Anesthetic considerations in mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes syndrome: a case series.

PURPOSE: Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes syndrome (MELAS) is a rare inherited mitochondrial disorder associated with severe multiorgan pathology and stress-induced episodes of metabolic decompensation and lactic acidosis. The purpose of this case series is to review the medical records of patients with MELAS who underwent anesthetic care at the Mayo Clinic to observe their perioperative responses to anesthesia and to assess outcomes. PRINCIPAL
FINDINGS: From September 1997 to October 2010, nine patients with MELAS were identified who underwent 20 general anesthetics, 12 prior to MELAS diagnosis. Debilitating neurologic symptoms involved eight patients, and three patients had substantial cardiac comorbidities. The patients tolerated commonly used anesthetics and muscle relaxants, including succinylcholine. Lactated Ringer's solution was used frequently. One patient was noted to have elevated postoperative serum lactate, but his serum lactate was chronically elevated. Metabolic acidosis was not observed in any patient. Hyponatremia and hyperkalemia, sometimes profound, were observed in seven patients, but these abnormalities also occurred at times remote from surgery. Two patients developed renal dysfunction following cardiac surgery and abdominal surgery for severe sepsis.
CONCLUSION: The MELAS patients developed episodes of hyponatremia and hyperkalemia of variable severity unrelated to the timing of surgery, suggesting these patients are prone to major electrolyte disturbances. Given the propensity to develop acid-base disturbances and lactacidemia, it is prudent to review and normalize electrolyte abnormalities and to adjust the anesthetic plan accordingly. Fortunately, the limited data suggest that patients with MELAS tolerate commonly used anesthetic drugs well.