Increased density of the thalamus on CT scans in patients with GM2 gangliosidoses

In 13 patients, the GM2 gangliosidoses, Sandhoff disease and Tay-Sachs disease, were found to be constantly associated with homogeneously and symmetrically in-creased CT attenuation within the thalami. In the only patient examined with MR imaging, a T2-weighted sequence showed hypointense thalami. It is suggested that this finding is caused by an accumulation of calcium, associated with the intracellular storage of GM2 ganglioside. The finding of dense thalami may be useful as a specific diagnostic criterion for GM2 gangliosidoses. In a few patients with blocks in adjacent steps in the sphingolipid metabolism, this finding was not present. AJNR 11:125-130, January /February 1990 The GM2 gangliosidoses are rare disorders of the sphingolipid metabolism in which a hexosaminidase defect causes a metabolic block leading to an abnormal accumulation of GM2 ganglioside in brain tissue. The most common GM2 disorder, Tay-Sachs disease [1], has a pronounced predilection for Ashkenazy Jews. A rarer GM2 disorder, Sandhoff disease [2] , of which a total of less than 100 cases ha