Amyotrophic lateral sclerosis. Its natural history.

ALS is the most common of the various MNDs, which also include the clinical entities of PBP, PMA, and PLS. Mean age of onset of ALS is 57 years, and there is a sex predilection for men in a ratio of 1.5:1. Area of first symptom is in the lower extremity is 36 per cent of cases, in the upper extremity in 32 per cent, and 25 per cent of patients have a bulbar onset. Motor cranial nerves in the lower brain stem from cranial nerve nuclei or corticobulbar tract degeneration are affected. This results in symptoms of speech and swallowing difficulty and emotional lability in up to 60 per cent of cases. One hundred per cent of cases have motor weakness, over 90 per cent have muscle atrophy and fasciculations, and 47 per cent have spasticity. There seems to be a pattern of progression of ALS signs and symptoms based on area of onset with LLE involvement tending to follow RLE weakness, LUE weakness following RUE onset, and RUE involvement following next in patients whose onset is bulbar. Significant numbers of ALS patients had sparing of involvement of parts of the body for follow-up times approaching 3 years. Although the majority of patients experience a deterioration that is significantly linear, seven of 28 patients or 25 per cent achieved a plateau lasting a minimum of 9 months. Survival in our series was 4.08 years for all forms of MND.(ABSTRACT TRUNCATED AT 250 WORDS)