Neuropediatrics 2013; 44 - PS21_1030
DOI: 10.1055/s-0033-1337862

Tectocerebellar dysraphism with occipital encephalocele is part of the Joubert syndrome spectrum

A Poretti 1, K Rostásy 2, XC Wei 3, C Fauth 4, J Koch 5, WJ Hader 6, EM Valente 7, TAGM Huisman 1, E Boltshauser 8
  • 1The Johns Hopkins University School of Medicine, Russell H. Morgan Department of Radiology, Baltimore, Maryland, United States
  • 2Pädiatrie I, Neuropädiatrie, Kinderklinik, Innsbruck, Austria
  • 3Departments of Radiology, Alberta Children's Hospital, Calgary, Canada
  • 4Abteilung für Humangenetik, Klinik für medizinische Genetik, Innsbruck, Austria
  • 5Neuropädiatrische Abteilung, Universitätsspital, Salzburg, Austria
  • 6Division of Neurosurgery, Department of Clinical Neuroscience, Calgary, Canada
  • 7Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, Roma, Italy
  • 8Neuropädiatrische Abteilung, Universitäts-Kinderklinik, Zürich, Switzerland

Aims: Tectocerebellar dysraphia with occipital encephalocele (TCDOE) describes vermian hypogenesis with tectal malformation and occipital encephalocele. Based on conventional MRI and diffusion tensor imaging (DTI) findings, we recently suggested that TCDOE may be part of the Joubert syndrome and related disorders (JSRD) spectrum. We report on clinical, neuroimaging (conventional and DTI), and genetic findings in four children with TCDOE.

Methods: Conventional MR images were evaluated for infra- and supratentorial abnormalities. Color-coded fractional anisotropy (FA) maps were evaluated for presence of the midbrain decussation of the superior cerebellar peduncles (SCP). Data about neurological findings, outcome, and genetic analysis were collected from clinical history and follow-up examinations.

Results: Four children were included (two females). All patients presented at birth because of an occipital encephalocele. Follow-up data were available for three children. At a mean age of 6.7 years (4 months to 15.8 years), truncal hypotonia was present in all patients. Two patients had cognitive impairment and one infant impaired global development. Ataxia, epileptic seizures, ptosis, neonatal breathing abnormalities, and choroidal colobomas were present in one patient. In all patients, MRI demonstrated hypoplasia of the cerebellar vermis, tectal beaking, and elongation, thickening, and horizontal orientation of the SCP with a deepened interpeduncular fossa forming a molar tooth sign (MTS). In one patient, subependymal heterotopia and focal cortical dysplasia were also noted. DTI data were available for three children and showed absence of the SCP decussation in all. Genetic analysis in one patient revealed a homozygous deletion leading to a frameshift and premature stop codon in the TMEM237 gene, one of the 19 JSRD genes known so far.

Conclusion: The presence of MTS in all, absence of the SCP decussation on DTI in three, and a homozygous mutation within the TMEM237 gene in one patient confirm our first hypothesis that TCDOE may represent a structural manifestation within the JSRD spectrum.