Joubert syndrome: the molar tooth sign of the mid-brain

Abstract

Joubert syndrome (JS) is a very rare, autosomal-recessive condition. It is characterized by agenesis of cerebellar vermis, abnormal eye movements with nystagmus, episodes of hyperpnea and apnea, delayed generalized motor development, retinal coloboma and dystrophy and, sometimes, multicystic kidney disease. The importance of recognizing JS is related to the outcome and its potential complications. Prenatal diagnosis by ultarsonography and antenatal magnetic resonance imaging (MRI) is also possible. We have diagnosed a case of JS in a male infant with history of delayed mental and motor milestone development, history of abnormal breathing pattern, abnormal limb movement, generalized hypotonia and abnormal head movements with nystagmus. MRI showed hypoplastic cerebellar vermis with hypoplasia of the superior cerebellar peduncle resembling the "Molar Tooth Sign" in the mid-brain.

Keywords: Joubert syndrome; Molar tooth sign; Vermian agenesis.

Figure 1

Photograph of the patient showing large protruding tongue

Figure 2

Magnetic resonance imaging of the axial T1-weighted image showing molar tooth appearance of the mid-brain

Figure 3

Magnetic resonance imaging of the axial T2-weighted image showing same molar tooth appearance of mid-brain

Figure 4

Magnetic resonance imaging of the sagittal T1-weighted image showing evidence of vermian agenesis and hypoplastic superior cerebellar peduncle

Figure 5

Magnetic resonance imaging of the axial T2-weighted image showing vermian agenesis and extension of the cerebrospinal fluid cleft through it