Peripheral Nerve Injury

Populations and Risk Factors

Individuals with mechanical trauma — compression (prolonged pressure, tourniquet, surgical retraction), laceration (knife wound, glass, surgical), stretch/traction (fracture displacement, joint dislocation, birth injury); compression and traction are the most common mechanisms
Post-surgical patients — nerve injury during orthopedic surgery (hip replacement, knee replacement, fracture fixation) occurs in 0.5–3% of major joint surgeries; surgical retractor compression is a common iatrogenic cause
Individuals with metabolic diseases — diabetes mellitus is the most significant systemic risk factor; diabetic neuropathy produces length-dependent nerve damage (longest nerves affected first), and diabetic nerves have reduced tolerance to compression (lower threshold for double crush)
Individuals exposed to toxins — chronic alcohol use (alcoholic neuropathy), lead exposure, chemotherapy agents (vincristine, cisplatin, taxanes)
Individuals with extremes of temperature exposure — frostbite (ice crystal formation disrupts axons and vasa nervorum), severe burns (thermal destruction of nerve tissue)
Electrical injury — high-voltage exposure produces thermal nerve damage along the current pathway
Individuals with prolonged immobility — ICU patients (critical illness neuropathy), comatose patients, intraoperative positioning injuries (peroneal nerve at the fibular head, ulnar nerve at the cubital tunnel)
Individuals with pre-existing nerve compression — the double/multiple crush phenomenon means proximal compression (cervical radiculopathy, thoracic outlet syndrome) reduces axoplasmic flow and makes the nerve more vulnerable to symptomatic injury at a distal compression site (carpal tunnel, cubital tunnel)

Causes and Pathophysiology

Peripheral Nerve Structure

Understanding the connective tissue layers of a peripheral nerve is essential because the Seddon and Sunderland classifications are defined by which layers are disrupted:

Axon: The functional conducting unit — each nerve contains thousands of axons, each one extending from a neuron cell body in the spinal cord (motor) or dorsal root ganglion (sensory) to its target tissue. Axons are wrapped in myelin (produced by Schwann cells in the PNS) which enables rapid saltatory conduction.
Endoneurium: The innermost connective tissue layer surrounding each individual axon and its Schwann cell sheath. The endoneurium forms the "tube" through which a regenerating axon grows after injury — it is the structural guide for axonal regeneration.
Perineurium: The middle connective tissue layer bundling groups of axons into fascicles. The perineurium provides a blood-nerve barrier (analogous to the blood-brain barrier) that protects the fascicular environment.
Epineurium: The outermost connective tissue layer enclosing the entire nerve trunk — all fascicles, the interfascicular connective tissue, and the vasa nervorum (the nerve's blood supply) are contained within the epineurium.
Neurilemma (Schwann cell sheath): The myelin-producing cells that wrap around peripheral nerve axons. Critically, the neurilemma is the reason peripheral nerves can regenerate while central neurons cannot — Schwann cells survive axonal injury, proliferate to form regeneration tubes (bands of Bungner), and secrete neurotrophic factors that guide regenerating axon sprouts.

Seddon Classification

Neurapraxia ("pinch"): The mildest injury. The axon remains intact, but focal demyelination at the injury site blocks conduction. No Wallerian degeneration occurs. Motor and sensory loss is immediate but temporary. Recovery is complete, typically within days to 12 weeks, as Schwann cells remyelinate the affected segment. Common causes: brief compression (Saturday night palsy, tourniquet), mild traction (stingers). Electrophysiology: conduction block across the lesion; normal conduction distal to the lesion.

Axonotmesis ("crush"): The axon is disrupted, but all three connective tissue layers (endoneurium, perineurium, epineurium) remain intact. Wallerian degeneration occurs distal to the injury — the distal axon segment and its myelin sheath degenerate and are phagocytosed by macrophages and Schwann cells. The proximal axon stump then sprouts new growth cones that advance through the intact endoneurial tubes toward the original target at approximately 1 mm/day (approximately 1 inch per month). Recovery is expected but slow — the distance from the injury to the target muscle determines recovery time. Common causes: moderate compression, crush injuries, fracture displacement.

