Neuropathies & Onychomycosis

• Study notes based on flashcard content are provided below

Neuropathies

• Neuropathy is a disease of the peripheral nerves
• Radiculopathy is a disease of the spinal nerve root
• Myelopathy is a disease of the spinal cord
• Functional B12 deficiency can lead to peripheral neuropathy

Onychomycosis & Related Conditions

• Trichophyton rubrum is the most common pathogenic dermatophyte
• Terbinafine (Lamisil) is a popular treatment for onychomycosis and dermatophyte skin infections
• The four types of onychomycosis include Proximal Subungual, Distal Subungual, Superficial white, and Candidal
• Proximal subungual onychomycosis is the most difficult to treat due to potential matrix and lunula involvement, possibly leading to dystrophic nails and is most common in immunocompromised patients
• Superficial white onychomycosis involves direct invasion of the nail plate, with randomly dispersed lesions coalescing to affect the entire plate
• Candidal Onychomycosis is the least common type, associated with edema and erythema of the proximal and lateral nail folds
• Onychomadesis is the proximal separation of the nail plate, and is associated with coxsackie virus infection
• Onychocryptosis is the curvature of the medial or lateral portion of the nail plate, known as Pincer nails

Nail Abnormalities

• The Lovibond angle is used to diagnose nail clubbing
• Koilonychia refers to spoon-shaped nails, often resulting from anemia
• Onychopuntata (pitting) can be the appearance of nails in association with psoriasis

Infections

• Staph aureus is the most common pathogen for acute paronychia
• T. metagrophytes is the most common pathogen to cause vesicular tinea pedis
• Erosio Interdigitalis Blastomycetica is a severe infection in toe webspaces, appearing as an eroded erythematous area surrounded by macerated skin

Procedures & Contraindications

• The Straight Back procedure for ingrown toenails leaves the matrix intact, making it a non-permanent solution
• P & A procedures or any "cold-steel" nail procedures (Winograd, Frost, Zadik) are contraindicated in PAD patients

Malignant Melanoma Subtypes

• The four subtypes of malignant melanoma include Superficial spreading, Nodular, Acral Lentiginous, and Lentigo Maligna
• Superficial spreading melanoma is the most common, characterized by a slow horizontal growth phase
• Nodular melanoma has a short horizontal growth phase and rapidly enters vertical growth
• Acral lentiginous melanoma frequently occurs on palms, soles, or beneath nail plates
• Lentigo maligna melanoma develops from a benign lesion and is more common in older individuals

Other Skin Conditions

• Bowen's disease is SCC in-situ, presenting as an erythematous, well-demarcated scaly patch/plaque
• Marjolin's ulcer is a rare SCC arising from wounds or scars, associated with non-healing chronic venous ulcers

Masses

• A mass that transilluminates and fluctuates in size is likely a ganglion cyst

Vascular Conditions

• Raynaud's phenomenon presents with color changes in the order of White → Blue → Red
• Mondor's sign is plantar ecchymosis specific for Lisfranc or calcaneal fracture

Fractures

• Zone 2 is associated with Jones fracture of the fifth metatarsal
• A shaft fracture of the fifth metatarsal is known as a Dancer's fracture

Anatomy

• The Lisfranc ligament supports the transverse arch, originating on the lateral aspect of the medial cuneiform and inserting on the medial aspect of the 2nd metatarsal base

Tendon Dysfunction

• PT tendon dysfunction is the most common cause of adult acquired flat foot

Ulcers

• Arterial ulcers are sharply demarcated, punched out, painful lesions usually near the lateral malleolus or dorsal aspect of the foot, and are treated with dependency
• Venous ulcers are superficial/shallow, painless ulcers with exudate and irregular margins, often found over the medial malleolus

Achilles Rupture

• Simmon's triad uses the matel's test, thompson test, and dell sign to diagnose an Achilles rupture
• Thompson's Test involves squeezing the calf; no foot movement indicates a positive test for Achilles rupture
• For Kager's triangle: Anterior = Achilles, Posterior = FHL, Inferior = Calcaneus; damage is indicated if it's not radiolucent

Medical Emergencies & Compartments

• Open fracture, gangrene, compartment syndrome, necrotizing fasciitis, and neurovascular compromise are five medical emergencies in podiatry
• The nine compartments of the foot are Medial, superficial, lateral, adductor, calcaneal, and 4 interossei
• Watershed zones: Achilles, Zone 2 fifth metatarsal, navicular, and PT tendon

Charcot

• A total contact cast is the best treatment for Charcot

Infections

• Necrotizing fasciitis is a painful infection of the fascia that travels proximally fast
• Gas gangrene is a non-painful, odorous infection of tissue and muscle that spreads deeper

Diagnosing DVT

• A venous ultrasound is the gold standard technique to diagnose DVT
• Elevated D-dimer

Osteoarthritis

• Osteoarthritis is the most common disorder of the entire musculoskeletal system, characterized by non-inflammatory destruction of articular cartilage
• PIPJ = Bouchards nodes, DIPJ = Heberden nodes
• Osteoarthritis is associated with uneven joint space narrowing
• Osteophytes and subchondral cysts are two findings associated with osteoarthritis on X-ray

