Serial diffusion-weighted imaging in a patient with MELAS and presumed cytotoxic oedema

Area of Science:

• Neurology
• Neuroimaging
• Mitochondrial Diseases

Background:

• Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a rare genetic disorder.
• Stroke-like episodes are a common and debilitating manifestation of MELAS.
• The pathophysiology of these stroke-like episodes, specifically the nature of edema, requires further elucidation.

Observation:

• Serial diffusion-weighted MRI (DWI) and apparent diffusion coefficient (ADC) mapping were performed on a patient with MELAS experiencing stroke-like episodes.
• Infarct-like lesions were monitored in the acute, subacute, and chronic stages.
• High signal on DWI and low ADC values were observed in acute and subacute stages, indicating restricted diffusion.

Findings:

• The observed DWI and ADC patterns in acute/subacute stages suggest cytotoxic edema, characteristic of cellular energy failure.
• In the chronic stage, ADC values increased beyond normal levels, differentiating the process from typical ischemic stroke.
• These findings challenge the assumption of vasogenic edema in MELAS stroke-like episodes.

Implications:

• The study suggests that stroke-like episodes in MELAS are primarily driven by energy failure leading to cytotoxic edema.
• Understanding the specific edema type has critical implications for diagnosis and potential therapeutic strategies.
• This research highlights the utility of advanced MRI techniques in characterizing MELAS pathophysiology.