Neurotmesis ("cut"): The most severe injury. The nerve is completely severed — axons and all connective tissue layers are disrupted. Wallerian degeneration occurs distally, but the regenerating axon sprouts have no endoneurial tubes to guide them. Without surgical repair, the sprouts form a disorganized neuroma at the proximal stump. Surgical repair (epineural or fascicular repair, nerve grafting, nerve transfer) is required to restore any function. Common causes: laceration, avulsion, severe crush.

Sunderland 5-Degree System

The Sunderland system refines Seddon's by subdividing based on which connective tissue layer is the most severely disrupted:

Sunderland Degree	Seddon Equivalent	Structure Disrupted	Recovery
1st degree	Neurapraxia	Myelin only (axon intact)	Complete; days to 12 weeks
2nd degree	Axonotmesis	Axon disrupted; endoneurium intact	Complete but slow; ~1 mm/day
3rd degree	Axonotmesis (severe)	Axon + endoneurium disrupted; perineurium intact	Incomplete; aberrant reinnervation likely
4th degree	(between axonotmesis and neurotmesis)	Axon + endoneurium + perineurium disrupted; epineurium intact	No useful recovery without surgery
5th degree	Neurotmesis	Complete transection — all layers	No recovery without surgery

The clinical significance of the Sunderland system is that 3rd-degree injuries occupy a critical gray zone — the endoneurial tubes are disrupted, so regenerating axons may enter the wrong tubes and reinnervate inappropriate targets (e.g., a motor axon reinnervates a sensory receptor, or a flexor motor axon reinnervates an extensor muscle). This produces aberrant reinnervation — the patient recovers some function but with co-contraction patterns, synkinesis, or mass movement rather than precise voluntary control.

Wallerian Degeneration

When an axon is severed (2nd degree and above), the distal segment undergoes a predictable degeneration sequence:

Axonal fragmentation (hours to days): The distal axon swells and fragments; the myelin sheath disintegrates into ovoid segments
Macrophage invasion (days to weeks): Macrophages infiltrate the distal nerve stump and phagocytose the axonal and myelin debris; this clearing process is essential — debris must be removed before regeneration can proceed
Schwann cell proliferation (1–2 weeks): The Schwann cells that previously myelinated the distal axon survive, proliferate, and organize into longitudinal columns within the endoneurial tubes — these are the bands of Bungner that guide regenerating axon sprouts
Proximal axon sprouting (2–3 weeks): The proximal axon stump sprouts multiple growth cones that advance into the distal nerve stump at approximately 1 mm/day, guided by neurotrophic factors secreted by the Schwann cells

The 2–3 week delay before sprouting begins is clinically important: electromyography (EMG) performed before 3 weeks cannot distinguish neurapraxia from axonotmesis because Wallerian degeneration has not yet completed. EMG must be delayed to at least 3 weeks post-injury for accurate classification.

Tinel's Advancing Sign as a Recovery Indicator

Tinel's sign — tingling or paresthesia in the nerve's distal distribution produced by percussion over the nerve — is both a diagnostic and prognostic tool:

At the injury site (static Tinel's): Percussion over the injury site produces distal tingling — this indicates neural irritability at the lesion and is present in all grades of injury
Advancing Tinel's (prognostic): Over serial assessments (weeks to months), the point at which Tinel's sign is most readily elicited moves distally along the nerve course. This distal migration maps the advancing front of axonal regeneration — the regenerating growth cones are the most mechanosensitive structures, and percussion produces tingling at whatever point the regeneration has reached. An advancing Tinel's at approximately 1 mm/day confirms active regeneration and a favorable prognosis.
Stationary Tinel's (unfavorable): If the Tinel's sign remains at the original injury site over serial assessments without distal migration, regeneration has stalled — the axon sprouts are not advancing, possibly due to scar tissue, neuroma formation, or a higher-grade injury than initially assessed. This finding may prompt surgical exploration.

