(730) Metabolic Masquerade: A Rare Presentation of Leigh Syndrome

Introduction: Leigh syndrome is a rare hereditary neurological disorder that typically appears within the first years of life. It is caused by mutations in mitochondrial DNA or deficiencies in the pyruvate dehydrogenase enzyme and characterized by generalized signs and symptoms of progressive loss of psychomotor abilities, seizures, weakness, respiratory failure, spasticity, ataxia, and episodes of lactic acidosis. We report a case of a severe, autosomal recessive variant of Leigh syndrome in an infant that was initially disguised by another neurological diagnosis.

Description: A 4-month-old previously healthy male with acute encephalopathy, acute respiratory failure, poor sucking ability, and concern for new onset seizures. The patient underwent a head CT, an EEG, and sepsis workup. MRI of the brain showed acute encephalomyelitis in the sub thalamic brainstem extending into the cervical spinal cord. Further history also revealed a left upper extremity weakness/paralysis. The patient received IVIG and solumedrol for 5 days. The patient recovered back to baseline and was discharged home. Fifteen days later, the patient was re-admitted to acute care unit with right hemiparesis, seizures, poor sucking ability concerning for acute flaccid myelitis relapse. Repeat brain MRI showed no changes. The patient once again required mechanical ventilation with concern for progressive encephalopathy. In collaboration with neurology, the patient received another course of IVIG. Further workup included MRI brain and spine spectroscopy which showed a lactate peak consistent with a possible metabolic disorder. Genetics consultation was obtained and whole genome sequencing was sent with findings consistent Leigh syndrome. Due to the patient’s rapid clinical progression without any treatment options, the family elected to withdraw life sustaining therapies.

Discussion: This case demonstrates the medical challenge of diagnosing Leigh syndrome due to its non-specific characterized signs and symptoms that may also be consistent with other neurological diagnosis. Although a uniformly fatal disease with no specific treatment, expediting the diagnostic work-up when there is high clinical suspicion can allow clinicians to discuss overall prognosis and in cases of familial inheritance, guide future family planning.