Carpal-tunnel and cubital-tunnel syndromes

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Localisation begins with the fingers. Median compression at the carpal tunnel typically wakes the patient with tingling in the thumb, index, middle and radial half of the ring finger; symptoms may radiate proximally and improve after shaking. Ulnar compression at the cubital tunnel affects the little finger and ulnar ring finger, worsens with sustained elbow flexion or leaning, and may produce medial elbow discomfort. Ask about dropping objects, buttoning, key pinch, keyboard or tool use, cycling, pregnancy, diabetes, thyroid disease, inflammatory arthritis, trauma and anticoagulation.

Inspect thenar and first dorsal interosseous bulk and look for clawing. Test abductor pollicis brevis by palmar thumb abduction and thumb opposition for median motor function. Test finger abduction and adduction, Froment key pinch and small-finger flexion for ulnar function. Map light touch rather than asking only whether the whole hand is numb. The thenar eminence is supplied by a palmar cutaneous branch that leaves before the tunnel; loss there suggests a more proximal median lesion. Dorsal ulnar-hand sparing can suggest Guyon-canal compression.

Tinel and sustained wrist-flexion or compression tests at the carpal tunnel can reproduce symptoms, while elbow flexion and percussion behind the medial epicondyle can provoke ulnar symptoms. These manoeuvres alter probability but do not stand alone. Examine elbow motion and ulnar-nerve subluxation, wrist and thumb-base joints, cervical movement, reflexes and proximal strength. Bilateral symptoms with gait or upper motor-neuron change require cervical myelopathy assessment; length-dependent foot symptoms suggest polyneuropathy.

A clinically typical mild case can begin treatment without electrodiagnosis. Nerve-conduction studies quantify slowed conduction and axonal loss, help localise elbow versus wrist disease and identify coexisting polyneuropathy. They are especially useful with atypical distribution, objective weakness, persistent symptoms or preoperative uncertainty. A normal study does not completely exclude intermittent early symptoms, and a severe study with denervation should accelerate referral. Ultrasound can demonstrate nerve enlargement or a mass, while radiographs assess previous fracture or arthritis.

For mild carpal symptoms, prescribe a correctly fitted neutral wrist splint at night, not one that holds the wrist flexed. Modify prolonged extremes and vibrating-tool exposure while retaining general hand use. A local corticosteroid injection can provide short-term relief and may be useful during pregnancy or while awaiting surgery, but recurrence is common. Persistent symptoms, severe electrodiagnostic abnormality, constant numbness, thenar weakness or wasting supports carpal-tunnel release after shared discussion.

For cubital symptoms, remove direct pressure, adjust workstation and telephone habits, and avoid sustained deep elbow flexion, especially during sleep. A towel wrap or dedicated night brace can limit flexion without causing pressure. Hand therapy can address nerve mobility and ergonomics, avoiding aggressive manoeuvres that reproduce sustained paraesthesia. Progressive weakness, wasting, severe conduction block or failure of a sufficient conservative trial leads to surgical discussion, which may involve in-situ decompression or transposition depending on anatomy and instability.

Surgical counselling should set realistic recovery. Intermittent tingling from demyelination may improve quickly, whereas constant numbness and muscle wasting from axonal loss recover slowly or incompletely. Carpal release may be open or endoscopic; cubital procedures vary. Wound infection, scar pain, pillar pain, nerve injury, incomplete release, instability and recurrence are relevant. Immediate postoperative advice should preserve safe finger movement and wound care while following procedure-specific loading restrictions.

Pregnancy-related carpal oedema often improves after delivery, so splinting and selected injection can bridge symptoms unless severe motor loss requires surgery. Diabetes or polyneuropathy may produce slower or incomplete recovery but does not invalidate decompression when focal compression is clear. Older adults require assessment of cervical myelopathy and frailty alongside hand function. Anticoagulants must be planned around injection or surgery with the prescribing and operative teams; acute bleeding-related compression is an emergency.

