The Author's Reply: Cerebellar Stroke-like Lesions?

The Authors Reply We thank Dr. Finsterer for his interest in our article (1) and for his comments.

Our patient had been suffering from a left hearing impairment since 9 years of age. None of her family members had any mitochondrial diseases. We did not examine the mtDNA of her family members. When she was 23 years old, she developed convulsions for the first time. At 24 years of age, she was admitted to our hospital with headache and nausea. Diffusion-weighted magnetic resonance imaging showed cerebellar hyperintensity lesions (1) and these lesions showed either isointense or hypointense findings on apparent diffusion coefficient (ADC) maps. She then developed focal seizure and a disturbance of consciousness. She did not have any manifestation related to the cerebellar lesions after her consciousness improved. Examinations of blood and cerebrospinal fluid showed elevated lactic acid levels. A mtDNA analysis of her peripheral blood leukocytes revealed the presence of an m.3243A＞G mutation and her heteroplasmy rate was 43%, however, no analysis of any other organs was performed. She had been administered arginine infusion (20 g/day), edaravone infusion (60 mg/day), levetiracetam infusion (1,000 mg/day), and intravenous methylprednisolone pulse therapy while her consciousness had been impaired. Thereafter, she received arginine (21 g/day), tocopherol nicotinate (200 mg/day),vitamin C (1,200 mg/day), vitamin B₁ (225 mg/day), coenzyme Q10 (30 mg/day), carnitine (750 mg/day), levetiracetam (1,000 mg/day), and lamotrigine (100 mg/day).

Our patient showed the dilatation of the intracranial vessels on magnetic resonance angiography and hyperperfusion of the cerebellum was detected by arterial spin labeling (1). Although the cause of stroke-like lesions in mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) remains unknown, it is suggested that the stroke-like lesions might have been caused by not only mitochondrial angiopathy characterized by the mitochondrial dysfunction in vascular smooth muscle cells and endothelial cells, but also by some intrinsic mitochondrial malfunction of the neuronal cells (2). In MELAS, the abnormal accumulation of mitochondria is observed in smooth muscle cells, endothelial cells of the cerebral blood vessels (3) and in the cactus formation of the cerebellar Purkinje cells (2). In view of these reports of MELAS, our patient might have had an abnormal accumulation and dysfunction of the mitochondria in the intracranial blood vessels and the neurons of the cerebellum.

The authors state that they have no Conflict of Interest (COI).