Abstract
We report on the conventional and diffusion tensor imaging (DTI) findings of a 2-year-old
child with clinical presentation of Joubert's Syndrome (JS) and brainstem structural
abnormalities as depicted by neuroimaging.
Conventional magnetic resonance imaging (MRI) showed a “molar tooth” configuration
of the brainstem. A band-like formation coursing in an apparent axial plane anterior
to the interpeduncular fossa was noted and appeared to partially cover the interpeduncular
fossa.
DTI maps and three-dimensional (3D) tractography demonstrated a prominent red-encoded
white matter bundle anterior to the midbrain. Probable aberrant course of the bilateral
corticospinal tracts (CST) was also depicted. Absence of the decussation of the superior
cerebellar peduncles and elongated thickened, horizontal superior cerebellar peduncle
(SCP) reflecting the molar tooth sign were also shown.
Our report and the review of the published cases suggest that DTI and tractography
may be very helpful to differentiate between interpeduncular heterotopias and similarly
located white matter bundles corroborating the underlying etiology of axonal guidance
disorders in the complex group of ciliopathies including JS. Our case represents an
important additional puzzle piece to explore the variability of these ciliopathies.
Keywords
Joubert's syndrome - interpeduncular mass - diffusion tensor imaging - tractography
- ciliopathy