Double/Multiple Crush Phenomenon

Peripheral nerves depend on continuous axoplasmic flow — the transport of proteins, organelles, and signaling molecules from the cell body to the axon terminal. When the nerve is compressed at one site, axoplasmic flow is reduced. This makes every segment distal to the compression more vulnerable because it is receiving fewer trophic factors. If a second compression site exists distally, the cumulative effect exceeds the threshold for symptomatic neuropathy even though neither site alone would be sufficient. Clinically, this explains:

Why carpal tunnel syndrome patients sometimes have incomplete relief after surgical release — a proximal compression at the pronator teres or cervical spine persists
Why diabetic patients develop entrapment neuropathies at lower thresholds — the baseline metabolic neuropathy reduces axoplasmic flow system-wide
Why treatment must always assess the proximal chain — releasing only the distal compression may produce incomplete results if a proximal crush exists

Signs and Symptoms

By Fiber Type Affected

Motor fiber involvement: Muscle weakness progressing to flaccid paralysis; muscle fasciculations (in partial injuries, denervated motor units may fire spontaneously); muscle atrophy developing within 2–3 weeks (visible wasting by 4–6 weeks); "trick movements" — compensatory substitution patterns using intact muscles to approximate the lost movement
Sensory fiber involvement: Paresthesia (tingling, pins and needles) in the nerve's cutaneous distribution; numbness (hypoesthesia or anesthesia); burning neuropathic pain (dysesthesia); hypersensitivity in the zone of partial innervation (partially denervated territory may become hyperesthetic as surviving fibers become hyperexcitable)
Autonomic/sympathetic fiber involvement: Vasomotor changes — initially warm and flushed (loss of vasoconstrictor tone produces vasodilation), progressing to cool and cyanotic in chronic cases; sudomotor changes — dry, smooth skin (loss of sweat gland innervation) in the denervated territory; trophic changes — thin, shiny, hairless skin; brittle, ridged nails; subcutaneous tissue atrophy; osteoporosis of underlying bone in chronic severe denervation

By Injury Grade (Clinical Differentiation)

Feature	Neurapraxia	Axonotmesis	Neurotmesis
Motor loss	Present; resolves within weeks	Present; recovers slowly (~1 mm/day from lesion to target)	Present; no recovery without surgery
Sensory loss	Present; resolves first	Present; recovers with motor	Complete and permanent without repair
Tinel's sign	At lesion site; resolves with recovery	Advancing distally over weeks/months	At lesion site only; does not advance (neuroma)
Muscle atrophy	Minimal (disuse only)	Progressive over weeks	Severe and progressive
Wallerian degeneration	None	Present	Present
EMG (after 3 weeks)	Conduction block; no denervation potentials	Fibrillation and positive sharp waves (denervation)	Fibrillation and positive sharp waves; no voluntary motor units
Recovery	Complete; days to 12 weeks	Slow; prognosis depends on distance and degree	None without surgical repair

Classic Peripheral Nerve Injury Presentations

Wrist drop: Radial nerve injury — loss of wrist and finger extension; sensory loss over the dorsal hand; common after humeral shaft fracture (radial nerve in the spiral groove)
Claw hand: Ulnar nerve injury — MCP hyperextension with IP flexion in digits 4–5; interosseous and hypothenar wasting; positive Froment's sign
Ape hand: Median nerve injury — loss of thenar opposition; sensory loss in the radial 3.5 digits; loss of precision pinch
Foot drop: Common peroneal nerve injury — loss of ankle dorsiflexion and eversion; steppage gait (the patient lifts the knee high to clear the drooping foot); sensory loss over the dorsal foot; common after fibular head compression or knee surgery

