[Two siblings of familial amyotrophic lateral sclerosis with multisystemic degeneration characterized by mild involvement of the middle root zone of the posterior column, Clarke's nuclei and spinocerebellar tract]

Abstract

The aim of this study is to clarify the clinicopathological characteristics of the multisystem degeneration seen in two male siblings with familial amyotrophic lateral sclerosis (FALS). A similar neurological disorder affected their elder sister and paternal uncle, but not their parents. The older brother (case 1) developed muscular weakness at 50 years of age and the younger brother (case 2), at 42 years of age. The duration of illness was 19 months in case 1 and 31 months in case 2. The clinical picture was the common (suspended) form in case 1 and the pseudopolyneuritic form in case 2. Pyramidal tract sign was obscure in both cases and cerebellar sign, sensory disturbance, sphincter disturbance and oculomotor palsy were not observed in either case. Neuropathological examination revealed similar findings in the two cases: 1) marked loss of lower motor neurons in the spinal anterior horn and motor nuclei of the lower brain stem in both cases, with neuronal loss of Onuf's nuclei in case 2; 2) very mild involvement in Clarke's nuclei, the dorsal and ventral spinocerebellar tracts and the middle root zone of the posterior column; 3) relatively well preserved Betz cells in the upper motor cortex with the appearance of a few macrophages, and mild changes in the pyramidal tract of the spinal cord; and 4) mild degenerative changes in the pallidoluysian system and the dentatorubral system. The most characteristic pathological findings common to both cases were the extremely mild involvement of the middle root zone of the posterior column, Clarke's nuclei and spinocerebellar tracts. The pattern of lower motor neuron system degeneration paralleled the development of clinical features. Genetic studies demonstrated no mutations in exons 1, 2 and 4 of Cu/Zn-binding superoxide dismutase gene. We emphasized the existence of mild involvement of middle root zone of posterior column, Clarke's nuclei and spinocerebellar tract in FALS with multisystemic degeneration.