VCMT Peripheral Nervous System Review PDF

Peripheral Nervous System Review For this course, you will be expected to review your notes from Neuro 300/500, Gen Path, and A&P. The following is a brief overview of what you have already learned. You are responsible for additional review as necessary. Please review: Pathology, Goodman/Fuller, Ch...

Peripheral Nervous System Review For this course, you will be expected to review your notes from Neuro 300/500, Gen Path, and A&P. The following is a brief overview of what you have already learned. You are responsible for additional review as necessary. Please review: Pathology, Goodman/Fuller, Ch 39 / Rattray/Ludwig, Ch 60 & 61 / Kisner & Colby, Ch 13, 6th ed (available on Canvas) Structural overview The peripheral nervous system (PNS) includes all neural structures outside the brain and spinal cord -​ sensory receptors -​ peripheral nerves -​ their associated ganglia -​ efferent motor endings. The PNS provides the link to the outside world -​ it receives stimuli via afferent nerves -​ it responds to stimuli via efferent nerves Recall that peripheral nerves are supported & covered by 3 connective tissue layers; from deep to superficial: -​ Endoneurium surrounds each axon and is the innermost layer -​ Perineurium surrounds groups of neurons (fascicles) and is the middle layer -​ Epineurium surrounds the entire nerve and is the outermost layer Myelinated nerves -​ larger in diameter and have an extra membrane around them to provide electrical insulation which speeds nerve impulse conduction. Unmyelinated -​ smaller in diameter and do not have this extra membrane, so their conduction time is slower. VCMT Peripheral Nervous System Treatments. Class 1 - Review Terminology Neuropathy -​ A functional disturbance and/or pathological change in nerve function. Neuralgia -​ Pain in the distribution of nerves generally in the absence of objective signs/structural damage to nerve Neuritis -​ Inflammation of the nerve Neuroma -​ An overgrowth of nerve cells Radiculitis -​ Inflammation of a spinal nerve root Radiculopathy -​ Compression of a nerve root, causing numbness and/or weakness Polyradiculopathy -​ Describing more than 1 nerve root being affected Plexopathy -​ A disorder involving one of the major neural plexuses – cervical, brachial, or lumbosacral Fasciculation -​ Spontaneous contraction of muscle fibers in denervated tissue Flaccidity -​ Paralysis in which muscle tone is lacking in the affected muscles and in which tendon reflexes are decreased or absent. Atrophy -​ Decrease in size or wasting away of a body part or tissue Double Crush Syndrome -​ Condition where a nerve is compressed or injured in more than one location. Eg, median nerve compression at both the carpal tunnel and pronator teres. VCMT Peripheral Nervous System Treatments. Class 1 - Review Peripheral Neuropathy Peripheral nerves serve many functions – motor, sensory & autonomic. Therefore, different neuropathies will present differently depending on what kind of nerve has been affected Motor Neuropathy: -​ Results in weakness, flaccid paralysis, atrophy, decreased reflexes Sensory Neuropathy: -​ Results in paresthesias (tingling, prickling), dysesthesias (abnormal sensation), pain, numbness Autonomic Neuropathy: -​ Results in hypotension (BP), anhidrosis (reduced sweating), diaphoresis (excessive sweating), diarrhea/constipation Mixed Neuropathy: -​ Can present as a combination of any of the above MMN - multifocal motor neuropathy showing demyelination VCMT Peripheral Nervous System Treatments. Class 1 - Review Nerve Injuries (Therapeutic Exercise, Kisner & Colby, 6th ed. pg 388) Neuropraxia: Compression of a nerve with no structural damage to the axon or to the tissue distal to the lesion In other words, the endo, peri & epineurium are intact, and the axon is preserved There is some loss of myelin (segmental demyelination) resulting in reduced conduction of action potential This often occurs after nerve compression which causes mild ischemia of the nerve