonates by breech / traumatic labor. - Can also be caused by injuries such as grabbing onto tree branch while falling. - Upper brachial plexus injury (C5-C6). - Sometimes rather than Erb-Duchenne written as the diagnosis, the answer will just be “upper brachial plexus” when they ask for what’s injured. Erb-Duchenne - Arm is adducted, pronated, and wrist flexed. - Lower brachial plexus injury (C8-T1). - Sometimes rather than Klumpke written as the diagnosis, the answer will just be “lower brachial plexus” when they ask for what’s injured. Klumpke MEHLMANMEDICAL.COM211  MEHLMANMEDICAL.COM Other upper limb DDx for FM - Tenosynovitis means inflammation of tendon sheaths. - deQuervain is classic in breastfeeding women and is worsened with Finkelstein test (shown below) à 1) thumb is placed in palm; 2) 2nd-5th fingers are wrapped over the palm; 3) patient ulnar deviates the wrist à this causes pain. deQuervain tenosynovitis - Patient should avoid offending activity, but since this is often breastfeeding, steroid injection can provide immediate relief. - Gelatinous collection of joint fluid; can occur on ankles and flexor areas as well, but classic location is dorsum of hand/wrist. Ganglion cyst - If Q asks you most likely trajectory if untreated, answer = spontaneous regression. - Tx is needle drainage if disturbing to the patient; recurrence common because the root opening to the tendon sheath is not removed. - Tennis elbow. - Lateral elbow pain worsened when patient extends wrist against resistance. Lateral epicondylitis - NBME asks “extensor carpi radialis brevis” as answer for site of inflammation. - Tx = “forearm strap” on 2CK FM forms. - Golfer elbow. - Medial elbow pain worsened when patient flexes wrist against resistance. Medial epicondylitis - Inflammation at flexor carpi radialis and pronator teres. - Tx = forearm strap. - “Nursemaid elbow”; HY for 2CK Peds. - Child stops using arm + arm pronated and partially flexed. Radial head - Hx of child having arm pulled/yanked, or child holding hands and running with subluxation older sibling + the child falls, resulting in elbow pull. - Tx = hyper-pronation, OR supination when arm partially flexed. Either is correct. Both will not be listed at the same time as answers. - Elbow pain, usually following contact injury. Olecranon bursitis - Tx = compression bandage + NSAIDs. Steroid injection is wrong answer on USMLE. MEHLMANMEDICAL.COM212  MEHLMANMEDICAL.COM HY MSK spinal conditions for USMLE Cervical spondylosis - The answer on USMLE if they say patient over 50 has neck pain + MRI shows degenerative changes of cervical spine. - Can occur in lumbar spine, but USMLE likes cervical spine for this. - Technically defined as degeneration of pars interarticularis component of vertebral body. - Increased mobility between the first (atlas) and second (axis) vertebrae. - Really HY on 2CK Surg and Neuro forms in patients who have rheumatoid arthritis. Atlantoaxial - Must do CT or flexion/extension x-rays of cervical spine prior to surgery when a subluxation patient will be intubated; I’ve seen both of these as answers for different Surg Qs. - Q on one of the Neuro CMS forms gives patient with RA not undergoing surgery who has paresthesias of upper limbs à answer is just MRI of cervical spine (implying atlantoaxial subluxation has already occurred). - Narrowing of the spinal canal. - The answer on USMLE if they mention a patient over 50 who has lower back pain that’s worse when walking down a hill (i.e., relieved when leaning forward), or when standing/walking for extended periods of time. - Can cause “neurogenic claudication,” where the vignette sounds like the patient has intermittent claudication, but they’ll make it clear the peripheral pulses are normal and that the patient doesn’t have cardiovascular disease; this shows up in particular on 2CK Neuro CMS forms. - Technically an osteoarthritic change of the spine; therefore increased risk in obesity (but not mandatory for questions). Lumbar spinal stenosis - The answer on USMLE if they say old woman has difficulty fastening buttons + weakness of hand muscles + loss of sensation of little finger à answer = “C7-T1 Cervical foraminal foraminal stenosis” (offline NBME 20). stenosis - Not stenosis of cervical spinal canal, but stenosis of foramen where nerve exits. MEHLMANMEDICAL.COM213  MEHLMANMEDICAL.COM Spondylolisthesis - The answer on USMLE if they a “step-off” between infra-/suprajacent vertebrae. In other words, they’ll say one vertebra “juts out” or has a “step-off” compared to those above/below it. - Can be due to trauma or idiopathic development. Disc herniation - Herniation of nucleus pulposus through a tear in annulus fibrosis. - The answer on USMLE if they mention radiculopathy (i.e., shooting pain down a leg) after lifting a heavy weight or bending over (e.g., while gardening). They can write the answer as “herniated nucleus pulposus.” - As I mentioned with the radiculopathies above, be aware of the L4, L5, and S1 differences. - Be aware that cervical disc herniation “is a thing,” meaning it’s possible and also assessed on USMLE. 2CK neuro forms ask this a couple times, where patient has shooting pain down an arm, and answer is “C8 disc herniation.” MEHLMANMEDICAL.COM214  MEHLMANMEDICAL.COM - If suspected, newest NBMEs want “no diagnostic studies indicated.” X-ray and MRI are not indicated unless there is motor/sensory abnormality (i.e., weakness or numbness). But for mere radiculopathy (i.e., radiating pain), no imaging necessary on new NBME content. - Straight-leg raise test is not reliable. Mere pain alone is a negative test. The test is only positive when they say it reproduces radiculopathy/radiating pain. There is a 2CK Q where they say straight-leg test causes pain (i.e., negative test) and answer is “no further management indicated” (i.e., Dx is only lumbosacral strain). - Tx is NSAIDs + light exercise as tolerated. Bed rest is wrong answer on USMLE. - The answer on USMLE if they say patient has paraspinal muscle spasm following lifting of heavy box without radiculopathy. If they say radiculopathy, the answer is disc herniation instead. - Straight-leg test can cause pain (i.e., negative test). The test is only positive if Lumbosacral strain they it reproduces radiating pain. - Do not x-ray. This is really HY for 2CK. Apparently lumbar spinal x-rays are one of the most frivolously ordered tests, and USMLE wants you to know that you do not order one for simple lumbosacral strain. - Tx is NSAIDs + light exercise as tolerated. Bed rest is wrong answer on USMLE. - 90% of the time is due to disc herniation. Sciatica - Straight-leg test classically (+) – i.e., reproduces radiating pain. - Tx = Light exercise as tolerated + NSAIDs. Bed rest is wrong answer on USMLE. - On one of the 2CK CMS forms, ibuprofen straight-up is listed as the answer. - The answer on USMLE if they say patient has pain or paresthesias running down the lateral thigh. Meralgia paresthetica - Due to entrapment of lateral femoral cutaneous nerve. - Often seen as incorrect answer choice on Step, so at least be aware of it. MEHLMANMEDICAL.COM215  MEHLMANMEDICAL.COM - Sideways curvature of spine, creating an S- or C-shaped curve. - Usually idiopathic; affects 3% of population; girls 4:1. Scoliosis - Can be associated with Marfan syndrome, Friedreich ataxia, NF1. - Adams forward bend test used to diagnose. - USMLE wants you to know most children do not need treatment, but that curvatures will remain throughout life. - Answer = bracing if curvature is >25 degrees and child is still growing. - I’ve never seen surgery as answer for scoliosis on NBME; literature says recommended only when curvature >40 degrees. - Abnormal convex curvature of thoracic spine. - Usually idiopathic due to old age; can be due to degenerative disc disease and Kyphosis compression fractures (osteoporosis). - If severe, can in theory cause restrictive lung disease due to impaired chest wall expansion. MEHLMANMEDICAL.COM216  MEHLMANMEDICAL.COM Lower limb nerve HY Points for USMLE - The answer on USMLE if patient loses both eversion and dorsiflexion of the foot. Common peroneal - Sensation to upper third of lateral leg (around and below lateral knee). (fibular) nerve - Splits into superficial and deep peroneal (fibular) nerves. - The answer on USMLE if patient loses only eversion of the foot, but dorsiflexion Superficial peroneal stays intact. nerve - Sensation to lower lateral leg and dorsum of foot. - The answer on USMLE if patient only loses dorsiflexion of the foot, but eversion stays intact. - Deep for Dorsiflexion, which means superficial is the one that does eversion instead. Deep peroneal nerve - Loss of dorsiflexion causes a high-steppage gait (patient has to lift foot high into the air with each step). - Also does sensation to webbing between 1st and 2nd toes. I’ve never seen NBME Qs ask or give a fuck about this sensation detail, but students get fanatical about it as if it’s supposed to be high-yield. - The answer on USMLE if patient loses plantarflexion of the foot (can’t stand on Tibial nerve tippytoes). - Sensation to bottom of foot / heel. - The answer on USMLE if patient has motor dysfunction of tibial and common peroneal nerves at the same time, or has sciatica (shooting pain down leg). - Splits into the common peroneal nerve and tibial nerve. - Does not supply sensation to thigh; sensation encompasses that supplied by the combination of the common peroneal nerve and tibial nerves. Sciatic nerve - Supplies some motor function to muscles of thigh but USMLE doesn’t care. - Sciatica = shooting pain from the lower back down the leg usually as the result of disc herniation; 2CK Neuro forms simply want NSAIDs as treatment; straight- leg test is classically used in part to diagnose, but I’ve seen this test show up on NBME material for simple lumbosacral strain (i.e., the test is non-specific and not reliable). - The answer on USMLE if patient has inability to adduct the hip with loss of Obturator nerve sensation to medial thigh. - The answer on USMLE if patient cannot extend knee and/or has buckling at the Femoral nerve knee. MEHLMANMEDICAL.COM217  MEHLMANMEDICAL.COM - Also does sensation to anterior thigh + medial leg (not thigh), although I haven’t seen sensation specifically asked for femoral nerve. - The answer on USMLE if patient loses sensation to medial leg. Saphenous nerve - Pure sensory branch of the femoral nerve. - The answer on USMLE if patient loses sensation to lower lateral leg. In contrast, if sensation loss is upper lateral leg, that’s common peroneal nerve instead. Sural nerve - Often confused with saphenous. Good way to remember is: suraL is Lateral, therefore saphenous must be the one that’s medial. - The answer on USMLE if patient has Trendelenburg gait à opposite side of pelvis will fall while walking, so patient will tilt trunk toward side of lesion while Superior gluteal nerve walking to maintain level pelvis. - Innervates gluteus medius and minimus. - The answer on USMLE if patient cannot squat, stand up from a chair, or go Inferior gluteal nerve up/down stairs. - Innervates gluteus maximus. Lower limb reflexes / radiculopathies - The answer on USMLE if patient loses knee (patellar) reflex + has weakened knee extension. L4 radiculopathy - Pain / paresthesias / numbness in L4 distribution (anterior thigh + medial leg). - Disc herniation of L3-4. - Just remember that L4 is the one where the knee reflex is fucked up. - The answer on USMLE if patient loses dorsiflexion. L5 radiculopathy - Pain / paresthesias / numbness in L5 distribution (lateral + anterior leg). MEHLMANMEDICAL.COM218  MEHLMANMEDICAL.COM - Disc herniation of L4-L5. - The answer on USMLE if patient loses ankle (Achilles) reflex + has weakened plantar flexion. - Pain / paresthesias / numbness in S1 distribution (sole of foot + lower leg). S1 radiculopathy - Disc herniation of L5-S1. - Just remember that S1 is the one where the ankle reflex is fucked up. - SALT à S1, Achilles, Lateral leg dermatome, Tibial motor issue (plantar flexion). Lower limb DDx for FM - Vignette will be lateral hip pain that is worsened with palpation + lying on one’s Trochanteric bursitis side in bed. - Tx = NSAIDs. - USMLE will give inflammation of knee joint that sounds like septic arthritis, but they will say there’s no joint effusion. This is how it presents in a 2CK NBME Septic bursitis vignette, where students constantly ask “why not septic arthritis?” And they say in the vignette there’s no joint effusion. - Tx = antibiotics. - Aka housemaid’s knee; presents as anterior knee pain in people who are Prepatellar bursitis frequently on their knees (painters, plumbers, etc.). - Tx = NSAIDs. - Inflammation of patellar tendon. Patellar tendonitis - The answer on USMLE if they describe anterior knee pain that initially occurs only (“Jumper’s knee”) after finishing sports (e.g., basketball game), then progresses to more chronic pain. - Tx on NBME = “quadricep strengthening exercises.” - Presentation is annoyingly similar to patellar tendonitis, but do not confuse. - Patellofemoral instability is misalignment of the patella at the trochlear groove of the femur. Patellofemoral - Q can mention crepitus. instability - Shows up on 2CK Peds CMS form 6 as teenage girl who has knee pain worse after jumping or running + has crepitus à answer = “patellofemoral instability” (patellar tendonitis / “jumper’s knee” not listed as answer). - Aka chondromalacia patellae; name implies softening of cartilage in the knee. - The answer on NBME if they say pain that worsens when sitting for long periods of Patellofemoral pain time, or when going up or down stairs. syndrome - Classic in obesity or those who squat heavy weight (knees think you’re obese). - Tx = quadriceps strengthening exercises. - ACL is answer if (+) anterior drawer test or Lachman test à excessive anterior Anterior cruciate displacement of tibia relative to femur. ligament injury - Classically injured when knee is hyper-extended, or with a rotational force on a fixed, planted knee. - PCL is answer if (+) posterior drawer test à excessive posterior displacement of Posterior cruciate tibia relative to femur. ligament injury - Classically injured when knee hits the dashboard in car accident. - LCL is the answer