Frontal dynamic activity as a predictor of cognitive dysfunction after pontine ischemia

: BACKGROUNDThere is a tendency to pay little attention to cognitive dysfunction after a subcortical stroke, resulting in this condition being overlooked. Damage to the brainstem may affect cognition, probably originating from the fronto-cerebellar circuit, but details remain obscure.OBJECTIVETo investigate the effect of damage to pons on frontal function via the fronto-cerebellar circuit.METHODSWe measured frontal dynamic responses in patients with acute pontine ischemia during phonemic verbal fluency task using near-infrared spectroscopy (NIRS). Furthermore, to determine whether the fronto-cerebellar circuit is affected by pontine ischemia, 99 mTc-ECD single photon emission computed tomography (SPECT) was performed.RESULTSTwenty-five patients with pontine isolated infarction met the criteria. Especially, 80 percent of the pontine lesioned patients affected cognition. The patients exhibited hyper-frontal activity according to the neuropsychological tests. Follow-up NIRS showed increased frontal activity as being linked to improved cognition. This may indicate the involvement of frontal activity in cognitive recovery. The SPECT showed consistently hyper-frontal perfusion as well as hypo-cerebellar perfusion.CONCLUSIONSThis suggested that hyper-frontal activity might contribute to compensation for cognitive dysfunction after pontine ischemia and that recovery from the cognitive deficits is attributable to frontal activity.