fibre Results in mild weakness up to paresis/paralysis, with no atrophy Full recovery Axonotmesis: The axon has been damaged, but the epi, peri & endoneurium are intact Wallerian Degeneration occurs – axonal degeneration distal to the lesion Often occurs after severe or prolonged compression Results in paresis/paralysis, with atrophy Prognosis for recovery is variable Neurotmesis: Complete severance of the axon, and disruption of the endo, peri & epineurium Wallerian Degeneration occurs – axonal degeneration distal to the lesion Often occurs after gunshot or stab wounds, avulsion injuries Surgical intervention is required if any neural re-growth is to occur Results in paresis/paralysis, with atrophy Recovery is incomplete Neuropraxia Axonotmesis Neurotmesis Tissue damage Segmental demyelination Axons damaged Axons damaged Connective tissue Connective tissue undamaged damaged Degeneration None Wallerian degeneration Wallerian degeneration MOI Mild Prolonged compression Severance, rupture compression/traction Muscle No atrophy Atrophy Atrophy Sensory Paresthesia, dysesthesia Sensory loss Sensory loss Prognosis Good. Full recovery Poor. May need surgery Poor. Needs surgery VCMT Peripheral Nervous System Treatments. Class 1 - Review Regeneration Peripheral nerves have the ability to regenerate, even if the axon is damaged, provided that the cell body of the nerve is still intact. If the endoneurial tube is still intact, as in axonotmesis, prognosis for recovery is good, as the tube provides a good pathway for the regenerating nerve to follow. Segmental Demyelination Compression on the nerve causes the myelin to break down, leaving the axon exposed The remaining Schwann cells will be stimulated to reproduce to form more myelin Axonal Degeneration / Wallerian Degeneration The degeneration of an axon distal to a site of lesion If a nerve fiber is severed, the part distal to the injury will degenerate The segment between the nerve cell body & the site of the injury will remain intact The proximal & distal ends of the endoneurium are usually attached surgically for better outcome The axon continues to re-grow until it reaches a muscle or sensory receptor VCMT Peripheral Nervous System Treatments. Class 1 - Review Causes of Peripheral Nerve Lesions (Rattray/Goodman) Compression: -​ Internal: bony callus, tight muscles, tumor, edema etc -​ External: crutches, casts etc Trauma -​ Crush injuries, severance (knife, bullet), industrial accidents, birth trauma Systemic Disorders -​ Leprosy Systemic Edematous Conditions: -​ Pregnancy, hypothyroidism, diabetes, kidney & heart conditions Common Symptoms of Peripheral Nerve Lesions (Rattray) Edema: If lesion is due to injury, there will be edema due to inflammation If the autonomic nerve fibres are damaged the edema will remain until vasomotor function returns Altered tissue health: Due to loss of autonomic function, resulting in changes to skin, hair & nails (trophic changes) If damage is permanent, trophic changes & muscle wasting increase over time Altered motor function Flaccid paralysis and muscle wasting can occur within 3 weeks Fibrillation of denervated tissue can occur a few weeks after injury Diminished deep tendon reflexes Holding patterns Depending on how severely the nerve has been injured, limb positions such as wrist drop or claw hand may be present Contractures Will develop since the unopposed antagonist muscles are much more powerful, even at rest, than the​ affected flaccid muscles Pain May be present, and can develop into Causalgia or RSD (Reflex sympathetic dystrophy) There may be decreased or altered sensation which may or may not be interpreted as pain VCMT Peripheral Nervous System Treatments. Class 1 - Review Scar tissue May be present at the lesion site and can interfere with regeneration of the nerve Compensatory changes Will be present in permanent nerve lesions where function has been lost. Secondary conditions such as tendonitis may be present Management Guidelines - Recovery from peripheral nerve