Spasms in children with definite and probable mitochondrial disease*

Abstract

The diagnosis of mitochondrial encephalomyopathies is complex and a system for classification of the diagnosis as definite, probable, and possible has been proposed. The objective of this study was to explore the spectrum of epileptic disorders associated with probable and definite mitochondrial disease in children using this classification system. The patient population with mitochondrial disease and epilepsy was selected from a tertiary care children's hospital. Interictal electroencephalograms and video-EEG recordings were used to characterize seizure types. Ten children fulfilled the criteria for probable or definite mitochondrial disease and had epilepsy. Four had siblings with a similar clinical phenotype. Spasms were the most common seizure type and were the initial seizure type in seven patients and two siblings. Four patients had only partial seizures, with or without generalization, and one patient had seizures that were difficult to classify. Blood lactate concentrations were elevated consistently in patients with partial seizures alone but were occasionally normal in children with spasms. Spasms were the most common presenting seizure type in children with probable and definite mitochondrial disease.

Mitochondrial respiratory chain defects: Underlying etiology in various epileptic conditions

“…There have been several sporadic reports discussing MRC enzyme defects or named mitochondrial dysfunction syndromes that are associated with epileptic conditions such as West syndrome, but none have collectively reported on the spectrum of epilepsy caused by MRC defects (Shoffner et al, 1990; Jaksch et al, 1998; Sadleir et al, 2004).…”

Hypotonia and Infantile Spasms: A New Phenotype of Coenzyme Q10 Deficiency?

“…This is partly due to the difficulty in diagnosing some mitochondrial diseases. Normal blood and CSF lactate are not uncommon in children with a mitochondrial disease 11 . Sadleir et al demonstrated that forty percent of children with confirmed or suspected mitochondrial disease had infantile spasms, while conversely eight percent of all children with spasms were shown to have a mitochondrial disease 11 .…”

The neurologic manifestations of mitochondrial disease

“…Atypical absence, primary generalized and atonic events can also occur, although isolated generalized epilepsy is rare in mitochondrial disease. Infantile spasms (West syndrome) do not occur frequently and are seen more commonly in pyruvate dehydrogenase deficiency [Sadleir et al, 2004]. It is possible that mitochondrial diseases remain underdiagnosed in children with West syndrome [Blanco-Barca et al, 2004].…”