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Neuropsychological Significance of Anosmia following Traumatic Brain Injury

Callahan, Charles D. PhD, ABPP; Hinkebein, Joseph PhD

Journal of Head Trauma Rehabilitation: December 1999 - Volume 14 - Issue 6 - p 581–587
Focus on Clinical Research and Practice, Part 2

Objectives: To investigate the incidence of anosmia following traumatic brain injury (TBI) using a standardized instrument and to test hypotheses that post-TBI anosmics perform significantly more poorly than do post-TBI normosmics on measures of executive skills and functional outcome.

Design: Prospective quasi-experimental between-groups design.

Participants: Sixty-eight adults diagnosed with TBI.

Setting: Brain injury rehabilitation program based at a Midwestern medical center.

Main Outcome Measures: University of Pennsylvania Smell Identification Test (UPSIT), selected neuropsychological measures of executive skills, the Disability Rating Scale (DRS), and the Community Integration Questionnaire (CIQ).

Results: Forty-four subjects (65%) demonstrated impaired olfaction; only 13 (30%) acknowledged smell dysfunction. Anosmic and normosmic groups did not differ in demographics, IQ, chronicity, or admission Glasgow Coma Scale (GCS). Anosmics had longer coma (P = .01), more severe deficits in complex attention (Trailmaking Test, Part B, P = .01), new learning/memory (California Verbal Learning Test Trial V [CVLT-V], P = .001), and problem solving (Wisconsin Card Sorting Test [WCST], P = .001), leading to greater functional impairment (Disability Rating Scale [DRS], P = .003). No differences emerged on the CIQ.

Conclusions: Anosmia is a common sequela of TBI, although only a minority of patients are aware of this deficit. Further, anosmics demonstrated greater impairment in a variety of frontal-lobe mediated executive functions, as well as greater functional disability.

Administrator, Center for Neuromuscular Sciences, Memorial Medical Center, Springfield, Illinois (Callahan)

Clinical Team Leader, Brain Injury Program, Center for Neuromuscular Sciences, Memorial Medical Center, Springfield, Illinois (Hinkebein)

Address correspondence to Charles D. Callahan, PhD, ABPP, Memorial Medical Center, 701 North 1st Street, Spring field, IL 62781, email

© 1999 Lippincott Williams & Wilkins, Inc.