Proximal dentatothalamocortical tract involvement in posterior fossa syndrome

Abstract

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.

Cerebellar mutism

“…53,82 Miller et al, 63 using another perfusion imaging technique (dynamic susceptibility-weighted contrast-enhanced perfusion MRI), found that there is a strong (potentially predictive) relationship between bilateral damage to proximal efferent cerebellar pathways and the development of PFS. This finding was also supported by Kusano et al 57 and Morris et al, 65 the first who used diffuse-tensor imaging (DTI). Authors of a recent study from Berlin 91 also used DTI in a 3-T MRI suite and showed that volumes of frontocerebellar fibers had significantly diminished fractional anisotropy (FA) values in pediatric patients with CMS after surgery compared with patients without CMS and healthy peers.…”

“…63 Multiple studies have supported the theory of cerebellocerebral diaschisis using different imaging techniques that revealed decreased blood flow, metabolic action, and function within supratentorial structures that play a crucial role in speech production, such as the thalami, inferior frontal gyrus, and temporal lobe. 26,34,63,65,83 In almost every case the abnormal findings returned to normal when mutism resolved.…”

“…Neuroimaging studies have shown bilateral hypodense areas at the level of the dentate nuclei 2,5 or abnormalities in T2 signal on MRI, within the dentate nuclei, mainly bilaterally. 65 However, Dailey et al 14 reported on 9 patients with CM with no edema or infarction of the dentate nucleus postoperatively; in addition, most of the children with CM were still able to perform other functions that diffuse dentate destruction or swelling would render impossible. Moreover, Morris et al 65 suggested that neither unilateral nor bilateral dentate damage was required for CMS to appear.…”

Effects of Cranial Radiation on Structural and Functional Brain Development in Pediatric Brain Tumors

“…Damage to white matter connections within the cerebellar-thalamiccerebral network during surgical resection can cause posterior fossa syndrome, a clinical syndrome characterized by significant speech deficits including loss of expressive language (Morris et al 2009). The duration of speech difficulties associated with surgery can last from weeks to over a year with varying and nonlinear levels of language recovery.…”

Tractografía de la vía dento-rubro-talámica en mutismo cerebeloso postoperatorio en niños con tumores de fosa posterior

“…En el mutismo cerebeloso y en el síndrome de mutismo cerebeloso el sustrato anatómico más citado en la literatura tiene relación con el núcleo dentado y el tracto dento-rubro-talámico [17][18][19][20][21][22][23] .…”