Inventi Impact: Radiology

Inventi:him/25/12

ULTRASONOGRAPHIC MEDIAN NERVE CROSS-SECTION AREAS MEASURED BY 8-POINT â??INCHING TESTâ? FOR IDIOPATHIC CARPAL TUNNEL SYNDROME: A CORRELATION OF NERVE CONDUCTION STUDY SEVERITY AND DURATION OF CLINICAL SYMPTOMS

Background: Incremental palmar stimulation of the median nerve sensory conduction at the wrist, the ââ?¬Å?inching\r\ntestââ?¬Â, provides an assessment with reference to segments proximal and distal to the entrapment. This study used\r\nhigh-resolution ultrasonography (US) to measure the median nerveââ?¬â?¢s cross-section areas (CSAs) like the ââ?¬Å?inching\r\ntestââ?¬Â and to correlate with the nerve conduction study (NCS) severity and duration of carpal tunnel syndrome\r\n(CTS).\r\nMethods: Two hundred and twelve (212) ââ?¬Å?CTS-handsââ?¬Â from 135 CTS patients and 50 asymptomatic hands\r\n(ââ?¬Å?A-handsââ?¬Â) from 25 control individuals were enrolled. The median nerve CSAs were measured at the 8-point\r\nmarked as i4, i3, i2, i1, w, o1, o2, and 03 in inching test. The NCS severities were classified into six groups based on\r\nmotor and sensory responses (i.e., negative, minimal, mild, moderate, severe, and extreme). Results of US studies\r\nwere compared in terms of NCS severity and duration of clinical CTS symptoms.\r\nResults: There was significantly larger CSA of the NCS negative group of ââ?¬Å?CTS-handsââ?¬Â than of ââ?¬Å?A-handsââ?¬Â. The cutoff\r\nvalues of the CSAs of the NCS negative CTS group were 12.5 mm2, 11.5 mm2 and 10.1 mm2 at the inlet, wrist\r\ncrease, and outlet, respectively. Of the 212 ââ?¬Å?CTS-handsââ?¬Â, 32 were NCS negative while 40 had minimal, 43 mild, 85\r\nmoderate, 10 severe, and two extreme NCS severities. The CSAs of ââ?¬Å?CTS-handsââ?¬Â positively correlated with different\r\nNCS severities and with the duration of CTS symptoms. By duration of clinical symptoms, 12 of the 212 ââ?¬Å?CTShandsââ?¬Â\r\nwere in the 1 month group; 82 in >1 month and =12 months group, and 118 in >12 months group. In\r\nââ?¬Å?inching testââ?¬Â, segments i4-i3 and i3-i2 were the most common ââ?¬Å?positive-siteââ?¬Â. The corresponding CSAs measured\r\nat i4 and i3, but not at i2, were significantly larger than those measured at points that were not ââ?¬Å?positive-siteââ?¬Â.\r\nConclusions: Using the 8-point measurement of the median nerve CSA from inlet to outlet similar to the ââ?¬Å?inching\r\ntestââ?¬Â has positive correlations with NCS severity and duration of CTS clinical symptoms, and can provide more\r\ninformation on anatomic changes. Combined NCS and US studies using the 8-point measurement may have a\r\nhigher positive rate than NCS alone for diagnosing CTS.