Benign spinal muscular atrophy arising in childhood and adolescence

Chronic generalized spinal muscular atrophy of infancy and childhood. Arrested Werdnig-Hoffman disease

Recent studies have shown that the acute fatal form of infantile spinal muscular atrophy (acute Werdnig-Hoffmann disease or spinal muscular atrophy Type I) is a distinct genetic and clinical entity. This has prompted clinical re-examination of the disease known as `arrested Werdnig-Hoffmann disease' which hitherto was thought to be a spectrum variant of the acute fatal form. A total of 18 such patients with the chronic generalized form of spinal muscular atrophy has been known to The Hospital for Sick Children over the past 10 years. Patients with this characteristic clinical syndrome comprise approximately one-fifth of children with chronic spinal muscular atrophy. Clinically, no patient was even able to crawl normally or progress further with motor milestones. Median age of clinical onset is 6 months of age, and life expectancy ranges from 2 years to the third decade. Inevitable spinal and joint deformities occur by the second decade of life. Management should be based on vigorous antibiotic therapy, orthopaedic and neurological surveillance, and a carefully planned educational programme aimed at realistic employment in late adolescence.

Spinal muscular atrophy in childhood. Two clues to clinical diagnosis

A coarse tremor was noted in 13 children suffering from the childhood form of spinal muscular atrophy. Tremor has not been seen in any other condition producing proximal muscle weakness in childhood, and its presence should therefore suggest the diagnosis of spinal muscular atrophy. In addition, the feet of patients with spinal muscular atrophy tended to evert, whereas in Duchenne muscular dystrophy there was either no deformity or a tendency to toe walking.

Electromyographic studies in parents of children with spinal muscular atrophy

Electromyographic studies have been carried out on the quadriceps and deltoid muscles of a number of healthy parents of children with infantile spinal muscular atrophy (types I and II) and the results compared with those obtained in healthy controls of the same sex. The results indicated an increase in mean amplitude of action potentials in quadriceps and deltoid muscles in both fathers and mothers (statistically significant in the quadriceps in the latter) of children with type I spinal muscular atrophy (Werdnig-Hoffmann disease). Increase in the mean amplitude in the quadriceps and deltoid muscles in mothers of children with type II spinal muscular atrophy and the mean duration of action potentials in the quadriceps muscle in mothers of children with type I and type II spinal muscular atrophy were also observed, but the differences from controls were not significant.

The nosology of the spinal muscular atrophies

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Werdnig-Hoffmann-Wohlfart-Kugelberg-Welander disease. Nosological unity and clinical variability in intrafamilial cases

Two members of an Italian family are affected with progressive spinal muscular atrophy. One, a male, has had the disease since his early infancy and, though severely disabled, is still living at the age of 13. In his sister, the first symptoms appeared at the age of 15, and the disease seems to be rapidly advancing. Their parents were consanguineous. Their mother, however, married twice, her second marriage being nonconsan-guineous and producing no affected children.

The study of this family and an analysis of the literature led to the following conclusions: (a) early onset of the disease does not necessarily mean that the course will be malignant; (b) the disease usually has a similar onset and course in subjects belonging to the same family.

In many families, however (and these have been examined in the present paper) malignant Werdnig-Hoffmann disease is found to coexist with the Werdnig-Hoffmann disease with a prolonged course, the Wohlfart-Kugelberg-Welander disease with infantile onset, and the Wohlfart-Kugelberg-Welander disease with juvenile onset. We feel, therefore, that from a genetic point of view all these forms should be included into one and the same group.