Skip to main content

Undecussated Superior Cerebellar Peduncles and Absence of the Dorsal Transverse Pontine Fibers: a New Axonal Guidance Disorder?


Axonal guidance disorders are a newly recognized group of diseases of the human central nervous system. These disorders are characterized by white matter tracts with abnormal course and failure to cross the midline or presence of ectopic white matter tracts. Diffusion tensor imaging (DTI) and fiber tractography are suitable neuroimaging tools to detect morphological abnormalities in the course, decussation, and location of white matter tracts. We report on a 6.5-year-old child with significant global developmental delay. Axial color-coded fractional anisotropy (FA)-maps revealed absence of (1) the midline “focal red dot” at the level of the pontomesencephalic junction representing absence of decussation of the superior cerebellar peduncles and (2) the dorsal component of the transverse pontine fibers. These findings are highly suggestive of an axonal guidance disorders. The complete neuroimaging phenotype of this child does not match well-known diseases with similar DTI findings. We show how DTI reveals important information of microstructural brain malformations that may go undetected or remains underestimated and consequently DTI may suggest the possible pathomechanism. We conclude that this child may be suffering from a not yet described subtype of an axonal guidance disorder.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3


  1. Patel S, Barkovich AJ. Analysis and classification of cerebellar malformations. AJNR Am J Neuroradiol. 2002;23:1074–87.

    PubMed  Google Scholar 

  2. Parisi MA, Dobyns WB. Human malformations of the midbrain and hindbrain: review and proposal classification scheme. Mol Genet Metab. 2003;80:36–53.

    Article  CAS  PubMed  Google Scholar 

  3. Barkovich AJ, Millen KJ, Dobyns WB. A developmental and genetic classification for midbrain-hindbrain malformations. Brain. 2009;132:3199–230.

    Article  PubMed Central  PubMed  Google Scholar 

  4. Pajevic S, Pierpaoli C. Color schemes to represent the orientation of anisotropic tissues from diffusion tensor data: application to white matter fiber tract mapping in the human brain. Magn Reson Med. 1999;42:526–40.

    Article  CAS  PubMed  Google Scholar 

  5. Ciccarelli O, Catani M, Johansen-Berg H, Clark C, Thompson A. Diffusion-based tractography in neurological disorders: concepts, applications, and future developments. Lancet Neurol. 2008;7:715–27.

    Article  PubMed  Google Scholar 

  6. Poretti A, Meoded A, Rossi A, Raybaud C, Huisman TA. Diffusion tensor imaging and fiber tractography in brain malformations. Pediatr Radiol. 2013;43:28–54.

    Article  PubMed  Google Scholar 

  7. Chilton JK. Molecular mechanisms of axon guidance. Dev Biol. 2006;292:13–24.

    Article  CAS  PubMed  Google Scholar 

  8. Engle EC. Human genetic disorders of axon guidance. Cold Spring Harb Perspect Biol. 2010;2:a001784.

    Article  PubMed Central  PubMed  Google Scholar 

  9. Izzi L, Charron F. Midline axon guidance and human genetic disorders. Clin Genet. 2011;80:226–34.

    Article  CAS  PubMed  Google Scholar 

  10. Friede RL. Uncommon syndromes of cerebellar vermis aplasia. II: Tecto-cerebellar dysraphia with occipital encephalocele. Dev Med Child Neurol. 1978;20:764–72.

    Article  CAS  PubMed  Google Scholar 

  11. Parisi MA, Pinter JD, Glass IA, et al. Cerebral and cerebellar motor activation abnormalities in a subject with Joubert syndrome: functional magnetic resonance imaging (MRI) study. J Child Neurol. 2004;19:214–8.

    PubMed  Google Scholar 

  12. Poretti A, Boltshauser E, Loenneker T, et al. Diffusion tensor imaging in Joubert syndrome. AJNR Am J Neuroradiol. 2007;28:1929–33.

    Article  CAS  PubMed  Google Scholar 

  13. Haller S, Wetzel SG, Lutschg J. Functional MRI, DTI and neurophysiology in horizontal gaze palsy with progressive scoliosis. Neuroradiology. 2008;50:453–9.

    Article  PubMed  Google Scholar 

  14. Théoret H, Gleeson J, Pascual-Leone A. Neurophysiologic characterization of motor and sensory projections in Joubert syndrome. Clin Neurophysiol. 2013;124:2283–4.

    Article  PubMed  Google Scholar 

  15. Habas C, Cabanis EA. Anatomical parcellation of the brainstem and cerebellar white matter: a preliminary probabilistic tractography study at 3 T. Neuroradiology. 2007;49:849–63.

    Article  PubMed  Google Scholar 

  16. Sicotte NL, Salamon G, Shattuck DW, et al. Diffusion tensor MRI shows abnormal brainstem crossing fibers associated with ROBO3 mutations. Neurology. 2006;67:519–21.

    Article  CAS  PubMed  Google Scholar 

  17. Jissendi-Tchofo P, Doherty D, McGillivray G, et al. Pontine tegmental cap dysplasia: MR imaging and diffusion tensor imaging features of impaired axonal navigation. AJNR Am J Neuroradiol. 2009;30:113–9.

    Article  CAS  PubMed Central  PubMed  Google Scholar 

Download references

Grant/Financial Support

This work was not supported by grants.


All co-authors do not report conflicts of interest.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Andrea Poretti.

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Kweldam, C.F., Gwynn, H., Vashist, A. et al. Undecussated Superior Cerebellar Peduncles and Absence of the Dorsal Transverse Pontine Fibers: a New Axonal Guidance Disorder?. Cerebellum 13, 536–540 (2014).

Download citation

  • Published:

  • Issue Date:

  • DOI: