Influence of ethnic and geographic factors on the classic photoparoxysmal response in the electroencephalogram of epilepsy patients.

The classic photoparoxysmal response (CPPR) on photic stimulation in the electroencephalogram (EEG) of 128 patients with chronic epilepsy, constituting three different ethnic groups, was investigated. All patients were referred for routine clinical EEG investigation. There was a significantly higher occurrence in whites (2.7%, of 72 of 2,657) as compared with blacks (0.1%, 1 of 848) and subjects of "mixed race" (0.9%, 55 of 5,958). Interictal abnormalities and the range of responses were similar in the two main ethnic groups. There was no evidence of a seasonal association with CPPR. We conclude that genetic rather than environmental factors influence the CPPR.

An early-onset recessive cerebellar disorder with distal amyotrophy and, in two patients, gross myoclonia: a probable ataxia telangiectasia variant.

We report a family of 4 siblings from a non-consanguineous marriage, presenting with an early onset recessive cerebellar ataxia and progressive distal limb wasting. Ocular or other telangiectasias were absent. There were neither frequent infections nor immunodeficiencies. The two youngest patients exhibited an incapacitating myoclonus which abated markedly after 20 years. Late onset diabetes was demonstrated in 3 patients. Hypogonadism was not a feature and there was a prolonged survival in the 4 patients. The oldest sibling died of a pancreatic adenocarcinoma. alpha-Fetoprotein was elevated with normal carcinoembryonic antigen values in three patients. Cytogenetic analysis and radioresistant DNA synthesis was compatible with the diagnosis of ataxia-telagiectasia. This family probably represents a rare variant of ataxia-telangiectasia.

Prevalence of a photoparoxysmal response in the electroencephalograms of epileptics in the three main ethnic groups of Namibia.

This descriptive study consists of 1493 EEGs from patients with epilepsy referred to the State Hospital in Windhoek, over the years 1983-1988. Excluded were patients with febrile convulsions, acute symptomatic epilepsy and a history of alcoholism. A standardized procedure of intermittent photic stimulation (IPS) was performed. The three main population groups blacks, coloureds (people of mixed race) and whites, were adequately represented in the sample. Classical photoparoxysmal responses (PPR) occurred in 0.4, 4.2 and 5.2%, respectively. Climatic factors are not considered relevant in the elicitation of a PPR. It is postulated that different mutations occurred in the genes that were involved in the expression of the PPR in epileptic patients of different ethnic groups.

Mycotoxic peripheral myelinopathy, myopathy, and hepatitis caused by Diplodia maydis in vervet monkeys.

During recent historical times many Africans changed their diet to one based on maize. The grain is regularly contaminated by fungi which are toxigenic to domestic animals and birds. After one of the fungi, Diplodia maydis, in pure culture on maize, was added to the food of omnivorous primates there was demyelination of nerves, atrophy, degeneration and necrosis of muscle, and hepatitis. These preliminary results are applicable to veterinary and laboratory animal sciences. They may also be medically significant since neuromuscular syndromes of unknown cause are prevalent among Africans. Nerve conduction velocities and organ weights are defined for vervet monkeys.

Lafora-body disease with optic atrophy, macular degeneration and cardiac failure.

A 17-year-old boy was admitted to hospital in acute cardiac failure and psychosis. The clinical course, EEG records and tissue diagnosis, including biopsies of brain, skin, skeletal muscle, peripheral nerve and liver were compatible with Lafora-body disease (LBD). Unusual features were those of optic atrophy and macular degeneration, signs generally regarded as negative criteria for the diagnosis of this disease. We also present the findings on endomyocardial biopsy which was performed because cardiac failure as an early symptom of LBD has not been previously described. The patient died in status epilepticus a few months after discharge from hospital.

Diagnostic problems of leptomeningeal lymphoma. A report of 3 cases.

Three cases are presented in which occult lymphoreticular malignant tumour spread to the spinal and cranial subarachnoid spaces inducing a problematic neurological illness characterised by poorly localised neuralgic pain, slowly progressive paresis and, in 2 patients, papilloedema with computed tomographic evidence of ventricular dilatation. Despite intensive investigations, diagnosis was only achieved at autopsy. A progressive disturbance of spinal and cranial nerve function should direct the attention of the clinician to the possibility of diffuse meningeal involvement by a malignant or inflammatory process.

'Locked-in' but not 'locked-out'. A case report.

The application of modern electronic apparatus in patients with the 'locked-in' syndrome can significantly improve communication.

Standards for the assessment of visual evoked potentials in an ethnically heterogeneous adult population.

