The Value of 1H-MRS and MRI in Combined Methylmalonic Aciduria and Homocystinuria.

OBJECTIVE: The aims of this study were to describe the brain magnetic resonance imaging (MRI) features of methylmalonic aciduria and homocystinuria and to evaluate the additional value of H-MRS. PATIENTS AND METHODS: Twenty-eight children with methylmalonic aciduria and homocystinuria were included in this study. The control group included 21 healthy children. All the cases underwent MRI and H-MRS before treatment. We measured the N-acetylaspartate (NAA), choline (Cho), creatine (Cr), and myoinositol (mI) peaks in the basal ganglia regions. The NAA/Cr, Cho/Cr, mI/Cr, and NAA/Cho ratios were calculated. We also observed whether there were lactic acid peaks. RESULT: We identified that NAA/Cr and NAA/Cho significantly decreased in the basal ganglia and that 3 patients showed lactate peaks, but other metabolites were not significantly altered. Hydrocephalus and diffuse supratentorial white matter edema were the primary MR findings; 7 patients had thinning of the corpus callosum, and 2 patients had subdural hematoma. Six patients showed normal brain MRI findings. CONCLUSIONS: Methylmalonic aciduria and homocystinuria patients with metabolite changes in the basal ganglia demonstrate compromised neuronal integrity, and anerobic metabolism occurs in acute encephalopathic episodes. H-MRS is a useful tool for evaluating brain damage. Hydrocephalus and diffuse supratentorial white matter edema are the main MRI features.

Brain Magnetic Resonance Imaging Findings in Poorly Controlled Homocystinuria.

Homocystinuria is an inherited metabolic disorder most commonly caused by cystathionine ß-synthase deficiency. Severe cases can cause white matter abnormalities that can mimic other vascular, toxic and metabolic disorders on computed tomography and magnetic resonance imaging. We present such a case which demonstrates not only extensive white matter abnormalities on magnetic resonance imaging, but also previously unreported basal ganglia signal abnormalities and imaging manifestations of increased intracranial pressure, likely caused by elevated methionine and betaine therapy. We also review the literature and discuss the potential underlying biologic mechanisms of these imaging findings.

Vasospasmus: a rare manifestation of homocystinuria.

We report about a patient suffering from multiple spastic stenoses of varying degree of both iliac arteries and from occlusion of the left tibiofibular trunc. Laboratory investigations revealed increased levels of homocysteine and the diagnosis of homocystinuria was confirmed by fibroblast cell culture. The spasms responded well to vasodilative therapy with nitroglycerine, molsidomine (cGMP mediated) and prostaglandine E1 but not with nifedipine (Ca influx blocker). Our review of literature demonstrated that this arterial spastic abnormality is a very rare complication in patients suffering from homocystinuria.

Evidence of carotid artery wall hypertrophy in homozygous homocystinuria.

BACKGROUND: We aimed to determine whether intima-media thickness (IMT) was increased in the carotid artery of subjects with homocystinuria to better understand the in vivo contribution of homocysteine to early atherogenesis. METHODS AND RESULTS: We investigated ultrasonographically the right common carotid artery in 14 subjects with homozygous homocystinuria aged 3 to 34 years (mean, 13 years) and in 15 of their heterozygous parents aged 32 to 47 years (mean, 41 years) by comparison with 2 control groups of 15 healthy subjects of the same age. Far-wall IMT and lumen diameter were measured with a computerized program, and the cross-sectional area of the intima-media complex (CSA-IMC) was calculated from IMT and diameter. Comparison with their respective controls, adjusted for body surface area or height, showed that homozygotes had greater IMT (P<0.001) and CSA-IMC (P<0.05) and smaller diameter (P<0.05), whereas heterozygotes had values similar to their controls. Multivariate analysis of the arterial parameters with age, body surface area (or height), and plasma total homocysteine in the homozygous and heterozygous groups combined showed that IMT was related to age (P<0.05) and homocysteine (P<0.01), diameter was related to body surface area (P<0.001) or height (P<0.05), and CSA-IMC was related to age (P<0.05), body surface area (P<0.05) (but not height), and homocysteine (P<0.05). CONCLUSIONS: Homozygous homocystinuria was associated with common carotid wall hypertrophy, whereas heterozygous disease was not. Such hypertrophy may reflect a smooth muscle proliferation induced by hyperhomocysteinemia and represent a promising target for testing vascular effects of therapeutic measures to lower homocysteine.

