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The Pneumatic Compression Test and Modified Pneumatic Compression Test in the Diagnosis of Carpal Tunnel SyndromeFrom the Department of Physical Medicine & Rehabilitation, Rheumatology Unite, Faculty of Medicine, University of Yuzuncu Yil, Van, Turkey and the Department of Orthopaedics, Faculty of Medicine, University of Yuzuncu Yil, Van, Turkey
Correspondence: Dr
There are no precise criteria for the diagnosis of carpal tunnel syndrome (CTS): the history is useful but the value of the various provocative tests is questionable. The purpose of this study was to examine the diagnostic value of a new provocative test, the ‘modified pneumatic compression test’ in CTS. The study group consisted of 37 patients with 50 symptomatic CTS hands. A control group of 50 healthy volunteers was recruited. The diagnosis was based on a combination of the history, the clinical findings on examination and electrophysiological criteria. Sensitivity for the pneumatic compression and the modified pneumatic compression tests were 68% and 84%, respectively. Specificities for these tests were 97% and 95%, respectively. The modified pneumatic compression test demonstrated high sensitivity and specificity for CTS. This test facilitated the diagnosis and was easy to use. It may reduce referrals for neurophysiology testing, and so reduce costs.
Key Words: pneumatic compression test • modified pneumatic compression test • carpal tunnel syndrome Clinical signs, provocative tests and electrophysiological examination are all employed in the diagnosis of carpal tunnel syndrome (CTS). However, there is little uniformity of opinion regarding the sensitivity of sensory examination or of the commonly used provocative tests (Hadler, 2001; Nashel, 2003). The modified pneumatic compression test is a new provocative test. In this study, we evaluated this test in the diagnosis of CTS.
Thirty-seven patients with CTS in 50 hands in whom the diagnosis was confirmed by electrophysiological testing and 50 age-matched healthy control subjects, in whom clinical findings for CTS were normal, were included in the study. The patients were recruited from neurology out-patient clinics and the control group was recruited from the physical medicine and rehabilitation out-patient clinics. The mean age of the study group, which included 49 women and 1 man, was 43.7±10 years. Of the 37 patients, 13 had bilateral CTS and 24 had unilateral CTS, resulting in a total of 50 affected hands. Of these, 27 were right and 23 were left hands. Of the hands with CTS, 47 belonged to housewives, two to civil hospital secretaries and one to a self-employed individual (Table 1). The mean duration of symptoms was 37.4±29 months. Worsening of symptoms were experienced by 49 hands at night. Of the 50 hands, 14 had thenar atrophy and seven had alterations in strength of the abductor pollicis brevis muscle.
The owners of 32 hands had no concurrent diseases. The following disorders were recorded in association with the remaining 18 hands: diabetes mellitus in seven, fibromyalgia in three, pregnancy in two, hypothyroidism in two, rheumatoid arthritis in two, osteoarthritis in one and osteoporosis and hypertension in the same patient. Clinical examination included the Tinel’s (1915) test, the Phalen’s (1966) test, the pneumatic compression test (Gilliatt and Wilson, 1953) and the new modified pneumatic compression test. The observer performing the modified pneumatic compression test was not blinded. The pneumatic compression test was performed by wrapping a blood pressure cuff around the wrist and inflating it to 100 mm/Hg for 30 seconds. The modified pneumatic compression test was essentially the same, but with a specially designed wooden pencil-like object of 8 cm length and 8 mm diameter under the cuff in the carpal region and lying along the median nerve to apply pressure to the nerve (Fig 1).
We used a combination of positive nerve conduction studies and symptoms of CTS as the diagnostic standard for CTS. Electrodiagnostic tests, including motor and sensory conduction velocities, were performed on the median nerve at the wrist in all subjects in both groups. In suspicious cases, with clinical symptoms of CTS but no abnormality of motor and sensory conduction velocities of the median and ulnar nerves, we compared the peak sensory latencies of the median and ulnar nerves in the ring finger. If the difference between these latencies was 0.5 mseconds or over, we considered the finding to be pathological. Statistical differences between the two groups were assessed by the two-tailed Student’s t-test and Chi square tests. A p value of 0.05 was considered statistically significant for all tests.
