Gadolinium ring enhancement and mass effect in acute disseminated encephalomyelitis

A 9-year-old boy presented with a subacute history of optic neuritis followed by brainstem involvement, with fever and a lymphocytic pleocytosis in the cerebrospinal fluid. Gadolinium-enhancing ring lesions were demonstrate in the white matter of the cerebrum, brainstem and cerebellum on day 17 of the illness, all appearing simultaneously as part of a monophasic illness. A parietal lesion exerted mass effect. Needling and biopsy yielded no evidence of a pyogenic lesion, tumour or tuberculosis and showed vasculitis. There was insufficient material for myelin staining. Dexamethasone therapy lead to rapid improvement of the radiological lesions: MRI and CT on day 34 of the illness showed complete clearing of the lesions except for residual abnormality at the biopsy site.     

Auditory brainstem evoked potentials in leprosy

An electrophysiological study of conduction in the auditory nerve and brainstem auditory pathways using the brainstem auditory evoked potential was undertaken in a group of 47 leprosy patients. There were no statistically significant differences between mean conduction times (interpeak latencies) in the leprosy and the control groups. Abnormal interpeak latencies were encountered in 3 leprosy patients, 1 of whom had a positive serological test for syphilis. In the remaining 2 patients, caudal pathway dysfunction (I-III interpeak latency abnormality) was indicated but specific auditory nerve involvement (an abnormally prolonged I-II interpeak latency) was not demonstrated. An explanation for these findings, other than the patients' disease, was not apparent.     

Huntington's disease: genetic heterogeneity in black African patients.

OBJECTIVE: Huntington's disease (HD) has been reported to occur rarely in black patients. A new genetic variant- Huntington's disease-like 2 (HDL2)--occurring more frequently in blacks, has recently been described. The absence of an expanded trinucleotide repeat at the chromosome 4 HD locus was previously regarded as a way of excluding classic HD. The objective of this paper is to describe a number of black patients with genetically proven HD and to review its occurrence in Africa. METHODS: Eleven black families (12 subjects), with genetically proven HD, are described: 9 from the Dr George Mukhari Hospital, and 2 from private practice in Tshwane. RESULTS: Chorea was present in all 12 patients and cognitive decline in 9. Nine had an age of onset between 30 and 50 years. Six families exhibited expansion of the trinucleotide repeat at the chromosome 4, IT 15 gene (HD), and 5 a junctophilin (JPH3) trinucleotide expansion at chromosome 16 (HDL2). The HDL2 subtype showed a tendency towards a later age of onset. CONCLUSIONS: The clinical presentation of the two genotypes (i.e. HD and HDL2) appears to be similar. The actual rate of occurrence of HD in blacks may require re-assessment. Considering the number of Huntington's chorea patients occurring in our area (Garankuwa), the possibility of clustering of the condition arises.     

Effects of two anticholinergic drugs on electroretinograms and visual evoked potentials in healthy human subjects

A battery of electroretinograms (ERGs) and visual evoked potentials (VEPs) were recorded from 12 normal, male volunteers after the intravenous administration of either biperiden 2.5 mg, atropine 1.5 mg or placebo, at weekly intervals. Self-reports indicated that both drugs caused significantly reduced levels of alertness compared to placebo, but more so with biperiden than atropine. Biperiden was not, however, associated with significant changes to ERGs, while atropine caused a few isolated, significant increases to implicit times. There were no significant treatment effects on pattern ERGs or VEPs. The flash VEP latencies and amplitudes recorded after the anticholinergics did not differ from placebo. These preliminary findings suggest that these anticholinergics do not have marked effects on either ERGs or VEPs.     

Effects of clobazam and clonazepam on saccadic eye movements and other parameters of psychomotor performance

Summary The effects of two benzodiazepine anti-convulsants clobazam (20 mg) and clonazepam (2 mg) in a variety of psychomotor performance tests were compared in a placebo controlled double-blind acute oral dose study in ten healthy volunteers. Assessments included critical flicker fusion (CFF) threshold, the Sternberg memory scanning and choice reaction time (CRT), peak saccadic velocity (PSV) and visual analogue scales, all previously shown to be sensitive to the effects of benzodiazepines.Clobazam did not significantly impair saccadic eye movements, CFF threshold, Sternberg memory scanning and CRT compared to placebo. Clonazepam significantly lowered PSV, reduced the CFF threshold, slowed the Sternberg CRT and decreased an alertness factor in the visual analogue scales compared to placebo. Clonazepam significantly increased memory scanning time compared to clobazam. Clobazam was remarkably free of cognitive and psychomotor side-effects.     

