Molar Tooth Sign in Joubert Syndrome: A Case Report

The molar tooth sign refers to the appearance of the midbrain in axial section in which the elongated superior cerebellar peduncles give the midbrain an appearance reminiscent of a molar or wisdom tooth. Molar tooth sign is caused by lack of normal decussation of superior cerebellar peduncular fiber tracts which in turn leads to enlargement of the peduncles, which also follow a more horizontal course as they extend perpendicularly to the brainstem between the midbrain and the cerebellum. The absence of crossing fibers causes decresed anteroposterior diameter of midbrain and also causes interpeduncular cistern to be deeper than in the normal brain. It is seen in patients with joubert syndrome.