Diagnosis and Management of Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like Episodes Syndrome

Abstract

Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is a complex mitochondrial disorder characterized by a wide range of systemic manifestations. Key clinical features include recurrent stroke-like episodes, seizures, lactic acidosis, muscle weakness, exercise intolerance, sensorineural hearing loss, diabetes, and progressive neurological decline. MELAS is most commonly associated with mutations in mitochondrial DNA, particularly the m.3243A>G mutation in the MT-TL1 gene, which encodes tRNALeu (CUR). These mutations impair mitochondrial protein synthesis, leading to defective oxidative phosphorylation and energy failure at the cellular level. The clinical presentation and severity vary widely among patients, but the syndrome often results in significant morbidity and reduced life expectancy because of progressive neurological deterioration. Current management is largely focused on conservative care, including anti-seizure medications, arginine or citrulline supplementation, high-dose taurine, and dietary therapies. However, these therapies do not address the underlying genetic mutations, leaving many patients with substantial disease burden. Emerging experimental treatments, such as gene therapy and mitochondrial replacement techniques, aim to correct the underlying genetic defects and offer potential curative strategies. Further research is essential to understand the pathophysiology of MELAS, optimize current therapies, and develop novel treatments that may significantly improve patient outcomes and extend survival.

Keywords: MELAS; MT-TL1; mitochondrial disease; mitochondrial encephalopathy lactic acidosis and stroke-like episodes; stroke-like episode.

Figure 1

Pathophysiological mechanisms of stroke-like episodes in MELAS. ATP, adenosine triphosphate; CSF, cerebrospinal fluid; DNA, deoxyribonucleic acid; MELAS, mitochondrial encephalopathy lactic acidosis and stroke-like episodes; mtDNA, mitochondrial deoxyribonucleic acid; OXPHOS, oxidative phosphorylation; ROS, reactive oxygen species.

Figure 2

Current therapeutic strategies for MELAS. KD, ketogenic diet; LGIT, low-glycemic index treatment; MAD, modified Atkins diet; MELAS, mitochondrial encephalopathy lactic acidosis and stroke-like episodes; NO, nitric oxide.