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Neuroradiology Case of the Week

Case 55

Ravinder Sidhu MD, Leena Ketonen MD, PhD, Michel J Berg MD,
and P-L Westesson MD, PhD, DDS

Clinical Presentation: An 8-year-old male presents with history of episodic seizures and ataxia. The history dates back to almost 5 years duration. The laboratory abnormalities revealed CoQ 10 deficiency.

Radiological Findings: Axial T1-weighted MR image revealed prominent cerebellar folia (Fig. 1). Axial T2-weighted and coronal FLAIR MR images showed areas of hyperintensity involving cerebellar hemispheres and vermis (Figs. 2A & B). The rest of the brain parenchyma was unremarkable. Supratentorial ventricular system is normal. No midline shift/extraaxial collection was seen.

Diagnosis: Cerebellar degeneration associated with CoQ 10 deficiency

Discussion:  Coenzyme Q10 is a component of electron transport chain, which has oxidoreductase functions and also serves as an antioxidant and as a membrane stabilizer. Primary CoQ10 deficiency was first described in 1989 in two sisters with recurrent episodes of myoglobinuria and muscle biopsies characterized by red ragged fibres and lipid storage [1].
   The syndrome of cerebellar ataxia associated with primary CoQ10 enzyme appears as an autosomal recessive trait and is characterized by 1) recurrent myoglobinuria, 2) brain involvement (seizures, ataxia, mental retardation), and 3) ragged red fibres and lipid storage in the muscle biopsy. Primary muscle CoQ10 deficiency seems to be associated with a spectrum of clinical presentations always involving both muscle and brain but ranging from a predominantly myopathic to a predominantly encephalopathic syndrome [2].
   Musumeci et al. have described six patients of cerebellar ataxia associated with primary CoQ10 deficiency. Muscle biopsy was nonspecific in all the cases, however MR imaging showed severe cerebellar atrophy as seen in the index case. Lamperti et al. in 2003 described 13 patients with childhood onset cerebellar ataxia and marked CoQ10 deficiency in skeletal muscle. In all these cases, other causes of ataxia such as Friedrach ataxia and all known genetic causes of spinocerebellar ataxia had been excluded. All these patients benefited from oral CoQ10 administration [2,3].
   On imaging, atrophy of cerebellar hemispheres as well as vermis is the hallmark of primary CoQ10 deficiency. MR imaging is the modality of choice, and it is important to diagnose this entity of primary CoQ10 deficiency as a cause of cerebellar ataxia, since patients may improve with early administration of CoQ10 supplementation.

References:

1. Ogasahara S, Engel AG, Frens D, Mack D. Muscle coenzyme Q deficiency in familial mitochondrial encephalomyopathy. Proc Natl Acad Sci USA 1989; 86:2379-2386.
2. Musumeci O, Naini A, Slonim AE et al. Familial cerebellar ataxia with muscle coenzyme Q10 deficiency. Neurology 2001; 56:849-855.
3. Lamperti C, Naini A, Hirano M et al. Cerebellar ataxia and coenzyme Q10 deficiency. Neurology 2003; 60:1206-1208.