Motor neuron disease in Lehigh county, Pennsylvania: an epidemiologic study

Epidemiology of motor neuron disease in the Kii Peninsula of Japan, 1989-1993: active or disappearing focus?

During the period 1989-1993, the incidence and migration patterns of patients with motor neuron diseases (MND) in Wakayama Prefecture, including one of the high-incidence Kii Peninsula foci ('Kozagawa focus'), were surveyed to determine whether the focus had truly disappeared or not. Overall, the crude average annual incidence was 1.43 per 100000 population; when age-adjusted to the 1990 Japanese population, it was 1.25 (1.85 for males and 0.61 for females). The average annual age- and sex-specific incidence steadily increased to a peak between 60 and 69 years and dropped after 70. Geographically, the rates varied in the five regions of Wakayama Prefecture from 0.38 to 2.48. The areas with high incidence were distributed in the central and southernmost regions; the highest was in the Kozagawa focus with 9.54 (two ALS cases within five years; 4193 base population, 1990). During the study period, four emigrants from Kozagawa had developed MND one to four decades after leaving the focus. Although the remarkable clustering of MND was thought to have disappeared, the southern Kii Peninsula remains a high-risk area for MND, especially if one interprets the data so as to include the emigrants. In general, the age at onset has increased in the past 20 years from 56.5 to 61.7; male predominance is observed.

Clinical epidemiology of amyotrophic lateral sclerosis

The introduction of palliative therapies in amyotrophic lateral sclerosis (ALS) will alter the epidemiology of ALS as it is known now. Although incidence rates will remain unchanged in the near future, prevalence rates will likely increase dramatically. Better understanding of the age-specific presentation of motor neuron diseases worldwide will shed light on the vexing questions concerning the variable incidence rates in some countries and apparent incidence gradients in North America and Europe.

Adult onset motor neuron disease: worldwide mortality, incidence and distribution since 1950

This review examines the commonly held premise that, apart from the Western Pacific forms, motor neuron disease (MND), has a uniform worldwide distribution in space and time; the methodological problems in studies of MND incidence; and directions for future epidemiological research. MND is more common in men at all ages. Age-specific incidence rises steeply into the seventh decade but the incidence in the very elderly is uncertain. A rise in mortality from MND over recent decades has been demonstrated wherever this has been examined and may be real rather than due to improved case ascertainment. Comparison of incidence studies in different places is complicated by non-standardised methods of case ascertainment and diagnosis but there appear to be differences between well studied populations. In developed countries in the northern hemisphere there is a weak positive correlation between standardised, age-specific incidence and distance from the equator. There is now strong evidence for an environmental factor as the cause of the Western Pacific forms of MND. A number of clusters of sporadic MND have been reported from developed countries, but no single agent identified as responsible.

Epidemiology of amyotrophic lateral sclerosis in Hordaland county, western Norway

The incidence, prevalence and prognosis of amyotrophic lateral sclerosis (ALS) in the county of Hordaland, western Norway were determined for the years 1978 through 1988. The average annual incidence rate was 1.60 per 100,000 population with a male to female ratio of 1.26 (95% confidence interval: 0.76-2.09). The maximal age-specific annual incidence was 8.12 per 100,000 and occurred in the age-group between 61 and 65 years. The prevalence of ALS was 3.67 per 100,000 on December 31, 1988. The average age at the onset of the disease was 60.9 years ranging from 34 to 82 years of age. Survival was studied with life table techniques. Median survival from the onset of symptoms was 28.0 months overall. In patients with bulbar onset the median survival was 24.0 months whereas it was 40 months in patients with spinal onset of disease (log rank test, P = 0.0004). The difference in survival between ALS with bulbar or spinal onset was not explained by age or sex differences in the two groups.

Population frequencies of neuromuscular diseases--II. Amyotrophic lateral sclerosis (motor neurone disease)

A summary of the world literature on the prevalence of amyotrophic lateral sclerosis (motor neurone disease) has been carried out. Excluding those particular isolates with especially high prevalences (e.g. Guam and the Kii Peninsula of Japan), the mean prevalence among both sexes in other populations is around 41.6 x 10(-6) or 1 in 24,000.

Amyotrophic lateral sclerosis in Palermo, Italy: an epidemiological study

The incidence, prevalence and natural course of ALS were determined in the population of the province of Palmero, Italy. The average annual incidence calculated for the years 1973 through 1984, was 044./100.000 inhabitants. The prevalence rate on prevalence day December 31, 1984, was 1.67/100.000 population. The male/female ratio was 1.38. The mean age at onset was 54.3 +/- 11.02. The most common clinical form was the conventional one (61.4%); the bulbar form was more frequent among females than males. The mean duration of the disease was 33.7 +/- 35.8 months. The longest duration belongs to the pseudopolyneuritic form. The median survival was 36 months: 16 months for the bulbar, 36 months for the conventional and 51 months for the pseudopolyneuritic form.

Evidence for clustering of amyotrophic lateral sclerosis in Wisconsin

Clustering of amyotrophic lateral sclerosis (ALS) occurs in the western Pacific, but has not been convincingly demonstrated for the sporadic form of the disease which occurs throughout the rest of the world. Using death certificate data we identified 529 ALS-associated deaths in Wisconsin during the interval 1973-82, representing a statewide mortality rate of 1.12 deaths/100,000/yr. Using computer simulation we show that cases were not homogeneously distributed throughout the population and that there exists a significant cluster of cases in northeastern Wisconsin.

