Cerebral malformation associated with metabolic disorder. A report of 2 cases

Cerebral dysgenesis and lactic acidemia: an MRI/MRS phenotype associated with pyruvate dehydrogenase deficiency

Pyruvate dehydrogenase complex (PDHC) is an intramitochondrial multienzyme complex essential for the aerobic oxidation of glucose. The majority of patients with PDHC deficiency have abnormalities in the major catalytic and regulatory subunit, E1 alpha, which is encoded on the X chromosome. The clinical spectrum of PDHC deficiency is heterogeneous, particularly in heterozygous females, and diagnosis may be difficult. Three affected infant girls with PDHC deficiency were investigated. All had dysmorphic features, microcephaly with profound global developmental delay, and hypotonia. Systemic acidosis was absent, although serum lactate and pyruvate were abnormally elevated. Magnetic resonance imaging revealed hypoplasia of the corpus callosum in all patients. Proton magnetic resonance spectroscopy of brain revealed large increases in relative signal intensities for lactic acid and decreases in the relative signal intensities of N-acetylaspartate, a marker of neuronal damage or less. Phosphorus MRS of muscle revealed abnormally low phosphorylation potentials for all these patients, although the degree of abnormality was variable and not directly correlated with the amount of brain lactate. It is proposed that cerebral dysgenesis and cerebral lactic acidemia as shown by magnetic resonance imaging and proton magnetic resonance spectroscopy are useful diagnostic clues to PDHC deficiency, particularly in females in whom variable patterns of X-inactivation reduce sensitivity of laboratory diagnosis based on the biochemical studies of peripheral tissues. In addition, muscle bioenergetic abnormalities in conjunction with CNS dysfunction may contribute to profound hypotonia in this disorder.

Menkes disease: an X-linked neurological disorder of the copper metabolism

Menkes disease is an X-linked, recessive disturbance of copper metabolism associated with a progressive clinical course and abnormal hair. The disease is dominated by neurological symptoms combined with connective tissue manifestations, most of which can be explained by the lack of important copper enzymes. Despite excessive accumulation of the metal in various tissues, a functional copper deficiency is evident, probably caused by a defective intracellular copper transport protein of unknown nature. The molecular basis of the copper disturbance has proven difficult to define and will most likely have to await cloning of the gene. The chromosomal region of interest has now been narrowed down to a sub-band on the long arm of the chromosome (Xq13.3), and positional cloning is in progress in a number of laboratories including our own. Identification of the Menkes gene will be of importance for our understanding of the cellular handling of copper and other trace elements.

Disorders of neuronal migration

Neuronal migration constitutes one of the major processes by which the central nervous system takes shape. Detailed knowledge about this important process now exists for different brain regions in rodent and monkey models as well as in the human. In the human, distinct genetic, chromosomal and environmental causes are known that affect neuronal migration, often in a morphologically distinct pattern, but the underlying pathological mechanisms are largely unknown. This review is intended to integrate our basic knowledge of the field with the accumulated intelligence on a large number of disorders and syndromes that represent the human part of the story.

A Golgi study of the cerebral cortex in Fukuyama-type congenital muscular dystrophy, Walker-type "lissencephaly," and classical lissencephaly

The cortical neuronal organization of the brain was studied and compared in three conditions. The neurons in the polymicrogyric cortex from a subject with Fukuyama-type congenital muscular dystrophy and from a child with ocular dysplasia (Walker-type lissencephaly) were large, irregularly aligned, and not completely mature. In the former condition, the abnormal neuronal arrangement was predominantly in the superficial cortex; in the latter both the superficial and deep cortex were involved. These two diseases may have a similar pathogenetic mechanism. In classical lissencephaly without evidence of other disease manifestations, the neurons were arranged in a radial pattern with heterotopia but no large neurons. The pathogenesis of these conditions is discussed.

Neuronal and vascular disorders of the brain and spinal cord in Menkes kinky hair disease

A 3 2/12-year-old boy had recurrent seizures, chronic respiratory infection, and delayed physical and mental development. He also had low plasma copper content typical of Menkes syndrome. Autopsy showed marked neuronal loss and gliosis in most areas of the cerebral and cerebellar cortices, midbrain, pons, and medulla. The spinal cord showed severe demyelination in both ascending (spinocerebellar) and descending (lateral corticospinal) tracts from the cervical to the sacral level. In addition to these neuronal lesions, both the meningeal and parenchymal arterial and venous branches were remarkably dilated in the brain and spinal cord. Our previous study of this case showed abnormal perivascular innervation and abnormal axonal swelling of the postganglionic adrenergic fibers elsewhere in the body. The metabolic disorder caused by copper deficiency induces severe neuronal degeneration that is apparently exaggerated by extensive and progressive vascular abnormality.

Ornithine carbamoyl transferase deficiency: a neuropathological study

A detailed autopsy study of three children with ornithine carbamoyl transferase (OCT) deficiency is presented. Although variable in extent, a basic pattern of neuropathological lesions is discernible. Case 1 shows gross cerebral atrophy, cases 2 and 3 milder lesions in the basal nuclei but also multiple cerebellar heterotopias and delayed myelination. We suggest that the findings may provide evidence that OCT deficiency can have a teratogenic effect in utero and suggest that there is a need to monitor the pregnancies of carriers of this disorder.

