F. Norris et al., ONSET, NATURAL-HISTORY AND OUTCOME IN IDIOPATHIC ADULT MOTOR-NEURON DISEASE, Journal of the neurological sciences, 118(1), 1993, pp. 48-55
Cases of adult-onset idiopathic motor neuron disease (MND) identified
from January 1970 through December 1986 were studied in a defined area
of California. The patients were followed prospectively throughout th
e illness in 99% of cases. Among 708 cases aged 25-74 years at onset,
the most common type (86%) was typical, sporadic amyotrophic lateral s
clerosis (SporALS). The risk of bulbar onset and shorter survival time
s increased with age in both men and women. About 4%, mainly younger m
en, experienced unusually long courses with milder paralysis, but coul
d not be identified early in the illness. They probably represent one
extreme of the ALS spectrum rather than a distinct subtype. Familial A
LS (FamALS) was diagnosed in 7%. It developed earlier in life but ran
a slightly longer course, which suggests a different disease process.
Overall there was a statistically significant predominance of males, e
specially in 17 cases (2%) of progressive muscular atrophy (PMA). Ther
e were 26 cases (4%) classified as primary lateral sclerosis (PLS). Pr
ogressive bulbar palsy was not found; that diagnosis usually denotes m
erely the bulbar onset of ALS.