The Tinel’s sign was positive for 34 hands and the Phalen’s test was positive for 35 hands. Phalen’s test could not be performed on one hand because of rheumatoid arthritis joint contracture. The pneumatic compression test was positive for 40 hands and the modified pneumatic compression test was positive for 47 (Table 2).
In this study, the sensitivity for the pneumatic compression test was 82%, the specificity was 98%, the positive predictive value was 97% and the negative predictive value was 83%. These values for the modified pneumatic compression test were 94%, 92%, 92% and 93%, respectively. Pre-test probability for the modified pneumatic compression test was 50% (Table 3).
The same tests were performed on the hands of 50 healthy volunteers. They gave no history suggestive of symptoms of CTS. None had positive Phalen’s or Tinel’s tests. We found a positive pneumatic compression test in one volunteer and a positive modified pneumatic compression test in four volunteers. Electromyography examinations had positive findings for median nerve compression in the carpal tunnel in eight hands (Table 2).
The diagnosis of CTS is made on clinical and electro-physiological grounds in over 90% of cases. However, provocative tests are not favoured, or accepted, by some authors (Katz and Larson, 1990; Loeser, 1990). The gold standard remains electrophysiological studies, which were estimated to be positive in 98% of clinically diagnosed CTS cases by Gunnarsson et al. (1997). Jablecki et al. (1993) concluded that median sensory and motor nerve conduction studies are valid and reproducible clinical laboratory studies that confirm a clinical diagnosis of CTS with a high degree of sensitivity and specificity. The reported reliability of provocative tests in the literature is variable. LaJoie et al. (2005) found the sensitivity of Tinel’s and Phalen’s tests to be 97% and 95%, respectively. Bruske et al. (2002) reported these values as 67% and 68%, respectively. Ghavanini and Haghithat (1998) found the Tinel’s test to be the least sensitive and the most specific test. Heller et al. (1986) reported Tinel’s and Phalen’s sensitivity as 60% to 67%, and their specificity as 59% to 77%. Richter and Bruser (1999) reported Tinel’s sensitivity as 96% and Phalen’s sensitivity as 85% and both of their specificities as 96%. Kaul et al. (2001) found the pneumatic compression test to have a sensitivity of 54%, a specificity of 68%, a positive predictive value of 70% and a negative predictive value of 53%. We found the pneumatic compression test to have a sensitivity 82% and specificity 98%. The modified pneumatic compression test, described for the first time in this study, was found to be the most sensitive (94%) and specific test (92%). A weakness of the study was that the observer performing the modified pneumatic compression test was not blinded and this may explain the zero percentage of false positives among healthy controls. Use of two hands in one patient may not be statistically independent observations. However when the analysis was repeated on a reduced data set of one hand per patient, the results were similar to the presented results (Tables 2 and 3). The modified pneumatic compression test is a reliable provocative test for the diagnosis of CTS. This study was done with this pencil-like, wooden object, but more conveniently, the biro in everyone’s hand seems to work, although not rigorously tested. In association with the classical clinical symptoms and other commonly used provocative clinical tests, this test may obviate the need to perform additional electrodiagnostic studies, thus saving time and money. In patients with wrist contractures or arthritis, particularly, we recommend this test, as other tests can be painful.
Manuscript received January 6, 2006. Accepted for publication June 13, 2007.
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Journal of Hand Surgery (European Volume), Vol. 32, No. 6,
697-699 (2007)
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brahim Tekeo
lu, MD, Tip Fakültesi Fizik Tedavi AD, Van, Turkey. Tel.: +90 432 2251852; fax: +90 432 2167519. E-mail:
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Abstract
MATERIALS AND METHOD