Myoclonic Epilepsy With Ragged Red Fibers

Prevalence: 1:400,000

Maternal inheritance; less commonly a spontaneous mitochondrial gene mutation in those without family Hx

Lactic acidosis

Cardiac/respiratory insufficiency/failure

Delayed emergence

Respiratory failure following sedation.

Consider aspiration risk.

Lactic acidosis.

Seizures.

Mitochondrial myopathy most commonly characterized by cerebellar ataxia, myoclonus, epilepsy, lactic acidosis, hearing loss, peripheral neuropathy, and short stature.

Excess lactic acid load leads to nausea, vomiting, abdominal pain, fatigue, and tachypnea.

Most commonly maternal inheritance; less commonly results from a new mutation in a mitochondrial gene in those without a family Hx.

Onset is in late adolescence through early adulthood.

Muscle biopsy with hallmark appearance of ragged red fibers.

DNA point mutation results in mutation of respiratory chain complexes I + IV.

Inability to process lactate-containing fluids.

Anesthetic sensitivity may manifest as decreased MAC of inhaled anesthetics, with increased respiratory insufficiency from sedatives and narcotics.

Most common mutation is the m.8344A>G mutation in the mitochondrial DNA gene, MT-TK, which encodes mitochondrial transfer (t)RNA lysine.

Muscle biopsy shows ragged red fibers with deficient activity of COX, and presence of COX deficient vessels with SDH stain.