Symptoms affecting the upper extremities, particularly nocturnal paraesthesias and numbness, should be identified as manifestations of carpal tunnel syndrome.
Reduction of physical load factors together with conservative treatment options (night splint) are the primary management strategies in association with mild symptoms and findings.
If the sensory disturbance is prolonged and ENMG reveals severe nerve entrapment, or if motor weakness develops, surgical management should be considered.
Prevalence
The incidence of carpal tunnel syndrome increases with age.
Most common in middle-aged and elderly women
In approximately one third of the patients, the condition is bilateral.
Predisposing factors include overweight, smoking, diabetes, hypothyroidism, rheumatoid arthritis, osteoarthritis and previous wrist injury (e.g. wrist fracture). CTS associated with pregnancy will usually resolve spontaneously after delivery.
CTS may be an occupational disease. Highly repetitive and forceful work movements, vibration focused on hand, heavy lifting and wrist postures deviating from the neutral position predispose to CTS .
Find out about local policies concerning CTS as an occupational disease.
Symptoms
Numbness, sensory disturbances and pain in the thumb, index finger, middle finger and ring finger (the region innervated by n. medianus)
Usually most prominently as numbness and aching in the middle finger and the radial side of the ring finger, thenar pain, pain in the palmar aspect of the wrist.
The hand may feel clumsy and weak.
Symptoms appear particularly during the night-time: shaking the hand may relieve them.
The symptoms may be diffuse and felt in the entire upper arm.
Disturbances in muscle function, e.g. weakness of thumb abduction or pinch grip, may follow sensory disturbances.
Finely co-ordinated activities may deteriorate and, for example, buttoning may be difficult.
The symptoms may continue for years without objective clinical findings.
Diagnosis
The diagnosis of carpal tunnel syndrome is clinical. It is based on symptoms and typical findings and, as necessary, an ENMG examination.
Nocturnal sensory disturbance or numbness is the most important diagnostic clue.
Impaired sharp sensation and weakened abduction of thumb appear to be the most accurate diagnostic findings in physical examination.
The patient draws the localization of the symptoms in a so-called Katz hand diagram.
Sharp sensation may be a more sensitive indicator of median nerve injury than touch sensation.
Sharp sensation can be tested by using an injection needle or by pinching lightly. Compare the finding to the hand that has milder symptoms or is symptom-free. You may also compare the finding with the fifth finger of the same hand and, in the ring finger, you may compare the radial and ulnar aspects.
Clinical tests for carpal tunnel syndrome
Tetro's median nerve compression test: Press the patient's carpal tunnel region with your thumb while the patient keeps the wrist in 60-degree flexion. The symptom occurs within 20 to 60 seconds. Tingling or numbness in the area of skin innervated by the median nerve is a positive finding.
Tinel's test: Lightly tap the median nerve with the fingertip or a reflex hammer in the carpal tunnel area. The patient feels sensation resembling an electric shock in the area of skin innervated by the median nerve.
Phalen's test: Press the wrists in 90-degree flexion with the palms facing each other for 20-60 seconds. Tingling or numbness in the area of skin innervated by the median nerve is a positive finding.
Thumb abduction strenght: Ask the patient to place their palms together and lift their thumbs towards their nose. Thumb abduction strenght is impaired particularly in advanced carpal tunnel syndrome.
Test both hands and compare possible differences.
Thenar muscles may become atrophied (m. abductor pollicis brevis).
Untreated far progressed carpal tunnel syndrome may lead to permanent muscle atrophy and sensory loss in the area innervated by the median nerve.
ENMG is a useful additional test in the diagnosis of carpal tunnel syndrome.
When assessing the level and severity of peripheral nerve entrapment
When considering surgical treatment
ENMG can be used to predict the likelihood of spontaneous nerve recovery and post-operative recovery time.
Differential diagnosis
It is important to include the entire upper extremity in the examination, starting from the cervical spine.
