Clinical features, neurologic recovery, and risk factors of post-operative posterior fossa syndrome and delayed recovery: A prospective study.

BACKGROUND Posterior fossa syndrome (PFS) is a known consequence of medulloblastoma resection. Our aim was to clinically define PFS, its evolution over time, and ascertain risk factors for its development and poor recovery. METHODS Children with medulloblastoma treated at St Jude Children's Research Hospital from 6/2013-7/2019 received standardized neurological examinations, before and periodically after radiation therapy. Most (98.3%) were enrolled on the ongoing multi-institutional protocol (SJMB12; NCT01878617). RESULTS Sixty (34%) of 178 evaluated children had PFS. Forty (23%) had complete mutism (PFS1) and 20 (11%) had diminished speech (PFS2). All children with PFS had severe ataxia and 42.5% of PFS1 had movement disorders. By multivariable analysis, younger age (p=0.0005) and surgery in a low-volume surgery center (p=0.0146) increased PFS risk, while SHH tumors had reduced risk (p=0.0025). Speech and gait returned in PFS1/PFS2 children at a median of 2.3/0.7 and 2.1/1.5 months respectively, however, 12 (44.4%) of 27 PFS1 children with 12-months of follow-up were non-ambulatory at one-year. Movement disorder (p= 0.037) and high ataxia score (p< 0.0001) were associated with delayed speech recovery. Older age (p= 0.0147) and high ataxia score (p< 0.0001) were associated with delayed gait return. Symptoms improved in all children but no child with PFS had normal neurologic examination at a median of 23-months after surgery. CONCLUSIONS Categorizing PFS into types 1 and 2 has prognostic relevance. Almost half of the children with PFS1 with 12-month follow-up were non-ambulatory. Surgical experience was a major modifiable contributor to the development of PFS.