Menkes' disease and swayback. A comparative study of two copper deficiency syndromes

The neuropathological findings in two siblings with Menkes' disease were compared with representative material obtained from lambs suffering from swayback (enzootic ataxia). The aim of the study was to demonstrate the similarity of lesions in a genetic and a nutritional form of copper deficiency in support of the view that all lesions in Menkes' disease could be ascribed to simple hypocupraemia. All lesions of Menkes' disease were shown to have their counterpart in swayback, with exception of the abnormal arborisations of the Purkinje cell dendrites. These have often been interpreted as malformations and cited in evidence of the prenatal origin of the cerebral lesions. They are, however, non-specific and similar lesions have been reported in conditions arising in later life. While there is abundant collateral evidence of disturbed copper metabolism in utero, the problem of the prenatal versus postnatal origin of cerebral damage remains unresolved.

Involvement of the central nervous system in congenital muscular dystrophies

Three children, two siblings and one unrelated child, with congenital muscular dystrophy with central nervous system (CNS) involvement are discussed. The siblings appeared to suffer from a relatively mild myopathy with progressive brain disease, of which brain biopsy in one showed astrocytic proliferation in the white matter. In the patient with severe muscle disease, autopsy showed widespread patchy demyelination in the white matter and developmental abnormalities in the cerebral and cerebellar cortex. These patients differ from the Japanese (Fukuyama) cases of CMD in the severity of the changes in the cerebral white matter, and from Santavuori's cases in the absence of ocular abnormalities and hydrocephalus. Their unique nosology is discussed.

Brindled mottled mouse: morphological changes of brain and visceral organs in hemizygous males following copper supplementation

Intraperitoneal injections of cupric chloride prevent neuronal degeneration in the hemizygous brindled mottle mouse, MO br/Y, a murine model of kinky hair syndrome (KHS) in humans. At 6-9 months after two i.p. injections, the brain of MO br/Y revealed slightly increased amounts of lipofuscin pigments in the cerebral cortical neurons, cytoplasmic inclusions in the thalamic neurons, and axonal spheroid formation in the tuber cinereum, cerebellum and brain stem. Increased numbers of mitoses, bizarre hyperchromatic giant nuclei, and numerous clear vacuoles were frequently seen in the proximal renal tubular epithelium. Numerous myelin figures were conspicuous features in these epithelial cells at ultrastructural level. Such changes were not found in the littermate controls but in the heterozygous brindled mottled mouse, MO br/ +, identical changes were noted in equal or even higher frequency. These observations suggest that cupric chloride injections effectively modify the expression of the genetic defect in MO br/ Y.

An ultrastructural study on the cerebellum of the brindled mouse

Chronological morphological alterations of the cerebellum, with particular attention to the Purkinje cells, were investigated in the brindled mottled MObr mouse, a neurological mutant mouse with close clinical similarity to Kinky hair syndrome (KHS) in humans. Seven days post-natally, slight irregularity in the morphology of mitochondria of the Purkinje cell perikarya was the only significant difference between hemizygous MObr mice and litter mate controls. With advancing age the mitochondrial change became more pronounced gradually in the former, not only in the perikarya but also in the dendrites. However, by day 31 or later the mitochondrial change subsided gradually and by day 91, the mitochondria in the majority of Purkinje cells became indistinguishable from those of littermate controls. Despite the extensive mitochondrial alteration, degeneration and necrosis of Purkinje cells were rather mild. Degeneration of white matter was quite conspicuous in the mutant mouse older than 31 days. These morphological changes of the cerebellum are compared with those of other neurological mutant mice, Nervous and Purkinje cell degeneration, and with KHS in humans.

Degeneration of the cerebellar system in X-chromosome-linked copper malabsorption

Examination of the cerebellar system of 5 autopsied patients with X-chromosome-linked copper malabsorption led to the discovery that among cerebellar afferent systems, only the dorsal spinocerebellar tract showed consistent degenerative changes. Cerebellar cortical lesions comprised granule cell loss and Purkinje cell abnormalities that included nuclear and cytoplasmic degenerative changes with cell loss and deficient dendritic arborization as well as the presence of somatic sprouts. Perisomatic baskets were often absent in the area of sprouting Purkinje cells. Cerebellar cortical topographical analysis revealed relative sparing of the caudal portion of the cerebellum. The nodulus was intact in all patients. The dentate nucleus and the superior cerebellar peduncle were preserved. The red nucleus was consistently degenerated.

Thalamic degeneration in X-chromosome--linked copper malabsorption

Thalamic degeneration was present in 5 autopsied cases of X-chromosome-linked copper malabsorption (X-cLCM), Menkes' kinky hair disease. Among the thalamic nuclei, those in the formatio paraventricularis, intralamellaris, and extralamellaris were spared. The nuclei projecting to the granular cortices had severe neuronal depopulation. The thalamic nuclei that send axons to the agranular cortices were less often and less severely involved. The thalamic afferent system was intact except for degeneration of the red nucleus. Cerebral cortical lesions varied from case to case and usually were less marked than thalamic neuronal changes.

Menkes' disease: neurophysiological aspects

The evolution of neurophysiological features including the electroencephalogram (EEG), electroretinogram (ERG), and visual evoked potentials (VEP) is reported in eight cases of Menkes' "kinky hair" disease. All EEGs were severely abnormal, with some characteristic features seen from 3-5 months of age, after the onset of clinical symptomatology. From the age of 5 months, the EEGs resembled hypsarrhythmic patterns. The ERG was not affected in any patient, but the VEP was either of low amplitude or completely absent in all but one of the six patients tested. All eight patients received copper injections without substantial effect on either the clinical course of the disease or the EEG features.