venerdì 9 ottobre 2009

Leigh disease


Noncontrast axial FLAIR images through the brain demonstrate increased T2 signal hyperintensity within the bilateral putamen and caudate heads as well as in the gray matter structures of the midbrain. Corresponding noncontrast T1-weighted images show decreased signal within the same structures. Follow-up axial FLAIR image one year later demonstrates increased hyperintensity within with putamen and caudate heads indicating progression of disease.

Diagnosis: Leigh disease (subacute necrotizing encephalomyelopathy)

Leigh disease (subacute necrotizing encephalomyelopathy) is a progressive neurodegenerative disorder that results from an inherited (autosomal recessive or X-linked) mutation within mitochondrial DNA. This results in chronic energy deprivation within the CNS leading to necrosis, gliosis, demyelination, spongiosis, and/or capillary proliferation.

Age of onset is usually less than 2 years old, but juvenile and even adult forms exist. Patients may present with a wide variety of neurologic symptoms ranging from muscle weakness, dystonia, vision loss, ataxia, tachypnea, and seizures. Death generally occurs within a few years after symptom onset usually from respiratory failure. Laboratory findings may include elevated CSF lactate.

Imaging characteristically demonstrates symmetric involvement of the putamen with increased T2 signal and decreased T1 signal on MRI. Other gray matter structures may also be involved including the corpus striatum (caudate nucleus and globus pallidus), thalami, periaqueductal gray matter, and other gray matter structures within the brainstem. White matter changes on imaging are atypical but usually manifest as areas of periventricular increased T2 hyperintensity if present. In addition, MR Spectroscopy adds diagnostic value as elevated lactate levels may be seen within the affected structures such as the basal ganglia.

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