if varus test induces excessive lateral motion of the knee Lateral collateral compared to the unaffected side. ligament injury - Varus test = hand placed on medial knee and pushing outward + other hand placed on lateral ankle and pushing inward. - MCL is the answer if valgus test induces excessive medial motion of the knee Medial collateral compared to the unaffected side. ligament injury - Valgus test = hand placed on lateral knee and pushing inward + other hand placed on medial ankle and pulling outward. - Lateral knee pain where patient experiences “locking” or “catching” of the knee in Lateral meniscal tear partial flexion. MEHLMANMEDICAL.COM219  MEHLMANMEDICAL.COM - Diagnosed with McMurray test à internal rotation of leg with concurrent knee extension causes lateral knee pain / “catching.” - Medial knee pain where patient experiences “locking” or “catching” of the knee in partial flexion. Medial meniscal tear - Diagnosed with McMurray test à external rotation of leg with concurrent knee extension causes medial knee pain / “catching.” - Refers to a trio injury of the ACL, medial collateral ligament, and either the medial or lateral meniscus. “Unhappy triad” - Students are sometimes fanatical about this triad as though it has yieldness. USMLE doesn’t give a fuck. I cannot recall a single NBME question that has ever assessed this. This Dx primarily resides within the domain of Qbank, not the NBME. Pes anserine bursitis - The answer on USMLE if patient has inferomedial knee pain. - The answer on USMLE if they say lateral knee pain, usually in a runner. Iliotibial band - Iliotibial band runs from the hip to the knee. Pain may occur anywhere along the syndrome hip, lateral thigh, and lateral knee, but is worst in the latter. Tx = conservative with physiotherapy; NSAIDs for pain. - Buzzy vignette is knee pain in fast-growing teenage male who plays soccer. Don’t Osgood-Schlatter pigeon-hole things, but that’s classic vignette. disease - Inflammation of the patellar ligament at the tibial tuberosity. - Mechanism is repeated stress on the growth plate of the superior tibia. - The answer on USMLE if they give severe heel pain that is worst when first getting Plantar fasciitis out of bed in the morning. - The answer on USMLE if patient has pain + abnormal growth occurring between the 2nd and 3rd metatarsals, usually worsened with high-heel shoes. - Benign growth/tumor of intertarsal nerve; cause is idiopathic. Morton neuroma - First step in diagnosis is x-ray to rule out arthritis + fractures. Ultrasound is then done to confirm Dx, which will show thickening of interdigital/intertarsal nerve. - Tx = orthotics (comfortable shoes) + steroid injection. - Aka Charcot joint, where patient injures joint due to lack of joint sensation from peripheral neuropathy. Neurogenic joint - Usually seen in diabetes; can also be seen in neurosyphilis. - The answer on USMLE when they say diabetic patient has “disorganization of the tarsometatarsal joints” on foot x-ray. Ankle sprains - A sprain is an injury to ligaments (connective tissue holding two bones together). - Might seem pedantic, but ankle injuries are HY for Family Med. MEHLMANMEDICAL.COM220  MEHLMANMEDICAL.COM - Anterior talofibular ligament is on the lateral side of the ankle and will be injured if the foot inverts (rolls inward). This is the most commonly injured ankle ligament. - The deltoid ligament is stronger and on the medial side of the ankle. This injury is more rare and occurs if the ankle forcibly everts (rolls outward). - Below X-ray shows a ligamental ankle injury (left) followed by its repair (right). The Q wants to know which ligament was fucked up. - Answer = deltoid ligament. Notice the large joint space on the medial aspect of the ankle in the left x-ray. Ottawa criteria - Exceedingly HY for FM. Used to assess probability of ankle fracture and tells us whether we need to order an X-ray or vs supportive care, e.g., RICE (rest, ice, compression, elevation). Before development of this criteria, x-rays for the ankle used to be ordered frivolously, with most showing no fracture. - Only order an x-ray for the ankle if: - Pain in the malleolar zone, AND any of the following: - Tenderness posterior to the lateral or medial malleolus; OR - Tenderness on the tip of the lateral or medial malleolus; OR - Patient cannot bear weight when walking four steps. - The above might seem nitpicky and pedantic, but this is HY for 2CK FM as I said. Examples: - 25M + twisted ankle yesterday + moderate edema of lateral side of ankle with ecchymoses + tenderness to palpation lateral and anterior to lateral malleolus + patient can weight-bear; Q asks, in addition to 2-day ice pack application, what is next best step? à answer on Family Med form = “use a soft protective brace and early range of motion exercises”; wrong answer = “x-ray of the ankle to rule out fracture.” - 40M + playing basketball + rolls ankle + pain anterior to lateral malleolus + swelling of ankle + no pain posterior to lateral malleolus + patient can bear weight; Q wants next best step in management à answer = rest, ice, compression, elevation (RICE); wrong answer is x-ray; the patient doesn’t fulfill the Ottawa criteria for x-raying the ankle; he has pain in the malleolar zone but does not have pain posterior to the malleolus or on the tip of the malleolus, and he can bear weight. - 26F + went running and rolled her ankle + pain in lateral ankle + tenderness posterior to malleolus + can bear weight; Q wants next best step à answer = x-ray of ankle; patient fulfills Ottawa criteria for x-ray à she has pain in malleolar region + tenderness posterior to the malleolus; although she can bear weight, the former two findings satisfy the Ottawa criteria. MEHLMANMEDICAL.COM221  MEHLMANMEDICAL.COM HY Fracture points for FM - Pathognomonic for child abuse. Spiral fracture - Caused by rotational/twisting force applied to a limb. - USMLE doesn’t expect you to diagnose based on imaging. - Aka closed fracture – i.e., the skin is not broken and the underlying bone does not Simple fracture pierce the skin. - Aka open fracture – i.e., the skin is broken and the underlying bone pierces the Compound fracture skin. Comminuted fracture - Fracture where the bone is broken in at least two pieces. - Bone bends and cracks instead of breaking completely into two pieces. - More common in Peds than adults. - Children’s bones are more flexible than adult bones adults’ bones because they have ­ collagen content and ¯ mineral content, allowing them to bend more. Greenstick fracture - When a force that would cause a complete fracture in an adult bone is applied to a child's bone, it might only cause a greenstick fracture, which is an incomplete fracture with the bone bending and breaking only on one side, resembling a green branch of a tree that bends and splinters on one side without breaking completely. - Most common type of skull fracture, where there is a break in the skull but the bone has not moved. Linear skull fracture - USMLE wants you to know this is classically associated with epidural hematoma (asked on 2CK CMS form). - Presents with tetrad of Battle