Figure 1
Neuroradiology
Case TypeClinical Cases
AuthorsAndrés Cárdenas, MD; Silvia Cárdenas, MD.
Patient4 years, female
A 4-year-old female with recent and progressive bilateral sensorineural hearing loss, extrapyramidal symptoms and hyperlactacidaemia, came to our institution and a MRI was performed. She returned two years later for a control with right anacusia, left hearing loss and strength and motility deterioration. A second MRI was performed.
The first MRI, no significant findings are found in the morphological sequences; However, spectroscopy shows moderate increase of the lactic acid peak. On the second MRI, brain atrophy is observed. T2 and FLAIR images reveal abnormal hyperintensity with cortical and juxtacortical involvement over both cerebral hemispheres. They are located predominantly on both sides of the parasagittal convexity, perisylvian and perirolandic areas, as well as in the inferior and medial occipital cortical regions. These lesions have high signal on diffusion-weighted images (DWI), with variable values in the apparent diffusion coefficient (ADC). The spectroscopy again reveals a lactate peak although to a lesser degree.
Mitochondrial diseases (MD) are a heterogeneous group of disorders with symptoms of organ dysfunction across multiple body systems and occur when alteration of mitochondrial respiratory chain complex function caused by genetic mutation produces a detectable disease state [1]. Clinical features manifest typically in tissues with the highest energy requirements including skeletal muscles, brain, myocardium, and endocrine systems [2]. Several distinct MD syndromes have been described, comprising mitochondrial encephalomyopathy and lactic acidosis stroke-like episodes [3, 4, 5]. Clinically it presents with signs and symptoms of encephalomyopathies, growth disturbance, seizures, and stroke-like events that might be reversible or irreversible with permanent neurologic deficits [6, 7]. Muscle biopsies reveal the presence of ragged red fiber.
MRI remains the main imaging technique to evaluate metabolic disorders [8]. In an acute episode the disease appears on CT as hypodense cortical areas usually located in one or both parieto-occipital lobes and not confined to single vascular territory [9]. On MR, T2 hyperintense lesions may appear with a predilection for the cerebral cortex rather than underlying white matter. These lesions migrate over time, and have some predilection to occipital and parietal lobes [10, 11]. Progressive atrophy of the basal ganglia with calcifications, temporal- parietal-occipital cortex with preservation of hippocampal, entorhinal structures, and multifocal basal ganglia, deep white matter hyperintensities are chronic manifestations [12].
DWI shows high signal during acute episode, with variable ADC [13, 14]. Recent studies suggest that the development of cytotoxic oedema as represented by decreased ADC is likely due to initial neuronal energy insufficiency. Subsequent development of extracellular oedema in surrounding region leads to increased ADC signal [15].
MR spectroscopy shows a characteristic large lactate peak at 1.3 ppm [16], usually reflects anaerobic metabolism, though it has been reported to occur even in the normal-appearing brain [17]. Lactate peak has also been associated with increased disease severity and reduced survival. Elevated lactate in affected regions of the brain tends to gradually resolve as these lesions evolve further into cerebral atrophy [16].
There is no specific treatment for individuals with MELAS. Therapeutic compounds may ameliorate symptoms in individual cases; however, the available therapeutic interventions are not able to affect the essential progression of this disease. Some of the most frequently prescribed agents include ubidecarenone, idebenone, edaravone, levoarginine [18], complex B vitamins, vitamin C, E and levocarnitine.
Think MELAS in patient with acute "stroke-like" cortical lesion that crosses usual vascular territories.
Written informed patient consent for publication has been obtained.
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URL: | https://eurorad.org/case/15941 |
DOI: | 10.1594/EURORAD/CASE.15941 |
ISSN: | 1563-4086 |
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