Assessment Profile

Subjective Presentation

Chief complaint: Variable by nerve — "my hand is numb and I keep dropping things" (median/ulnar); "my foot slaps when I walk" (peroneal); "my wrist hangs down and I can't lift it" (radial); common theme: progressive weakness and sensory changes following a known event (trauma, surgery, compression)
Pain quality: Burning, electric, or lancinating neuropathic pain in the nerve's distribution; deep aching in the muscles attempting to compensate for the paralyzed group; numbness or "dead" sensation in the denervated territory; in partial injuries, hypersensitivity in the zone of incomplete denervation may be the most distressing symptom
Onset: Acute — immediately following trauma (fracture, laceration, dislocation), noticed upon waking from surgery or anesthesia, or upon waking after prolonged compression (Saturday night palsy); gradual — progressive entrapment neuropathy developing over weeks to months
Aggravating factors: Activities that use the affected muscle group (walking with foot drop, gripping with hand nerve injury); positions that compress or tension the nerve (elbow flexion in cubital tunnel, wrist flexion in CTS); cold exposure often intensifies neuropathic pain
Easing factors: Splinting the affected area (wrist splint for wrist drop, AFO for foot drop) provides functional support; rest; warmth may ease neuropathic symptoms; changing position to relieve nerve compression
Red flags: Rapidly progressive bilateral weakness → suspect Guillain-Barre syndrome, motor neuron disease, or spinal cord pathology; refer urgently; progressive weakness without trauma or known compression → suspect space-occupying lesion or systemic neuropathy; refer for electrodiagnostic testing; loss of bowel/bladder function → cauda equina syndrome; emergency referral

Observation

Local inspection: Characteristic posture of the affected limb (wrist drop, claw hand, foot drop); muscle atrophy — visible wasting in the territory of the affected nerve (thenar wasting for median, interosseous guttering for ulnar, anterior compartment atrophy for peroneal); trophic skin changes — thin, shiny, hairless skin in the denervated territory; nail changes (brittle, ridged); in chronic cases, joint contracture may be visible in the posture maintained by unopposed muscle groups
Posture: Compensatory patterns — the patient may support the wrist with the opposite hand (radial nerve); adopt a steppage gait (peroneal nerve); guard the hand against the body (ulnar/median nerve); postural adaptations vary by the specific nerve injured
Gait: Foot drop produces steppage gait (excessive hip and knee flexion to clear the drooping foot during swing phase); circumduction gait may substitute; femoral nerve injury produces knee buckling and hand-to-thigh support; upper extremity nerve injuries do not directly affect gait but the patient may have reduced arm swing if guarding the affected limb

Palpation

Tone: Denervated muscles — flaccid, soft, reduced bulk; distinctly different from the innervated contralateral side. Compensatory muscles are hypertonic from overuse (e.g., upper trapezius for deltoid in axillary nerve palsy, hip flexors for quadriceps in femoral nerve injury). Spasticity is absent — its presence indicates a UMN lesion, not a peripheral nerve injury.
Tenderness: At the injury or entrapment site — focal tenderness where the nerve is compressed or damaged; Tinel's sign may be elicitable (see Special Test Cluster); referred path tenderness: in neurally sensitized nerves, tenderness may extend along the full course of the nerve from the injury site to the distal distribution — this mapped tenderness follows the nerve, not the dermatome, and distinguishes peripheral nerve pathology from radiculopathy; palpate along the nerve course to identify whether the Tinel's response is at the injury site only (static) or has migrated distally (advancing = recovery)
Temperature: Acute phase — the denervated territory may be warm and flushed from loss of sympathetic vasoconstrictor tone. Chronic phase — the territory becomes cool and cyanotic from sluggish circulation. Temperature asymmetry between the affected and unaffected sides is a hallmark autonomic finding.
Tissue quality: Denervated muscles — progressively soft, atrophic, and fibrotic over time. Fasciculations may be visible or palpable in partially denervated muscles. Skin in the denervated territory is smooth, thin, glossy, hairless, and dry from sudomotor loss. Subcutaneous tissue atrophy gives the skin a taut, adherent feel. Scars from the causative injury may produce nerve adhesion.