sign (bruising over mastoid process), raccoon eyes Base of skull fracture (bruising around the eyes), rhinorrhea, and otorrhea. - The answer on USMLE for pain in the metatarsal area of the foot in long-distance runners with low BMI. Metatarsal stress - Rather than asking diagnosis directly, USMLE will often give a vignette where a fracture female long-distance runner with low BMI already has a metatarsal stress fracture, and then they’ll ask what she’s at greatest risk of developing à answer = osteoporosis. - Occurs with fall on outstretched hand (FOSH), or occasionally as a result of handlebar injury / impaction, with force transferred up to clavicle. Clavicular fracture - Most common site of break is the middle-third of the clavicle. - Tx = Figure-of-8 sling. - As discussed earlier, will present as pain over anatomic snuffbox in patient with FOSH. Scaphoid fracture - X-ray will usually be negative acutely. Must do thumb-spica cast to prevent avascular necrosis of scaphoid, followed by repeat x-ray in 2-3 weeks. - The answer on USMLE if FOSH with pain in central palm + no pain over anatomic Lunate fracture snuffbox. Hook of hamate - Cause of distal ulnar nerve injury / Guyon canal syndrome. fracture - Often from handlebar injury / impaction. Surgical neck of - Causes axillary nerve injury à loss of deltoid function + sensation over deltoid. humerus fracture Midshaft fracture of - Causes radial nerve injury à wrist-drop + pronated arm. humerus - Aka “distal shaft fracture.” Supracondylar - Causes median nerve injury à motor/sensory dysfunction of forearm muscles, fracture of humerus first three fingers and thenar region. - Synonymous with osteoporosis on USMLE (i.e., post-menopausal, corticosteroid- Vertebral use, Cushing syndrome). compression fracture - Will often give point tenderness over a vertebra. - Band of low-density bone that looks like fracture on x-ray but not actual fracture. - Synonymous with vitamin D deficiency (osteomalacia/rickets) on USMLE. Pseudofracture - Can be seen in renal failure, since 1,25-D3 is low. Osteomalacia due to renal failure is called renal osteodystrophy. MEHLMANMEDICAL.COM222  MEHLMANMEDICAL.COM - USMLE wants you to know this can cause entrapment of inferior rectus and inferior oblique muscles. Orbital floor fracture - Vignette will say guy got hit in eye by baseball + has impaired upward gaze. - I talk about extraocular muscles and lesions in my neuroanatomy document, but this is one notable point you should be aware of here. Bone issues in kids - Rickets = vitamin D deficiency in children. Osteomalacia = vitamin D deficiency in adults. - Rickets = craniotabes (soft skull), rachitic rosary (bony knobs at costochondral junctions), genu varum (bowing of tibias). - Activated vitamin D (1,25) is necessary to convert unmineralized osteoid into mineralized hydroxyapatite, therefore hardening bones. - In both rickets and osteomalacia, patient will have “increased unmineralized osteoid,” or “deficient mineralization of osteoid.” - Important cause of Vit D deficiency on USMLE is impaired intestinal malabsorption (i.e., CF, Crohn). For CF, answer can be written as “exocrine pancreas insufficiency.” - “Pseudofracture” on x-ray is buzzy finding in osteomalacia/rickets. - Patients have ¯ Ca2+, ¯ PO43-, ­ PTH (due to ¯ negative feedback at parathyroid glands). Rickets - Aka Blount disease. Tibia vara MEHLMANMEDICAL.COM223  MEHLMANMEDICAL.COM - Bowing of the tibias after the age of 2 years in a patient whom rickets has been ruled out. - Can be unilateral or bilateral. - Bowing of one or both tibias is sometimes normal until age 2 years. - Treatment is surgery (osteotomy). - Osteoclast dysfunction resulting in recurrent fractures in children due to bone density being too high. Sounds weird, but bone strength is based on balanced internal architecture of canals and networks, not just density alone. Osteopetrosis - HY DDx against osteogenesis imperfecta and child abuse. - Osteoclast dysfunction is due to deficiency of carbonic anhydrase II. This enzyme inside osteoclasts normally allows osteoclasts to form H+ to resorb bone. - No, this is not a joke. This is the answer straight-up on a 2CK NBME form. - Vignette is healthy child age 3-12 who awakens from sleep with throbbing pain in the Growing pains legs. - No treatment necessary. You just need to know this Dx is exists and isn’t a troll. - Aka clubbed foot. Talipes equinovarus - USMLE just wants you to know that this is treated initially with serial casting. - Usually idiopathic; can be seen in Potter sequence. - Not the same as rocker-bottom foot (aka congenital vertical talus), seen in Edward syndrome. - You just need to know this is fancy name for a child born with multiple joint contractures. Arthrogryposis - If they give you a child with not just a clubbed foot, but also knee and/or elbow contractures, etc., the answer is arthrogryposis. HY Pediatric hip disorders for USMLE - Aka developmental dysplasia of the hip. - Mechanism is “poorly developed acetabulum.” - Initial diagnosis is with Ortolani and Barlow maneuvers, where a “clicking and clunking” is elicited on physical exam. - After the O&A maneuvers, next best step is ortho referral. Sounds wrong, Primary hip dysplasia but if it’s listed, it’s the answer before going to imaging. - Definitively diagnose with hip ultrasound if 6 months of age. - Treatment is “abduction harness,” aka Pavlik harness, which positions the child’s legs in a frog-leg-appearing manner. - Aka idiopathic avascular necrosis of the femoral head. - If the etiology for the avascular necrosis is known (i.e., Gaucher, sickle Legg-Calve-Perthes cell, corticosteroids), then the diagnosis is just “avascular necrosis,” not LCP. MEHLMANMEDICAL.COM224  MEHLMANMEDICAL.COM - Vignette will be child 5-8 years old with hip pain. - First step in diagnosis is hip x-ray, which will show a “contracted” or flattened femoral head. The word “contracted” is HY and synonymous with avascular necrosis. - If x-ray is negative, diagnose with bone scan or MRI (on 2CK form). - Tx = hip replacement. X-ray showing flattened/contracted femoral head (compare with the normal side that looks rounder). On MRI, the right femoral head (left side of image) appears hypointense (more black). The necrotic / lack of bone in the black superior portion of the femoral head means the remaining white part of the femoral head is “flattened” or “contracted.” The left femoral head (right side of image) shows a small area of necrosis as well (black medial portion). - Classic vignette is a 10-13-year-old (pre-adolescent) overweight boy with a painful limp. - NBME will write answer / mechanism as “displacement of the epiphysis of the femoral head.” Slipped capital femoral - Resources tend to emphasize obesity as the main risk factor, but maybe epiphysis (SCFE) only ~1/2 of NBME Qs for SCFE give the child as overweight. This causes problems for students, where they rely on seeing high BMI to think SCFE. - This has led me to conclude that the age matters the most, since they will always give a kid who’s about 10-13-ish. If they give you a kid who’s younger, think LCP