Cervical radicular syndrome (symptoms from root C6 or C7) may cause similar symptoms. Upon examination, numbness in the hands may be the only symptom of cervical radicular syndrome.
Consider in the differential diagnostics also other nerve entrapments of the upper extremity, thoracic outlet syndrome (TOS) Thoracic Outlet Syndrome, osteoarthritis, conditions causing shoulder pain, tendinopathy of the elbow, polyneuropathies and tumours.
In rare cases, the median nerve may be entrapped at the cubital level (pronator teres syndrome) or at the forearm (anterior interosseal branch). These diagnoses are made in specialized care.
If the aetiology is clearly transient (e.g. pregnancy, physical exertion) and the symptoms are mild, of short duration or varying, conservative treatment, counselling and, as necessary, follow-up are sufficient.
Give instructions for exercising and self-treatment.
Assess the physical load factors at work and aim at reducing the load with technical solutions and re-arrangement of work tasks.
The symptoms often vanish when the provoking factor is resolved, e.g. pregnancy is over or work load is relieved .
Potential predisposing underlying diseases (diabetes, rheumatoid arthritis, hypothyroidism) should be treated and possible overweight should be reduced.
Night splint is the preferred treatment for carpal tunnel syndrome if the patient shows no signs of median nerve damage (muscle atrophy or loss of sensation).
Injection therapy Local Corticosteroid Injection for Carpal Tunnel Syndrome may be tried before surgical management. It may also be considered for severe symptoms during pregnancy. The injection technique 1 should be mastered since injection into the nerve may lead to permanent nerve damage.
The injection site is right at the proximal volar transverse skin fold at the junction of the palm and the forearm, on the ulnar side of the m. palmaris longus tendon (note the possible anatomical variant where the tendon is absent).
Direct the needle at an angle of 45 degrees both distally and radially to a depth of 5-9 mm, and inject 0.5-1 ml of a mixture containing glucocorticoid and local anaesthetic (methyl prednisolone and 0.5-1% lidocaine), 25G needle.
If the median nerve is hit and the patient feels pain like an electric shock, draw the needle carefully backwards. Do not inject against resistance into a nerve or a tendon. Numbness or paraesthesias in the distribution of the median nerve are normal reactions and will soon resolve.
Consultation with an orthopaedist or a hand surgeon is necessary when the diagnosis is probable and conservative treatment has not helped.
Surgery is indicated in the presence of prolonged symptoms and especially if the symptoms are progressive or severe, the patient develops atrophy of the thenar and ENMG shows a strong finding suggestive of demyelination or axonal damage.
Surgical treatment seems to promote recovery better than wrist support splint or a glucocorticoid injection in patients in whom carpal tunnel syndrome is suspected clinically or on the basis of neurography.
In an ambulatory procedure, the carpal ligament is transected under local anaesthesia and after exsanguination.
In advanced cases, the restoration of sensory and motor function may be only partial.
References
[Hand and forearm strain diseases]. A Current Care Guideline. Working group appointed by Finnish Medical Society Duodecim and Finnish Occupational Medicine Society. Helsinki: Finnish Medical Society Duodecim, 2022 (accessed 20 Sep 2022). Available in Finnish at: .
D'Arcy CA, McGee S. The rational clinical examination. Does this patient have carpal tunnel syndrome? JAMA 2000 Jun 21;283(23):3110-7. [PubMed]
Yang FA, Shih YC, Hong JP et al. Ultrasound-guided corticosteroid injection for patients with carpal tunnel syndrome: a systematic review and meta-analysis of randomized controlled trials. Sci Rep 2021;11(1):10417. [PubMed]
Baker NA, Dole J, Roll SC. Meta-synthesis of Carpal Tunnel Syndrome Treatment Options: Developing Consolidated Clinical Treatment Recommendations to Improve Practice. Arch Phys Med Rehabil 2021;102(11):2261-2268.e2. [PubMed]