Hyperlucent lung secondary to homocystinuria.

At 23 months of age, one of a pair of monozygotic twins with radiographic unilateral hyperlucent lung was evaluated by radionuclide ventilation/perfusion pulmonary studies, which revealed a ventilation/perfusion mismatch of an entire lung. This twin died, and autopsy revealed pulmonary arterial thrombosis and histological changes compatible with homocystinuria, which was subsequently shown to be present in the surviving twin as well. A ventilation/perfusion lung scan of the surviving twin revealed multiple ventilation/perfusion mismatched defects, suggestive of pulmonary embolism. The presenting manifestation of homocystinuria in these patients was the pulmonary thrombotic disease. Neither twin had any other stigmata of homocystinuria at the time of initial presentation.

Premature carotid atherosclerosis: does it occur in both familial hypercholesterolemia and homocystinuria? Ultrasound assessment of arterial intima-media thickness and blood flow velocity.

BACKGROUND AND PURPOSE: Homocystinuria due to cystathionine beta-synthase deficiency and familial hypercholesterolemia are inherited disorders of metabolism that are associated with premature development of cardiovascular disease. This study addresses the possibility that different patterns of carotid wall damage and cerebral blood flow hemodynamics are present in these two metabolic diseases. METHODS: Twelve patients with homocystinuria due to cystathionine beta-synthase deficiency (mean age, 24 years), 10 patients with homozygous familial hypercholesterolemia (mean age, 26 years), and 11 healthy control subjects (mean age, 26 years) underwent a vascular examination by noninvasive methods. B-mode ultrasound imaging was used to obtain measurements of intima-media thickness of common carotid, bifurcation, and internal carotid arteries as an index of atherosclerosis. Cerebral blood flow velocity was estimated from vascular examination of the middle cerebral artery by transcranial Doppler. Systolic, diastolic, and mean velocities were measured. Pulsatility index, a possible indicator of vascular resistance in the cerebral circulation, was also calculated. RESULTS: Mean maximum intima-media thickness was 1.4 mm in patients with familial hypercholesterolemia, 0.6 mm in patients with homocystinuria, and 0.6 mm in control subjects. The difference between hypercholesterolemic and homocystinuric patients or control subjects was statistically significant (P < .001). Diastolic blood flow velocities were significantly reduced in the middle cerebral arteries of hypercholesterolemic patients compared with homocystinuric patients or control subjects (P < .05), whereas systolic or mean velocities did not differ. The pulsatility index, a possible indicator of vascular resistance in the cerebral circulation, was significantly higher in hypercholesterolemic patients compared with homocystinuric patients or healthy control subjects (P < .01). A direct relation was demonstrated between pulsatility index of the middle cerebral artery and mean maximum intima-media thickness of carotid arteries on the same side (P < .001). CONCLUSIONS: Familial hypercholesterolemia is responsible for diffuse and focal thickening of carotid arteries and possibly also for hyperlipidemic endothelial dysfunction extending to small resistance arteries and leading to a disturbed cerebral blood flow. Patients with homocystinuria due to homozygosis for cystathionine beta-synthase deficiency seldom have plaques in their carotid arteries. They are similar to healthy control subjects with regard to both intima-media thickness and blood flow velocity in the middle cerebral artery. Therefore, it is unlikely that typical atherosclerotic lesions precede thrombotic events in homocystinuria. However, it is possible that arterial dilatations caused by medial damage lead to thrombosis in homocystinuric patients.

Impaired endothelial function occurs in the systemic arteries of children with homozygous homocystinuria but not in their heterozygous parents.

