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MELAS: a neuropsychological and radiological follow-up study. Mitochondrial encephalomyopathy, lactic acidosis and
1Department of Psychiatry, University of Regensburg, Germany. heinosartor@t-online.de
Abstract:
We report on a patient with long standing, full-blown mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS). In contrast to earlier publications, detailed neuropsychological assessment revealed no dementia but a pattern of distinct cognitive deficits with marked impairment of visuo-constructive and executive functions. Focal lesions and progressing atrophy mainly of the basal ganglia and the temporo-parieto-occipital area with preservation of hippocampal and entorhinal structures were present. Furthermore, a 4-year follow-up assessment revealed an increasing deterioration of distinct cognitive functions, including phasic alertness, tactile functions and the discrimination of tone pitch and rhythm. This may be because of chronic regional metabolic disturbances, as there was no further stroke-like episode in that period of time.
Insights
Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) patients show specific cognitive deficits, not dementia. Cognitive functions progressively decline over time due to metabolic disturbances.
Area of Science:
- Neurology
- Neuroscience
- Genetics
Background:
- Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is a genetic disorder.
- Previous studies suggested dementia in MELAS patients.
Observation:
- A patient with MELAS presented with distinct cognitive deficits, particularly in visuo-constructive and executive functions.
- Neuroimaging revealed focal lesions and atrophy in the basal ganglia and temporo-parieto-occipital regions, sparing the hippocampus.
Findings:
- Detailed neuropsychological assessment excluded dementia, identifying specific cognitive impairments.
- A 4-year follow-up showed progressive deterioration in functions like alertness, tactile sensation, and auditory discrimination.
Implications:
- Cognitive deficits in MELAS are distinct and progressive, not necessarily dementia.
- Chronic metabolic disturbances may underlie cognitive decline in MELAS.
- Further research is needed to understand the pathophysiology of cognitive impairment in MELAS.