Cerebral MRI in 3-hydroxy-3-methylglutaryl-coenzyme A lyase deficiency: case report

3-Hydroxy-3-methylglutaryl coenzyme a lyase deficiency with reversible white matter changes after treatment

We report the case of an 8-month-old infant with 3-hydroxy-3-methylglutaryl coenzyme A deficiency (OMIM 246450), an inborn error of leucine catabolism and ketogenesis, who presented with nonketotic hypoglycemia and seizures. He demonstrated reversible white matter changes on serial brain magnetic resonance imaging, together with clinical normalization, after initiation of a leucine-restricted diet.

Corticospinal tract involvement in a patient with 3-HMG coenzyme A lyase deficiency

3-Hydroxy-3-methylglutaryl coenzyme A lyase deficiency, an inborn error of ketone body synthesis and leucine degradation, is a rare disorder. There are few reports demonstrating clinical and neuroradiologic findings of this condition. This report describes a 3.5-year-old previously healthy male who was admitted with complex partial seizures and was diagnosed as having 3-hydroxy-3-methylglutaryl coenzyme A lyase deficiency. The patient's previous medical history was unremarkable. His development and neurologic examination were normal. Cranial magnetic resonance imaging indicated prominent corticospinal tract and pontine involvement with focal cerebral white matter changes which have not been described in the literature before.

MRI and MRS in HMG-CoA lyase deficiency

3-Hydroxy-3-Methylglutaryl coenzyme A lyase (HMG-CoA) deficiency is a rare inborn error of leucine catabolism. The disease is characterized by recurrent episodes of metabolic acidosis, hyperammonemia without ketosis, hypoglycemia, lethargy, hepatomegaly, and seizures. This study has evaluated the magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) findings of three patients with HMG-CoA deficiency. The common findings on all of the MRI scans were multiple, coalescent, marked lesions in periventricular white matter and arcuate fibers, most prominently in frontal or periatrial regions that were superimposed on diffuse, slightly hyperintense subcortical white matter signal. Involvement of the caudate nucleus and the dentate nucleus were observed in the reported patients. MRS studies by both STEAM and PRESS spectra of all patients revealed a decrease in N-acetylaspartate and elevation in both myoinositol and choline. A pathologic peak at 1.33 ppm, which is compatible with lactate, and a particular peak at 2.42 ppm in all patients were also found. The combination of both MRI and MRS findings could be considered as being specific in patients with HMG-CoA lyase deficiency.