injury (Therapeutic Exercise, Kisner & Colby, 6th ed. pg 389-390) Acute Phase Early after injury or surgery - emphasis on healing & preventing complications May be immobilized - time dictated by MD Splinting or bracing may be needed to prevent deformities Recovery Phase When reinnervation occurs - emphasis on retraining & re-education Motor retraining - eg. being able to hold muscle in shortened position Desensitization - eg. stroking the skin with different textures for sensory stimulation Discriminative sensory re-education - identification of objects with, then without, visual cues (stereognosis) Chronic Phase When the potential for recovery has peaked and there are significant physical deficits - emphasis on training compensatory function May continue to wear splint or brace VCMT Peripheral Nervous System Treatments. Class 1 - Review Muscle weakness (neurogenic weakness vs myogenic weakness) Due to neuropathy Due to myopathy Distribution Distal to proximal Proximal to distal Fasciculations Maybe No Reflexes Diminished Often preserved Sensory signs and symptoms Maybe No Precautions & treatment considerations for regenerating lesions (This is NOT an exhaustive list. See Rattray for a detailed description) Do not traction a regenerating nerve Treat edema with elevation, nodal pumping & drainage techniques, proximal to the edge of the edema Use segmental techniques proximal to the lesion – applied at right angles to the direction of the regenerating nerve Consider “blocking” with the ulnar border of the hand just proximal to the lesion to prevent placing drag on the healing tissue Do not work on lesion site until regeneration has passed that site – approx. 2 weeks post trauma or 3 weeks post surgery Flaccid or weakened muscles distal to lesion are treated with light strokes & gentle compressions PROM can be used to affected joints in the direction that shortens the affected tissue & nerve VCMT Peripheral Nervous System Treatments. Class 1 - Review Nerve Compressions vs Nerve Injuries Treatment of nerve compression/entrapment (neuropraxia) is very different to treatment for nerve injuries (axonotmesis, neurotmesis). Non-degenerative conditions Degeneration conditions (no regenerating lesion) (regenerating lesion) Neuropraxia Axonotmesis Neurotmesis These normally present with These normally present with -​ Paresthesia -​ Atrophy -​ Dysesthesia -​ Flaccidity -​ Pain -​ Significant weakness, paresis, or paralysis -​ Mild weakness -​ Sensory loss Palpation of nerve is indicated Palpation of nerve is not indicated Palpation of surrounding tissue is indicated Palpation of surrounding tissue is indicated These are simple compressions or entrapments from The list of precautions above, starting with Do not which no tissue damage has occurred. The key to traction a regenerating nerve, applies only to these treatment is to relieve the compression at the such conditions. A neurologist or MD would have compression site. been consulted for such a presentation. Extreme care must be taken with such a patient. Examples include most cases of: Examples include: Saturday night palsy Bell’s palsy Crutch palsy Erb’s paralysis Supinator syndrome Klumpke’s paralysis Cubital tunnel compression Injury to any nerve serious enough to cause atrophy, Guyon’s canal compression flaccidity, significant weakness, paresis, paralysis, Pronator teres syndrome sensory loss. Carpal tunnel syndrome Piriformis syndrome These present as the various deformities - ape hand, Thoracic outlet syndrome oath hand, benediction sign, claw hand, wrist drop, foot drop, calcaneovalgus, steppage gait, waiter’s tip etc - we discuss VCMT Peripheral Nervous System Treatments. Class 1 - Review Assessment Considerations for Assessment: (This is NOT an exhaustive list. See Rattray for a detailed description) NOTE: Acute injuries and tissue that is still regenerating must be handled with extreme caution. Contact the patient’s MD or Neurologist to confirm if movement assessment & treatment is safe. Palpation: compare