Late-Onset Melas with Midd: An Uncommon Age of Presentation

ABSTRACT Objective: Maternally inherited diabetes and deafness (MIDD) is a rare form of diabetes caused by a mutation in mitochondrial DNA, usually a point mutation at position 3243 in the leucine tRNA gene. This same mutation can cause a rare but severe syndrome called mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS). Methods: We describe a case of MIDD with acute mitochondrial decompensation that progressed to MELAS. Results: A 63-year-old male with MIDD and a history of hypoglycemic seizures presented for evaluation of altered mental status with fever, tachycardia, hypotension, and somnolence. His history was also significant for deafness and cochlear implants. The physical exam results were consistent with mild, proximal muscle wasting. The initial workup was concerning for sepsis and a urinary tract infection. Laboratory evaluation revealed lactic acidosis with normal white cell count, liver enzymes, and ammonia level. After fluid resuscitation and 4 days of broad-spectrum antibiotics, his mental status improved. Then he became obtunded again, and a stroke alert was called. Stroke workup results, including imaging studies, were negative, ammonia level was high, and he developed transaminitis. There was a concern for carnitine deficiency given the underlying mitochondrial disease, valproic acid use, and sepsis. He stabilized for a few days but then developed focal left-arm paresis. Stroke workup again was negative and diagnosis of MELAS was considered. Arginine supplementation was initiated with improvement of the focal weakness. He was discharged to rehabilitation. Conclusion: This case highlights that MIDD and MELAS are a spectrum of the same disease process, and emphasizes the importance of recognizing MELAS as a rare presentation in MIDD patients irrespective of age. Abbreviations: MELAS mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes MIDD maternally inherited diabetes and deafness