Guillain-Barré syndrome. Clinicoepidemiologic features and effect of influenza vaccine

A study of the epidemiologic and clinical features of Guillain-Barré syndrome in the population of Olmsted County, Minnesota, over the 46-year period 1935 through 1980 was conducted through the centralized diagnostic index maintained at Mayo Clinic, Rochester, Minn. A total of 48 cases were identified, giving an age- and sex-adjusted incidence of 1.8 per 100,000 person-years. The rate increased over time from 1.2 in the interval 1935 through 1956 to 2.4 in the interval 1970 through 1980. Males were affected more than females (age-adjusted rates of 2.3 and 1.2, respectively). The rate increased with age from 0.8 in those under 18 years old to 3.2 for those 60 years and older. Antecedent infectious diseases were reported in 65% of the cases. Implications with regard to the incidence of Guillain-Barré syndrome associated with the A/New Jersey/76 (swine flu) vaccine are discussed.     

Encephalitis and aseptic meningitis, Olmsted County, Minnesota, 1950-1981: I. Epidemiology

All cases fulfilling stated criteria for encephalitis and aseptic meningitis in Olmsted County, Minnesota, for the period 1950 through 1981 were identified. This is, to our knowledge, the first such incidence and trend study in a delineated population, providing rates per 100,000 person-years of 7.4 for encephalitis (189 cases) and 10.9 for aseptic meningitis (283 cases). These are about twelve and six times higher, respectively, than the rates reported by the Centers for Disease Control. The rates have been stable over successive 5- or 10-year periods except for a recent increase in aseptic meningitis. Both conditions were more common in the summer months, in childhood, and among males. Viral identification using conventional laboratory tests has improved with time; in the period 1970 through 1981, virus type was specified in about one-fourth of the cases. The most common agents identified were California and mumps viruses in encephalitis, and entero and mumps viruses in aseptic meningitis. Antecedent and/or concurrent infections were noted in 42 and 35% of encephalitis and aseptic meningitis cases, respectively. No case due to mumps, measles, or rubella viruses has occurred since 1972, reflecting the impact of immunizations. Recovery was reported at the end of the acute phase in 95% of patients with aseptic meningitis, and there were no deaths. Seventy-eight percent of encephalitis patients recovered completely; the case fatality rate was 3.8%. Of the encephalitis cases, 2% were diagnosed initially postmortem.     

Incidence of migraine headache: a population-based study in Olmsted County, Minnesota.

To determine the incidence of clinically detected migraine headache in the defined population of Olmsted County, MN, 1979-1981, we screened over 6,400 patient records from several diagnostic rubrics using the unique resources of the Rochester Epidemiology Project for population-based studies. We identified 629 Olmsted County residents who fulfilled the International Headache Society's 1988 criteria for newly diagnosed migraine headache between 1979 and 1981. The overall age-adjusted incidence was 137 per 100,000 person-years for males and 294 per 100,000 person-years for females. The highest incidence in females was among those aged 20 to 24 years (689 per 100,000 person-years), and in males, the highest incidence was among those aged 10 to 14 years (246 per 100,000 person-years). From 1979 to 1981, there was a striking increase in the age-adjusted incidence in those under 45 years of age: the incidence increased 34% in women and 100% for men. This is the first population-based study of migraine incidence across all ages.     

A reappraisal of the epidemiology of multiple sclerosis in Olmsted County, Minnesota

A review of multiple sclerosis (MS) case reports, using the unified record system at the Mayo Clinic for the Olmsted County population, revealed age- and sex-adjusted prevalence rates per 100,000 persons of 160 for Olmsted County and 173 for Rochester, Minnesota, on January 1, 1985. The annual age- and sex-adjusted incidence rate per 100,000 person-years from 1975 to 1984 for Olmsted County was 6.2 and for Rochester, 6.3. This incidence rate is significantly higher than what had been reported previously in Rochester (3.6/100,000) or in other communities. The estimated 25-year survival of the MS population was 76.2% +/- 4.5% compared with 87.7% for the general US white population of a similar age and sex. Survival for men was less than for women. There was no increase in survival for patients diagnosed with MS in more recent decades. No significant increase was found in cancer or autoimmune disease rates in the MS patients.     

