Audiospatial evoked potentials for the assessment of spatial attention deficits in patients with severe cerebrovascular accidents.

ABSTRACT

INTRODUCTION: Neuropsychological assessment of spatial orientation in post-acute patients with large brain lesions is often limited due to additional cognitive disorders like aphasia, apraxia, or reduced responsiveness. METHODS: To cope with these limitations, we developed a paradigm using passive audiospatial event-related potentials (pAERPs) Participants were requested to merely listen over headphones to horizontally moving tones followed by a short tone ("target"), presented either on the side to which the cue moved or on the opposite side. Two runs of 120 trials were presented and we registered AERPs with two electrodes, mounted at C3 and C4. Nine sub-acute patients with large left hemisphere (LH) or right hemisphere (RH) lesions and nine controls participated. RESULTS: Patients had no problems completing the assessment. RH patients showed a reduced N100 for left-sided targets in all conditions. LH patients showed a diminished N100 for invalid trials and contralesional targets. CONCLUSION: Measuring AERPs for moving auditory cues and with two electrodes allows investigating spatial attentional deficits in patients with large RH and LH lesions, who are often unable to perform clinical tests. Our procedure can be implemented easily in an acute and rehabilitation setting and might enable investigating spatial attentional processes even in patients with minimal conscious awareness.