Motion Assessment

AROM: Specific motor loss depends on the nerve injured — isolated weakness in the territory of the affected nerve with preserved function in adjacent nerve territories; "trick movements" may mask the deficit (e.g., wrist flexion produces passive finger extension through tenodesis, mimicking active finger extension in radial nerve palsy); strength grading (0–5 MRC scale) should be documented bilaterally for all affected muscles
PROM / end-feel: PROM typically exceeds AROM significantly (distinguishes from joint pathology where both are restricted); end-feel is empty or minimal resistance (the paralyzed muscles offer no resistance to passive movement); in chronic cases, end-feel may become firm or leathery if contracture develops in the unopposed muscle group; neural tension testing (ULTT, SLR, slump) may reproduce nerve symptoms depending on the specific nerve involved
Resisted testing: The hallmark of peripheral nerve injury is weakness confined to the territory of a single nerve or nerve root — specific muscles are weak while others innervated by different nerves are normal; pain on resisted testing suggests a musculotendinous origin; painless weakness suggests a neural origin; this distinction is clinically critical

Special Test Cluster

The special test cluster for peripheral nerve injury is general — it applies across all peripheral nerves. For specific nerve entrapments, refer to the individual condition articles (carpal tunnel, cubital tunnel, etc.).

Test	Positive Finding	Purpose
Tinel's sign (at injury site) (CMTO)	Percussion over the nerve at the injury or entrapment site produces tingling or electric sensation radiating distally in the nerve's distribution	Localizes the site of neural irritability; confirms nerve involvement at a specific anatomical point
Tinel's advancing sign (serial) (CMTO)	Over serial assessments (weeks to months), the point of maximal Tinel's response migrates distally along the nerve course at approximately 1 mm/day	Indicates active axonal regeneration — the most important prognostic clinical indicator; stationary Tinel's suggests stalled recovery
Neurodynamic testing (ULTT/SLR/slump) (CMTO)	Reproduction of the nerve's distribution symptoms during neural tension testing; symptoms change with structural differentiation (e.g., adding cervical lateral flexion)	Confirm neural mechanosensitivity; assess the mechanical interface along the entire nerve course; identifies proximal contributions (double crush)
Myotomal testing (CMTO)	Specific muscle weakness confined to the territory of the affected nerve or nerve root	Localizes the lesion to a specific nerve level; serial testing documents recovery; pattern of weakness distinguishes peripheral nerve from radiculopathy
Dermatomal/peripheral nerve sensory testing (supplementary)	Sensory loss (light touch, pinprick, two-point discrimination) mapped to a specific peripheral nerve or dermatome distribution	Maps the sensory deficit to confirm which nerve is affected; serial testing documents sensory recovery; two-point discrimination is the most sensitive test for recovery quality
Deep tendon reflex testing (CMTO)	Hyporeflexia or areflexia at the reflex arc involving the affected nerve (e.g., absent biceps reflex in musculocutaneous nerve injury, absent patellar reflex in femoral nerve injury)	Confirms LMN lesion; absent reflexes distinguish peripheral nerve injury from UMN pathology (which produces hyperreflexia)

LMN vs. UMN differentiation: Peripheral nerve injury produces a lower motor neuron (LMN) pattern: flaccid paralysis, hypotonia, muscle atrophy, fasciculations, hyporeflexia/areflexia, no pathological reflexes. Upper motor neuron (UMN) injury produces: spastic paralysis, hypertonia (velocity-dependent), minimal atrophy initially, hyperreflexia, clonus, pathological reflexes (Babinski, Hoffman). This distinction is the fundamental neurological framework and must be established before any treatment planning.

