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Abstract:
The present study describes the ability of the olfactory
event-related potential (OERP) to provide an objective quantitative
assessment of sensory and cognitive loss following traumatic brain
injury (TBI). Subjects included 22 TBI patients and 22 age and
gender matched healthy controls. Following standard clinical
evaluation of smell function, TBI patients were divided into 3
groups; 11 anosmics (loss of smell), 5 hyposmics (reduced smell)
and 6 normosmics (normal smell). Cognitive ability was assessed
using a battery of neuropysch-ological tests. OERPs were recorded
monopolarly from midline electrode sites using amyl acetate at a 60
second inter-stimulus interval, while subjects estimated the
magnitude of each odor stimulus. Results show that the sensory N1
and P2 amplitudes as well as the cognitive P3 amplitudes were
absent in the anosmic TBI patients and greatly reduced in the
hyposmic and normosmic TBI patients compared to healthy controls.
The onset of the OERP N1, P2, and P3 latencies were delayed in all
TBI patients compared to healthy controls. The relationship between
the OERP components and neuropsychological test performance support
the cognitive loss associated with TBI. The present study
substantiates the utility of OERP's in assessing sensory and
cognitive losses in applied settings. Supported by NIH grant DC
02064 (CM), training grant DC 00032 (MWG) and in collaboration with
the Defense and Veterans Head Injury Program (DVHIP) at the Naval
Medical Center, San Diego, CA.
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