Longitudinal cerebellar diffusion tensor imaging changes in posterior fossa syndrome

Abstract

Posterior fossa syndrome is a severe transient loss of language that frequently complicates resection of tumors of the cerebellum. The associated pathophysiology and relevant anatomy to this language deficit remains controversial. We performed a retrospective analysis of all cerebellar tumor resections at Seattle Children's Hospital from 2010 to 2015. Diffusion tensor imaging was performed on each of the patients as part of their clinical scan. Patients included in the study were divided into groups based on language functioning following resection: intact (N = 19), mild deficit (N = 19), and posterior fossa syndrome (N = 9). Patients with posterior fossa syndrome showed white matter changes evidenced by reductions in fractional anisotropy in the left and right superior cerebellar peduncle following resection, and these changes were still evident 1-year after surgery. These changes were greater in the superior cerebellar peduncle than elsewhere in the cerebellum. Prior to surgery, posterior fossa patients did not show changes in fractional anisotropy however differences were observed in mean and radial diffusivity measures in comparison to other groups which may provide a radiographic marker of those at greatest risk of developing post-operative language loss.

Diffusion Tensor Imaging Connectomics Reveals Preoperative Neural Connectivity Changes in Children with Postsurgical Posterior Fossa Syndrome

“…It is characterized by neurological signs and symptoms that typically occur 1‐2 days after surgery including severe loss of language ability, ataxia, hypotonia, cranial nerve palsies, and emotional lability . As tumors located in the posterior fossa represent 50‐70% of solid tumors in children, major loss of language ability represents a substantial burden of treatment for these patients and their families …”

“…While PFS is a known postsurgical complication, the exact underlying pathophysiological mechanism remains unclear. Several hypotheses have been proposed for the etiology of PFS including vasospasm, edema, transient disruption in release of neurotransmitter, or transient changes in autoregulation due to thermal injury . Factors that may contribute to PFS include permanent white matter changes due to direct damage from surgical resection, axonal injury, or inflammatory response …”

“…A number of preoperative conventional radiographic findings, such as location and size of the tumor, have been associated with development of PFS, but not in a consistent manner . Previous work has demonstrated that bilateral injuries to the proximal dentatothalamocortical pathways appear to predispose patients to the development of PFS …”

“…1,2,4,5 As tumors located in the posterior fossa represent 50-70% of solid tumors in children, major loss of language ability represents a substantial burden of treatment for these patients and their families. 6 While PFS is a known postsurgical complication, the exact underlying pathophysiological mechanism remains unclear. Several hypotheses have been proposed for the etiology of PFS including vasospasm, edema, transient disruption in release of neurotransmitter, or transient changes in autoregulation due to thermal injury.…”

“…Several hypotheses have been proposed for the etiology of PFS including vasospasm, edema, transient disruption in release of neurotransmitter, or transient changes in autoregulation due to thermal injury. [6][7][8] Factors that may contribute to PFS include permanent white matter changes due to direct damage from surgical resection, axonal injury, or inflammatory response. 4,9 A number of preoperative conventional radiographic findings, such as location and size of the tumor, have been associated with development of PFS, but not in a consistent manner.…”