instead. MEHLMANMEDICAL.COM225  MEHLMANMEDICAL.COM - 2CK NBME Q gives 13M with painful gait + no mention of weight à answer is SCFE. - Another 2CK Q outright says BMI 20 in a 13-year-old who’s 6 feet tall, and answer is SCFE. - X-ray shows “ice cream falling off the cone.” X-ray shows the “ice cream slipping off its cone.” - Offline 2CK gives Q where they say x-ray in 5-year-old shows “contracted capital femoral epiphysis” à answer is LCP, not SCFE. As I said above, “contracted” is HY for LCP. In this case, the younger age + the word “contracted” win over the words “femoral capital epiphysis.” Tx = surgical pinning. HY Arthritides / joint pathologies for FM - Juvenile idiopathic arthritis (formerly juvenile rheumatoid arthritis; JRA). - 2CK forms love JIA. It will sound like regular RA but just in a kid. - USMLE will structure these Qs where they want you to pick between JRA and septic arthritis (SA) as answer choices. This can be confusing since SA can occur in patients with JRA. They might say a kid has a low-grade fever and a warm, red, painful knee (sounds like SA), but then they say he’s had similar episodes in the past (i.e., they want JRA over SA). This is because SA is usually a one-off event; for JRA, however, the vignette will say “intermittent” or “episodic.” Low-grade fever can occur in autoimmune flares (not limited to JRA; HY for sarcoidosis as well). - “Salmon-pink” maculopapular rash only in ~50% of JRA Qs. Often described as a buzzy finding, but I’d say about half of JRA vignettes don’t even mention rash. - 2CK forms are obsessed with anemia of chronic disease in JRA. HY point is that JIA/JRA MCV can absolutely be low. Resources push normal MCV for AoCD. This is absolute nonsense. Plenty of 2CK NBME Qs give MCV as 70s in AoCD. - Can be associated with serous pericarditis. - If the Q asks what arthrocentesis will show in JRA, the answer is leukocytes. - For antibodies, anti-cyclic citrullinated peptide (anti-CCP) is more specific than rheumatoid factor. Both should be ordered for JRA (and RA in adults). - Tx for JRA has arms of management: 1) symptoms; 2) disease progression. For symptoms, give NSAIDs first, followed by steroids. These do not slow disease progression. NSAIDs and steroids are for symptoms only. For disease progression, we use disease-modifying anti-rheumatic drugs (DMARDs), which slow disease progression. Methotrexate is given first, followed by adding an anti-TNF-a agent (i.e., infliximab, adalimumab, or etanercept). - Plaques are described as silvery and scaly and over extensor regions (elbows); Psoriasis plaques can also show up on the face (i.e., forehead and lip). MEHLMANMEDICAL.COM226  MEHLMANMEDICAL.COM - Auspitz sign is bleeding of the scales if removed. - 15% of patients with psoriasis will get arthritis before any skin findings. - HY point for USMLE is that psoriasis is part of the HLA-B27 constellation (PAIR à Psoriasis, Ankylosing spondylitis, IBD, Reactive arthritis). - For example, if 17M has silvery plaque on elbow and forehead + bloody stool à the latter is most likely IBD due to HLA-B27 association. - Don’t confuse psoriasis + IBD combo with dermatitis herpetiformis + Celiac disease combo. - Treatment for plaque psoriasis is topicals first à USMLE wants calcipotriene (vitamin D derivative), triamcinolone or hydrocortisone (both corticosteroids), and coal tar. Choose in that order if you are forced. Chronic application of topical steroids causes dermal collagen thinning, so they are not preferred prior to topical vitamin D. - Oral meds are given if patient fails topicals, OR if patient has systemic psoriasis (i.e., arthritis). Oral methotrexate is HY on new NBME material as the first-line oral agent used. - An old NBME has oral acitretin (a vitamin A derivative) as an answer, where methotrexate is not listed. - Sacroiliitis is broad term that refers to arthritis of lower back; ankylosing spondylitis (AS) is most severe form. - Vignette will almost always be male 20s-40s who has lower back pain worse in the morning that improves throughout the day. However, there is Q on 2CK Peds form where AS is diagnosis in an 8-year-old, so you need to know it’s possible in peds. - Lower back pain in patient with IBD, psoriasis, or reactive arthritis points toward Sacroiliitis sacroiliitis (HLA-B27 PAIR). - High ESR and anemia of chronic disease high-yield. - Diagnose with x-rays of the lumbosacral spine and sacroiliac joints. - USMLE wants “slit-lamp examination” to look for anterior uveitis in ankylosing spondylitis. Any autoimmune disease can theoretically increase risk of this eye finding, but for whatever reason USMLE likes it for AS. - Treat same as JRA. - Arthritis is most common presenting feature of lupus (90%). USMLE vignette will pretty much always give arthritis in lupus Qs. - Anti-double-stranded-DNA (dsDNA) antibodies go up with acute flares and are most closely related to renal prognosis for lupus nephritis. - Anti-Smith (ribonucleoprotein) antibodies are most specific for SLE (more than dsDNA). - Anti-phospholipid syndrome due to lupus anticoagulant (antibodies against b2- microglobulin or cardiolipin in patient with SLE). - Anti-phospholipid syndrome can cause false-positive syphilis VDRL test (HY). - Malar rash is type III hypersensitivity. Harder Qs won’t mention this finding because it’s too buzzy. You need to know thrombocytopenia is frequently seen in lupus due to anti-hematologic cell line antibodies. Antibodies can also target WBC Lupus and RBC à looks like aplastic anemia, but it’s not à answer = “increased peripheral destruction,” not “decreased bone marrow production.” - Can cause lupus cerebritis (confusion / delirium-like episodes) and transverse myelitis (presents as Brown-Sequard syndrome). Peds form gives lupus cerebritis. - Similar to RA, lupus can cause pericarditis. - Flares cause decreased serum complement protein C3. - Congenital complement protein C1q deficiency causes ­ risk of developing SLE; sounds nitpicky but it’s on new Step 1 NBME exam. - For lupus nephritis, biopsy as the first step in management; steroids first is wrong answer; biopsy first sounds wrong but it guides management. - Lupus nephritis = diffuse proliferative glomerulonephritis (DPGN) on USMLE. - Treat flares of lupus with steroids. USMLE doesn’t care about other Txs. MEHLMANMEDICAL.COM227  MEHLMANMEDICAL.COM - Shows up as young healthy patient with recent trauma (e.g., car accident) or high- intensity exercise causing microtrauma (e.g., kickboxing/soccer tournament, long hike), as well as in sickle cell disease. - Also occurs in patients with Hx of RA/JRA, OA, and prosthetic joints. - USMLE will give hot, red, painful joint in one of the above patient groups, almost always with a fever. - First step in management is arthrocentesis. A high-yield point is that joint aspirate can be negative for organisms. Do not rule-out SA if NBME says no organisms. - Staph aureus is most common pathogen overall. Septic arthritis - Choose Salmonella in sickle cell. But you have to use your head. Salmonella is a gram-negative rod, so if they say gram-positive cocci is cultured in sickle cell, the answer is still staph