Previous studies of human stroke by 1H nuclear magnetic resonance spectroscopy have shown elevation of lactate lasting 3 to 6 months. Complete metabolic turnover of the elevated lactate pool has been demonstrated 5 weeks after a stroke. Its cellular localization is among the first questions requiring clarification. Information pertinent to this question came to us from a patient with a 2-week-old stroke by 1H nuclear magnetic resonance spectroscopic imaging 1 week before his death led to neuropathologic examination of the brain. 1H spectra from voxels including the infarcts showed increased lactate and decreased N-acetylaspartate. Histopathology showed sheets of foamy macrophages in the infarct, but few neurons. Macrophage density ranged from 196 cells/mm2 near the surface of the infarct to 788 near its medial margin. Glial density was 500 to 800 cells/mm2. Lactate concentration in voxels including portions of the infarct was estimated at 7 to 14 mM. Voxels showing low N-acetylaspartate and high lactate on spectroscopic imaging were associated with histopathologic sections containing foamy macrophages. Brain macrophages--which begin to appear 3 days after infarction and gradually disappear over several months--could be a major source of elevated lactate signals that persist for months after stroke.

Childhood ataxias are a complex set of inherited disorders. Ataxias associated with generalized tonic-clonic epilepsy are usually included with the progressive myoclonus epilepsies (PME). Five disease entities, Unverricht-Lundborg disease, Lafora's disease, neuronal ceroid lipofuscinoses, myoclonic epilepsy with ragged red fibres and sialidoses, account for the majority of PME cases. Two rare forms of ataxia plus epilepsy, sensory ataxic neuropathy, dysarthria and ophthalmoparesis, and infantile onset spinocerebellar ataxia were described recently and found to be caused by defective mitochondrial proteins. We report here a large consanguineous family from Saudi Arabia with four affected children presenting with generalized tonic-clonic epilepsy, ataxia and mental retardation, but neither myoclonus nor mental deterioration. MRI and muscle biopsy of one patient revealed, respectively, posterior white matter hyperintensities and vacuolization of the sarcotubular system. We localized the defective gene by homozygosity mapping to a 19 Mb interval in 16q21-q23 between markers D16S3091 and D16S3050. Linkage studies in this region will allow testing for homogeneity of this novel ataxia-epilepsy entity.

Dissemination of a pilocytic cerebellar astrocytoma is a very rare occurrence. So far only eight cases have been reported in the literature and in only one of these cases had the tumour spread into the ventricles. We report a case of a child who presented with communicating hydrocephalus and a small cerebellar lesion. The patient was initially treated by a ventriculoperitoneal (VP) shunt and the lesion was followed-up. Two years later, intraventricular and leptomeningeal dissemination of the tumour which proved to be a pilocytic astrocytoma was documented. The role of the VP shunt in diverting metastasizing tumour cells into the ventricles is discussed.

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) is a neonatal intestinal syndrome, characterized by defective peristalsis and bladder dilatation, refractory to pharmacological treatment. Examinations of bowel and bladder have failed to demonstrate a pathological explanation for this syndrome. We describe a 7-month-old female infant with MMIHS who had generalized axonal dystrophy of her central, peripheral, and autonomic nervous systems, which may provide a neuropathological explanation for some cases of MMIHS.

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