Migratory stroke-like lesions in a case of adult-onset mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome and a review of imaging findings

Abstract

Imaging findings of adult-onset mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is poorly documented. The authors present a 48-year-old woman with subacute onset of word-finding difficulties and right arm stiffness. Magnetic resonance imaging performed 2 weeks prior revealed left temporal lobe diffusion and fluid-attenuated inversion recovery hyperintensity predominantly involving the cortex. The apparent diffusion coefficient map showed preserved signal in the temporal cortex. Subsequent magnetic resonance imagings demonstrated a new diffusion signal abnormality extending to the left parietal cortex and occipital cortex with resolving diffusion hyperintensity in the temporal lobe. MR spectroscopy showed scattered areas of lactate deposition. Diagnosis of MELAS syndrome was confirmed by genetic analysis. Fluctuating, migratory stroke-like lesions with a predilection for the parietal, temporal, and occipital cortex that do not conform to a vascular territory and a lactate spike at 1.3 ppm on MR spectroscopy are characteristic of MELAS syndrome. Preserved signal intensity on apparent diffusion coefficient is useful to distinguish MELAS syndrome from ischemic infarction where the signal is typically reduced.

Gyriform restricted diffusion in adults: looking beyond thrombo-occlusions

“…They resolve with clinical improvement only to recur in new locations with new symptom onset. Contrast enhancement may occur, and MR spectroscopy may show an elevated lactate peak at 1.33 ppm [38,42]. Extensive petechial haemorrhages along the involved cortices have also been reported [42].…”

“…This abnormal DNA causes poor energy production, microvascular angiopathy and nitric oxide deficiency. Thus, high-energy requiring tissues, such as the brain and skeletal muscles, are affected [38].…”

“…These include delayed and stunted growth, headache, recurrent stroke-like episodes, sensorineural hearing loss and cortical blindness [39,40]. Genetic analysis or muscle biopsy to identify ragged red fibres using modified Gomori trichrome or succinate dehydrogenase stains are essential for a definitive diagnosis [38].…”

“…On MRI, MELAS shows a predilection for the parietal, temporal and occipital cortices, not conforming to vascular territories. Within 24 h of a stroke-like episode, affected areas demonstrate GRD with T2W prolongation (because of cytotoxic oedema from energy insufficiency) [38,41] ( Fig. 11).…”

Single Gene Causes of Stroke

“…For migraine prevention, though no one medication is preferred over another, 15 there are observational reports of particular benefit from acetazolamide, possibly improving the hypoperfusion characteristic of CADASIL. 27,28 For acute migraine treatment, serotonin (5-hydroxytryptamine 1 [5-HT 1 ]) receptor agonists (triptans) are not routinely used because of a presumed potential to increase stroke risk. However, one observational study reported that 11% of CADASIL patients with migraine had tried triptans without adverse events, and experienced about a 50% response rate.…”