Key points

Carpal-tunnel syndrome causes nocturnal or activity-related paraesthesia in thumb, index, middle and radial ring finger, often relieved by shaking; thenar eminence sensation is usually spared.
Cubital-tunnel syndrome affects the little and ulnar half of the ring finger and may worsen during sleep, telephone use, driving or leaning with the elbow flexed.
Look for high-yield motor findings: weak abductor pollicis brevis or thumb opposition at the wrist, and weak first dorsal interosseous, finger abduction or key pinch at the elbow.
First-line investigation is clinical localisation. Provocative tests support but do not rule in or rule out disease alone; always examine neck, reflexes and other nerve territories.
Nerve-conduction studies with electromyography are the reference physiological tests for severity and localisation when diagnosis is uncertain, motor loss is present or surgery is planned, but urgent decline should not wait.
First-line mild carpal treatment is a neutral wrist splint at night plus activity adjustment; a corticosteroid injection can provide temporary relief, while decompression is appropriate for severe or persistent disease.
First-line mild cubital treatment is avoiding prolonged flexion and direct pressure, with night positioning or a towel wrap and nerve-friendly activity change; routine elbow steroid injection is not standard care.
Refer urgently for progressive weakness, wasting, constant sensory loss or acute traumatic compression; delayed decompression can leave permanent axonal deficit.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Anatomical tunnel pressure

Median nerve crowding beneath the transverse carpal ligament or ulnar nerve compression behind the medial epicondyle increases during characteristic wrist or elbow positions.

Systemic susceptibility

Diabetes, hypothyroidism, rheumatoid disease, obesity, acromegaly and generalised neuropathy increase vulnerability, while pregnancy can produce reversible oedema-related carpal symptoms.

Local structural causes

Fracture malunion, arthritis, ganglion, synovitis, tumour, anomalous muscle or scar can narrow a tunnel and may cause unilateral or atypical disease.

Position and repeated exposure

Sustained wrist flexion or extension, vibrating tools and prolonged elbow flexion or leaning increase symptoms, though occupational exposure rarely explains every case alone.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Intermittent ischaemic conduction block
Early pressure impairs intraneural blood flow and saltatory conduction, causing position-dependent paraesthesia that may initially resolve when the limb is moved.
2
Demyelination and axonal loss
Persistent compression damages myelin and later axons, converting nocturnal sensory attacks into constant numbness, motor weakness and muscle wasting.
3
Median motor compromise
Advanced carpal compression weakens abductor pollicis brevis and thumb opposition, impairing pinch and causing thenar flattening while the palmar cutaneous branch is usually spared.
4
Ulnar motor compromise
Cubital compression affects intrinsic hand muscles, causing weak finger abduction and adduction, reduced key pinch, clawing and wasting in severe longstanding disease.
5
Dynamic ulnar tension
Elbow flexion reduces cubital-tunnel volume and stretches the ulnar nerve, explaining night symptoms, telephone provocation and benefit from avoiding sustained flexion.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Median nocturnal paraesthesia

Thumb, index, middle and radial ring-finger tingling that wakes the patient and improves with shaking is strongly suggestive of carpal compression.

Thenar motor loss

Weak palmar thumb abduction or opposition and visible thenar flattening indicate advanced median dysfunction and justify expedited referral.

Ulnar flexion-provoked symptoms

Little and ulnar ring-finger tingling during prolonged elbow flexion, sleep or leaning localises toward cubital tunnel.

Intrinsic weakness

Weak finger abduction, first dorsal interosseous wasting, Froment sign or developing claw posture indicates significant ulnar motor involvement.

Proximal median clue

Sensory change over the thenar eminence, proximal forearm pain or pronation provocation suggests median disease above the carpal tunnel.

Spinal clue

Hyperreflexia, gait dysfunction, bilateral clumsy hands or weakness outside one peripheral nerve requires cervical cord assessment.

