[Acute posterior cord lesions in multiple sclerosis. An MRI study of the clinical course in 20 cases].

Twenty patients with multiple sclerosis (MS), 19 women and 1 man, with acute proprioceptive sensory disturbances related to the presence of plaques on the posterior columns (posterior column syndrome) at the cervical or thoracic levels of the spinal cord, were selected among 138 new patients with MS assisted in our neurological unit over the past five years. In 17 of these patients, the acute posterior cordonal syndrome was responsible for the first clinical manifestations of the disease. The other 3 patients had a history suggestive of MS. These 20 patients were followed with a minute analysis of neurological function with repeated clinical evaluation combined with repeated MRI study of the spinal cord. Brain MRI (strongly suggestive of MS in 15 patients), evoked potentials (EP) and cerebrospinal fluid electrophoresis analysis (with oligoclonal bands present in all patients were it was performed) were also obtained at least once in each patient. Spinal cord MRI demonstrated more lesions in the cervical region (90 p.100) than in the thoracic regions (10 p.100). Eighty percent of the cervical lesions were located high, between C1 and C4. The most characteristic clinical expression was the deafferentation of one upper limb, preferentially the "useless hand" (Oppenheim) or even a pseudoathetosic or dystonic limb. Propioceptive ataxia or spontaneous cervical or brachial pain were other forms of clinical expression. No major motor deficit or sphincter disorders were noted at any time in the clinical course in any of the patients. There was a good correlation between localization and morphology of the plaques detected by spinal cord MRI and clinical signs. Intrinsic medullary lesions were seen as high intensity signals on T2-weighted images which were enlarged more than the same lesion visualized on T1-weighted images after injection of paramagnetic contrast agents. This reflected the presence of edema extending beyond the main inflammatory lesion. There was also a good correlation between improvement of clinical symptoms and total or, mor frequently, partial reduction of the plaques, analyzed morphologically by successive spinal cord MRI series. The diagnosis of MS was clinically definitive in 60 p.100 of cases and laboratory-supported definitive in 40 p.100. During the follow-up period (average 36 months), 15 patients (75 p.100) presented one or more exacerbations, all of them presenting a favorable course: at last follow-up, 9 patients were asymptomatic, EDSS was 1 in 6 patients, 1.5 in 4 patients and 2 in 1 patient. This study confirms the contribution of serial spinal cord MR studies to understanding the natural history and pathophysiology of medullary forms of MS presenting as a cordonal posterior syndrome. It also shows a good relationship between the clinical manifestations and course of this form of MS and the localization and variable morphology of plaques. Finally, our results suggest the predictive benign course for this medullary form of MS that seems to be almost exclusively restricted to the female gender.