Pediatric post-operative cerebellar mutism syndrome, cerebellar cognitive affective syndrome, and posterior fossa syndrome: historical review and proposed resolution to guide future study

Background: Cerebellar mutism (CM), pseudobulbar palsy, posterior fossa syndrome (PFS), and cerebellar cognitive affective syndrome (CCAS) are terms that have been used, sometimes interchangeably, to refer to the complex neurological constellation that occurs following surgical removal of cerebellar and fourth ventricular tumors, mostly in children, but also sometimes in adults.

Methods: This paper reviews the origins of what is now regarded as pediatric post-operative cerebellar mutism, the cerebellar cognitive affective syndrome, and the neurological manifestations of injury to or disruption of brainstem and cerebellar structures. It examines the specific components of each of these phenomena in the context of the evolving understanding of the role of the cerebellum in nervous system function.

Results: Children undergoing surgical management of tumors in the posterior cranial fossa are at risk of experiencing cranial neuropathies, corticospinal damage, cerebellar ataxia and related motor disorders, neuropsychiatric and cognitive changes, and in some patients, mutism. These clinical presentations are differentiated from each other and examined in the context of the relevant anatomical structures and distributed neural circuits. The term posterior fossa syndrome is not sufficiently helpful in distinguishing the different elements of the clinical phenomena from each other, and because of this lack of precision and specificity, there is consensus among investigators in the international Posterior Fossa Society that the designation be retired.

Conclusions: Using contemporary brain imaging methods and guided by careful clinical observation and meticulous definition of clinical phenomenology, it is now feasible to perform detailed structure function correlation analyses to achieve two critical goals in the care of children with tumors in the posterior cranial fossa. The first goal is to identify and understand the neural circuits responsible for the different manifestations-arousal, cranial neuropathies, long tract signs, cerebellar motor syndrome, cerebellar vestibular syndrome, cerebellar cognitive affective syndrome including emotional dyscontrol, and mutism. The second goal is to transform this knowledge into practical clinical intervention, preventing the complications inherent in the necessary surgery whenever possible, and develop new approaches to treatment with methods including brain modulation targeting interconnected nodes of the damaged neural circuits.