Ashraf A, Daghaghzadeh A, Naseri M, Nasiri A, Fakheri M. A study of interpolation method in diagnosis of carpal tunnel syndrome.
Ann Indian Acad Neurol 2013;
16:623-6. [PMID:
24339593 PMCID:
PMC3841614 DOI:
10.4103/0972-2327.120495]
[Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 07/09/2013] [Accepted: 07/25/2013] [Indexed: 11/29/2022] Open
Abstract
Context:
The low correlation between the patients’ signs and symptoms of carpal tunnel syndrome (CTS) and results of electrodiagnostic tests makes the diagnosis challenging in mild cases. Interpolation is a mathematical method for finding median nerve conduction velocity (NCV) exactly at carpal tunnel site. Therefore, it may be helpful in diagnosis of CTS in patients with equivocal test results.
Aim:
The aim of this study is to evaluate interpolation method as a CTS diagnostic test.
Settings and Design:
Patients with two or more clinical symptoms and signs of CTS in a median nerve territory with 3.5 ms ≤ distal median sensory latency <4.6 ms from those who came to our electrodiagnostic clinics and also, age matched healthy control subjects were recruited in the study.
Materials and Methods:
Median compound motor action potential and median sensory nerve action potential latencies were measured by a MEDLEC SYNERGY VIASIS electromyography and conduction velocities were calculated by both routine method and interpolation technique.
Statistical Analysis Used:
Chi-square and Student's t-test were used for comparing group differences. Cut-off points were calculated using receiver operating characteristic curve.
Results:
A sensitivity of 88%, specificity of 67%, positive predictive value (PPV) and negative predictive value (NPV) of 70.8% and 84.7% were obtained for median motor NCV and a sensitivity of 98.3%, specificity of 91.7%, PPV and NPV of 91.9% and 98.2% were obtained for median sensory NCV with interpolation technique.
Conclusions:
Median motor interpolation method is a good technique, but it has less sensitivity and specificity than median sensory interpolation method.
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