Red flags requiring action

Rapidly progressive thumb-abduction weakness, finger-abduction weakness, constant dense sensory loss or visible wasting warrants expedited surgical assessment.
Acute symptoms after wrist or elbow fracture, dislocation, bleeding, cast application or infection require urgent decompression and trauma evaluation.
Pain out of proportion, tense swelling, passive-stretch pain or deteriorating perfusion suggests compartment syndrome and demands emergency surgical review.
Bilateral hand symptoms with gait disturbance, hyperreflexia, sphincter change or widespread weakness raises cervical myelopathy or systemic neuropathy.
A neck-provoked dermatomal syndrome or motor deficit crossing several peripheral nerves requires cervical root or plexus localisation.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
First-line clinical nerve localisationFirst stepFirst line
Why
Map sensory territory and motor loss and distinguish median wrist from ulnar elbow, root, cord and polyneuropathy disease.
Interpretation and limitations
A coherent symptom and examination pattern can support initial conservative care; objective deficit increases urgency and need for physiological confirmation.
02
Reference physiological testing with nerve conduction and EMG
Why
Confirm site, grade demyelination or axonal loss and identify coexisting neuropathy when the result changes surgery or differential.
Interpretation and limitations
Severe slowing, low amplitudes or denervation supports faster referral; a normal result does not absolutely exclude intermittent mild compression.
03
Neuromuscular ultrasound
Why
Assess nerve enlargement, subluxation, structural compression or mass and guide selected carpal injection.
Interpretation and limitations
Cross-sectional enlargement supports focal neuropathy but must be matched to clinical site and physiological severity.
04
Plain wrist or elbow radiographs
Why
Investigate previous fracture, deformity, arthritis, calcification or a local bony cause.
Interpretation and limitations
Not routine in a typical atraumatic presentation; abnormal alignment can explain secondary compression and alter surgical planning.
05
Targeted systemic tests
Why
Investigate diabetes, thyroid disease, inflammatory arthritis, B12 deficiency or paraprotein when history and distribution suggest them.
Interpretation and limitations
Treating systemic disease may improve susceptibility but does not remove established focal compression with motor loss.
06
Cervical MRI when cord or root disease suspected
Why
Assess myelopathy, radiculopathy or another proximal lesion with neurological red flags.
Interpretation and limitations
Urgency rises with upper motor-neuron signs, gait change, sphincter symptoms or progressive multi-myotomal weakness.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Cervical radiculopathy or myelopathy

Neck provocation, reflex change, myotomal weakness, upper motor-neuron signs or sensory distribution beyond one nerve points to spinal disease.

Generalised polyneuropathy

Symmetrical distal foot symptoms, absent ankle reflexes and several nerve territories suggest diabetes, alcohol, nutritional, toxic or inherited neuropathy.

Pronator or proximal median syndrome

Proximal forearm pain, provocation with pronation and sensory involvement of the thenar eminence suggest compression above the carpal tunnel.

Ulnar tunnel at the wrist

Cycling or hypothenar pressure, dorsal-hand sensory sparing and selective deep-branch weakness may localise ulnar compression to Guyon canal rather than elbow.

Tendon or joint disease

Thumb-base arthritis, flexor tenosynovitis and medial epicondylitis cause local pain and grip limitation without a coherent median or ulnar sensory-motor pattern.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01First-line localisationName the nerve and the levelFirst stepFirst lineIntermittent hand paraesthesia occurs without acute trauma, compartment features or rapidly progressive weakness.

1Map affected digits and palmar versus dorsal surfaces and identify provoking wrist, elbow or neck positions.
2Test abductor pollicis brevis, opposition, first dorsal interosseous, finger abduction, key pinch, reflexes and proximal power.
3Examine tunnel sites, thumb base, elbow stability and cervical spine and screen the feet for length-dependent neuropathy.
4Document constant sensory loss, wasting or functional dropping because these features accelerate investigation and referral.

02Carpal first-lineKeep the wrist neutralFirst lineMedian symptoms are intermittent or mild and objective motor loss is absent.

1Fit a neutral wrist splint for night use and adjust prolonged wrist extremes or vibrating exposure.
2Review after six to twelve weeks using night waking, sensation and hand function rather than provocation tests alone.
3Consider one local corticosteroid injection for short-term relief when splinting fails, pregnancy creates a temporary driver or surgery is delayed.
4Refer for release if symptoms persist, electrodiagnosis is severe or constant numbness, weakness or wasting develops.

03Cubital first-lineReduce elbow flexion and pressureFirst lineUlnar symptoms are intermittent, position related and unaccompanied by objective motor deficit.

1Stop leaning on the medial elbow and alter phone, driving and workstation positions that maintain deep flexion.
2Use a towel wrap or comfortable night brace to limit prolonged flexion without compressing the nerve.
3Add hand-therapy advice on activity and gentle nerve mobility, stopping sustained symptom provocation.
4Reassess motor function and refer if symptoms remain disabling or weakness, wasting or severe physiology appears.

04Urgent escalationProtect axons and muscleEscalationConstant numbness, progressive weakness, wasting, severe electrodiagnostic change or acute post-traumatic compression is present.