Autopsy patterns for Parkinson's disease and related disorders in Olmsted County, Minnesota.

Using a records-linkage system, we determined the frequency and distribution of brain autopsies in residents of Olmsted County, Minnesota, in whom parkinsonism developed during 1976 through 1990. Of the 364 incident cases identified, 235 patients were deceased at the time of record abstraction. The overall autopsy rate was low (23%). Diagnostic certainty (for PD), diagnostic type (PD versus other parkinsonism), sex, age at death, and location at death were important selection factors for autopsy.     

Incidence of Epilepsy and Unprovoked Seizures in Rochester, Minnesota: 1935–1984

Summary: The incidence of epilepsy and of all unprovoked seizures was determined for residents of Rochester, Minnesota U.S.A. from 1935 through 1984. Ageadjusted incidence of epilepsy was 44 per 100,000 personyears. Incidence in males was significantly higher than in females and was high in the first year of life but highest in persons aged ≥75years. Sixty percent of new cases had epilepsy manifested by partial seizures, and two thirds had no clearly identified antecedent. Cerebrovascular disease was the most commonly identified antecedent, accounting for 11% of cases. Neurologic deficits from birth, mental retardation and/or cerebral palsy, observed in 8% of cases, was the next most frequently identified preexisting condition. The cumulative incidence of epilepsy through age 74 years was 3.1%. The age-adjusted incidence of all unprovoked seizures was 61 per 100,000 person-years. Age-and gender-specific incidence trends were similar to those of epilepsy, but a higher proportion of cases was of unknown etiology and was characterized by generalized onset seizures. The cumulative incidence of all unprovoked seizures was 4.1% through age 74 years. With time, the incidence of epilepsy and of unprovoked seizures decreased in children and increased in the elderly.     

The risks of epilepsy after traumatic brain injury.

The aim of this study is to present the incidence of traumatic brain injury (TBI) and identify those characteristics of brain injuries that are associated with the development of seizures. We identified 5984 episodes of TBI (loss of consciousness, post-traumatic amnesia, or skull fracture) in Olmsted County, Minnesota, from 1935 to 1984. Of these, 4541 were followed for seizure. Injuries were classified as mild (loss of consciousness or amnesia less than 30 minutes), moderate (loss of consciousness 30 minutes to 1 day or a skull fracture), or severe (loss of consciousness of more than 1 day, subdural hematoma, or brain contusion). The incidence of TBI in the period from 1975 to 84 peaked at 800 per 100 000 in males aged 15-24. The relative risk of seizures was 1.5 (95 percent confidence interval 1.0-2.2) after mild injuries, but with no increase after 5 years; 2.9 (95 percent confidence interval 1.9-4.1) after moderate injuries; and 17.2 (95 percent confidence interval 12.3-23.6) after severe injuries. Significant risk factors were brain contusion with subdural hematoma, skull fracture, loss of consciousness or amnesia of 1 day or more, and age over 65 years. We conclude that TBI is a major public health problem and contributes to the occurrence of seizures and epilepsy.     

Incidence and effectiveness of cerebrospinal fluid shunts in Olmsted County, Minnesota, 1956-1981

In the period 1956 through 1981, 129 cerebrospinal fluid (CSF) shunt operations were performed on 50 patients who were residents of Olmsted County, Minn. The overall average annual age- and sex-adjusted incidence of initial CSF shunts during this 26-year period was 2.3 per 100,000 person-years. Within 5-year calendar time intervals, the average annual incidence rates per 100,000 person-years ranged from 0.8 (1956-1960) to 4.6 (1971-1975). There were 4 shunt-related deaths, 1 due to a CSF shunt infection and 3 due to acute increases in intracranial pressure. In this analysis of shunt procedures in a defined population, the diagnostic indications and changes over time in CSF shunting devices are also described.     