OBJECTIVES: Because endothelial dysfunction is an early event in atherogenesis, we aimed to determine whether endothelial function is normal or impaired in the systemic arteries of children with homozygous homocystinuria or in those of heterozygous adults, or both. BACKGROUND: Homocystinuria is strongly associated with premature vascular disease in homozygotes, and even heterozygotes have been shown to be at increased risk from early atherosclerosis associated with hyperhomocystinemia. METHODS: We conducted noninvasive studies on the superficial femoral or brachial arteries of 9 children aged 4 to 17 years (mean 11) with homozygous homocystinuria and on the brachial arteries of 14 obligate heterozygous parents age 33 to 49 years (mean 41). Each subject was matched with two control subjects. Using high resolution ultrasound, we measured vessel diameter at rest, during reactive hyperemia (with flow increase causing endothelium-dependent dilation) and after sublingual administration of nitroglycerin (an endothelium-independent vasodilator). RESULTS: Flow-mediated dilation was observed in the control children (9 +/- 0.6%, range 6% to 14%) but was impaired in the children with homocystinuria (2.8 +/- 0.7%, range 0% to 7%, p < 0.0001). In contrast, nitroglycerin-mediated dilation was similar in both groups (15.7 +/- 1.6% vs. 13.1 +/- 1.2%, p = 0.27), indicating that the impaired flow-mediated dilation is secondary to endothelial dysfunction. In the heterozygous parents, both flow-mediated dilation and nitroglycerin responses (6.3 +/- 0.9%, 17 +/- 1.4%, respectively) were similar to control values (6.8 +/- 0.7%, 20.7 +/- 1.7%, p > 0.10). CONCLUSIONS: Children with homozygous homocystinuria had impaired endothelial function in the systemic arteries as early as 4 years of age, representing an early event in their premature vascular disease. However, endothelial function was preserved in the heterozygous adults.

Short fourth metacarpal in homocystinuria.

Homocystinuria due to cystathionine synthase deficiency is an autosomal recessive multisystem disease which affects the eye, the cardiovascular system, the central nervous system, the skeleton and occasionally other organs. Archibald's metacarpal sign and Kosowicz's phalangeal sign were evaluated in 11 patients with homocystinuria. A short fourth metacarpal was demonstrated in four patients. Our study represents, to our knowledge, the first systematic evaluation of these skeletal signs in a rather large group of homocystinuric patients.

[Bone changes in homocystinuria in childhood]. / Le alterazioni scheletriche dell'omocistinuria in età pediatrica.

Homocystinuria due to cystathionine synthase deficiency is an autosomal recessive error of sulphur amino acid metabolism characterized clinically by lens dislocation, mental retardation, skeletal abnormalities and thromboembolic phenomena. We have evaluated roentgenologically our series of 12 pediatric homocystinuric patients to detect skeletal abnormalities. Bone changes are widespread and occur mainly in dorsolumbar spine and in epi-metaphyseal growth areas. Osteoporosis is the most important finding. Dolichostenomelia and arachnodactily are relatively common. Calcific spicules occur frequently in the wrist physes.

Angiographic findings in homocystinuria.

Homocystinuria (HC) is an inborn error of amino acid metabolism characterized by ectopia lentis, mental retardation, and skeletal abnormalities. Vascular disorders may also occur in HC, although they are less common. Arteriographic studies of two sisters with HC are described. The younger woman's renal arteries showed wall irregularities and aneurysms, narrowing of the celiac and superior mesenteric arteries, and some aneurysmatic changes. In the older patient, irregular right carotid and splenic arteries were seen and a splenic aneurysm was present.

Homocystinuria and carotid arteriography.

This is a report of a case of homocystinuria where the diagnosis was suggested by the carotid arteriogram.

Annual oration. Diagnostic clues in the growing ends of bone.

Abnormalities of the growth plate account for many of the radiologic manifestations in non-neoplastic pediatric bone disease. A good understanding of the physiology of this area is helpful in radiologic diagnosis.