SUBACUTE NECROTIZING ENCEPHALOMYOPATHY (Leigh syndrome)

MR imaging revealed symmetrical areas of signal abnormality in bilateral putamen. These areas of signal alteration were seen as hyperintense signal on FLAIR coronal [Figure - 1] and hypointense signal on inversion recovery [Figure - 2] MR images. Areas of signal alteration were also seen in the periaqueductal region [Figure - 1],[Figure - 4] in the substantia nigra bilaterally [Figure - 3] and in the medulla oblongata [Figure - 4].

The clinical presentation, presence of lactic acidosis and the congruent MR findings of bilateral symmetrical areas of T2 prolongation involving the putamen, periaqueductal gray matter and brainstem suggested a diagnosis of Leigh syndrome.

Leigh disease, or subacute necrotizing encephalomyopathy is an inherited, progressive, neuro-degenerative disease of infancy or early childhood [1]. Affected infants and children typically present with hypotonia and psychomotor deterioration. Ataxia, ophthalmoplegia, ptosis, dystonia and swallowing difficulties inevitably ensue [2]. Acute respiratory failure may occur.

Pathologic Features

Characteristic pathologic abnormalities include microcystic cavitation, vascular proliferation, neuronal loss and demyelination of the midbrain, basal ganglia and cerebellar dentate nuclei and occasionally of the cerebral white matter [3].

Imaging Features

Typical MR finding in Leigh disease is the remarkably symmetrical involvement, most frequently in the putamen [4]. Other areas of involvement include the paraventricular white matter, corpus callosum, substantia nigra, decussation of superior cerebellar peduncles, periaqueductal region, brainstem and the gray matter in the spinal cord [5]. Loss of respiratory control in Leigh disease has been found to correlate with lower brainstem lesions (particularly situated in the periaqueductal gray matter and reticular formation of the medulla oblongata). Upper brainstem signal abnormalities are often transient and the associated respiratory difficulties resolve.

Proton MR spectroscopy with voxel placement in the basal ganglia typically demonstrates an abnormal lactate peak with a decrease in NAA/Cr.