Differential Diagnoses

Condition	Key Distinguishing Feature
Radiculopathy (cervical or lumbar)	Dermatomal pattern (follows nerve root) rather than peripheral nerve distribution; neck or back pain as a primary complaint; Spurling's or SLR positive; multiple muscles from different peripheral nerves but the same root are affected
Upper motor neuron lesion (stroke, spinal cord injury, MS)	Spastic paralysis (velocity-dependent hypertonia), hyperreflexia, clonus, pathological reflexes (Babinski, Hoffman); no muscle atrophy initially; no fasciculations; distribution follows corticospinal tract patterns, not individual nerves
Guillain-Barre syndrome	Ascending bilateral weakness (feet → legs → trunk → arms); areflexia; rapid onset over days to weeks; often follows a viral illness; emergency referral — respiratory muscles may be involved
Motor neuron disease (ALS)	Combined UMN and LMN signs (a hallmark); fasciculations with hyperreflexia; progressive; no sensory loss; multiple nerve territories affected; refer for neurological evaluation
Myopathy (inflammatory, metabolic)	Proximal weakness pattern (shoulder and hip girdle); normal reflexes until late; no sensory loss; elevated CK levels; weakness does not follow peripheral nerve distributions

CMTO Exam Relevance

Seddon's classification (neurapraxia, axonotmesis, neurotmesis) is a high-frequency exam topic — know the definition, mechanism, pathology, and prognosis of each grade
Sunderland 5-degree system refines Seddon's — the key added concept is that 3rd-degree injuries (endoneurial disruption) produce aberrant reinnervation (wrong axons in wrong tubes), explaining co-contraction and synkinesis during recovery
LMN vs. UMN distinction is the most fundamental neurological concept tested — flaccid/hypotonic/areflexic/atrophic (LMN/peripheral) vs. spastic/hypertonic/hyperreflexic/minimal atrophy (UMN/central)
Wallerian degeneration: the distal axon and myelin degenerate; Schwann cells survive and form bands of Bungner; EMG must be delayed 3 weeks because fibrillation potentials do not appear until Wallerian degeneration is complete
Tinel's advancing sign: distal migration = active recovery at ~1 mm/day (~1 inch/month); stationary Tinel's = stalled recovery; this is the bedside prognostic indicator
Double/multiple crush phenomenon: proximal compression reduces axoplasmic flow, making distal sites more vulnerable — expect exam questions about incomplete relief after distal surgery prompting assessment of the proximal chain
The neurilemma (Schwann cell sheath) is why peripheral nerves can regenerate and central neurons cannot — PNS Schwann cells survive injury and guide regeneration; CNS oligodendrocytes do not provide this function
Peripheral nerve regeneration rate: approximately 1 mm/day or 1 inch/month — this value is frequently tested and is used to estimate recovery timelines based on the distance from the injury to the target muscle

Massage Therapy Considerations

Primary therapeutic target: The mechanical interface around the injured nerve (muscles, fascia, scar tissue that may compress or tether the nerve) and the compensatory muscle patterns that develop when the primary muscles are paralyzed. For entrapment neuropathies, the compressive structure is the direct target (e.g., pronator teres in pronator syndrome, psoas in femoral nerve injury). For traumatic injuries, scar tissue and adhesions at the injury site become the primary target once the acute phase resolves.
Sequencing logic: Release the mechanical interface (muscles and fascia surrounding the nerve) first to decompress or free the nerve → address compensatory overuse patterns in muscles that substitute for the paralyzed group → maintain tissue elasticity in the denervated muscles → neural mobilization as the final step (gentle neurodynamic gliding to restore nerve sliding through the decompressed tunnel). This sequence decompresses before mobilizing — moving a nerve through a compressed space is counterproductive.
Safety / contraindications: Areas of sensory loss are a major caution — the patient cannot provide accurate pressure feedback, requiring reduced pressure and visual monitoring; do not apply deep transverse friction or aggressive manipulation directly over a known nerve injury site — the nerve is fragile and may be further damaged; acute traumatic nerve injuries (within the first 2–4 weeks) are locally contraindicated — limit to gentle effleurage and positioning until inflammation resolves; if active denervation signs are progressing (worsening weakness, advancing atrophy), the nerve may require surgical exploration — do not delay referral by providing conservative treatment for a neurotmesis; vigorous deep massage to the denervated muscles risks tissue damage because the muscles lack protective reflex
Heat/cold guidance: Moist heat to the compressive structures (muscles forming the tunnel or compartment) before treatment to improve tissue pliability; avoid sustained heat directly over the nerve injury site in acute cases (may increase neural edema); in chronic denervation with cool extremities, gentle warming (warm water immersion, warm towels) improves local circulation and tissue pliability before treatment; contrast hydrotherapy post-treatment to promote circulation in atrophied muscles

