Auditory P3 event related potentials (ERP) and brainstem auditory evoked responses (BAER) after spinal cord injury in humans.

Previous studies have observed altered somatotopic sensory fields after experimental deafferentation in animals as well as enhanced somatosensory evoked potentials and altered cortical motor pathways following spinal cord injury (SCI) in humans. These observations indicate that cortical reorganization may occur subsequent to SCI. In earlier work, we have observed attenuated amplitudes for both tactile P3 and auditory N1/P2 orienting event-related potentials (ERP) in spinal cord injured groups. These results suggest that the reorganization process may have functional perceptual and cognitive consequences. In an effort to determine if deafferentation affects the P3 ERP using stimuli other than somatosensory, we measured brain activity from central recording sites during an auditory "oddball" task. Additionally, we obtained brainstem auditory evoked responses (BAER) in order to assess subcortical primary auditory pathways as well. Results show that the SCI groups produced significantly attenuated N1/P2 complexes and P3 when compared to controls. Also, the quadriplegic group exhibited increased latencies of the P3 at frontal and central sites. There were no differences between groups in BAER results. These findings suggest that primary subcortical auditory information processing stages remain intact after SCI although later stages may be significantly altered.