Incidence and distribution of parkinsonism in Olmsted County, Minnesota, 1976-1990

OBJECTIVE: Limited information is available on the frequency and distribution of parkinsonism as a syndrome. We studied the incidence of parkinsonism and its specific types among residents of Olmsted County, MN, for the period from 1976 through 1990. METHODS: We used the medical records linkage-system of the Rochester Epidemiology Project to identify all individuals whose records contained documentation of any form of parkinsonism, related neurodegenerative diseases, or tremor of any type. A nurse abstractor screened the records, and, when applicable, a neurologist reviewed them to determine the presence of parkinsonism using specified diagnostic criteria and to define the year of onset. RESULTS: We found 364 incident cases of parkinsonism: 154 with PD (42%), 72 with drug-induced parkinsonism (20%), 61 unspecified (17%), 51 with parkinsonism in dementia (14%), and 26 with other causes (7%). The average annual incidence rate of parkinsonism (per 100,000 person-years) in the age group 50 to 99 years was 114.7; incidence increased steeply with age from 0.8 in the age group 0 to 29 years to 304.8 in the age group 80 to 99 years. The cumulative incidence of parkinsonism assuming no competing causes of death was 7.5% to age 90 years. PD was the most common type of parkinsonism, followed by parkinsonism in dementia in men and drug-induced parkinsonism in women. Men had higher incidence than women at all ages for all types of parkinsonism except drug-induced. CONCLUSIONS: Parkinsonism is a common disease among the elderly; its incidence increases steeply with advancing age and is consistently higher in men. The distribution by type changes with age and gender.     

Short-term outcomes of skull fracture: a population-based study of survival and neurologic complications

All Olmsted County, Minnesota, residents who experienced brain injury from 1935 through 1979 were identified and their medical records reviewed for survival and neurologic outcome. Minimum inclusion criteria included loss of consciousness or post-traumatic amnesia or neurologic evidence of brain injury or skull fracture. Of 4,660 cases identified, skull fractures were observed in 28%. Over half of brain-injured patients who died did so within 24 hours of trauma; among 1-day survivors, subsequent survival was moderately impaired, especially in older individuals. Mortality was lowest in subjects without a skull fracture and increased with fracture severity. Associated neurologic injuries, complications, and deficits were generally more common in patients with skull fracture than those without and were much more frequent with more severe skull fractures. The types of neurologic deficits differed little between those with and without fractures, except that subjects with complicated skull fractures had higher proportions of special sensory deficits and multiple deficits.     

Long-term survival after traumatic brain injury: a population-based analysis

This population-based retrospective cohort study identified all Olmsted County, MN residents with any diagnosis indicative of potential traumatic brain injury (TBI) during the years 1985 to 2000. The complete community-based medical records of a random sample (n = 7,175) were reviewed to confirm and characterize the event, and to determine vital status through 2002. The review identified 1,448 confirmed incident cases; 164 (11%) were moderate to severe; 1,284 were mild. The estimated 30-day case fatality rate was 29% for moderate to severe cases and 0.2% for mild cases. Comparison of observed mortality over the full period of follow-up with that expected revealed a risk ratio (95% CI) of 5.29 (4.11-6.71) for moderate to severe cases and 1.33 (1.05-1.65) for mild cases. Proportional hazards modeling showed the adjusted hazard of all-cause mortality for moderate to severe cases relative to mild cases was 5.18 (3.65-7.3) within six months of the event and 1.04 (0.57-1.88) for the remaining follow-up period. This analysis indicates that persons who experience mild TBI exhibit a small but statistically significant reduction in long-term survival compared to the general population. The case fatality rate for persons with moderate to severe TBI is very high, but among six-month survivors, long-term survival is similar to that for persons with mild TBI.     

Amyotrophic lateral sclerosis in Olmsted County,Minnesota, 1925 to 1998

The authors sought to determine trends in the incidence of ALS in Olmsted County from 1925 to 1998. Seventy-seven cases of ALS were identified during the period studied. The incidence rate remained stable at 1.7 cases per 100,000 people per year. Mean age at onset was 63 years. Mean survival was 23 months from diagnosis. Mean survival for patients <60 years old was 31 months; for patients aged >or=60 years, it was 20 months (p = 0.02). Mean time from symptom onset to diagnosis was 13 months. Neither survival nor time to diagnosis changed significantly over time.     

