CT and MR of the brain in the diagnosis of organic acidemias. Experiences from 107 patients

Acute movement disorders with bilateral basal ganglia lesions in uremia

Acute and subacute extrapyramidal movement disorders are rarely reported in uremic patients. We report three such cases with basal ganglia lesions. All three had advanced renal failure with high serum creatinine levels. One of the patients had a history of ischemic heart disease and acute pulmonary edema with hypoxemia. Another patient had experienced arterial hypotension during previous hemodialysis. The third had prominent metabolic acidosis. One of the patients developed generalized dyskinesias, whereas the other two developed gait disturbances. Neuroimaging studies in all three cases showed bilateral changes in the basal ganglia. The natural history was self-limiting with gradual improvement. Diminution of the basal ganglia lesions was demonstrated on follow-up imaging in two of the three cases. We conclude that acute or subacute movement disorders with bilateral basal ganglia lesions may occur in uremia. Hypoperfusion with global brain ischemia and selective vulnerability of the basal ganglia to uremic toxins may account for these lesions.

Propionic and methylmalonic acids inhibit the in vitro phosphorylation of a 85 kDa cytoskeletal protein from cerebral cortex of rats

In this study we examine the action of methylmalonic (MMA) and propionic (PA) acids, metabolites which accumulate in methylmalonic and propionic acidemias respectively, on the endogenous phosphorylating system associated with the cytoskeletal fraction of cerebral cortex of young rats. Chronic treatment with PA and treatment of tissue slices with MMA or PA are effective in decreasing the in vitro phosphorylation into a 85 kDa cytoskeletal associated protein. We tested the effect of the acids on the endogenous kinase activities by using specific kinase activators and inhibitors. Results demonstrated that the acids interfere with the endogenous cAMP-dependent and Ca2+/calmodulin-dependent kinase activities. Furthermore, in vitro dephosphorylation of the 85 kDa protein was totally inhibited in brain slices treated with the acids. Considering the importance of protein phosphorylation to cellular function, we speculate that alteration in the phosphorylating level of cytoskeletal associated phosphoproteins induced by MMA and PA treatments may somehow be involved in steps leading to brain damage.

Chronic administration of propionic acid reduces ganglioside N-acetylneuraminic acid concentration in cerebellum of young rats

Elevated levels of propionate comparable to those of human propionic acidaemia were achieved in the blood of young rats by injecting subcutaneously buffered propionic acid (PPA) twice a day at 8-h intervals from the 6th to the 28th day of life. A matched group of animals (controls) was treated with the same volumes of saline. The animals were weighed and sacrificed by decapitation at 28, 35 or 60 days of age. Cerebellum and cerebrum were weighed and their protein and ganglioside N-acetylneuraminic acid (G-NeuAc) contents determined. Body, cerebral and cerebellar weights were similar in both groups, suggesting that PPA per se neither alters the appetite of the rats nor causes malnutrition. Brain protein concentration was also not affected by chronic administration of PPA, in contrast to G-NeuAc concentration which was significantly reduced in the cerebellum. Since ganglioside concentration is closely related to the dendritic surface and indirectly reflects synaptogenesis, our results of an important ganglioside deficit in the brain of PPA-treated animals may be related to the neurologic dysfunction characteristic of propionic acidaemic patients.

Neurological outcome of methylmalonic acidaemia

OBJECTIVE

To assess the long term outcome of patients with methylmalonic acidaemia in a cross sectional study.

PATIENTS

All 35 patients with methylmalonic acidaemia seen at Great Ormond Street Hospital for Children in London, UK between 1970 and 1996 were studied. They were divided into cobalamin responsive (n = 6) and non-responsive (n = 29), and early and late onset groups.

RESULTS

There was a significant difference between cobalamin responsive and non-responsive groups in severity, survival, and incidence of neurological sequelae. Cobalamin responsive patients had mild disease, irrespective of age at presentation, their neurological complications were less severe, and they are all alive. The cobalamin non-responsive group comprised 19 early and nine late onset patients. The early onset patients had more severe disease at presentation and 14 have died; all late onset patients are alive. There was no significant difference in abnormal neurological signs, although early onset patients had a significantly reduced full scale intelligence quotient and poor cognitive outcome. In both groups, abnormal neurological signs continue to increase with age.

CONCLUSIONS

Cobalamin responsive patients have a better long term outcome. The outcome in the non-responsive patients, particularly the early onset group, remains poor and alternative treatments should therefore be considered early in this group.

3-Hydroxyisobutyric aciduria in two brothers

Two Japanese brothers with 3-hydroxyisobutyric aciduria (3HiB-uria) are studied. The elder brother died of a ketoacidotic episode at the age of 4 years; the younger brother also manifested repeated episodes of ketoacidosis after 1 year of age. He is diagnosed as having 3HiB-uria by gas chromatography/mass spectometry analysis, using the unique fragment ions of 3HiB. Magnetic resonance imaging reveals focal white matter abnormalities. Protein restriction is effective for preventing the ketoacidotic episodes, although carnitine therapy seems less effective.

