Prevalence and pattern of spinocerebellar degenerations in northeastern Libya

An intensive search over a two-year period for cases of cerebellar and spinocerebellar degenerations in Benghazi, Libya, made through polyclinics, university hospitals and a centre for the handicapped, revealed a total of 52 patients, among whom 30 were index cases; the remainder were detected on family study. Twenty-five patients lived in Benghazi, giving a crude prevalence of 4.8/100 000 population. There were 24 patients (10 families) with hereditary spastic paraplegia (HSP), 13 (9 families) with early onset cerebellar ataxia with retained tendon reflexes (EOCA), 3 with Friedreich's ataxia (FA), 5 (1 family) with late onset cerebellar ataxia (LOCA) with pigmentary retinal degeneration and autosomal dominant inheritance, 6 single cases of LOCA and 1 with ataxia telangiectasia. There were 14 families with definite autosomal recessive inheritance and only 2 with dominant transmission. The large family size (average of 6.2 children per married woman in the patient group) and the high rate of consanguineous marriages contribute to the high incidence of familial cases, especially those with autosomal recessive inheritance. Nerve conduction studies were normal in HSP and abnormal in EOCA and FA. Computed tomographic scans revealed atrophy of the brainstem and cerebellum in 3 cases of EOCA and 2 with LOCA. No indigenous forms of the disease were observed and the clinical features differed little from the descriptions in literature. However, the relative rarity of patients with FA, in comparison with other types of hereditary ataxias, is striking.