Carpel tunnel syndrome

Definition

  • Collection of symptoms and signs caused by compression of the median nerve in the carpal tunnel

  • Typical symptoms include numbness and tingling mainly in the first 3 fingers, aching and pain in the anterior wrist and forearm, and clumsiness in the hand

Risk Factors

  • Age >30

  • High BMI

  • Female

  • Damage to wrist

  • RA

  • Diabetes

  • Square wrist

  • Dialysis

    • deposition of amyloid on tendons and other structures within the carpal tunnel

  • Pregnancy

  • Congenital carpal tunnel stenosis

  • Repetitive bending, vibration, twisting of wrist

  • Smoking

Differential diagnosis

  • OA

  • Stroke

  • C6/C7 radiculopathy

  • Ulnar neuropathy

  • Amyotrophic lateral sclerosis

  • Motor neurone disease

  • De Quervain's syndrome

  • Lateral epicondylitis

  • Rotator cuff tendonitis

  • Polyneuropathy

  • Brachial plexopathies

  • Proximal median neuropathy

  • MS

Epidemiology

  • US incidence 3.5 cases per 1000 person-years

  • Prevalence 3.7%

  • Appears to be much more rare in developing countries and in other ethnic groups

  • Rates of CTS have risen considerably over the past several decades, but whether this is due solely to better recognition or a rise in risk factors is debatable

  • CTS is at least 3 times more common in females

Aetiology

  • It is rare to find any single definite cause in a patient

  • Causation is very likely multi-factorial.

Clinical features

  • Numbness of hand(s)

    • Median nerve distribution

  • Weakness in hand / thenar muscle weakness

    • Median nerve distribution

    • LOAF

      • Lumbricals 1+2

      • Opponens pollicis

      • Abductor pollicis brevis

      • Flexor pollicis brevis

  • Clumsiness

  • Aching and pain in arm

  • Worse at night

  • Intermittent symptoms

  • Gradual onset

Pathophysiology

  • The final common pathway is the development of raised pressure within the carpal tunnel and/or the median nerve segment that lies within the tunnel

  • The increased pressure could trigger off a chain of negative events that ultimately leads to ischaemia and scarring of the nerve

  • Ischaemia is likely to be the cause of the typical intermittent sensory symptoms of CTS

    • if it remains intermittent, then no axonopathy occurs

  • Pressure on the nerve will also lead to demyelination (and ultimately axonal loss), which is the main finding on neurophysiological testing

    • Demyelination per se causes no symptoms to the patient

    • This may explain in part the subgroup of individuals who have no symptoms of CTS but who have abnormalities on nerve conduction studies

Investigations

  • Electromyogram

    • focal slowing of conduction velocity in the median sensory nerves across the carpal tunnel

    • prolongation of the median distal motor latency

    • possible decreased amplitude of median sensory and/or motor nerves

  • Wrist ultrasound/MRI

    • Hard to distinguish the median nerve

Management

a) conservative

  • Wrist splints, especially at night

b) medical

  • 40-mg methylprednisolone acetate (1 mL volume) +/- local anaesthetic is used

    • The volume should be kept low, as an increase in fluid could exacerbate the already raised pressure in the carpal tunnel

  • Oral steroids do work, but not as well as intracarpal injection

  • Potentially a mild diuretic (e.g., hydrochlorothiazide) if wrist oedema present

  • NSAIDS

c) surgical

  • Surgical release

Prognosis

  • Untreated CTS can spontaneously improve in up to one third of individuals, particularly in younger females

  • Most studies show about a 70% chance of improvement with splints after a period of weeks to months

  • Most studies show a success rate of between 60% and 70% up to 6 months post-injection with corticosteroids

  • Surgical success rates are about 80% to 90%