Familial cortical myoclonic tremor with epilepsy and cerebellar changes: description of a new pathology case and review of the literature

Abstract

Background: Over 60 Asian and European families with cortical myoclonic tremor and epilepsy have been reported under various names. Cerebellar changes may be part of the syndrome. In this study, we report the neuropathology findings in a new Dutch familial cortical myoclonic tremor with epilepsy case and review the literature on this syndrome.

Methods: Neuropathological investigations were performed for a third case of the Dutch pedigree. In addition, we searched the literature for pedigrees meeting the criteria for benign familial myoclonic tremor and epilepsy.

Results: Our third Dutch case showed cerebellar Purkinje cell changes and a normal cerebral cortex. The pedigrees described show phenotypical differences, cerebellar symptoms and cerebellar atrophy to a variable degree. Japanese pedigrees with linkage to chromosome 8q have been reported with milder disease features than members of Italian pedigrees with linkage to chromosome 2p. French pedigrees (5p) possibly show even more severe and progressive disease, including cognitive changes and cerebellar features.

Discussion: Currently, familial cortical myoclonic tremor is not listed by the International League Against Epilepsy, although it can be differentiated from other epileptic syndromes. Genetic heterogeneity and phenotypical differences between pedigrees exist. Cerebellar changes seem to be part of the syndrome in at least a number of pedigrees.

Keywords: Cortical myoclonus; benign; cerebellar; epilepsy; hereditary; tremor.

Figure 1.. Pedigree of the Dutch Family with Familial Cortical Myoclonic Tremor with Epilepsy (FCMTE).

▪, affected male; •, affected female; ^•, possibly affected; □,○, no established diagnosis; /, diseased; PA, pathological investigations performed; *, one or more additional functional tests performed. The described patient is indicated by an arrow.

Figure 2.. Histological Findings in the Cerebellum.

(A) Hematoxylin and eosin: loss of Purkinje cells ; insert, cell with abnormal morphology and unclear outlines of the cytoplasmic membrane. (B) Bielschowski silverstaining: empty baskets (arrows and insert in B). (C–F) Calbindin staining: presence of numerous Purkinje cells with radial sprouting (arrows in C–E and insert in E), reduced and abnormal dendritic arborization of Purkinje cells in the molecular layer (ml; asterisks in D), with swelling of dendritic arborizations (F). (G) Neurofilament staining: swellings of Purkinje cell axons (torpedoes) within the granular layer (gl). Scale bars: A, D: 80 µm; B–C: 160 µm; E–F: 40 µm; G and insert in B: 30 µm; inserts in A and E: 20 µm.