aureus. - Gonococcus is the answer for sexually active patients; presents two ways on USMLE: 1) monoarthritis of the knee in sexually active young patient, with no other information provided; or 2) as a triad: mono- or polyarthritis, cutaneous papules, and tenosynovitis (inflammation of tendon sheaths). - Treatment is surgical drainage of the joint + antibiotics. USMLE doesn’t care about the exact antibiotics. - Aka transient synovitis. - Presents as hip inflammation/pain in child after a viral infection. - Toxic synovitis is diagnosis of exclusion, meaning the vignette gives you various findings that make septic arthritis less likely. Leukocytosis and inability to bear Toxic synovitis weight make septic arthritis the likely answer over toxic synovitis. Hard questions will not mention warmth or redness as ways to differentiate. Fever can present in both. - Treatment is NSAIDs (ibuprofen) à asked on 2CK Peds. - Classically presents as triad of 1) urethritis or abdominal infection, 2) polyarthritis, and 3) “eye-itis” (i.e., conjunctivitis, episcleritis, or anterior uveitis). - Chlamydia is the classic organism that causes reactive arthritis. Gonococcus does Reactive arthritis not cause reactive arthritis on USMLE. - Rubella, Hep B+C, and Yersinia can also cause reactive arthritis. - Part of HLA-B27 constellation (PAIR), as mentioned above. Paget disease - Idiopathic disorder of increased bone turnover. Bone is described as having mixed osteoblastic and -clastic phases, where bone appears heterogenous on x-ray. - Buzzy vignette is male over 50 who’s hat doesn’t fit him anymore + has tinnitus (narrowing of acoustic foramina). - 19/20 questions will give isolated increase in serum ALP. You need to know Ca2+, PO43-, and PTH are all normal in Paget disease. There is one Q on a 2CK CMS form where ALP is given as not elevated, but it’s a one-off Q and rare. - High-output cardiac failure can occur due to intraosseous AV-fistulae, where patient has an S3 heart sound with high, rather than low, ejection fraction. Osteoporosis - Bone density >2.5 SD below mean compared to young adult woman. Osteopenia is 1.5-2.5 SD below mean. - Bone densitometry done at age 65 (2CK Family medicine). - If Q forces you to choose between female gender and age as most important risk factor, choose gender. - If Q gives you a female and forces you to choose between family history and age, choose family history. - Males are unlikely to develop osteoporosis, even with family history of females with the disorder. - If Q gives two women without family history and asks what is most protective against osteoporosis, answer is ethnicity. Black race is protective against osteoporosis. MEHLMANMEDICAL.COM228  MEHLMANMEDICAL.COM - If Q gives old woman who has femoral fracture + no mention of osteoporosis in the question, answer = “activity level before fracture” as most important predictor of success in the rehabilitation of the patient à weight-bearing exercise during life is protective against osteoporosis later. - USMLE loves corticosteroids and Cushing as causes of osteoporosis. - Compression fractures = osteoporosis on USMLE; e.g., patient with RA on steroids who has compression fracture à easy Dx of osteoporosis. - Low/low-normal BMI causing osteoporosis is HY; 2CK NBMEs have a couple of nonsense Qs where they give BMI of 19 and 20 in young woman, where they ask what patient is at increased risk of; answer = osteoporosis. Student says, “Wait, but isn’t low BMI under 18.5?” I agree. But it’s on NBME. - Metatarsal stress fracture HY in low-BMI young female runners who have low bone density. - USMLE also is known to assess low vitamin D in the setting of intestinal malabsorption (i.e., CF, Crohn) as cause of osteoporosis, even though that makes no sense, since low Vit D causes osteomalacia. - Serum calcium, phosphate, PTH, and ALP are all normal in osteoporosis. - Tx = weight-bearing exercise first (NBME has “go for a long walk outside daily” as correct; wrong answer = “increase participation in swimming pool-based exercise classes to at least three times weekly”). - Calcium and vitamin D are the first medical / pharmacologic treatment. - Bisphosphonates can be used after Ca2+/VitD. - Teriparatide is an N-terminus PTH analogue that stimulates bone development. - Denosumab is a RANK-L monoclonal antibody. HY bone tumor points for FM - Most common primary bone cancer; usually in patients age 10-30. - Rb mutations (congenital retinoblastoma) are associated with osteosarcoma (HY) – i.e., 1-year-old boy has enucleation of eye for retinoblastoma; what is he at risk of developing later in life? à answer = osteosarcoma. - Can also occur in Paget disease of bone patients (older age). - Buzzy findings are “Codman triangle” and “Sunburst appearance.” - Codman triangle = periosteal reaction with lifting of periosteum off the bone. - Sunburst appearance = periosteal reaction described on NBME as “spiculated new born formation.” Osteosarcoma - The white arrow is the Codman triangle; the white star is the sunburst appearance. - I’ve seen osteosarcoma on Step 1 NBME written as “pleomorphic neoplastic cells producing new woven bone” as correct answer choice. Chondrosarcoma - Can occur in any long bone, as well as the pelvis/hip. MEHLMANMEDICAL.COM229  MEHLMANMEDICAL.COM - USMLE describes it as “glistening” or “shiny” in appearance. - The histo is exceedingly HY for Step 1 but not for Family Med. Just know this as DDx. - The answer on USMLE if they give bone tumor in a child that presents similarly to osteomyelitis (i.e., fever and bone pain in a kid). - If bone scan is performed, it is most likely to show uptake in the diaphysis; in Ewing sarcoma contrast, osteomyelitis will show uptake in the metaphysis. - Histo will show “small blue cells of neuroendocrine origin” and/or “onion-skinning.” - Associated with t(11;22) translocation; don’t confuse this with the 22q11 deletion in DiGeorge syndrome. Osteoid osteoma - Answer on USMLE for bone tumor that presents with pain relieved with NSAIDs. - Answer on USMLE for bone tumor in Gardner syndrome (Familial adenomatous Osteoma polyposis + soft tissue tumors [usually osteomas or lipomas]). - Benign bone tumors that usually grow from the skull. - Aka osteoclastoma. Giant cell tumor - Age of onset usually 20-40. - Has a “soap bubble” appearance. - Underrated diagnosis for USMLE. Asked on 2CK exam. - Benign bone tumor that looks similar to osteoclastoma but age of onset usually birth to age 20, rather than 20-40. - Unicameral means “one chamber”; it is fluid-filled. Unicameral bone cyst 2CK wants you to know this image for unicameral bone cyst. - USMLE loves mets to the vertebrae, particularly from breast, prostate, and lung. - The exam will not show images of spinal cancer mets, but they will give vignette of either lytic lesions of vertebrae in patient with background of cancer, or will give Metastases neurologic syndrome (i.e., of cauda equina). - Diffuse bone pain in patient with background of cancer = mets. MEHLMANMEDICAL.COM230  MEHLMANMEDICAL.COM - Above image shows Technetium-99 bone scan of cancer mets. Similar imaging is on 2CK forms for