Abstract

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.