1Contact a hand or peripheral-nerve service promptly and communicate the documented motor and sensory trajectory.
2Do not delay an acute deteriorating compression for routine outpatient electrodiagnosis when trauma, cast or haematoma is causative.
3Address fracture, infection, bleeding or systemic neuropathy in parallel without assuming it will reverse focal mechanical pressure.
4Counsel that advanced axonal loss may recover incompletely even after technically adequate decompression.

Key medicines and prescribing safety2 treatments · regimens, roles and cautions

Provides temporary reduction of carpal-tunnel symptoms and can bridge pregnancy-related disease or a surgical wait.

Carpal-tunnel corticosteroid injection

Under a trained local protocol, inject one dose such as triamcinolone acetonide 10–20 mg into the carpal tunnel using safe landmark or ultrasound-guided technique, keeping clear of the median nerve and reviewing response before any repeat.

Discuss pain flare, skin depigmentation, fat atrophy, transient glucose rise, tendon or nerve injury and rare infection; assess anticoagulation and never inject through infected skin.

May help concomitant aching or postoperative discomfort but does not decompress either nerve or reverse objective deficit.

Simple analgesia for associated pain

If needed, use paracetamol 500–1000 mg orally at intervals of at least 4–6 hours, maximum 4 g in 24 hours, with a lower maximum in low body weight, frailty, malnutrition or liver risk.

Avoid duplicate paracetamol-containing products and chronic escalation; neuropathic tingling often responds poorly, so lack of benefit should not delay definitive assessment.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Irreversible motor loss

Prolonged axonal compression can leave thenar or intrinsic wasting and incomplete strength recovery even after technically successful decompression.

Persistent sensory deficit

Constant numbness may not fully resolve when severe nerve injury predates surgery, increasing burn, cut and dexterity risk.

Work and sleep impairment

Night waking, dropping objects, weak pinch and tool intolerance affect safety, occupation, driving and caring responsibilities.

Postoperative problems

Scar tenderness, pillar pain, infection, stiffness, incomplete release, nerve injury or recurrence can follow surgery and require diagnosis rather than assumed normal recovery.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Record distribution and frequency of paraesthesia, night waking, constant numbness, dropping objects and work or self-care limitation.
Repeat thenar and first dorsal interosseous bulk, thumb abduction, finger abduction and key pinch at every review.
Check splint fit and skin pressure and confirm that a cubital brace reduces flexion without compressing the medial elbow.
Review electrodiagnostic severity alongside clinical progression and accelerate referral for low amplitudes, denervation or motor decline.
After injection, monitor glucose when relevant and provide return advice for worsening numbness, severe pain, infection or weakness.
After surgery, monitor wound, scar, sensory recovery and motor return, recognising that axonal recovery can take months and remain incomplete.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Thenar skin can be spared

The palmar cutaneous median branch leaves before the tunnel, so numbness over the thenar eminence should prompt a more proximal localisation.

Elbow flexion is a functional test

Cubital-tunnel pressure and nerve tension rise in flexion, explaining symptoms with sleep, telephone use and driving better than a single tap sign.

Motor findings set urgency

Night tingling permits conservative treatment, while wasting or progressive weakness signals axonal loss that may not recover completely after delay.

A normal study is not absolute

Intermittent early compression can escape electrodiagnostic detection; reconcile physiology with examination and revisit alternative levels rather than dismissing coherent symptoms.

Double pathology exists

Diabetic polyneuropathy or cervical radiculopathy can coexist with a focal tunnel lesion, so treatment decisions require localisation rather than one exclusionary label.

Pregnancy often changes timing

Oedema-related carpal symptoms frequently improve postpartum, making splint or injection a bridge unless objective motor loss requires earlier decompression.

11Common pitfallsFrequent interpretation and management errors.

01
Calling whole-hand numbness carpal tunnel without mapping digits, thenar skin, dorsal surface and cervical findings.
02
Relying on Tinel or wrist-flexion testing alone instead of documenting motor power and atrophy.
03
Treating progressive weakness with splinting while waiting months for routine electrodiagnosis.
04
Using a flexed wrist splint or a cubital brace that presses directly on the ulnar nerve.
05
Assuming surgery will fully reverse longstanding constant numbness and muscle wasting.
06
Stopping anticoagulation independently before injection or overlooking acute bleeding-related compression after trauma.