Joubert Syndrome: The Molar Tooth Sign of the Mid-Brain
A 1 year and 4 month-old male baby was admitted in our department with history of delayed developmental milestone, mental retardation, abnormal limb movement, generalized hypotonia and abnormal head movements with nystagmus. There was also history of abnormal breathing pattern with episodes of alternate rapid breathing and normal breathing. There was history of feeding difficulties on and off and frequent chest infection from the early months of life.\nPast history revealed that the child was born by normal vaginal delivery in a hospital at term pregnancy, with history suggestive of birth asphyxia. The birth weight of the baby was 3 kg. His parents had a consanguineous marriage. From the early days of life, his mother noticed feeding difficulties and frequent chest infections of her baby. She also noticed abnormal movement of his head and peculiar eye movement with deviation of the eyes, but relative paucity of movement of the limbs. There was history of episodic rapid breathing lasting for 2-3 min with frequent opening of the mouth and protrusion of the tongue interspersed with normal breathing. There was weak cry and floppiness of all the muscles from the first few months of life. But, no convulsion was noted. Hearing was normal as the child was able to turn the head toward the source of sound. Symptoms were progressively increasing. Prenatal history was uneventful. No similar illness in any siblings in the family was reported. Immunization was incomplete. There was gross delay in development of mental and motor milestones.\nPhysical examination revealed a hypotonic child with constant efforts of abnormal head movement sideways and limb movements, opened mouth with protruded tongue [], and the child showed abnormal breathing pattern with hyperpnea and tachypnea. Head circumference and other anthropometric examinations were normal. No morphological abnormality was detected. Cardiovascular and respiratory system examinations were normal. No organomegaly was present. Ocular examinations revealed bilateral divergent squint, inability to follow moving object, restricted upward gaze of eye and bilateral horizontal gaze-evoked nystagmus. Retinoscopy revealed refractory error of both eyes. Ophthalmoscopic examination was normal and no pigment changes in the retina were detected; optic disc was also normal. Complete blood count, renal function test and liver function test were normal.\nAxial T1- and T2-weighted magnetic resonance imaging (MRI) images showed hypoplastic cerebellar vermis with hypoplasia of the superior cerebellar peduncle resembling the “Molar Tooth Sign” in the mid-brain [Figures and ]. MRI sagital T1-weighted image revealed partial agenesis of cerebellum agenesis and hypoplasia of the superior cerebeller peduncle was noted []. MRI axial (at the level of post-fossa) T2-weighted image revealed hyperintensity of basal cisterns communicating with the fourth ventricle suggestive of vermian agenesis []. Renal ultrasound showed no abnormality.