7.3 Peripheral Nerve Compression and Neurodynamics

7.3 Peripheral Nerve Compression and Neurodynamics

Quick Answer: Map symptoms to nerve root and peripheral nerve distributions, grade severity, and protect progressive motor loss with urgent referral. Use neurodynamic assessment as one part of a broader exam—not as forced nerve stretching for every paraesthesia. Consider double-crush (proximal + distal) contributors, and treat load, posture/task demands, and contributing MSK impairments while knowing when surgery or medical pathways are needed.

Peripheral nerve and neural tissue problems sit at the interface of musculoskeletal and neurological physiotherapy. APC Written Assessment cases expect you to localise, judge urgency, and choose safe first-line care for presentations such as carpal tunnel syndrome (CTS), cubital tunnel symptoms, cervical or lumbar radiculopathy radiating to the limb, and activity-related neural mechanosensitivity.

Clinical Localisation: Root Versus Peripheral Nerve

Start with a clear map:

• Radiculopathy — nerve root irritation or compression (commonly cervical or lumbar). Pain may radiate into the limb; expect possible dermatomal sensory change, myotomal weakness, and reflex change. Neck or lumbar movement and axial loading often influence symptoms.
• Peripheral entrapment / mononeuropathy — focal compression along a peripheral nerve (median at the carpal tunnel, ulnar at the cubital tunnel, peroneal/fibular at the fibular head, etc.). Symptoms follow that nerve’s sensory and motor territory distal to the lesion.
• Plexus or multi-level lesions — broader patterns; trauma, post-surgical, or systemic clues matter.
• Polyneuropathy — often distal symmetric, systemic or metabolic context (e.g., diabetes)—different reasoning and medical liaison.

Core neuro screen (entry-level)

• Sensation (light touch ± pinprick as appropriate) in dermatomes and peripheral nerve patches.
• Myotomal strength key muscles; functional tasks (heel/toe walk, grip, hand intrinsics).
• Reflexes relevant to the segment.
• Upper motor neuron screen when cord or central signs possible (especially cervical presentations).
• Neural mechanosensitivity tests used judiciously (see below).
• Red flags: saddle anaesthesia, bladder/bowel change, progressive bilateral leg weakness (cauda equina pathway); gait ataxia and hand clumsiness with upper motor signs (cord).

Never treat “tingling in the hand” as automatically CTS without considering C6–C7 radiculopathy, pronator syndrome territory nuances, or systemic neuropathy clues.

Carpal Tunnel Syndrome (CTS)

CTS is compression of the median nerve at the wrist under the flexor retinaculum. Classic features include nocturnal paraesthesia in the median-innervated digits, shaking the hand for relief, aggravation with sustained wrist flexion/extension or gripping, and—in more advanced disease—thenar weakness and sensory loss.

Assessment highlights

• History: night symptoms, occupational keyboard/tools vibration exposure, pregnancy, diabetes, hypothyroidism, inflammatory arthritis as risk associations.
• Sensory distribution: thumb, index, middle, and radial half of ring finger typically; palm sensation may be relatively spared depending on palmar cutaneous branch anatomy teaching—use standard clinical patterns taught in your curriculum.
• Motor: abductor pollicis brevis strength; functional fine motor complaints.
• Provocative tests (Phalen-type, compression) support but do not replace the full picture; false positives/negatives occur.
• Differential: cervical radiculopathy, other median entrapments, ulnar neuropathy, referred pain, thoracic outlet-type presentations (less common, careful diagnosis).

Physiotherapy management (mild–moderate, non-progressive)

• Education on symptom drivers and sleep positioning.
• Night wrist splinting in neutral is a common first-line strategy for CTS symptoms.
• Activity modification: reduce sustained end-range wrist postures, manage tool grip force, work station adjustments within scope and workplace processes.
• Tendon and nerve gliding exercises used carefully when irritability allows—not aggressive stretching into severe symptom flares.
• Address contributing proximal impairments (cervical, shoulder girdle loading) when double-crush or concurrent neck pain exists.
• Medical pathway: persistent or progressive symptoms, thenar atrophy, constant numbness, or failed conservative care → medical review for electrodiagnostic testing consideration and possible surgical decompression discussion.

CTS versus cervical radiculopathy (high-yield contrast)

Urgency

Progressive thenar weakness, rapidly worsening sensory loss, or severe functional hand decline should not wait for months of passive-only care. Document baseline strength and reassess.

Radiculopathy Presenting in the Periphery

Patients often point to the arm or leg, not the spine. APC cases test whether you still examine the spine and neurological status.

Cervical radiculopathy clues

• Neck pain with radiating arm pain or paraesthesia.
• Symptom change with cervical extension/rotation/compression or relief with unloading positions (individual patterns vary).
• Myotomal weakness (e.g., C5–C7 patterns), reflex change, dermatomal sensory change.

Lumbar radiculopathy clues

• Low back/buttock pain with leg symptoms below the knee more suggestive of radicular involvement than simple somatic referred pain (still use full reasoning).
• Positive neural tension/SLR-type findings interpreted with the whole exam.
• Myotomal weakness (e.g., L4/L5/S1), reflex changes, sensory change.

Management principles (uncomplicated)

• Education and stay-active messaging when serious pathology excluded.
• Directional preference or comfortable movement strategies when they centralise or reduce peripheral symptoms for that individual.
• Graded activity and motor control; avoid fear-inducing absolute bed rest for typical radicular pain without cauda equina.
• Manual therapy as adjunct when indicated and safe—not as sole care.
• Monitor neurology at each key review.

