Posterior fossa syndrome in adults: a new case and comprehensive survey of the literature.

Although the posterior fossa syndrome (PFS) can be considered as an aetiologically heterogeneous condition affecting children and adults, it most often occurs in paediatric patients after cerebellar tumour surgery. In patients with a tumoural aetiology, the syndrome is typically characterised by a short symptom-free postoperative period followed by mutism of variable duration and behavioural and affective changes. More than 200 paediatric cases have been described but reports of adult patients are extremely rare. This paper discusses PFS in adults on the basis of a comprehensive literature survey and describes the pre- and postoperative findings in a new adult patient. In the preoperative phase, cognitive, behavioural and affective abnormalities were identified, matching a diagnosis of cerebellar cognitive affective syndrome (CCAS) (Schmahmann and Sherman, 1998; Schmahmann, 2004). The immediate postoperative course was characterised by prefrontal-like behavioural and affective abnormalities, peduncular hallucinations and confusion evolving to psychosis. Akinetic mutism subsequently developed, lasted for 12 days and then alternated with episodes of diminished responsiveness in which pathological laughing and crying (PLC) occurred. Akinetic mutism resolved after treatment with a non-ergoline dopamine-agonist but CCAS persisted during longitudinal follow-up. From a semiological point of view "relapsing-remitting akinetic mutism" and PLC in our patient might add relevant information to current insights in the clinical expression of the PFS. As evidenced by a close parallelism between single photon emission computed tomography (SPECT) and clinical findings, CCAS as well as PFS seem to reflect functional disruption of the cerebello-cerebral network involved in cognitive, behavioural and affective functions. These findings may indicate that both syndromes share overt semiological resemblances and a common pathophysiological substrate. Consequently, CCAS and PFS may both be regarded as cerebellar-induced clinical conditions showing different aspects of a spectrum that range in degree of severity and symptom duration.