Neurological dysfunction in methylmalonic acidaemia is probably related to the inhibitory effect of methylmalonate on brain energy production

Methylmalonic acidaemia is an inherited metabolic disorder caused by a severe deficiency of the activity of the enzyme L-methylmalonyl-CoA mutase or its cofactor 5'-deoxyadenosylcobalamin, resulting in tissue accumulation of large quantities of methylmalonic acid. Among the various clinical features, neurological symptoms are frequently observed. Patients may present cerebral atrophy and basal ganglia abnormalities are common. In the present report, we update the current knowledge on the influence of methylmalonic acid on brain metabolism in the hope of better understanding the neurological dysfunction characteristic of methylmalonic acidaemia. We present evidence showing that the metabolite inhibits brain energy production by various mechanisms and propose that a fall in cellular ATP generation leading to excitotoxicity is crucial for the occurrence of the neurological damage observed in these patients.

Effective immunoglobulin therapy for brief tonic seizures in methylmalonic acidemia

We report on a patient with methylmalonic acidemia (MMA). He experienced a metabolic acidosis attack at 3 weeks of age. He immediately received peritoneal dialysis and exchange transfusion, and recovered from the attack. His MMA phenotype was mut0. Dietary therapy (strict protein restriction) was found to be effective in preventing further attacks, and he had mild hypotonia and impaired psychomotor development. At 9 months of age, he developed brief tonic seizures, which showed polyspike bursts under EEG. His psychomotor development continued to deteriorate. However, intravenous administration of immunoglobulin (200 mg/kg/day for 5 consecutive days) had a dramatic effect; his seizures disappeared and his psychomotor development improved.

Methylmalonyl-CoA mutase induction by cerebral ischemia and neurotoxicity of the mitochondrial toxin methylmalonic acid

Differential screening of gerbil brain hippocampal cDNA libraries was used to search for genes expressed in ischemic, but not normal, brain. The methylmalonyl-CoA mutase (MCM) cDNA was highly expressed after ischemia and showed a 95% similarity to mouse and 91% similarity to the human MCM cDNAs. Transient global ischemia induced a fourfold increase in MCM mRNA on Northern blots from both hippocampus and whole forebrain. MCM protein exhibited a similar induction on Western blots of gerbil cerebral cortex 8 and 24 hr after ischemia. Treatment of primary brain astrocytes with either the branched-chain amino acid (BCAA) isoleucine or the BCAA metabolite, propionate, induced MCM mRNA fourfold. Increased concentrations of BCAAs and odd-chain fatty acids, both of which are metabolized to propionate, may contribute to inducing the MCM gene during ischemia. Methylmalonic acid, which is formed from the MCM substrate methylmalonyl-CoA and which inhibits succinate dehydrogenase (SDH), produced dose-related cell death when injected into the basal ganglia of adult rat brain. This neurotoxicity is similar to that of structurally related mitochondrial SDH inhibitors, malonate and 3-nitropropionic acid. Methylmalonic acid may contribute to neuronal injury in human conditions in which it accumulates, including MCM mutations and B12 deficiency. This study shows that methylmalonyl-CoA mutase is induced by several stresses, including ischemia, and would serve to decrease the accumulation of an endogenous cellular mitochondrial inhibitor and neurotoxin, methylmalonic acid.

Neuropathophysiology of movement disorders in cerebral palsy

Recent developments in understanding the pathophysiology of disordered motor control in cerebral palsy are reviewed. In spastic cerebral palsy, evidence for abnormal segmental as well as supraspinal control of motor neuron output exists. Impaired Ia inhibition of antagonist muscles has been suggested but recently contested. Evidence also supports the role of decreased presynaptic inhibition of Ia afferents and decreased nonreciprocal Ib inhibition. Furthermore, early cerebral injury results in reorganization of supraspinal (corticospinal) inputs to motor neuron pools. In extrapyramidal cerebral palsy, injury of basal ganglia or thalamus has been demonstrated. A scheme for understanding the neurochemical circuitry of the extrapyramidal system is discussed. Animal models and certain specific human diseases provide examples of how this circuitry may be disturbed, thereby resulting in an imbalance between the direct and indirect striatal output systems and in impaired motor control. Future studies employing postmortem neurochemical analysis, functional magnetic resonance imaging, and positron emission tomographic scanning may foster progress in this area.

Magnetic resonance imaging in lactic acidosis

Mitochondrial defects, defects in gluconeogenesis, and biotin-responsive multiple carboxylase deficiency are disorders characterized by primary lactic acidosis. In this review, characteristic findings in magnetic resonance imaging (MRI) of the brain, as related to histopathological abnormalities, are described for the different disorders and the diagnostic value of the MRI findings is discussed. Inborn errors of metabolism with primary lactic acidosis should be considered in particular when MRI shows lesions similar to or reminiscent of effects of focal or generalized hypoxia-ischaemia, or when MRI shows signs of chronic neurodegeneration, but rarely in cases with predominantly white-matter changes.