Visual evoked potentials (VEPs) were recorded by chequerboard pattern-reversal stimulation in 276 normal adult subjects aged 15-73 years. The sample comprised comparable white, coloured and black groups of both sexes. Significantly shorter latencies of the major positive component were found in both male and female black subjects compared with those in whites. No significant differences were found between the amplitudes in the different population groups, but females in each population group showed significantly higher amplitudes of the major positive component than males. There was a close relationship between latency and amplitude for both right and left eyes. Except in coloured females, a non-linear relationship of the major positive component with age was demonstrated, the shortest latency being at about 35 years of age. It is suggested that the following criteria be used in the evaluation of VEP recordings: latency as well as the difference between latencies and amplitudes of the two sides of the major positive component (P1) as compared with standardized values for ethnic, sex and age groups.

The spectrum of disease in weakness and wasting of the quadriceps muscles. Case reports.

Three patients who presented with weakness and wasting of the quadriceps muscles ('quadriceps myopathy'), are reported. In each, electrophysiological and biopsy studies revealed completely different pathological processes, including motor unit disease, polymyositis and muscular dystrophy. Double biopsies performed in 2 of the patients showed the disease process to involve upper as well as lower limbs. The diffuse and heterogeneous nature of this form of neuromuscular disease is confirmed.

A study of a family with inherited disease of cardiac and skeletal muscle. Part II. Skeletal muscle morphology and mitochondrial oxidative phosphorylation.

Skeletal muscle morphology and mitochondrial oxidative phosphorylation capacity were examined in a family whose members showed very combinations of mental subnormality, cardiomyopathy and muscle weakness. Light and electron microscopic findings suggested a neuropathic process, while tests of mitochondrial function indicated a state of tight coupling of oxidative phosphorylation, a feature in marked contrast to those in biochemical studies so far reported.

A study of a family with inherited disease of cardiac and skeletal muscle. Part I. Clinical, electrocardiographic, echocardiographic, haemodynamic, electrophysiological and electron microscopic studies.

A family consisting of parents and their 6 sons were investigated to elucidate the relationship between a hypertrophic cardiomyopathy, musculoskeletal abnormalities and mental subnormality. The proband was diagnosed as having definite hypertrophic obstructive cardiomyopathy and the remaining family members were shown to have a spectrum of hypertropic non-obstructive cardiomyopathy. Mild muscle weakness was present in 3 sons. All the subjects except for 1 son showed definite signs of electromyographic abnormality, whereas sensory and motor conduction velocities were normal. All the EEGs except for that of the proband were normal. Testicular hypoplasia was present in 3 sons. The inheritance pattern appears to be polygenic autosomal recessive in type. Definite evidence of linkage between hypertrophic cardiomyopathy and HLA awaits further data.

A study of a family with inherited disease of cardiac and skeletal muscle. Part III. Genealogical considerations and associations with low intelligence.

A family with inherited cardiac and skeletal muscle disease was also found to have members with low intelligence. The effects of social and environmental conditions upon the behaviour of family members are described, with particular attention to the sociomedical problems created by the combination of a hereditary disease and low intelligence.

Photoparoxysmal responses in the electroencephalograms of some ethnic groups of the Cape Peninsula.

A comparative investigation of the frequency of photoparoxysmal responses (PPR) in the white, mixed and African populations of the Cape Peninsula is presented, based on 9697 consecutive referrals for EEG. PPR were observed in 2.5% of the white, in 1.3% of the mixed and in 0.9% of the African population groups. In the present material there were more patients with epilepsy in the mixed than in the white group, the frequencies changing with age in the two groups. Minor interrelationships of PPR exist with sex, age and race considered separately. Another minor relationship could be demonstrated between PPR and epilepsy. Three-factor interaction exists among epilepsy, age and race, and a further three-way interaction could be shown among sex, age and epilepsy. These relations and interactions were all significant below the 1% level. Standard EEG records (including response to hyperventilation) sensitivity limits to PPR, and the types of seizures themselves, did not differ significantly between the two main ethnic groups.

Occurrence of Taenia solium in a Cape fur seal (Arctocephalus pusillus).

The larval stage of Taenia solium was recovered from the brain, skeletal muscles, heart, lungs and liver of a Cape fur seal collected near Cape Town. This is apparently the second record of the larval stage of this cestode in a marine mammal.

Treatment of rheumatoid pachymeningitis involving the entire thoracic region.

A 67-year-old woman developed a spinal cord compression syndrome due to rheumatoid pachymeningitis with a roentgenological block from T2 to T11. The dura was surgically split from T1 to T12 and carefully dissected away from the spinal cord and then left open without grafting. The patient imporved and 3 years after the operation the spinal subarachnoid space and the circulation of cerebrospinal fluid were normal.