bilaterally Muscle bulk – atrophy Sweating - anhidrosis (dry skin) or diaphoresis (moist skin) Edema – boggy tissue Contractures Tenderness – hyper/hypo/dysesthesia ROM testing: Avoid all actions that traction/stretch a regenerating nerve. Once minimal muscle contraction is possible, ROM testing can be used on the affected muscles. PROM Can be used with a regenerating nerve to assess contracture of the unopposed antagonistic muscles only, as long as the motion does not traction or stretch the regenerating nerve AAROM Can be used with minimal assistance provided by therapist Deep Tendon Reflexes: ​ Will be negative with complete lesion, and diminished with a partial lesion (hyporeflexia) ​ Hyperreflexia usually indicative of an upper motor neuron (CNS) lesion Sensory Testing Areas of dysfunction will appear in a very distinct area correlating to the normal function of the affected nerve Deep & light touch 2 point discrimination Piloerector response Temperature VCMT Peripheral Nervous System Treatments. Class 1 - Review Cutaneous nerves (on final exam) Cutaneous nerves are C-fibres. Unmyelinated C fibers respond to thermal, mechanical, and chemical stimuli and produce the sensation of dull, diffuse, aching, burning, and delayed pain. VCMT Peripheral Nervous System Treatments. Class 1 - Review Nerve Roots (dermatomes) Remember that nerve root compression will have a different clinical presentation than a peripheral nerve lesion. Nerve root compression causes altered sensation in the DERMATOME patterns. You may, upon observing an abnormal dermatome pattern, then assess the corresponding MYOTOME (muscle function of that nerve root). Nerve roots are part of the PNS. VCMT Peripheral Nervous System Treatments. Class 1 - Review Palpation Guide Nerves are physical structures. They are sometimes quite big and definitely palpable. If a nerve is being compressed or has been tractioned, or is suffering some chemical imbalance in the surrounding tissue, it becomes swollen (intraneural edema). Consider that the nerve is a living tissue which is highly active metabolically. It is like a hose which is sending materials, nutrients, and fluids up and down along its length. If the hose is compressed, it swells. Identifying a nerve ​ Tight bands/wires/nodules in tissue Which, on palpation, elicit sensation (referral) in the distribution of the nerve. This sensation could be dull, achy pain; bright, sharp, electric pain; numbness, tingling, prickling. Most common would be numbness or tingling, but dull ache does not rule out a nerve. Knowledge of referral patterns is important. The following will be repeated and expanded upon in each relevant class. Here is a brief overview. Tissue Proximal Distal Common sticky points Cranial Nerve 5 Pons Skin of face and Supratrochlear foramen head Supraorbital foramen Infraorbital foramen Mental foramen Cranial Nerve 7 Pons Muscles of face Inner ear Anterior ⅔ tongue and skin of ear canal Brachial plexus C5-T1 Musculocutaneous Medial 3rd supraclavicular fossa Axillary Between ant-mid scalenes Median Between first rib-clavicle Radial Between Pec minor-coracoid process Ulnar Median C5-T1 Forearm flexors Medial intermuscular septum Skin over palmar Pronator teres surface of digits 1-3 Carpal tunnel and lateral 4th Fingertips of 1-3 and lateral 4th Radial C5-T1 Extensors Triangular interval (scapula) Dorsum of hand and Belly of lateral head triceps digits 1-3 and lateral Supinator (arcade of Frohse) 4th Brachioradialis tendon Ulnar C8-T1 Intrinsic hand Medial intermuscular septum muscles Ulnar groove Digits 4-5 Cubital tunnel (FDP-FCU) Guyon’s canal VCMT Peripheral Nervous System Treatments. Class 1 - Review Lateral femoral cutaneos L2-3 Skin over vastus Inguinal ligament lateralis Over TFL Through ITB/fascia Obturator L2-4 Adductors Ob externus Knee joint Skin over proximal medial thigh Sciatic L4-S3 Hamstrings Piriformis Adductor magnus Piriformis-superior gemellus Tibial Sciatic nerve Posterior Popliteal fossa anterior compartments Deep to soleus division