New insight into cervical myelopathic hand sign : a pilot study

Background: The myelopathy hand was first described by Ono et al. on the analysis of finger motion impairment caused by cervical myelopathy. The clumsiness associated with intrinsic finger weakness decreases the number of grip-and-release cycles a patient can perform within 10 seconds. However, this quantitative analysis only provides a crude representation. The purpose of this study is to perform electromyographic (EMG) analysis of this myelopathic hand sign in pre- and postoperative patients. Methods: Patients diagnosed with cervical myelopathy and planned for surgical decompression were recruited into the study. Clinical examination including the presence of myelopathy hand and modified Japanese Orthopaedic Association (mJOA) scores, and EMGs during the grip-and-release tests were performed pre- and postoperatively. Results: Ten patients were recruited into the the pilot study. Five patients had improvement of mJOA score by 2 points or more postoperatively, whereas the remaining Five had similar scores. For patients who had improved mJOA scores, there was a statistical significance in improvement in low frequency EMG amplitudes compared with preoperative during the 10 second grip-and-release tests, whereas there was no difference in high frequency amplitudes. For those who had no change in mJOA scores, EMG amplitudes did not change pre- and postoperatively in high or low frequencies. Conclusions: Improvement in low frequency EMG amplitudes may represent a sensitive method in detecting improvement in hand function post surgical decompression of cervical myelopathy. Further studies are required to determine if this will allow objective documentation and prognostication of surgical outcomes.