Electrophysiological study of subjects occupationally exposed to lead and with low levels of lead poisoning.

The relationship between the length of exposure to lead, blood lead level (PbB), and peripheral nerve damage in a population occupationally exposed to low lead levels was evaluated. Sixty-two foundry workers were studied whose length of exposure ranged from 5 months to 10 a; their mean PbB in the last 2 a had not exceeded 50 microgram/100 ml (2.4 mumol/l). The referents were 27 hospital employees, of comparable ages, not occupationally exposed to lead. The electrophysiological examination consisted of the determination of the motor conduction velocity (MCV) of the median, and peroneal nerves, sensory conduction velocity (SCV) of the median and sural nerves, and the latency of the T and H reflexes. The mean MCV, SCV and the amplitude of the sensory action potential (SAP) of the median nerve were significantly lower in the group of exposed workers than in the reference group. When the exposed subjects were divided into three groups according to length of exposure, no difference was observed between the three groups. When they were divided into different groups according to the maximum PbB (max PbB) value, the observed differences with respect to the reference groups were already present in those with a max PbB of less than 50 microgram/100 ml (less than 2.4 mumol/l), but were more evident in the subjects with a max PbB of greater than 70 microgram/100 ml (greater than 3.4 mumol/l). Within the group of subjects with a max PbB of 50-69 microgram/100 ml (2.4-3.3 mumol/l), the differences with respect to the reference values were more evident for subjects with a short length of exposure (less than 2 a). The MCV of the median nerve correlated with the time since the PbB exceeded 50 microgram/100 ml (2.4 mumol/l). In conclusion, the electrophysiological changes observed in lead-exposed subjects do not seem correlated with the length of exposure. Such alterations seem more evident in those subjects whose PbB has been greater than 70 microgram/100 ml (3.4 mumol/l) at least once during the preceding 2 a and in those subjects who, at the time of the neurophysiological examination, have a PbB greater than 50 microgram/100 ml (2.4 mumol/l). The apparently greater sensitivity to lead in new employees, compared to workers with a longer exposure time, remains to be clarified.

Relationship between clinical and electrophysiological findings and indicators of heavy exposure to 2,3,7,8-tetrachlorodibenzo-dioxin.

In this study the prevalence rate of peripheral neuropathy in a population living in an area polluted with 2,3,7,8-tetrachlorodibenzo-dioxin (dioxin-TCDD) was determined. Of the 723 subjects invited to the first screening in 1977, 470 (65%) attended. At the second screening in 1978, of the 710 invited subjects, 319 (45%) attended. Prevalence rate ratios for peripheral neuropathy and the associated 95% confidence limits were calculated for subgroups determined by the presence of (i) predisposing factors to neuropathy (alcoholism, diabetes, occupational exposure to neurotoxic agents, etc) or (ii) conditions thought to result from exposure to dioxin-TCDD such as chloracne or abnormal serum hepatic enzyme levels. The prevalence rate of peripheral neuropathy among those subjects with predisposing factors and among those with chloracne or abnormal serum hepatic enzyme levels was nearly three times greater than among those without these manifestations. The results derived from this study may be useful qualitative pointers for identifying subjects at risk in the neurological follow-up.

Incidence and survival of brain tumors: a population-based study.

Since 1976 the Lombardy Cancer Registry (RTL) has recorded all malignant tumors and the benign tumors of the nervous system, bladder and liver occurring in the Varese province. The aims of this report are: to describe age-specific incidence rates of the different oncotypes of primary nervous system tumors (PNSTs) and to analyze the duration of survival of the patients according to the histotype of the neoplasm. From 1976 to 1981, the RTL recorded 498 PNST: 213 tumors of glial origin, 132 tumors of mesodermal tissues, 15 tumors of multipotential cell origin, 37 tumors of nerve roots, 8 of vascular origin, and 54 PNST in which the histotype was not specified. For tumors of glial origin, the 60-69 year age class showed the highest incidence rate: 16 per 100,000/year. The incidence rate of tumors of mesodermal tissues reached the maximum value of 7.9 per 100,000/year in the age group of 75 years and over. Tumors of multipotential cell origin had a maximum incidence of 2.2 in the 60-69 year age class. The probability of survival at 5 years after diagnosis was computed by the method of Kaplan and Meier, and the log rank procedure was used to test statistical differences among survivors. Tumors of glial origin, excluding ependymomas and papillomas of choroid plexus, had a 5-year survival probability of 14%. Age (categorized in less than or equal to 50 and greater than 50 years) and histologic grade (grades I + II and grades III + IV) were analyzed as prognostic factors for tumors of glial origin: a younger age was the most predictive prognostic factor in grade I + II tumors (probability of survival = 53% in the group less than or equal to 50 years vs 0 in the group greater than 50 years; p less than 0.005). In the less differentiated tumors there were no differences between the two age groups. Patients with tumors of mesodermal tissues had a 5-year probability of survival of 83%. Subjects younger than 50 years had a probability of survival of 95%, whereas older patients had a probability of 79%. For the other oncotypes, the 5-year survival probability was: 50% for tumors of multipotential cell origin, 63% for ependymomas and papillomas of the choroid plexus, 64% for tumors of vascular derivation, and 21% for PNST with not specified histotype.