prostate mets. HY myopathies / muscular dystrophies for USMLE - XR disorder caused by mutation in dystrophin (DMD) gene. - Mutation results in disruption of a-/b-dystroglycan, which is required for proper internal cytoskeletal anchoring of the muscle cell to the extracellular matrix. - Presents with pseudohypertrophy, where muscles appear large but are Duchenne / Becker replaced with fibroadipose tissue (connective tissue stromal cells). muscular dystrophy - Duchenne presents in a young boy who implements Gower maneuver to stand up (uses arms to walk up off the floor because leg muscles are weak). - Becker presents in adolescence or young adulthood (less severe form of Duchenne). - Duchenne is classically frameshift mutation; Becker is classically not frameshift. - Usually patient over 50 with proximal muscle pain and stiffness. - No weakness on physical exam + creatine kinase (CK) levels are normal. If one or both of these findings is present, the answer is polymyositis, not PMR. - Can present with high ESR and low-grade fever (any autoimmune disease flare can present with low-grade fever). - PMR can present with or without temporal (giant cell) arteritis. Temporal Polymyalgia rheumatica arteritis can present bilaterally on NBME exams; do steroids first to prevent (PMR) blindness, followed by biopsy second. - Temporal arteritis can cause jaw claudication (pain in the jaw during episodes). In contrast to temporomandibular joint dysfunction (a separate diagnosis), jaw claudication will not be precipitated by eating. - No specific diagnostic test; diagnosis is made clinically. - Tx = steroids. NSAIDs are wrong answer and are not proven to be effective. - Usually patient over 50 with proximal muscle pain and stiffness. These findings are not unique to PMR. The USMLE will happily give pain and stiffness in polymyositis vignettes. - Key distinction between polymyositis and PMR is that polymyositis will present Polymyositis / with 1) muscle weakness on physical exam, and/or 2) increased serum CK. Dermatomyositis - The muscle weakness *must be on physical exam.* If the patient complains of “weakness” but there is no physical exam findings mentioned in vignette or physical exam shows 5/5 strength, there’s no weakness. Patients will sometimes mention “weakness,” even though they really just have pain and/or stiffness. MEHLMANMEDICAL.COM231  MEHLMANMEDICAL.COM - If polymyositis presents with skin findings, it is called dermatomyositis – i.e., Gottron papules (violaceous papules on the knuckles), mechanics’ hands (rough- surfaced hands), shawl rash (body rash), heliotrope rash (violaceous eyelids / periorbital rash; don’t confuse with malar rash of SLE). - Patients often positive for anti-Jo1 antibodies. - USMLE wants “electromyography and nerve conduction studies” as first step in management for polymyositis/dermatomyositis. This is what they ask on 2CK NBME forms. I have not seen them ask anti-Jo1 antibodies vs EMG+NCS as two separate answer choices. Usually anti-Jo1 antibodies are mentioned in the vignette rather than as the test you need to order. - Muscle biopsy is confirmatory, showing CD8+ T cell infiltration. The histo can be described as “CD8 + T cells and macrophages surrounding muscle fibers.” - For whatever reason, dermatomyositis can be a paraneoplastic syndrome of ovarian cancer (shows up on NBME). Tx = steroids. Gottron papules - This is a psych condition, not an actual muscle disorder, but is often confused with polymyositis and PMR. - Labs will be normal. ESR will not be elevated. Patient will not have fever. - Will be described as woman 20s-50s with multiple (and often symmetric) Fibromyalgia muscle tenderness points. - Treatment is SSRIs. USMLE can write this as “anti-depressant therapy.” This confuses students (“But she doesn’t have depression though.”) à Right. But SSRIs are still anti-depressant medication. - The answer on USMLE if they give jaw pain that is precipitated by eating. Temporomandibular - Often confused with jaw claudication seen in temporal arteritis. In the latter, joint dysfunction however, the pain is not precipitated by eating. - Autosomal dominant, CTG trinucleotide repeat expansion disease. - Myotonia is inability to relax muscles. Myotonic dystrophy - The answer on USMLE if they say patient cannot relax grip on doorknob / handshake, or cannot let go of golf club. - Sometimes associated with early / frontal balding. - Myopathy can occur in both hypo- and hyperthyroidism, yes, but this is especially HY for hypothyroidism on USMLE. Hypothyroid myopathy - They will often sneak this in as proximal muscle weakness or increased CK in patient who has ongoing fatigue, dysthymia, menstrual irregularities, etc. - Classically seen when statins and fibrates are combined, but both drugs can cause myopathy independently. - Mild CK elevations are normal and expected in patients when commencing Drug-induced myopathy these agents. Dose does not need to be decreased for mild CK elevations. - USMLE wants “P450-mediated interaction” as the cause of the myopathy when statins and fibrates are combined. Mitochondrial myopathy - Broad term that can refer to numerous mitochondrial diseases. MEHLMANMEDICAL.COM232  MEHLMANMEDICAL.COM - USMLE wants you to know the patient has a mitochondrial disorder when he/she presents with hypotonia, ear/eye problems, and lactic acidosis. You want to memorize this tetrad as synonymous with mitochondrial disorders. - “Ragged red fibers” can be a buzzy descriptor in mitochondrial myopathy Qs. - Mitochondrial disorders are maternally inherited only. - Heteroplasmy refers to offspring having varying disease severity based on variation in allocation of diseased mitochondrial genes (I talk more about this stuff in my HY biochemistry PDF). - The answer on USMLE if they tell you patient 50 or older has months to years Inclusion body myositis of progressive muscle weakness + biopsy of muscle shows basophilic rimmed vacuoles. Connective tissue disorders - Autosomal dominant; chromosome 15, FBN1/2. - Codes for fibrillin, which is a glycoprotein that forms a sheath around elastin. - Tall, lanky body habitus with flat feet, chest wall abnormalities (i.e., pectus excavatum or Marfan carinatum), flat feet (pes planus), scoliosis, mitral valve prolapse (mid-systolic click), increased risk for aortic dissection (can retrograde propagate toward aortic root, causing root dilatation and aortic regurgitation [decrescendo diastolic murmur]). - Is not associated with berry/saccular aneurysms (unlike Ehlers-Danlos and ADPKD). - Defect in collagen III synthesis; can be written as “Defect in synthesis of fibrillar collagen.” - This can be confusing because fibrillin is completely unrelated and refers to Marfan syndrome. It is just coincidental that “fibrillar collagen” means type III collagen. - Wrong answer = “abnormal synthesis of extracellular glycoprotein” (refers to fibrillin for Marfan syndrome, which as mentioned above, is a glycoprotein that forms a sheath around elastin. - Presents as easy bruising + hyperextensible skin. Ehlers-Danlos - Collagen I defect that results in recurrent fractures in a child; important