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Neuropsychological status of mitochondrial encephalomyopathies
1Neurological Hospital, University of Erlangen-Nuremberg at Erlangen, Schwabachanlage 6, D-91054 Erlangen, D-97080 Würzburg, GermanyNeurological Hospital, University of Würzburg, Josef-Schneider-Straße 11, D-97080 Würzburg, Germany.
Abstract:
We studied 15 patients suffering from mitochondrial encephalomyopathies (MEM) by a neuropsychological screening procedure. Eight of the patients were diagnosed as having progressive external ophthalmoplegia (PEO), four mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS), and three Kearns-Sayre syndrome (KSS). Based on test results covering memory, orientation, non-verbal intelligence, drawing, arithmetics, word list generation, trail making and digit span, only four patients were regarded as normal, two in the PEO and two in the KSS groups, while five patients were found to be demented (two patients in the PEO and three patients in the MELAS groups). Although memory problems were very common, it is concluded that no uniform pattern of neuropsychological deficits is seen in MEM, that MELAS patients apparently are severely handicapped cognitively, and that considerable mental deterioration may be seen even with normal computer-assisted tomography findings.
Insights
Mitochondrial encephalomyopathies (MEM) patients show varied cognitive deficits. Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) patients exhibit severe cognitive impairment, even with normal brain imaging.
Area of Science:
- Neurology
- Neuropsychology
- Genetics
Background:
- Mitochondrial encephalomyopathies (MEM) are a group of rare genetic disorders affecting energy production.
- Neuropsychological deficits are common in MEM, but the pattern can vary significantly between subtypes.
- Understanding these deficits is crucial for patient management and prognosis.
Purpose of the Study:
- To investigate the neuropsychological profiles of patients with different types of mitochondrial encephalomyopathies.
- To identify patterns of cognitive impairment in progressive external ophthalmoplegia (PEO), MELAS, and Kearns-Sayre syndrome (KSS).
- To correlate cognitive findings with clinical presentation and neuroimaging results.
Main Methods:
- A neuropsychological screening procedure was administered to 15 patients with MEM.
- Tests assessed memory, orientation, non-verbal intelligence, drawing, arithmetic, word list generation, trail making, and digit span.
- Patients were categorized into PEO, MELAS, and KSS groups.
Main Results:
- Four out of 15 patients were considered neurologically normal.
- Five patients exhibited dementia, including two with PEO and three with MELAS.
- Memory problems were frequently observed across different MEM subtypes.
Conclusions:
- No uniform pattern of neuropsychological deficits exists in mitochondrial encephalomyopathies.
- Patients with MELAS appear to experience severe cognitive handicaps.
- Significant mental deterioration can occur in MEM patients even with normal computer-assisted tomography (CT) findings.
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