Reye's syndrome: incidence and time trends in Olmsted County, MN, 1950-1981

Incidence and time trends of Reye's syndrome have been determined in Olmsted County, MN, using the facilities of the Rochester Epidemiology Program Project at Mayo Clinic. Incidence rates in individuals under 18 years of age were 1.1 per 100,000 person-years in the 1970-75 time interval and 1.7 in the 1976-81 interval. Failure to identify any case in the earliest time interval yields a rate of zero, and an incidence higher than 0.6 per 100,000 can be excluded with 95% probability. This finding is consistent with an increasing incidence over time in this community and does not exclude the possibility that Reye's syndrome did not exist in Olmsted County before 1970.     

A clinical and autopsy study of dementia in Olmsted County, Minnesota, 1980-1981

The clinical records and autopsy protocols were studied from 350 cases in which an autopsy was done in Olmsted County, MN, in 1980 and 1981. Overall autopsy rate was 33.6%, and autopsy rate for those aged 60 years or more was 29%. Preselected criteria were used for diagnosis of dementia. Thirty-two demented and 68 nondemented patients had complete autopsies; all were more than 60 years old. Twenty-three of 32 (72%) demented patients had Alzheimer's disease. The frequency of cerebral infarcts among the nondemented patients was significantly higher than among the demented patients (p = 0.02).     

Levodopa-dyskinesia incidence by age of Parkinson's disease onset.

We assessed the 5-year risk of levodopa-induced dyskinesias by age of Parkinson's disease (PD) onset in a population-based cohort. The medical records linkage system of the Rochester Epidemiology project was used to identify residents of Olmsted County, Minnesota, with incident PD for the period 1976 through 1990. In this population-based study, the 5-year dyskinesia incidence declined with age. With PD onset after 70 years of age, the incidence was 16%. With onset from 40 to 59 years of age, the incidence was higher at 50%. These incidence data may overestimate the functional importance, because patients with minimal or reversible dyskinesias were counted.     

Number of children and risk of Parkinson's disease.

We investigated the association between number of children and Parkinson's disease (PD) in two independent studies. In a case-control study, we identified all subjects who developed PD in Olmsted County, MN, from 1976 through 1995, and matched them individually by age (+/-1 year) and sex to population controls (193 cases and 193 controls). The replication study was a population-based cohort study of 6,341 subjects from Rotterdam, the Netherlands (2,610 men). In the Olmsted County study, men who fathered at least one child had an increased risk of PD (unadjusted OR, 2.7; 95% CI, 1.2-6.1; P = 0.02), and the risk increased with increasing number of children. The findings in women were not significant. In the Rotterdam Study, the risk of PD increased significantly with increasing number of children in men (test for linear trend, unadjusted; P = 0.04), but not in women. The findings from both studies remained consistent in direction but reduced in magnitude of the association, and lost significance after simultaneous adjustment for education, cigarette smoking, alcohol consumption, and coffee consumption. The independent replication in two distinct populations and using different epidemiologic study designs may suggest a link between the number of children and PD restricted to men.     

