MEDIAL AND BILATERAL LESIONS ARE NECESSARY FOR DEVELOPMENT OF POSTERIOR FOSSA SYNDROME IN CHILDREN

Posterior fossa syndrome (PFS) is a well-characterized clinical syndrome arising from surgical resection of posterior fossa tumors in children that involves mutism, emotional instability and motor impairment. It is estimated that over 30% of patients develop this disorder following posterior fossa surgery, but its etiology is unknown. Of particular interest to the pathophysiology of PFS is the location of cerebellar lesions that are associated with the subsequent development of PFS. In this study, we performed an analysis of postoperative high-resolution structural magnetic resonance imaging scans of 13 pediatric patients with cerebellar tumors. The extent and location of tumor resection was traced for each subject and normalized into standard space. Surgical complications were noted and patients completed measures of behavior and affect. Patients developing PFS (N=4) and one with motor difficulties all showed a pattern of tumor resection bilaterally in the medial cerebellum, including damage to cerebellar lobules VI, IX and X. Patients who did not develop PFS did not have medial cerebellar damage, with most of the resection limited to cerebellar lobules VIIb and Crus II. These findings suggest that medial, bilateral damage is necessary for the development of PFS.