Tuesday, September 23, 2008

PHYSICAL TESTS FOR CTS: A REVIEW

Sharma KR (2001) studying on Median sensory nerve conduction velocity: found digit 1 to wrist is more sensitive than the median sensory nerve conduction velocity distoproximal ratio in the diagnosis of mild CTS. However, Electrodiagnostic studies have significant false-positive and false-negative rates in CTS, and therefore provocative tests remain important in its diagnosis. Tinel's (nerve-percussion test), Phalen's(wrist-flexion test,), Reverse Phalen's and carpal tunnel compression tests (tourniquet test) are more sensitive and very commonly employed for physical diagnosis of CTS. In a study consisting of 50 control subjects with electrodiagnostically proved carpal-tunnel syndrome found following:

The sensitivity and specificity of each test of the above were calculated. The wrist-flexion test was found to be the most sensitive while the nerve-percussion test, although least sensitive, was most specific. The tourniquet test was quite insensitive and not very specific, and should not be used as a routine screening test in the diagnosis of carpal tunnel syndrome.
NEWER TESTS:
DURKAN test of carpal tunnel compression is already mentioned above.
1. DURKAN JA (1991) suggested a new test, called the carpal compression test, consists of application of direct pressure on the carpal tunnel and the underlying median nerve. The results of the Tinel percussion test, the Phalen wrist-flexion test, and the new test were evaluated in thirty-one patients (forty-six hands) in whom the presence of carpal tunnel syndrome had been proved electrodiagnostically, as well as in a control group of fifty subjects.
DURKAN found, the carpal compression test was found to be more sensitive and specific than the Tinel and Phalen tests.
2. According to AHN DS (2001) Hand elevation can reproduce the symptoms of carpal tunnel syndrome. This phenomenon prompted the idea of developing a simple hand elevation test to diagnose carpal tunnel syndrome. AHN DS found the sensitivity and specificity of the elevation test were higher than those of Phalen's test and Tinel's test.

Sensitivity of a combined test:
In a study by TETRO AM et al (1998) to establish the value of median nerve compression with wrist flexion as a provocative test for carpal tunnel syndrome (CTS), they recorded results for the common provocative tests (Tinel's percussion test, Phalen's wrist flexion test and the carpal compression test) and the new test which combines wrist flexion with median nerve compression.
TETRO AM et al found that the optimal cut-off time for the wrist-flexion and median-nerve compression test was 20 s, giving a sensitivity of 82% and a specificity of 99%. They have also shown that wrist flexion combined with the median-nerve compression test at 20 s, is significantly better than the other methods, and may thus be clinically useful.
Possibility of a double crush:
Physios do not ever forget to test at least a transverse glide or CPA to Lower Cervical spine to rule out possibility of a double crush in all cases of suspected CTS.

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