Anesthetic implications of a parturient with MELAS syndrome
Abstract Number: 88
Abstract Type: Case Report/Case Series
MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) syndrome is a rare, progressive neurodegenerative disorder requiring careful anesthetic management. Patients may have a history of seizures, diabetes mellitus, hearing loss, short stature, peripheral axonal neuropathy, cardiomyopathy, and respiratory compromise. Patients present with a varied phenotypic response; most will be diagnosed as children. The genetic disorder is mitochondrial, and therefore, all offspring of an affected female will carry the defective genotype. Death from MELAS is usually premature resulting from respiratory failure, cardiomyopathy or neurologic compromise.
A 20 y.o. G1P0 presented for elective c-section at term. Height and weight were: 58" and 125lbs, respectively. Physical exam was notable for small stature and mild kyphosis. PMH included: MELAS syndrome (by muscle biopsy),IDDM and sickle cell trait. Meds included insulin and metoclopromide. Labs revealed anemia, normal blood glucose, and normal lactate. ECG revealed low voltage. An operating room free of MH triggering agents was prepared. Spinal anesthesia was administered at the L3-L4 interspace using hyperbaric bupivacaine (11.25mg), fentanyl (10mcg) and morphine (0.25mg). The patient was placed supine in left uterine displacement. A small (5mg) dose of ephedrine was given following a small decrease in SBP. A sensory anesthetic level to T2 was achieved, and a 3450g male infant was successfully delivered with normal Apgars. Postoperative course was without incident.
Elective cesarean section is preferred in MELAS patients in order to avoid lactic acidosis or seizures during painful labor (stress). Elevations in lactate are due to decreased or defective oxidative phosphorylation, which reduces aerobic respiration, resulting in elevated serum and cerebrospinal fluid lactate, a phenomenon exacerbated by stress. Regional anesthesia may be complicated by respiratory compromise in MELAS patients with poor pulmonary reserve, while GA may be associated with an increased risk of malignant hyperthermia. There may be either hypersensitivity or resistance to nondepolarizing neuromuscular blocking agents. Myocardial depression may occur with inhaled anesthetics. MELAS patients have nonetheless successfully undergone surgery using neuromuscular blockade and inhaled anesthetics without incident. Choosing regional versus GA for MELAS patients should depend upon the specific disease manifestations as there is great phenotypic variability.Finally, the inability to maintain normothermia in MELAS is a concern, and patients should receive active warming.
Because of the paucity of clinical experience with MELAS patients, clinicians are encouraged to report their cases to the National Registry: med.umich.edu/ anes/melas.
References: 1. ACTA ANAESTHESIOL SIN 38:107-110, 2000 2. ACOG VOL. 93, NO. 5, PART 2, MAY 1999 3. ANESTH ANALG 1997;85:1404-6