Specific Imaging Findings

Imaging findings in Tay–Sachs (Infantile GM2 Gangliosidosis Type B) and Sandhoff diseases (Infantile GM2 Gangliosidosis Type O) are quite similar. The lesion pattern in a macrocephalic infant is highly suggestive and includes symmetrical hyperdensities within the thalami and/or basal ganglia on brain CT. The thalami are typically hyperintense on T1-weighted images and hypointense on T2-weighted images. In Tay–Sachs disease the posterior part of the thalami may be T2 hyperintense. The putamina, caudate nuclei and globi pallidi are swollen and hyperintense on T2-weighted images. Widespread white matter changes within the cerebral hemispheres are also noted with sparing of corpus callosum, anterior commissure, and posterior limbs of the internal capsules. Brain atrophy appears in the final stages of the disease. Diffusion imaging is usually unremarkable. Brain MRS shows decline in the NAA, increased choline and progressive elevation of myo-inositol. In juvenile and adult GM2 gangliosidosis, there is cerebral and cerebellar atrophy, generally in combination with slight white matter signal changes. A decrease in T2 signal intensity of the thalami is also found in a number of other diseases caused by genetic mutations and it seems to be a sign of lysosomal disease.