Movement disorders in childhood organic acidurias. Clinical, neuroimaging, and biochemical correlations

Over the last 5 years the Pediatric Neurology service at King Faisal Specialist Hospital and Research Centre (KFSH&RC) has seen 131 infants and children with movement disorders. Forty-nine (37%) had identifiable biochemical defects, 25 of which were organic acidemias. Nineteen of 29 patients with dystonia had organic acidemias, primarily glutaric aciduria type 1 (7 patients), bilateral striatal necrosis (4 patients), and 3-methyl glutaconic aciduria (3 patients). All patients with parkinsonian rigidity (n = 11) had organic acidemias; again, the greatest number accounted for by glutaric aciduria type 1 (7 patients), who had both parkinsonian rigidity combined with dystonia. Myoclonus occurred in only 1 of 25 and chorea in 7 of 25 patients with organic acidemias. At the least all patients had bilateral lesions of putamen and head of caudate, seen best in MRI brain scans as increased T2 signal intensities with normal volume, and later with volume loss.

Neurophysiologic correlates of organic acidemias: a survey of 107 patients

The files of 107 patients with 19 different types of organic acidemia were reviewed retrospectively. Approximately 50% of the patients had abnormal electroencephalogram (EEG) at the time of initial study. In patients who had serial studies, the EEG deteriorated in 38% and improved in 15%. The predominant EEG abnormality encountered was slowing of the background activity in various degrees. Focal or generalized paroxysmal activity occurring in conjunction with slow background activity indicated a poor prognosis. Brainstem auditory evoked potentials (BAEP), visual evoked potentials (VEP), and somatosensory evoked potentials (SEP) were analyzed. The VEP was abnormal in 44%, BAEP in 39%, and SEP in 29% of the patients. Given the magnitude and frequency by which neurophysiological abnormalities occur in organic acidemias, neurophysiology testing provides complementary functional information and has an important place in the clinical work-up of these diseases.

Malonic aciduria

Three infants with malonic aciduria are reported, one of whom could be studied in detail. All children had severe and progressive encephalopathy with intermittent ketoacidosis and hypoglycemia. One infant died of cardiomyopathy. Biochemical studies revealed that one patient had neither malonyl-CoA decarboxylase nor glutaryl-CoA dehydrogenase deficiencies. This variant of malonic aciduria is different from that of four patients previously reported, both in its clinical and biochemical presentations. The biochemical pathology of this variant malonic aciduria is unknown.

3-Methylglutaconic aciduria: ten new cases with a possible new phenotype

3-Methylglutaconic aciduria is an organic aciduria with diverse phenotypic presentations. In more than half of the cases it is a 'neurologic or silent organic aciduria', and, except for one subtype, the biochemical defect is unknown. This report describes 10 new patients. Four of them presented with early global neurologic involvement and arrested development. They rapidly became demented, developed myoclonus or tonic-clonic seizures, spastic quadriplegia, deafness and blindness, and died. Three had acidosis and hypoglycemia neonatally; later, myoclonus and deafness, and eventually severe mental retardation and spastic quadriplegia developed. One patient died. In three children who presented with sudden onset of extrapyramidal tract symptoms, with or without optic atrophy, the clinical presentation was significantly different from that described either for 'unspecified' type or for Costeff syndrome. All three patients showed clinical improvement soon after treatment with coenzyme Q.

Emergency presentations of patients with methylmalonic acidemia, propionic acidemia and branched chain amino acidemia (MSUD)

The charts of 16 patients with branched chain amino acidemia (MSUD) who had 48 emergency room (ER) visits, of 10 patients with propionic acidemia (PA) who had 57 ER visit, and of 13 patients with methylmalonic acidemia (MMA) who had 154 ER visits, were reviewed retrospectively for the most common clinical presentations, physical and laboratory findings. The most common clinical presentation was acute or chronic vomiting and the most common physical finding was dehydration. When hypoglycemia was found, the mental status of 55% of patients with MSUD and MMA and 20% of patients with PA, was alert. Mixed acid/base disturbance, i.e. alkalosis caused by vomiting mixed with metabolic acidosis caused by the disease, was present in 30% of MSUD, in 33% of PA, and 45% of MMA. There was no relationship between acidosis detected by the blood pH and mental status of the patients. A good correlation between base excess < -5 and serum bicarbonate < 21 mmol/l was found. Blood cultures were positive for bacteria and fungi in 15% of the visits with MSUD, in 23% with PA, and 3% with MMA. Patients with positive blood cultures did not necessarily have a temperature > 39 degrees C nor hypothermia. The results suggest that the mental status of the patients should not detract the ER physician from obtaining blood pH, gases and glucose and in all instances a blood culture should be secured, even if the patient has no fever.