Transient subacute cerebellar ataxia in a patient with Lambert-Eaton myasthenic syndrome after intracranial aneurysm surgery

Abstract

*These authors contributed equally to this work. AbstractSeveral reports have presented patients with subacute cerebellar ataxia (subacute CA) and Lambert-Eaton myasthenic syndrome (LEMS). Some clinical features of those patients have been described in the previous reports, such as priority of subacute CA to LEMS or a concurrent occurrence of both diseases, a high incidence of malignancy, less efficacy of the treatment for subacute CA compared with that for LEMS. Cerebellar ataxia in some patients with LEMS has been demonstrated to be caused by serum antibodies to P/Q-type voltage-gated calcium channels (VGCCs). Here, we report a 63-year-old woman with subacute CA and LEMS. Cerebellar ataxia appeared 15 months after the incidence of LEMS, and the onset of cerebellar ataxia was thought to be due to serum anti-P/Q-type VGCCs antibodies. The clinical course of this patient was atypical in that 1) LEMS preceded subacute CA which developed after intracranial aneurysm surgery, 2) no malignancy was detected when both diseases coexisted, 3) symptoms of LEMS did not progress with the onset of cerebellar ataxia, and 4) cerebellar ataxia showed a definite improvement in symptoms and by 123 I-IMP SPECT imaging after steroid administration. In addition, it is remarkable that LEMS became aggravated in electrophysiological examinations in contrast to subacute CA. We suggest that these atypical features of subacute CA and the changes in LEMS may be associated with a balance between the amount of serum anti-P/Q-type VGCCs antibodies and the susceptibility of the cerebellum and presynaptic nerve terminals to the antibodies. More cases are needed to investigate the mechanisms involved. The subacute CA and LEMS in this patient have remained comparatively silent after the withdrawal of steroid, and we are continuing to observe her condition.

Autoimmune cerebellar ataxia

“…This suggests the importance of paraneoplastic syndrome in ACA, as well as a classification based on the presence of autoantibodies including anti‐GAD antibody and anti‐mGluR1 antibody 15 . In other words, only cerebellar ataxia in which antibodies that appear in paraneoplastic syndrome (i.e., anti‐GAD antibody and anti‐mGluR1 antibody) are detected is definite ACA, so that, for example, an anti‐VGCC antibody‐positive case 13,16 would be classified as definite ACA, even if no tumor is identified.…”

“…This suggests the importance of paraneoplastic syndrome in ACA, as well as a classification based on the presence of autoantibodies including anti-GAD antibody and anti-mGluR1 antibody. 15 In other words, only cerebellar ataxia in which antibodies that appear in paraneoplastic syndrome (i.e., anti-GAD antibody and anti-mGluR1 antibody) are detected is definite ACA, so that, for example, an anti-VGCC antibody-positive case 13,16 would be classified as definite ACA, even if no tumor is identified. However, if these autoantibodies are absent, the diagnosis may be difficult to make in the presence of (a) subacute onset (rapid pro- paraneoplastic syndrome-specific antibodies, but does include autoantibodies, which are reported rarely, while a history of an autoimmune disease or CSF findings during the subacute course of the disease is diagnostic, even if there are no autoantibodies.…”

Review of the Diagnostic Challenges of Lambert–Eaton Syndrome Revealed Through Three Case Reports

“…The clinical course of LES is generally progressive, with less fluctuation and a lower spontaneous remission rate than myasthenia gravis (MG). [3][4][5] In paraneoplastic LES patients (P-LES), symptoms and findings spread far more rapidly and can be initially attributed to cachexia and/or effects of cancer or its treatment. 6 LES presents with fatigue, proximal weakness, particularly in the lower limbs, and unanticipated falls.…”