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Neuroimaging pattern and pathophysiology of cerebellar stroke-like lesions in MELAS with m.3243A>G mutation: a case
Munenori Oyama1, Takahiro Iizuka2, Jin Nakahara1
1Department of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan.
Background:
Stroke-like episodes (SLEs) in mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) with m.3243A > G mutation usually develop in the cerebral cortex. Few reports have documented SLEs in the cerebellum. The clinical neuroimaging features of cerebellar SLEs have not been fully investigated. We report distinctive features of cerebellar stroke-like lesions (SLLs) in a case of MELAS with m.3243A > G mutation.
Case Presentation:
A 47-year-old Japanese man with type-2 diabetes presented to our hospital with acute onset of aphasia. A brain MRI obtained on admission (day 1) showed increased diffusion-weighted imaging (DWI)/fluid-attenuated inversion recovery (FLAIR) signal in the left anterolateral temporal lobe, which subsequently spread along the cortex posteriorly accompanied by a new lesion in the right anterior temporal lobe. The patient was initially treated with acyclovir and subsequently with immunotherapy. However, on day 45, cerebellar ataxia developed. The brain MRI showed extensive increased DWI/FLAIR signals in the cerebellum along the folia without involvement of deep cerebellar nucleus or cerebellar peduncle; SLLs were incongruent with a vascular territory, similarly to classic cerebral SLLs. Apparent diffusion coefficient (ADC) map did not show reduction in ADC values in the affected folia. Genomic analysis revealed m.3243A > G mutation (heteroplasmy in leukocytes, 17%), confirming the diagnosis of MELAS. After the treatment with taurine (12,000 mg/day), L-arginine (12,000 mg/day), vitamin B1 (100 mg/day), and carnitine (3000 mg/day), the patient became able to follow simple commands, and he was transferred to a rehabilitation center on day 146. The follow-up MRI showed diffuse brain atrophy, including the cerebellum.
Conclusions:
SLLs develop in the cerebellum in MELAS with m.3243A > G mutation. The neuroimaging similarities to cerebral SLLs suggest the presence of the common pathophysiological mechanisms underlying both SLEs, which include microangiopathy and increased susceptibility of the cortex to metabolic derangements.
Insights
Stroke-like episodes (SLEs) in mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) can affect the cerebellum. This case highlights cerebellar stroke-like lesions (SLLs) in MELAS with the m.3243A>G mutation, suggesting common underlying mechanisms with cerebral SLEs.
Area of Science:
- Neurology
- Genetics
- Mitochondrial Diseases
Background:
- Stroke-like episodes (SLEs) are characteristic of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) but typically affect the cerebral cortex.
- Cerebellar involvement in MELAS is less common, and the specific neuroimaging features of cerebellar SLEs remain under-investigated.
Observation:
- A 47-year-old man with MELAS and the m.3243A>G mutation presented with acute aphasia, followed by cerebellar ataxia.
- Brain MRI revealed extensive stroke-like lesions (SLLs) in the cerebellar folia, incongruent with vascular territories, and without involvement of deep cerebellar structures.
- Apparent diffusion coefficient (ADC) mapping did not show reduced ADC values in the affected cerebellar regions.
Findings:
- The study confirms the occurrence of cerebellar SLLs in MELAS patients with the m.3243A>G mutation.
- Neuroimaging findings in cerebellar SLLs share similarities with cerebral SLLs, suggesting common pathophysiological mechanisms.
- These mechanisms likely involve microangiopathy and heightened cortical susceptibility to metabolic disturbances.
Implications:
- This case expands the understanding of MELAS manifestations, emphasizing the potential for cerebellar involvement.
- The findings suggest that similar pathophysiological processes underlie both cerebral and cerebellar SLEs in MELAS.
- Further research into the specific mechanisms of cerebellar SLLs in MELAS is warranted to guide therapeutic strategies.
