Brain Advance Access originally published online on October 5, 2009
Brain 2009 132(11):3087-3095; doi:10.1093/brain/awp241
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Proximal dentatothalamocortical tract involvement in posterior fossa syndrome
1 Department of Oncology, St Jude Children's Research Hospital, Memphis, TN 38105, USA, 2 Department of Neurology, St Jude Children's Research Hospital, Memphis, TN 38105, USA 3 Department of Radiological Sciences, St Jude Children's Research Hospital, Memphis, TN 38105, USA 4 Department of Biostatistics, St Jude Children's Research Hospital, Memphis, TN 38105, USA 5 Department of Neurosurgery, St Jude Children's Research Hospital, Memphis, TN 38105, USA 5 Department of Epidemiology and Cancer Control, St Jude Children's Research Hospital, Memphis, TN 38105, USA
Correspondence to: E. Brannon Morris, MD, Department of Oncology, Division of Cancer Survivorship, St Jude Children's Research Hospital, 332 North Lauderdale St, Memphis, TN 38105, USA E-mail: Brannon.morris{at}stjude.org
Posterior fossa syndrome is characterized by cerebellar dysfunction, oromotor/oculomotor apraxia, emotional lability and mutism in patients after infratentorial injury. The underlying neuroanatomical substrates of posterior fossa syndrome are unknown, but dentatothalamocortical tracts have been implicated. We used pre- and postoperative neuroimaging to investigate proximal dentatothalamocortical tract involvement in childhood embryonal brain tumour patients who developed posterior fossa syndrome following tumour resection. Diagnostic imaging from a cohort of 26 paediatric patients previously operated on for an embryonal brain tumour (13 patients prospectively diagnosed with posterior fossa syndrome, and 13 non-affected patients) were evaluated. Preoperative magnetic resonance imaging was used to define relevant tumour features, including two potentially predictive measures. Postoperative magnetic resonance and diffusion tensor imaging were used to characterize operative injury and tract-based differences in anisotropy of water diffusion. In patients who developed posterior fossa syndrome, initial tumour resided higher in the 4th ventricle (P = 0.035). Postoperative magnetic resonance signal abnormalities within the superior cerebellar peduncles and midbrain were observed more often in patients with posterior fossa syndrome (P = 0.030 and 0.003, respectively). The fractional anisotropy of water was lower in the bilateral superior cerebellar peduncles, in the bilateral fornices, white matter region proximate to the right angular gyrus (Tailerach coordinates 35, –71, 19) and white matter region proximate to the left superior frontal gyrus (Tailerach coordinates –24, 57, 20). Our findings suggest that multiple bilateral injuries to the proximal dentatothalamocortical pathways may predispose the development of posterior fossa syndrome, that functional disruption of the white matter bundles containing efferent axons within the superior cerebellar peduncles is a critical underlying pathophysiological component of posterior fossa syndrome, and that decreased fractional anisotropy in the fornices and cerebral cortex may be related to the abnormal neurobehavioural symptoms of posterior fossa syndrome.
Key Words: posterior fossa; cerebellum; mutism; medulloblastoma
Abbreviations: FA, fractional anisotropy; FMRIB, Functional Magnetic Resonance Imaging of the Brain; PFS, posterior fossa syndrome; SPECT, single photon emission tomography; TBSS, tract-based spatial statistics
Received April 23, 2009. Revised August 11, 2009. Accepted August 12, 2009.