Erps as an Index of Impaired Cognitive Control in an Ischemic Brain Stroke Aphasic Patient

Abstract

Stroke is a sudden-onset neurological deficit resulting from focal vascular lesions. This is either due to a clot-induced obstruction of a vessel (ischemic stroke) or a rupture of a vessel causing haemorrhage (hemorrhagic stroke). The appropriate diagnosis of brain stroke aphasic patients is a major public health problem one so important for effective rehabilitation. Here an important role is played by the diagnosis of impaired cognitive processes. The aim of the research was to find the index of impaired cognitive control with the use of ERPs in a patient following an ischemic stroke with aphasia. A male patient, aged 69, after an ischemic brain stroke experienced 4 months previously with resulting naming problem, was admitted to the Reintegrative and Teaching Center of the Polish Neuropsychological Society. In the neuropsychological evaluation three neuropsychological tests were employed: (a) the Boston Naming Test-Polish version, to evaluate the naming and word finding problem; (b) the nonverbal Bell test to ascertain a selective, visuospatial and strategic attentional evaluation; (c) the Digit Memory test to evaluate working memory capabilities; (d) ERPs as a neurophys- iological index of impaired cognitive control. Significant changes were observed in testing. All cognitive functions including naming, non- verbal, visuospatial and strategic attention, along with the digit memory deviate substantially from the norm. The patient obtained a lo wer score, compared to the norm (p <0.05). Boston Naming Test (patient = 21< Mean-Norm = 57.29; SD= 0.52). Bell test (patient = 23 < Mean-Norm = 31.29; SD= 2.52). Digit Memory Test scores: Forward digit span (patient = 3 < Mean-Norm = 7.65, SD = 0.49). Backward digit span (patient = 2 <Mean-Norm = 6.51, SD = 0.7). Significant changes were observed also in neurophysiological testing: behavioral parameters (except RT) deviate substantially from the reference. EEG spectra show clear abnormalities on the left side within the left Rolandic fis- sure. The deviations include excessive mu-rhythm and beta activity, which means that this area is inhibited. The ERPs show no difference between GO and NOGO conditions in the patient in comparison to the norm from HBI database indicating poor cognitive control. ERPs could be treated as an index of impaired cognitive control in the ischemic stroke aphasic patient.