Clinical outcome in adult onset idiopathic or paraneoplastic opsoclonus-myoclonus. Bateller L, Graus F, Saiz A, Vilchez JJ, for the Spanish Opsoclonus-Myoclonus Study Group. Brain 2001;124:437–443.

Abstract

Opsoclonus is a disabling disorder of saccadic eye movements causing involuntary, chaotic saccades that occur in all directions, so-called “saccadomania”. Opsoclonus is usually associated with arrhythmic-action myoclonus that predominantly involves the trunk, limbs and head, sometimes with associated cerebellar dysfunction. The opsoclonus-myoclonus syndrome (OMS) is most commonly as an autoimmune phenomenon, either paraneoplastic or idiopathic. In this study, a series of 24 adult patients with idiopathic (10 cases) and paraneoplastic (14 cases) OMS were analyzed to ascertain possible differences in clinical course and response to immunotherapies between both groups. Associated tumors were small-cell lung cancer (SCLC) (nine patients), breast carcinoma (two patients), gastric adenocarcinoma (one patient), and kidney carcinoma (one patient). Patients with paraneoplastic OMS were older (median age: 66 years versus 40 years) and had a higher frequency of encephalopathy (64% versus 10%). Serum from 10/10 idiopathic and 12/14 paraneoplastic OMS patients showed no specific immunoreactivity on rat or human brainstem or cerebellum, lacked specific antineuronal antibodies (Hu, Yo, Ri, Tr, glutamic acid decarboxylase, amphiphysin or CV2) and did not contain antibodies to voltage-gated calcium channels. The two paraneoplastic exceptions were a patient with SCLC, whose serum contained both anti-Hu and anti-amphiphysin antibodies and a patient with breast cancer who had serum anti-Ri antibodies. The clinical course of idiopathic OMS was monophasic except in two elderly women who had relapses of the opsoclonus and mild residual ataxia. Most idiopathic OMS patients made a good recovery, but residual gait ataxia tended to persist in older patients. Immunotherapy (mainly intravenous immunoglobulins or corticosteroids) seemed to accelerate recovery. Paraneoplastic OMS had a more severe clinical course, despite treatment with intravenous immunoglobulins or corticosteroids, and was the cause of death in five patients whose tumors were not treated. The eight patients whose tumors were treated showed a complete or partial neurological recovery. The authors conclude that idiopathic OMS occurs in younger patients, the clinical evolution is more benign and the effect of immunotherapy appears more effective than in paraneoplastic OMS. In patients aged 50 years and older with OMS who develop encephalopathy, early diagnosis and treatment of a probable underlying tumor, usually SCLC, is indicated to increase the chances of neurological recovery. At present, there are no consistent immunological markers to identify the adult patients with paraneoplastic OMS.—Nancy J. Newman