The clinical consideration of the dissociated motor loss syndrome (Keegan) in diseases of the cervical spine
Itoh, T.; Tsuji, H.; Tamaki, T.; Miyasaka, H.; Toyoda, A.
Nihon Seikeigeka Gakkai Zasshi 54(2): 135-151
1980
ISSN/ISBN: 0021-5325 PMID: 7391620 Document Number: 154372
The dissociated motor loss syndrome in cervical spondylosis was first reported in 1965, and the etiology of this syndrome was thought to be the selected damage by bony spurs to the motor roots. Among 450 patients with cervical spondylosis operated during the past 10 years at our clinic, dissociated motor loss was noted only in 10 patients or 2.2%. The special feature of neurological findings consisted of severe weakness with marked muscle atrophy, in a segmental distribution, most frequently involving the 5th and 6th cervical segments. About 1/3 of patients had minimal sensory disorder and/or long tract sign. EMG was evaluated to be markedly improved. Improvement of the symptoms with some remaining weakness and impaired ADL occurred in 5 patients, the condition of 1 patient was unchanged. The main cause of the pathology is thought to be the lesion of motor root at the pre-foraminal part, since 3 patients had definite lesion at this site. The other 7 cases had lesion not only in the pre-foraminal part but also in the para-medial part. EMG, myelogram and X-ray findings indicated bilateral lesions and operation revealed wide and severe compression to the spinal cord. There may be a subclinically spread spinal cord lesion around the anterior horn caused by the compression of para-medial osteophyte and the lesion of anterior root at the preforminal part may also contribute to the development of unilateral muscle weakness. Anterior decompression with interbody fusion is recommended as soon as possible when amyotrophy is presented in the course.