Escalate urgently when

• Progressive myotomal weakness.
• Cauda equina cluster (saddle anaesthesia, new urinary retention/incontinence, faecal incontinence, severe bilateral deficit).
• Suspected myelopathy (upper motor signs, gait disturbance, hand dexterity loss with cord compression concern).
• Trauma with fracture risk, infection, or malignancy red flags.

Neural Tissue Dysfunction and Neurodynamics

Neurodynamics refers to the mechanical and physiological continuum of the nervous system—nerves need space, movement, and blood flow. Neural tissue dysfunction or heightened neural mechanosensitivity describes when nerve-related structures reproduce the patient’s symptoms under loading or elongation tests, often with reduced range compared with the other side.

Using neurodynamic tests wisely

Common tests (ULNT/ULTT variants for upper limb; SLR, slump for lower limb) are assessment tools:

• Reproduce familiar symptoms?
• Structural differentiation (change a distant joint to alter neural load while keeping local MSK tension similar) supports neural contribution.
• Compare sides and relate to function.

Positive tests do not automatically mean “the nerve is trapped and must be stretched hard.” Aggressive end-range nerve stretching into highly irritable radiculopathy can flare symptoms. Treatment dosing should match irritability: gentle neural mobilisations (sliders more than tensioners early when irritable), concurrent load management, and treatment of interfaces (muscle, joint, swelling) that may reduce space or increase demand.

Treatment principles

1. Reduce aggravating postures and task loads temporarily.
2. Restore comfortable movement and confidence.
3. Use gentle neurodynamic techniques when indicated and tolerated.
4. Strengthen and condition the kinetic chain for return to work/sport demands.
5. Reassess neurology—never let a “nerve slider program” mask progressive motor loss.

Double-Crush Concept

The double-crush hypothesis proposes that serial constraints along a nerve (e.g., cervical root irritation plus carpal tunnel compression) can combine so that neither site alone fully explains the disability, yet together they produce significant symptoms. Clinical takeaways for APC:

• Always screen proximal and distal when limb paraesthesia is present.
• Treat relevant contributors at both ends when findings support them.
• Do not promise that distal splinting alone will fix a primarily radicular problem—or that neck care alone will fix clear severe CTS with thenar wasting.
• Systemic factors (diabetes) can reduce nerve resilience—medical optimisation matters.

Other Common Peripheral Compressions (Exam Breadth)

• Ulnar nerve at elbow (cubital tunnel): paraesthesia in little finger and ulnar half of ring finger; intrinsic weakness in advanced cases; aggravation with prolonged elbow flexion.
• Superficial sensory or fibular (peroneal) nerve at fibular head: foot drop or sensory change over dorsum of foot after compression (cast edge, leg crossing, trauma)—urgent attention to new foot drop.
• Meralgia paraesthetica (lateral femoral cutaneous): pure sensory lateral thigh burning/paraesthesia—usually not a motor loss pattern.
• Tarsal tunnel–type presentations: less common; careful differential with plantar heel pain and radiculopathy.

When Progressive Motor Loss Needs Urgent Referral

This is a hard safety rule for the exam and practice:

Document objective strength (e.g., MRC grades or functional equivalents), compare over visits, and escalate if worsening.

Integrating MSK Load with Neural Care

Neural symptoms often coexist with tendinopathy, joint hypomobility, or soft-tissue overload. A keyboard worker may have CTS plus neck loading; a runner may have lumbar-referred leg symptoms plus calf capacity deficits. Build plans that address the driver of irritability while protecting nerve recovery—not endless isolated “nerve flossing” disconnected from function.

Communication

Explain: “Nerves need space and blood flow; we reduce the positions that squash or pull them hard while keeping you moving safely. If strength gets worse, we get you reviewed quickly—that is not optional.” Shared decisions about work modification and timing of surgical opinion for severe CTS are part of professional practice.

Pitfalls

• Missing cervical radiculopathy labelled as CTS.
• Aggressive tensioner neurodynamics on highly irritable radiculopathy.
• Ignoring progressive weakness because pain improved slightly.
• Treating cauda equina features with outpatient advice only.
• Forgetting double-crush and only treating one site.

Australian-Style Case Reasoning

Case A — night hand tingling (office worker): nocturnal median-digit paraesthesia, flick sign, mild Phalen reproduction, normal thenar strength, mild neck stiffness without arm reproduction. Plan: night neutral splint, workstation and sleep advice, gentle tendon/nerve glides if tolerated, screen cervical contribution, review; escalate if weakness or constant numbness develops.

Case B — progressive C7 weakness (tradesperson): neck–arm pain, middle-digit paraesthesia, elbow extension strength worsening over 10 days, reflex reduced. Plan: document objective strength, urgent medical/specialist pathway for progressive motor deficit; do not rely on aggressive ULNT tensioners alone; modify work loads; safety-net cord/cauda features if relevant regionally.

Case C — foot drop after leg crossing / cast edge: new ankle dorsiflexion weakness, sensory change dorsum of foot. Plan: treat as significant peripheral nerve motor loss—urgent medical review pathway, protect from falls, do not wait months of “nerve flossing only.”

Case D — double-crush pattern: CTS symptoms plus clear cervical radicular features. Plan: address wrist load/splinting and cervical contributors; avoid promising single-site care will fix everything; escalate advanced thenar atrophy or progressive root weakness appropriately.

Decision Table for Exam Traps

Self-check

1. Can I map median, ulnar, and common root patterns for the upper limb?
2. Can I list first-line CTS care and when to escalate for thenar weakness?
3. Can I dose neurodynamics to irritability without abandoning neurology monitoring?
4. Can I apply double-crush thinking without absurd over-treatment?
5. Do I treat progressive motor loss as a hard referral trigger?

Safe localisation, dosed neurodynamics, and ruthless attention to progressive motor loss will carry you through most peripheral nerve APC items.