Treatment Plan Foundation

Clinical Goals

Decompress the nerve by releasing the muscular and fascial structures forming the mechanical interface around the injury or entrapment site
Reduce compensatory muscle hypertonicity and overuse patterns that develop from functional substitution
Maintain tissue elasticity and circulation in denervated muscles to support potential reinnervation
Restore neural sliding through the mechanical interface via gentle neurodynamic mobilization

Position

Depends on the specific nerve injured — the nerve should be in a slackened (non-tensioned) position during decompression work, and the affected region should be accessible without excessive stretch
For upper extremity nerves: supine with the arm supported on a bolster in a neutral position
For lower extremity nerves: supine with knees flexed (femoral nerve); prone or side-lying (sciatic, peroneal)
Avoid positions that place the injured nerve under tension during treatment

Session Sequence

General effleurage to the affected region — assess tissue state bilaterally; identify areas of muscle wasting, compensatory hypertonicity, and trophic changes; note temperature and skin quality differences between sides
Release the mechanical interface — specific technique depends on the nerve: scalene release for brachial plexus, pronator teres release for median nerve at the forearm, psoas release for femoral nerve, piriformis release for sciatic nerve, peroneal retinaculum release for peroneal nerve; sustained compression, cross-fiber work, and myofascial release to the compressive structure
Address compensatory muscle patterns — identify and release the muscles substituting for the paralyzed group (e.g., upper trapezius for deltoid, hip flexors for quadriceps, toe flexors for ankle dorsiflexors); these muscles develop chronic hypertonicity and trigger points from overuse
Scar tissue mobilization — if the injury was traumatic and a scar is present, cross-fiber and longitudinal myofascial release to the scar tissue to reduce adhesion between the nerve and surrounding structures; scar work should be gentle and progressive [subacute/chronic phase only — not before 6–8 weeks post-trauma]
Denervated muscle maintenance — gentle effleurage and myofascial release to the paralyzed muscles; purpose is circulation and tissue elasticity, not strengthening; reduced pressure is required because the muscles lack protective tone and sensory feedback may be impaired
Gentle neurodynamic mobilization — the specific neurodynamic test position (ULTT1/2/3, SLR, slump, prone knee bend) taken to first onset of neural tension, then oscillated gently within a pain-free range; performed last, after all mechanical interface release; defer if neural irritability is high [subacute/chronic phase only]

Adjunct Modalities

Hydrotherapy: Moist heat to the mechanical interface structures before treatment (steps 2–3) to improve tissue pliability for deep release work; contrast hydrotherapy to the denervated territory post-treatment (warm 3 minutes / cool 1 minute, 3 cycles) to promote circulation; test temperature tolerance in areas of sensory loss before applying thermal modalities
Joint mobilization: Joints crossed by the affected nerve may develop stiffness from altered movement patterns — gentle mobilization maintains joint health and contributes to overall neural mobility; specific mobilization targets depend on the nerve (e.g., carpal bone mobilization for median nerve, patellofemoral glides for femoral nerve, subtalar joint for peroneal nerve)
Remedial exercise (on-table): Passive range of motion through all joints crossed by the affected nerve to maintain joint mobility and prevent contracture; active-assisted exercises for movements where partial reinnervation allows voluntary contraction; nerve gliding exercises (sliders, not tensioners) — gentle rhythmic excursion through progressive positions to maintain neural mobility through the mechanical interface

