Mitochondrial myopathy and myoclonic epilepsy

Abstract

The authors describe a family (mother, son and two daughters) with mitochondrial myopathy. The mother was asymptomatic. Two daughters had lactic acidosis and myoclonic epilepsy, mild dementia, ataxia, weakness and sensory neuropathy. The son suffered one acute hemiplegic episode due to an ischemic infarct in the right temporal region. All the patients studied had hypertension. EEG disclosed photomyoclonic response in the proband patient. Muscle biopsy disclosed ragged-red fibers and abnormal mitochondria by electron microscopy. Biochemical analysis showed a defect of cytochrome C oxidase in mitochondria isolated from skeletal muscle. Several clinical and genetic aspects of the mitochondrial encephalomyopathies are discussed.

When should MERRF (myoclonus epilepsy associated with ragged-red fibers) be the diagnosis?

“…Although the main manifestation of this group of patients with mitochondrial disease is the presence of myoclonus and epilepsy, other multisystemic alterations can be found as follows: deafness, exercise intolerance, dementia, peripheral neuropathy, short stature, abnormal cardiac conduction, cardiomyopathies, opthalmoparesis, pigmentary retinopathy, and lipoma, among others 3,4 . In Brazil, the first report of MERRF was made by Arruda et al in 1990 who described a family in which three siblings had myoclonic epilepsy associated with dementia, cerebellar ataxia, muscle weakness and sensory neuropathy 5 . The siblings all showed an elevation of lactic acid, electroencephalogram (EEG) with photoparoxysmal response, muscular COX activity deficiency, muscle biopsy with ragged-red fibers (RRF) and abnormal mitochondria as viewed by electron microscopy.…”

“…The siblings all showed an elevation of lactic acid, electroencephalogram (EEG) with photoparoxysmal response, muscular COX activity deficiency, muscle biopsy with ragged-red fibers (RRF) and abnormal mitochondria as viewed by electron microscopy. Since this first description in Brazil, few MERRF patients have been described in the country to date 5,6 . Two other important medical landmarks are ascribed to MERRF.…”

A importância da biópsia muscular no diagnóstico de neuromiopatias

“…Recentes observações na estrutura primária das glicoproteínas corroboram a hipótese de que a redução nesta substância em pacientes com Duchenne e Becker levaria a perda de ligações entre o sarcolema e a matriz extracelular, tornando as fibras mais susceptíveis a necrose 9 . A elevada incidência nesta casuística de miopatias mitocondriais, doença rara, deve-se à identificação de diversos membros de uma mesma família residente nesta localidade e afetados por miopatia mitocondrial e epilepsia mioclônica 1 . As miopatias mitocondriais (aproximadamente 7% dos nossos casos) compõem grupo complexo e heterogêneo de desordens neuromusculares devidas a defeitos bioquímicos afetando o metabolismo mitocondrial.…”

Oxidative Stress and Mitochondrial Injury in Chronic Multisymptom Conditions: From Gulf War Illness to Autism Spectrum Disorder

“…Yes 67, 106, 107, 148, 180-182, 200, 280, 281 Hypertension Yes 6,26,153,282,283 Yes [284][285][286][287][288][289] Weight gain Yes 7,26,153 Yes [290][291][292][293] Amyotrophic lateral sclerosis Yes [294][295][296] Yes [297][298][299][300] Hearing loss / tinnitus Yes 5,6,10,26 Yes 28,234,[301][302][303][304][305][306][307] Fracture risk and reduced bone formation Yes 308,309 Yes [310][311][312][313] Significant elevations in self-reported hearing loss after 1990 or 1991 in GWV vs control groups have been reported 5,6,10,…”