Amyotrophic lateral sclerosis in Nova Scotia

A study of ALS incidence in Nova Scotia for a ten year period was carried out with the cooperation of neurologists, neurosurgeons, physiatrists and major medical hospitals. Over a ten year period 161 cases occurred, an incidence of 1.95 per 100,000 population in a province with a population of 825,000. There was an increase in incidence over the ten year period, with an incidence for the first five years of study of 1.50 per 100,000, and 2.40 per 100,000 for the latter five years. The peak incidence in 1981-1982 was 2.66 per 100,000. Although this is the highest incidence in community studies of ALS (excepting the unusual circumstances in Guam), it may reflect the realistic incidence of ALS rather than an unusual focus, as ascertainment was likely greater than in many other studies. The more significant finding is the suggestion of an increasing incidence, as noted in other studies in the U.S., England and Israel.

A survival analysis of 155 cases of progressive muscular atrophy

We performed a survival analysis of 155 cases of progressive muscular atrophy (PMA). In about half the cases, hands were involved first, the lower limbs in 30% and the shoulder girdle in 23%. The lifetables of PMA, adjusted to the expected mortality, showed a survival rate of 61.3% and 56.4% at three and five years, respectively. The location of onset symptoms did not modify the life expectancy, whereas the age of the patients at the moment of first diagnosis had a great influence on the course of the disease. The patients were further subdivided in two groups on the basis of the diffusion of the neuromuscular damage at the moment of the diagnosis. The course of the patients with a localized disease was markedly better than that of subjects with widespread disease. Some hypotheses are made about the latter group of cases.

Epidemiologic study of amyotrophic lateral sclerosis in Sardinia, Italy

From 1957 to 1980 in Sardinia, 182 cases of ALS with a mean annual incidence of 0.51 per 100,000 inhabitants and a prevalence rate of 3.65 per 100,000 inhabitants (prevalence day 21.10.1971) were observed. The disease was found to be more common in males, in subjects aged 50 to 70 years and in farmers and shepherds. Incidence in various areas of the island was found to be different. The common form was more frequent, had earlier onset and greater median survival rate.

Motor neuron disease in the Province of Turin, Italy, 1971-1980

The incidence and prevalence of motor neuron disease (MND) in the Province of Turin, North-West Italy, were investigated for the period 1971-1980. The crude incidence rate of MND was 0.67/100,000/year. The annual incidence rate, age and sex adjusted to the Italian population in 1971 was 0.69 cases per 100,000 inhabitants, 0.94 for men and 0.45 for women, with a male to female incidence ratio of 2.09:1. The prevalence of MND was 2.62/100,000, 3.57 for males and 1.71 for females. The mean age at the time of diagnosis was 55.6 years. Annual incidence rates increased with advancing age. Amyotrophic lateral sclerosis was found to be 4 times more frequent than progressive muscular atrophy (0.53/100,000/year v. 0.14/100,000/year). The distribution of MND was uneven in the Province suggesting a proportional relationship to the distribution of population density. Possible explanations of this finding are discussed.

Epidemiology of motor neuron disease in northern Sweden

All cases of motor neuron disease (MND), encompassing amyotrophic lateral sclerosis (ALS), progressive bulbar paralysis (PBP) and progressive spinal muscular atrophy (PSMA), in northern Sweden, diagnosed between 1969-1980 have been analysed. 128 cases were found, corresponding to an average annual incidence rate of 1.67 per 100,000. The prevalence on December 31, 1980 was 4.8 per 100,000. Age-specific incidence rates were higher in the high age groups with a maximum at 60-64 years for males, at 70-74 years for females and at 65-69 years for the sexes combined. The median age at onset was 61 years. Clustering was not found in mining districts and overrepresentation of miners and stone treaters was not observed. Minor differences in incidence rates, as measured by the standardized morbidity ratio, SMR, were found between the inland, coastal and mountain areas. The median survival time after onset of disease was 32 months for ALS, 30 months for PBP and 70 months for PSMA. The combined survival rate for all MND cases was 28% after 5 years and 15% after 10 years. The male to female ratio was 1.1:1, and 4.7% were familial cases.

Amyotrophic lateral sclerosis in Middle-Finland: an epidemiological study

Amyotrophic lateral sclerosis (ALS) was diagnosed in 36 patients in Middle-Finland Central Hospital District during 1976-1981. The annual incidence of ALS was 2.4 per 100,000 population and the prevalence rate was 6.4 per 100,000 population. The age-specific incidences of ALS were similar for men and women with a maximum of 14/100,000/year in the age group 60-69 years. The initial symptoms originated in 37% of the patients from bulbar and in 63% from spinal levels. Bulbar onset was more common in patients aged 60 years or more compared with younger patients. Patients with bulbar onset had a significantly poorer prognosis than those with spinal onset, which explained the poorer prognosis of older patients. 4 matched controls were chosen for each ALS patient from the files of the Central Hospital. There was no difference between the patients and the controls with respect to previous injuries, surgical operations, malignant neoplasms, or exposure to domestic animals. An earlier observation that evacuees from Karelia ceded to USSR after World War II should have a prevalence twice that of the remaining population was not substantiated.