Time trends in the incidence of parkinsonism in Olmsted County, Minnesota

OBJECTIVE: To investigate time trends in the incidence of parkinsonism and PD over a 15-year period (1976 to 1990). METHODS: The authors used the medical records-linkage system of the Rochester Epidemiology Project to identify incidence cases of parkinsonism in Olmsted County, MN, over three 5-year periods, 1976 to 1980, 1981 to 1985, and 1986 to 1990. PD and other types of parkinsonism were classified using defined criteria. Population denominators were derived from census data and were corrected by removing prevalent cases of parkinsonism. RESULTS: Over the 15 years of the study, 364 cases of parkinsonism were identified; 154 (42%) of them had PD. The incidence of parkinsonism remained stable over the three 5-year periods for the age classes 0 to 39, 40 to 59, and 60 to 69 years. For the age class 70 to 99 years, there was some increase over time mainly owing to an increased incidence of drug-induced parkinsonism. The incidence of PD remained stable over the three 5-year periods for all age classes. Results were similar when considering men and women separately. No birth-cohort effect was present for parkinsonism. Comparison with three previous studies in the same population did not reveal any major long-term secular trends in the incidence of parkinsonism. CONCLUSIONS: The findings for PD over 15 years and comparison of the findings with historical data for parkinsonism over half a century suggest that no major environmental risk factors for PD (e.g., environmental toxins, drugs, diet constituents, or infectious agents) were introduced or removed from this population during these periods.     

Brain injury and neurologic sequelae: a cohort study of dementia, parkinsonism, and amyotrophic lateral sclerosis

We reviewed the medical records of 821 Olmsted County residents who had suffered head trauma with presumed brain injury between 1935 and 1974 and were more than 40 years old at the time of their last medical assessment. These patients were followed over 15,000 person-years for dementia and other degenerative neurologic diseases. The standardized morbidity ratio (SMR) for dementia was 1.06, and the SMR for dementia of the Alzheimer type was 1.00. These values are not significantly elevated and are inconsistent with studies that suggest that head trauma is a risk factor for Alzheimer's disease. In addition, the SMRs for parkinsonism (1.04), Parkinson's disease (0.94), and amyotrophic lateral sclerosis (1.05) were not significantly elevated, providing no evidence that head trauma is a risk factor for these disorders. However, these latter results are based on smaller total case numbers.     

Late effects of paralytic poliomyelitis in Olmsted County, Minnesota

We identified a cohort of 300 individuals who had paralytic polio between 1935 and 1955. All lived in Olmsted County, Minnesota. From the 247 survivors, we selected 50 subjects for detailed historical, functional, psychological, clinical, and electrophysiologic evaluation. Sixty-four percent of these 50 survivors complained of new symptoms of muscle pain, fatigue, and weakness after a period of prolonged stability. This led to changes in lifestyle or activity in only 18%. The likelihood of expressing new complaints was not related to present age or interval since polio, and electrophysiologic testing did not distinguish between those with or without new problems. The development of new difficulties in a limb was most strongly predicted by significant paralysis of that limb at the time of the acute illness. Patients with leg weakness were twice as likely to complain of new problems compared to those with arm weakness. Elevated creatine kinase levels were present only in those with new complaints.     

Incidence of neuroepithelial primary brain tumors among adult population of Emilia-Romagna Region,Italy

Incidence of neuroepithelial Primary Brain Tumors (nPBT) varies, ranging from 7.3 to 11.6 cases/100,000/year across Europe. We present incidence and survival of nPBT in the Emilia-Romagna region (ER), Italy. This study is the largest in Southern Europe. Specialists in neurosurgery, neurology, neuroradiology, oncology, radiotherapy, genetics, and pathology of ER notified all suspected nPBT adult cases residing in ER (4,337,966 inhabitants) observed during 2009. Furthermore, through ICD-9 discharge codes, we identified and reviewed all possible cases. Neuroepithelial PBT diagnosis was based on histological or radiological findings. We included 400 incident nPBT cases, of which 102 (25%) were retrospectively identified. These latter were significantly older. The standardized incidence was 10.5/100,000/year (95% CI 9.4–11.5), higher for men. It was 9.2/100,000/year (95% CI 8.3–10.2) for astrocytic tumors, 0.6/100,000/year (95% CI 0.4–0.9) for oligodendroglial tumors, and 7.1 (95% CI 6.3–8.0) for glioblastoma (GBM). Among GBM patients, median survival was 249 days if prospectively identified vs. 132 days when identified through ICD-9 codes (p < 0.0001). The incidence of nPBT in the ER region is among the highest in the literature. Older patients were more likely to escape an active surveillance system. This should be considered when comparing incidence rates across studies, giving the increasing number of elderly people in the general population.