Carpal Tunnel Syndrome
Carpal tunnel syndrome (CTS) is the result of increased pressure in the carpal tunnel (CT) leading to pressure of the median nerve. About 3% of adults in the general population have symptomatic CTS confirmed by nerve conduction studies.
Clinical Features
CTS characteristically presents with pins/needles (paraesthesia), numbness and pain affecting the palmar side of the thumb, index finger, middle finger and radial half of the ring finger, as well as the radial side of the palm. These symptoms must last more than 1 week, or if intermittent, occur on multiple occasions before the diagnosis of CTS is considered. Another prominent feature is the occurrence of the symptoms at night relieved by flicking the hand.
Findings on physical examination indicative of CTS include a positive Tinel’s sign and Phalen’s test.
Other useful clinical tools in assisting diagnosis include the use of hand diagrams, and two-point discrimination test.
Investigations
Investigations used to establish the diagnosis of CTS include nerve conduction studies. The false positive rate of the investigation is ~ 76% (positive nerve conduction study in those without symptoms of CTS).
Response from steroid injection proximal to the carpal tunnel is also a useful tool.
Causes
As a general guide, occupational causes include work which involve:
- Repetitive use of the same or similar movements of the hand/wrist.
- Regular tasks requiring generation of high force by the hand.
- Regular or sustained tasks requiring awkward hand positions.
- Regular use of vibrating hand tools.
- Frequent or prolonged pressure over the wrist.
Interestingly, a recent survey done by the Mayo Clinic found that the frequency of CTS syndrome in computer users was similar to that in the general population.
Non-occupational conditions associated with CTS include:
- Metabolic conditions such as hypothyroidism, diabetes, gout, acromegaly, pregnancy, alcoholism, obesity.
- Systemic inflammatory conditions such as rheumatoid arthritis, lupus, amyloid.
Other important conditions presenting similar symptoms include tendonitis/tenosynovitis, referred symptoms from the cervical spine and other causes of peripheral neuropathy.
Management
General management of this condition would have to include a worksite assessment and workplace modifications to ensure optimal work methods and workplace setup, together with avoidance of any aggravating activity.
Medical management options fall into the non-surgical and surgical groups.
Non-surgical treatment consists of steroid injection proximal to the carpal tunnel. The benefit of night splinting is unknown.
Surgical CT release can be done as an open procedure or endoscopically. Recovery to full function is said to occur after about 6-12 weeks for the open procedure and is somewhat shorter for the endoscopic technique.
Post-operative complications can occur in up to about 15%. Complications include residual palm discomfort for many months (Pillar pain), persistent CTS, local nerve trauma, wound problems, local bleeding, scar hypertrophy and tenderness and reflex sympathetic dystrophy.
Dr. John Low
MBBS (UWA) Grad Dip OHS FAFOM
Occupational Physician
OccuMED Consulting
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