Abstract
Carriers of the m.3243A>G variant typically manifest with stroke-like episodes (SLEs), of which the morphological correlate on imaging is the stroke-like lesion (SLL). The pathophysiology of SLLs is poorly understood but acute and chronic stages are delineated. Here we present the case of an m.3243A>G carrier who presented with hypometabolism during his second SLL.The patient was a 56-year-old male who was diagnosed with MELAS (mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes) at the age of 50 upon a third SLE, muscle biopsy, and the detection of the m.3243A>G variant in the muscle. A fluorodeoxyglucose-positron emission tomography (FDG-PET) during the second SLE revealed hypometabolism in the occipital lobes bilaterally. The patient was misdiagnosed for years and was repeatedly exposed to mitochondrion-toxic drugs (metformin, steroids, valproic acid, oxcarbazepine, zolpidem). The previous data and the present findings indicate that the hypometabolism on FDG-PET together with reduced oxygen-extraction fraction (OEF) on OEF-MRI and hyperperfusion on perfusion-weighted imaging (PWI) characterise best the acute stage of an SLL.In conclusion, an acute SLE in m.3243A>G carriers typically manifests with a mismatch between hyperperfusion on PWI or single-photon emission computed tomography (SPECT) and hypometabolism on FDG-PET and hypointensity on OEF-MRI. Since SLEs are not vascular events, they should be managed by a multispecialist approach and not by general or stroke neurologists.
Highlights
The variant m.3243A>G manifests with syndromic or non-syndromic phenotypes [1]
We present an m.3243A>G carrier who presented with hypometabolism during the acute stage of an stroke-like episode (SLE)
The presented patient is interesting for multisystem mitochondrial disorder (MID) due to the variant m.3243A>G, phenotypically manifesting in the brain in recurrent SLEs, ataxia, epilepsy, cognitive impairment, psychiatric disease, eyes, ears, endocrine system, heart, muscle, and the peripheral nerves
Summary
The variant m.3243A>G manifests with syndromic or non-syndromic phenotypes [1]. Among the syndromic phenotypes, mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is the most prevalent [2]. At age 42 years, he presumably experienced the first SLL in the right parieto-occipital area manifesting with a transient flickering of the left eye, quadrantanopia to the lower left, left-sided ataxia, depressive mood, multimodal memory deficits, and a holocrane headache. At age 50 years, the patient experienced a third SLE in the right parieto-occipital area, manifesting with weakness of the left lower leg and seizures. This time, a mitochondrial disorder (MID) was suspected, being confirmed by a muscle biopsy. At age 56 years, the patient experienced a fourth SLE, manifesting as vertigo, confusional state, speech disturbance, and difficulties in finding words, starting two days prior to admission, in addition to ataxic gait and impaired concentration.
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