Background: Cytochrome C Oxidase deficiency is a rare inherited metabolic disorder characterized by deficiency of the enzyme cytochrome C oxidase; an essential enzyme active in oxidative phosphorylation.It is clinically heterogeneous, ranging from isolated myopathy to severe multisystem presentation. Acute disseminated encephalomyelitis (ADEM) is a monophasic polysymptomatic inflammatory condition of the CNS that principally involves the white matter although the grey matter may also be affected. Case report: A 6-year-old boy,a product of a consanguineous marriage with a history of progressive weakness and convulsions noted at 2 years of age in his sister who died at the age of 5 years with no definite diagnosis. At the age of 2 years, he presented with fever, encephalopathy, and seizures, proceeded by varicella skin infection. Diagnosed as ADEM based on MRI. He showed slow recovery but remained with poor speech and ataxic gait. At 4 years of age, he developed the 2nd episode of ADEM, was admitted in a coma state and ventilated for 10 weeks.Progressive neurologic decline and frequent myoclonic seizures were noted despite full support with immunosuppressive therapy, antiviral treatment, antiepileptic drugs, and megavitamins.MRI showed generalized cortical swelling and high signal intensity diffusely involving cerebral cortex, cerebellum, and deeper gray matter.He remained in a vegetative state with spastic quadriplegia. Muscle biopsy showed reduced cytochrome C oxidase activity and abnormal accumulation of mitochondria at the subsarcolemmal membrane.Conclusion:This case serves as a reminder of the clinical heterogeneity of cytochrome C oxidase deficiency, and physicians should consider a broader differential diagnosis for ADEM.

Amal Kentab
King Saud University
Saudi Arabia