Cognitive and affective disturbances following focal brainstem lesions: a review and report of three cases.

Although insights in cerebellar neurocognition and affect are continuously growing, little is known about the role of the brainstem in cognitive and behavioural processing. In this paper, it is hypothesized that the brainstem is an inherent functional part of the cerebellocerebral network subserving cognition and affect, and that isolated brainstem damage may cause a constellation of symptoms closely resembling the cerebellar cognitive affective syndrome (CCAS) following cerebellar pathology. In order to investigate these premises, the available literature on cognitive and affective disturbances following brainstem lesions was critically reviewed starting from the pioneer descriptions in the 1950s till June 2012. Three personal cases were added to a study group of 75 cases with isolated vascular brainstem damage. In a cohort of 30 patients that allowed construction of anatomoclinical correlations in a reliable way, a range of cognitive and behavioural symptoms, typically associated with impairment of cortical or limbic areas, were identified. Executive dysfunction, attentional deficits and a decline in general intellectual capacity represent the most common cognitive findings, but memory, visuospatial skills, language and praxis may be impaired as well. Almost half of the cases presented with behavioural or affective changes. Analysis of SPECT findings indicates that functional suppression of frontal, parietal and to a lesser extent also the temporal areas are common phenomena after isolated brainstem stroke. As reflected by diaschisis affecting the cerebellocerebral network, a loss of excitatory input from the brainstem to the cerebellum and cerebrum may induce disruption of several cortical regions as well as emotional control centres resulting in and a constellation of symptoms closely resembling the CCAS. The pathophysiological mechanism underlying brainstem-induced cognitive and affective disturbances is discussed.