DDx are child abuse and osteopetrosis. Osteogenesis - Blue sclerae too buzzy and often not mentioned. imperfecta - Conductive hearing loss due to defective ossicles (middle ear bones). - Many different types of OI, some resulting in miscarriage. Harder vignette can mention child with multiple fractures, where the mom has Hx of recurrent miscarriage. - Autosomal dominant; chromosome 7. - Defect in elastin. Williams - Elfin-like facies, hypercalcemia, well-developed verbal skills. - Can cause supravalvular aortic stenosis. MEHLMANMEDICAL.COM233  MEHLMANMEDICAL.COM - Answer on USMLE if they give you a patient who has anti-U1-ribonucleoprotein (U1-RNP) Mixed antibodies. connective - Patient presents as having combined features/symptoms from three different disorders tissue disease à LPS à Lupus, Polymyositis, Scleroderma. Basic hernia points for FM - Occurs usually in older men. - Small bowel herniates medial to inferior epigastric vessels. - Occurs due to weakness of abdominal wall musculature / transversalis fascia. Direct inguinal - Q might say older patient has palpable mass in groin that reduces when he lies down, hernia or worsens when he coughs. Tx = “operative management” or “elective hernia repair,” since it is not an overt emergency but closure should be performed prior to any type of incarceration and strangulation (ischemia leading to pain, fever, and necrosis). - Seen classically in male infants, but can occur any age. - Small bowel herniates lateral to inferior epigastric vessels, through deep inguinal ring. - Mechanism is patent processus vaginalis. This is also the mechanism for hydrocele (asked on NBME). Indirect inguinal - Since it passes through deep inguinal ring, it can be reduced with pressure / a finger hernia placed over deep inguinal ring. Direct inguinal hernia, since it does not pass through deep inguinal ring, will not reduce with pressure applied here. - Tx = elective hernia repair. - For hydroceles, observation is the answer under the age of 1 (HY on Peds forms). HY neck MSK masses for FM - The answer on USMLE if they say there’s a painless, midline neck lump in a child that moves upward with swallowing or protrusion of the tongue. This buzzy description is seen for maybe only about half of Qs. Thyroglossal duct cyst - Can also be described as painless mass inferior to the hyoid bone that demonstrates uptake with a Technetium-99 scan. - USMLE wants “endoderm of foramen cecum” as the embryology. Sternocleidomastoid - The answer on USMLE if they say nodular mass in the lateral neck in an infant injury who had been born via forceps delivery (risk factor for damage to the muscle). - The answer on USMLE if they give idiopathic lateral neck mass in infant that may Branchial cleft cyst or may not have an opening to the skin. - Neonates or infants. - Answer for hypothyroidism + a midline neck lump located high in the neck. - They say nothing about protrusion of the tongue or uptake into the mass (of Lingual thyroid course this is thyroglossal duct cyst instead). - Can sometimes cause dysphagia (trouble swallowing), dysphonia (voice changes), or dyspnea (difficulty breathing). Highest yield “MSK pharm” for FM - I discussed some of these in the Neuro and Psych sections, but I reiterate a few due to their yieldness. - Bisphosphonate; inhibits osteoclasts. This MOA is HY. - Used for osteoporosis after Ca2+/VitD. - I’ve seen pamidronate (not alendronate) show up on 2CK forms for Tx of Alendronate hypercalcemia (after normal saline is given). - Students get fanatical about bisphosphonates causing osteonecrosis of the jaw. The yieldness of this adverse effect is basically non-existent on NBME exams. MEHLMANMEDICAL.COM234  MEHLMANMEDICAL.COM USMLE wants you to know bisphosphonates cause pill-induced esophagitis. This is very HY for 2CK FM forms in particular (K+ supplements also cause esophagitis). - N-terminus PTH analogue that can induce bone formation. Even though PTH causes bone resorption, this agent stimulates osteoblast-mediated bone formation Teriparatide more than it induces RANK-L-mediated activation of osteoclasts. - Can be used for severe/advanced osteoporosis. - Monoclonal antibody against RANK-L. Denosumab - Can be used for severe/advanced osteoporosis. - Agonizes GABAB. - Used for spasticity, classically in multiple sclerosis, but I’ve seen one NBME Q where it’s used for random spasticity in an older dude. Baclofen - Students frequently remember GABAB for this drug, but often say “antagonist” when I probe them further. So remember: it’s an agonist, not an antagonist, at GABAB. - Muscle relaxant used for spasms. Cyclobenzaprine - Structurally similar to TCAs; helps modulate pain sensation at brain stem. - Muscarinic (cholinergic) receptor antagonist. - Used to treat acute dystonia due to anti-psychotics. Benztropine - If patient starts anti-psychotic and then gets stiff neck, oculogyric crisis (abnormal eye movements), or muscle rigidity without fever, the answer = benztropine. - First-generation histamine-1 (H1) antagonists. - Diphenhydramine is quite possibly the highest-yield drug on USMLE. - Used to treat acute dystonia, similar to benztropine, as well as motion sickness. - H1 blockers can treat allergies in theory, but they have nasty anti-cholinergic (anti-muscarinic) side-effects. - The anti-cholinergic side-effects are interestingly a good thing, however, when we want to treat acute dystonia. Psych Qs will either list benztropine or diphenhydramine (or chlorpheniramine) as the answer, but not both at the same time. Diphenhydramine / - For whatever reason, anti-cholinergic effects treat motion sickness. Scopolamine Chlorpheniramine is an anti-cholinergic used to treat motion sickness classically. But I’ve seen NBME ask diphenhydramine straight-up for this as well – i.e., the nasty anti-cholinergic side-effects are, once again, a good thing if the aim is Tx of motion sickness. - 1st-gen H1 blockers can cause cognitive dysfunction (delirium, as well as worsening of dementia) and drowsiness. Therefore avoid in elderly and locomotive/machine operators if at all possible. - 1st-gen H1 blockers can also cause anti-a1-adrenergic effects (orthostatic hypotension). - I talk about all of the pharm-related stuff in a lot more detail in my free pharm modules on the website. - Blocks ryanodine Ca2+ channel. - Tx for neuroleptic malignant syndrome (NMS) and malignant hyperthermia (MH). - If patient gets muscle rigidity and fever following commencement of anti- psychotic, or following administration of succinylcholine during surgery, answer = dantrolene. (Bromocriptine for NMS is low-yield and rarely seen on NBME). - NBME will sometimes give vignette of NMS or MH, and then the answer for Tx is Dantrolene “decreases sarcoplasmic calcium release.” - In NMS and MH, the ryanodine channel, which allows calcium to move from the sarcoplasmic reticulum into the cytosol, gets stuck open, so high amounts of calcium moves into the cytoplasm. The cell then needs to use a lot of ATP to pump the calcium back into the sarcoplasmic reticulum. This generates heat à fever. Dantrolene closes this channel. MEHLMANMEDICAL.COM235