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Acronym for myoclonus epilepsy with ragged-red fibers. Belongs to a group of rare muscular disorders called mitochondrial encephalomyopathies. The most characteristic symptom is myoclonic seizures that are usually sudden, brief, jerking spasms that can affect the limbs or the entire body. Ataxia, lactic acidosis, dysarthria, optic atrophy, short stature, hearing loss, dementia, and nystagmus may occur.

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Fukuhara Syndrome.

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Mitochondrial; incidence of affected children is dependent upon maternal mutant load.

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Defect of the respiratory chain enzymes, mainly complexes I and IV.

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Clinical and laboratory confirmation of elevated pyruvate and lactate. Muscular biopsy shows ragged-red muscle fibers, and the biochemical defect is often segmental on histochemistry.

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Clinical spectrum is proportional to the amount of normal and mutant DNA. Onset is in the neonatal period, with mental deterioration, intention tremor, myoclonic epilepsy, spasticity, ataxia, muscle weakness and atrophy, myopathy, and sensory neural hearing loss. The neuropathologic findings are (a) degeneration of dentate nucleus, red nucleus, globus pallidus, subthalamic nucleus, and pontine tegmentum; (b) degeneration of the Clarke column (the dorsal nucleus of the spinal cord), spinocerebellar tract, posterior column and corticospinal tract, and posterior spinal nerve root and sural nerve; and (c) degeneration of substantia nigra, locus caeruleus, cerebellar cortex, and inferior olivary nucleus.

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Diagnosis of mitochondrial disease should be considered in any child with a multisystem neurologic disorder or who is being investigated for hypotonia. Anesthesia-related morbidity and mortality risk is essentially linked to the preoperative status of the child, that is, the number and extent of organ dysfunction. The presence of a mitochondrial disease is not considered a risk for malignant hyperthermia. Avoid any elective anesthesia/surgery in the presence of infection or temperature because cytokines (mainly tumor necrosis factor (TNF)), inhibit some complex of the respiratory chain. The following should be checked: central nervous system (seizures, myoclonus, strokes, swallowing problems); metabolic (usual venous or arterial concentration of lactates and glucose); muscles (hypotonia, contractures, scoliosis); cardiac (even if the child is asymptomatic, ECG and echocardiography to exclude conduction disorders and cardiomyopathy, respectively; check functioning of pacemaker, if present); pulmonary (frequent infections, chronic aspiration, pulse oximetry breathing room air, obstructive and/or central apnea; reduced ventilatory drive is common, and many patients have an abnormal response to both hypoxia and hypercarbia, and deaths have been reported following sedation with chloral hydrate or diazepam); hepatic and renal dysfunctions; nutritional status and diet (glucose and/or lipid rich; tolerance to fasting and treatment [carnitine, vitamin Q, antiepileptic drugs]).

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Usual treatment until the morning of surgery. Preoperative fasting as short as possible; if fasting is usually poorly tolerated, a glucose-containing solution should be started when fasting period starts. A sedative premedication is best avoided because of the possible abnormal response to hypoxia/hypercarbia. Induction: No contraindication to choice of anesthetic; however, the dosage of sedative agents might require reduction; sevoflurane is the best choice for inhalation induction; ...

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