Gliomas and occupational exposure to carcinogens: case-control study.

Patients with gliomas of the central nervous system hospitalized during the period January 1979--March 1980 at the Neurological Institute C. Besta of Milan were compared with controls admitted to the Institute in the same period for nonneoplastic neurologic diseases or benign tumors. The comparison was based on occupational history, smoking habits, and alcohol consumption. Two analyses were carried out: the first by case-control pairs matched for age, sex, and residence; the second by age, sex, and residence stratification. Patients with glioma were more likely than controls to have worked in agricultural activities and showed a relative risk of 5.0 (p = 0.043) in the matched analysis and 1.9 (p = 0.113) in the analysis by stratification. This high risk was confined to those who performed agricultural work after 1960, suggesting a possible etiologic role of exposure to organic pesticides, fertilizers, and herbicides, which have only recently been commonly used in Italy. No significant difference was observed between cases and controls in regard to other analyzed occupations and habits.

A randomized trial on the treatment of the first epileptic seizure. Scientific background, rationale, study design and protocol. First Seizure Trial Group (FIR.S.T. Group).

Observational studies suggest that the sooner treatment is started after the onset of seizures the better is the outcome of the disease. However, when to start antiepileptic treatment is still debated and this may explain the different behaviour of practising physicians. For these reasons, a multicenter randomized controlled trial comparing the treatment of the first seizure and the treatment of the recurrences (the two most common strategies in clinical practice) has been started in Italy. The scientific background, the study rationale and design, and the general characteristics of the study population (498 patients) are presented here.

Electrophysiologic changes in workers with "low" blood lead levels.

In spite of numerous studies, the minimum level of lead exposure at which "sub-clinical" electrophysiologic abnormalities appear is still under discussion. Furthermore, it has not been clarified whether the electrophysiologic changes are directly related to PbB levels or to duration of exposure. This study was conducted on a group of 62 subjects occupationally exposed to lead with average blood lead levels below 50 microgram/100 ml and durations of exposure of less than 10 years. A reduction of motor and sensory nerve conduction velocities and sensory action potential amplitude of the median nerve was found in the subjects exposed to lead, as compared with a control group. Such abnormalities were already present in workers with the lowest blood lead levels, but were more severe in workers whose blood lead levels had exceeded 70 microgram/100 ml, even if this occurred only once in the last two years. The electrophysiologic changes did not correlate with duration of exposure but occurred very soon after initial exposure to lead.

Plasma levels of di-no-propylacetate and clonazepam in epileptic patients.

Plasma levels of DPA and CNP and associated antiepileptic drugs were measured in groups of respectively 106 and 30 epileptic patients aged from 3 to 49 years. A poor correlation between daily oral dose and plasma levels of both drug was observed when the whole group of patients was considered. A better correlation was seen in a group of adult patients who received DPA and PB. Children below 10 years of age disposed both drugs faster than adults and the difference was significant (p less than 0.01) in groups receiving PB as associated drug. Patients medicated with PB and DPA or CNP showed lower plasma levels of both drugs; on the other hand DPA appeared to cause a decrease of PB clearance which was more marked in children. The clinical significance of the fluctuations of daily plasma levels of both drugs are discussed in relationship to the schedule of administration and plasma sampling. Observations on the therapeutic ranges and adverse effect of the drugs are reported.

The Multiple Sclerosis Cooperative Etiological Study in Italy: preliminary analysis of CSF findings.

295 newly diagnosed Multiple Sclerosis (MS) patients were investigated for interdependence of CSF abnormalities: leukocyte count, CSF/serum albumin ratio, CSF IgG index and intrathecal synthesis of oligoclonal IgG. Only 7% of patients had no CSF abnormality. The most frequent abnormal finding was the presence of intrathecal synthesis of oligoclonal IgG. Polyacrylamide isoelectric focusing appeared more sensitive than agarose electrophoresis for the detection of abnormal CSF fractions. CSF IgG index had low negative and high positive predictive value when compared with electrophoretic methods. Suspected MS had the lowest frequency of abnormal CSF parameters. Patients with oligoclonal CSF bands (OB+) did not differ in age, sex, disease duration or annual bout rate from patients without oligoclonal bands (OB-). CSF leukocyte count was higher in OB+ than in OB- patients. Low CSF cell count was a hallmark of progressive disease. In OB+ patients CSF cell count correlated with CSF IgG index during the first five years of disease and declined with increasing disease duration. In later disease phases CSF IgG index correlated negatively with CSF/serum albumin ratio. 5 years follow-up of this series of patients is in progress to assess the diagnostic and prognostic values of CSF abnormalities in Multiple Sclerosis.