Tarsal tunnel (L4-S3) Common fibular Sciatic nerve Anterior compartment Head of fibula (crush injury) posterior (deep fibular) Between ext digitorum and tib ant division Lateral compartment (deep fibular) (L4-S2) (superficial fibular) Between ext digitorum and fib long (superficial fibular) Under extensor retinaculum of ankle (superficial fibular) VCMT Peripheral Nervous System Treatments. Class 1 - Review Function & Dysfunction Guide Important note All cutaneous nerves could have symptoms of pain (dull, ache, sharp, bright), or numbness or tingling or prickling or loss of sensation in the area of their distribution (see above) All motor nerves could have weakness, paresis, paralysis of the muscles they innervate All motor nerves could then lead to atrophy or flaccidity depending on length and severity of condition The following will be repeated and expanded upon in each relevant class. Here is a brief overview. Tissue Motor Sensory Condition/Signs/Symptoms Cranial Nerve 5 Muscles of mastication Skin of face and head Tic douloureux Tensor veli palitini Teeth Tensor tympani Tongue (not taste) Lacrimal glands Cornea Nasal cavity (not smell) Pharynx Cranial Nerve 7 Facial expression Taste anterior ⅔ tongue Bell’s Palsy Stapedius Skin of ear canal Brachial plexus Myotomes Dermatomes Depending, C5 C5 Erb’s palsy C6 C6 Klumpke’s paralysis C7 C7 Horner’s syndrome C8 C8 Waiter’s tip T1 T1 Claw hand (all fingers) Thoracic Outlet Syndrome Median Forearm flexors Skin over palmar Ape hand Forearm pronators surface of digits 1-3 Oath hand Lateral lumbricals and lateral 4th Trophic changes & edema Thenar eminence Fingertips of 1-3 and Causalgia lateral 4th Pronator teres syndrome Carpal tunnel syndrome Radial Brachial extensors Dorsum of hand and Wrist drop Antebrachial extensors digits 1-3 and lateral Radial nerve / Saturday night Supinator 4th palsy / supinator syndrome Cheiralgia paresthetica Ulnar Flexor carpi ulnaris Intrinsic hand muscles Bishop’s hand Hypothenar eminence Digits 4-5 Ulnar claw Intrinsic hand muscles Cubital tunnel syndrome Handlebar palsy Lateral femoral None Skin over vastus Meralgia paresthetica cutaneous lateralis VCMT Peripheral Nervous System Treatments. Class 1 - Review Obturator Skin over proximal Adductors medial thigh Obturator externus Sciatic Hamstrings None Sciatica Adductor magnus Piriformis syndrome Technically, any of the conditions of the tibial and common fibular nerves Tibial Gastrocnemius, Soleus, Via plantar nerves Claw toe Popliteus, Plantaris, Calcaneovalgus Tibialis posterior, FDL, Severe trophic changes and FHL edema Causalgia Tarsal tunnel syndrome Common fibular Fib longus, Fib brevis, Anterolateral leg Foot drop Tib ant, Ext dig longus, Dorsum of foot Ext hal longus, Fib Skin between pedal tertius digits 1-2 VCMT Peripheral Nervous System Treatments. Class 1 - Review Focus for Quizzes & Exams Basic definitions Know the terminology from class 1 notes Basic anatomy Know nerve roots Know associated anatomical structures (eg radial nerve runs through supinator) Know common compression sites (eg median nerve compressed at pronator teres) Basic function ​ Know what motor function each nerve is responsible for ​ Know what sensory function each nerve is responsible for ​ Understand how dysfunction presents in a nerve Nerve injuries ​ Know neuropraxia, axonotmesis, and neurotmesis - how they present, treatment considerations etc ​ Be able to match nerves to conditions - eg carpal tunnel = median nerve Assessments ​ Be able to recognise assessments from descriptions Be able to use clinical reasoning to choose assessments for presentations, and to choose treatment based on assessment findings Be able to match nerves and/or conditions to assessments - eg Adson’s test = TOS (brachial plexus) Cutaneous nerve diagram ​ Is on the final exam. Be able to label it. Deep tendon reflexes ​ Prior knowledge from clinical assessment will be assessed in this course’s final written exam VCMT Peripheral Nervous System Treatments. Class 1 - Review