Effects of single doses of diazepam, chlorpromazine, imipramine and trihexyphenidyl on visual-evoked potentials

There is increasing evidence that the P 100 peak of the pattern-reversal visual-evoked potential (VEP-PR) is delayed by drug-induced dopamine antagonism and in Parkinson's disease. Recent studies have reported that components of the flash-VEP (VEP-F) are delayed by an anticholinergic which does not affect the VEP-PR. The present study found that a single dose of chlorpromazine increased the latencies of the VEP-PR and of the VEP-F and increased the VEP-F P2 amplitude. Trihexyphenidyl increased the VEP-PR amplitude but had only minor effects on the VEP-F. There was a tendency for imipramine to increase VEP-F latencies, especially the N3 peak, but had no effect on the VEP-PR. Both VEPs were unaffected by diazepam. These VEP findings add further support to the role of dopamine in the human visual system. Possible reasons are advanced for the failure of trihexyphenidyl to cause previously reported VEP changes associated with hyoscine hydrobromide. Several important issues need to be addressed by future research.     

Effect of Acute Doses of Controlled-Release Carbamazepine on Clinical,Psychomotor, Electrophysiological,and Cognitive Parameters of Brain Function

Summary: The neurotoxic effect of acute doses of carbamazepine controlled-release (CBZ-CR) divitabs (800, 1,200, and 1,600 mg) was assessed on clinical, psychomotor, electrophysiological, and cognitive parameters of brain function in 10 healthy volunteers in a double-blind, randomised, placebo-controlled, phase I study. Significant changes compared to placebo were demonstrated for the clinical scales, ataxia (AT), convergence of the nearpoint (CNP), peak saccadic velocity (PSV), critical flicker fusion (CFF), spectral analysis of the EEG, and brainstem auditory evoked potential (BAEP) tests. Digit repetition, digit symbol substitution, Sternberg memory scanning time, Sternberg choice reaction time, saccadic latency, and saccadic accuracy showed important negative findings. Significant clinical tolerance to side effects developed within 20 to 33 h after CBZ-CR dosage during a period in which the mean CBZ blood levels remained virtually unchanged. CBZ-CR, 800, 1,200, and 1,600 mg yielded low, medium, and high therapeutic blood levels, respectively, for + 10 to + 33 h after dosage without the development of severe clinical side effects.     

Myotonic dystrophy. Part II. A clinical study of 96 patients

To demonstrate the widespread manifestations of myotonic dystrophy the clinical features of 96 patients are reviewed. The study includes 24 children, 6 of whom have congenital myotonic dystrophy.     

Myotonic dystrophy. Part I. A genealogical study in the northern Transvaal

Myotonic dystrophy is a disabling multisystem disorder which appears to be more common in South Africa than is generally recognized. Twenty white kindreds with the disease were studied; of these 4 large kindreds had a common ancestry. Genealogical data for 1 527 individuals were acquired. The minimum prevalence of myotonic dystrophy in the northern Transvaal was found to be 14,3/100 000 of the population. Recognition of the disorder is important since some of its complications are preventable and others potentially treatable.     

X linked severe mental retardation, craniofacial dysmorphology, epilepsy, ophthalmoplegia, and cerebellar atrophy in a large South African kindred is localised to Xq24-q27

To date over 150 X linked mental retardation (XLMR) conditions have been documented. We describe a five generation South African family with XLMR, comprising 16 affected males and 10 carrier females. The clinical features common to the 16 males included profound mental retardation (100%), mutism despite apparently normal hearing (100%), grand mal epilepsy (87.5%), and limited life expectancy (68.8%). Of the four affected males examined, all had mild craniofacial dysmorphology and three were noted to have bilateral ophthalmoplegia and truncal ataxia. Three of 10 obligate female carriers had mild mental retardation. Cerebellar and brain stem atrophy was shown by cranial imaging and postmortem examination. Linkage analysis shows the gene to be located between markers DXS424 (Xq24) and DXS548 (Xq27.3), with a maximum two point lod score of 3.10.