Exam Station Notes

Perform bilateral comparison of muscle bulk and function before selecting treatment approach — documenting the deficit demonstrates clinical assessment skill
Demonstrate awareness of the LMN vs. UMN distinction — state what you expect to find (flaccid, hypotonic, areflexic) and confirm it on examination; if UMN signs are present (spasticity, hyperreflexia, clonus), the diagnosis is not peripheral nerve injury
Use Tinel's sign both diagnostically (localize the lesion) and prognostically (track the advancing front of regeneration) — explain serial monitoring to the examiner
Verbalize the reason for reduced pressure in areas of sensory loss — the patient cannot provide pressure feedback, so the therapist must monitor visually

Verbal Notes

Sensory impairment: explain that areas of numbness or reduced sensation require lighter treatment pressure — the patient should report any unusual sensations, but the therapist will also monitor visually because the patient's feedback may be unreliable in these areas
Neural mobilization: warn that the nerve gliding technique may temporarily reproduce their familiar tingling or numbness — this should be mild and resolve within seconds; if it intensifies or persists, the technique will be stopped
Recovery expectations: for axonotmesis, explain that nerve recovery occurs at approximately 1 mm per day — this means recovery may take months depending on the distance the nerve must regrow; regular follow-up assessments (Tinel's tracking, myotomal testing) will monitor progress
Referral trigger: if weakness is progressing rather than improving, or if no Tinel's advancement is detected after 3–4 months, the patient may need electrodiagnostic testing or surgical consultation

Self-Care

Nerve gliding exercises specific to the affected nerve — gentle, rhythmic excursion through progressive positions; 5 repetitions, 2–3 times daily; stop if symptoms worsen; the specific exercise depends on which nerve is injured (median nerve glides for CTS, ulnar nerve sliders for cubital tunnel, etc.)
Splinting — use functional splints to support the paralyzed muscles and prevent contracture in the unopposed group (wrist splint for wrist drop, anti-claw splint for ulnar nerve, AFO for foot drop); wear during functional activities and at night
Active range of motion — perform available active movements through full range to maintain joint mobility and stimulate any recovering motor units; frequency based on fatigue level
Skin and thermal protection — denervated skin may have impaired temperature sensation and reduced sweating; wear protective clothing in extreme temperatures; test water temperature with the unaffected side before immersing the affected area; moisturize dry, denervated skin to prevent cracking

Key Takeaways

Seddon's classification defines three grades of peripheral nerve injury: neurapraxia (conduction block, full recovery in weeks), axonotmesis (axonal disruption with intact connective tissue, slow recovery at ~1 mm/day), and neurotmesis (complete severance, no recovery without surgery)
Sunderland's 5-degree system refines axonotmesis — 3rd-degree injuries disrupt the endoneurium, causing regenerating axons to enter wrong tubes and producing aberrant reinnervation (co-contraction, synkinesis)
Wallerian degeneration is the predictable sequence of distal axon and myelin breakdown after axonal disruption — it must complete (2–3 weeks) before EMG can accurately classify the injury
Tinel's advancing sign is the bedside hallmark of recovery — distal migration of the Tinel's response at approximately 1 mm/day indicates active axonal regeneration; stationary Tinel's indicates stalled recovery
The neurilemma (Schwann cell sheath) is the reason peripheral nerves can regenerate — Schwann cells form bands of Bungner that guide regenerating axon sprouts; this regenerative capacity does not exist in the central nervous system
LMN pattern (flaccid, hypotonic, areflexic, atrophic, fasciculations) must be distinguished from UMN pattern (spastic, hypertonic, hyperreflexic, clonus, Babinski) — this is the foundational neurological distinction
The double/multiple crush phenomenon means proximal compression reduces the nerve's tolerance to distal compression — treatment must assess and address the entire neural pathway, not just the symptomatic site