Hallux Rigidus

• Hallux Rigidus is end stage osteoarthritis of the first MTPJ

Other Conditions

• Blount's disease is progressive tibia vara, reoccurance and osteoarthritis can result
• Chondromalacia patellae (runner's knee) causes anterior knee pain in young athletes (especially women) due to patellar cartilage changes
• Osgood-Schlatter disease is traction apophysitis at the tibial tuberosity, more common in males during development (9-14 y.o), and is self-limiting until fusion of growth plates
• Sever's Disease is traction apophysitis of achilles inserting into posterior calcaneus from overuse injuries (athletes)
• Slipped Capital Femoral Epiphysis (SCFE) involves the proximal epiphysis of the femur slipping posterior & inferior on the metaphysis in the hip joint and can be seen using Klein's line on x-ray
• Legg-Calve-Perthes Disease is idiopathic avascular necrosis of the femoral head affecting the hip joint with a crescent sign seen on radiography
• Growing pains are idiopathic pain in the afternoon/nighttime due to overuse in an active child, and are non-pathogenic

Myopathies

• Polymyositis is an inflammatory myopathy typically affecting adults (females > males) resulting in painful bilateral proximal weakness
• Dermatomyositis differs from polymyositis by affecting both children and adults, and has skin manifestations
• A heliotrope rash is face rash associated with dermatomyositis
• Calcinosis, telangiectasias, and Gottron's papules are all manifestations of dermatomyositis
• A muscle biopsy is the gold standard diagnostic technique for inflammatory myopathy
• Polymyositis = CD8+ lymphocytes infiltrate endomysium, Dermatomyositis = CD4+ lymphocytes infiltrate perimysium
• Corticosteroids are the treatment for myopathies and vasculitis
• Cancer is often associated with dermatomyositis
• Inclusion body myositis affects older males w/ asymmetric proximal and distal muscle weakness that does not respond well to corticosteroids
• Inclusion bodies and rimmed vacuoles would be seen on a muscle biopsy from a patient with inclusion body myositis
• Necrotizing myopathy is typically a result of statin therapy
• Duchenne Muscular Dystrophy (DMD) is X-linked non-inflammatory myopathy from deficient dystrophin, typically 5-6 y.o males with waddling gait & pseudohypertrophy
• Dystrophin is abnormal, not deficient in Becker's muscular dystrophy making it less severe than Duchenne's
• AD = Laminin, X-lined = Emerin is defective in AD & X-linked Emery-Dreifuss disease

Autoimmune & Systemic Diseases

• Guillain-Barre syndrome is acute demyelinating polyneuropathy from immune response attacking myelin, follows viral or bacterial infection, and presents as symmetrical distal limb weakness
• Myasthenia gravis: Auto-Ab attack AChR at NMJ, weakness that improves with rest, worsens with activity. Ptosis, thymoma, dysphagia diagnosed with edrophonium test
• Rheumatoid arthritis is a chronic inflammatory systemic disease affecting bilateral joints in the morning with Boutonniere, swan neck deformity, and ulnar deviation and elevated rheumatoid factor/anti-CCP
• Uniform joint space narrowing & erosions seen on rheumatoid arthritis X-rays
• Systemic lupus erythematosus (SLE) is chronic autoimmune disease that has a multisystem affect and causes fever, joint pain, and rash with Jaccoud's arthropathy and Libman sacks endocarditis
• SLE exhibits elevated ANA, anti-dsDNA, and anti-smith Ab
• Scleroderma is thickening of skin typically triggered by raynauds with Anti-Scl-70 & Anti-centromere
• Giant cell arteritis = large vessel vasculitis affecting temporal artery often causing headache
• Kawasaki disease = medium-vessel vasculitis affecting children 5-6 y.o, associated with rashes and increased risk of CV disease
• Behcet's disease = vasculitis associated with oral/genital ulcers w/ a negative STD & positive pathergy
• c-ANCA: Wegener's, p-ANCA: Microscopic polyangitis & Churg-Strauss, Medication induced: Both
• Sjögren syndrome targets salviary & lacrimal glands with Anti-Ro (SSA) and Anti-La (SSB) serology

Seronegative Spondyloarthropathies

• Positive HLA-B27, asymmetric peripheral involvement, dactylitis, and enthesitis

Ankylosing Spondylitis

• Ankylosing Spondylitis (AS) affects males < 40 y.o at the axial skeleton especially the sacroiliac joint
• Acute, unilateral uveitis is associated with ankylosing spondylitis
• X-ray: Bamboo spine, MRI: Romanus lesion are the scans for diagnosis
• Diffuse idiopathic skeletal hyperostosis (DISH) has more ossification (esp. ALL) and sparring of the sacroiliac joint than ankylosing spondylitis

Psoriatic Arthritis

• Ivory phalanx, acro-osteolysis, and "pencil-in-cup" deformity
• DIP predominent = Dactylitis, Arthritis mutilans = Telescoping digits