Diagnostic utility of waveform analysis of compound muscle action potentials for carpal tunnel syndrome

A novel approach to the diagnostic assessment of carpal tunnel syndrome based on the frequency domain of the compound muscle action potential

Conventional electrophysiological (EP) tests may yield ambiguous or false-negative results in some patients with signs and symptoms of carpal tunnel syndrome (CTS). Therefore, researchers tend to investigate new parameters to improve the sensitivity and specificity of EP tests. We aimed to investigate the mean and maximum power of the compound muscle action potential (CMAP) as a novel diagnostic parameter, by evaluating diagnosis and classification performance using the supervised Kohonen self-organizing map (SOM) network models. The CMAPs were analyzed using the fast Fourier transform (FFT). The mean and maximum power parameters were calculated from the power spectrum. A counter-propagation artificial neural network (CPANN), supervised Kohonen network (SKN) and XY-fused network (XYF) were compared to evaluate the classification and diagnostic performance of the parameters using the confusion matrix. The mean and maximum power of the CMAP were significantly lower in patients with CTS than in the normal group (p < 0.05), and the XYF network had the best total performance of classification with 91.4%. This study suggests that the mean and maximum power of the CMAP can be considered as less time-consuming parameters for the diagnosis of CTS without using additional EP tests which can be uncomfortable for the patient due to poor tolerance to electrical stimulation.

Carpal tunnel syndrome: electrophysiological grading and surgical results by minimum incision open carpal tunnel release

The safety and effectiveness of the minimum incision technique were assessed in 138 hands of 108 consecutive patients with carpal tunnel syndrome treated from April 1, 1997 to March 31, 2006. Clinical and electrophysiological examinations were conducted before and after surgical decompression. All hands were divided into early, mild, moderate, and severe groups based on preoperative electrophysiological severity. We examined the surgical outcomes of the affected hands in each group. Nocturnal or daytime dysesthesia, which had been present in 132 (96%) of the 138 hands preoperatively, was completely relieved in 124 (94%) of the 132 hands. Complete relief was achieved in 7 (100%) of the 7 hands in the early group, 68 (99%) of the 69 hands in the mild group, and 45 (94%) of the 48 hands in the moderate group. Complete relief was achieved only in 4 (50%) of the 8 hands in the severe group, and 3 (38%) of the 8 hands did not show any improvement. No painful or hypertrophic scar formation was observed in this series. Only 2 patients complained of postoperative scar discomfort after more than 12 months, which completely disappeared by 14 months after surgery. Minimum incision open carpal tunnel release is a safe and reliable procedure with a high rate of functional improvement and patient satisfaction. Postoperative results were satisfactory regardless of the degree of preoperative electrophysiological severity if preoperative sensory nerve action potentials were detected.