Recovery of Olfactory Function Following Closed Head Injury or Infections of the Upper Respiratory Tract | Traumatic Brain Injury | JAMA Otolaryngology–Head & Neck Surgery | JAMA Network
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Original Article
March 2006

Recovery of Olfactory Function Following Closed Head Injury or Infections of the Upper Respiratory Tract

Author Affiliations

Author Affiliations: Smell & Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany (Drs Reden, A. Mueller, Konstantinidis, Frasnelli, and Hummel); Department of Otorhinolaryngology, University of Vienna, Vienna, Austria (Dr C. Mueller); and Unité de Rhinologie-Olfactologie, Service d’ Oto-Rhinologie-Laryngologie, Hopitaux Universitaires de Genève, Genève, Switzerland (Dr Landis).

Arch Otolaryngol Head Neck Surg. 2006;132(3):265-269. doi:10.1001/archotol.132.3.265
Abstract

Objective  To investigate the outcome of olfactory function in patients with olfactory loss following infections of the upper respiratory tract (post-URTI) or head trauma.

Design  Retrospective patient-based study.

Setting  Smell and Taste Outpatient Clinic at a university hospital.

Patients  A total of 361 patients (228 women, 133 men) were included.

Main Outcome Measures  Olfactory function was assessed using the “Sniffin’ Sticks” test battery, which result in a threshold, discrimination, and identification score. The mean interval between first and last visit was 14 months.

Results  In comparing the overall threshold, discrimination, and identification scores between the last and first visit, olfactory function improved in 26% of the patients whereas it decreased in 6%. The cause of olfactory impairment had a significant effect on the recovery rate of olfactory function. Within the post-URTI group (n = 262), 32% of the patients improved, but in the posttraumatic group (n = 99) only 10% improved. In patients with post-URTI olfactory loss, a negative correlation was found between age and recovery of olfactory function. In general, the factor “sex” had no significant effect on recovery of smell function.

Conclusions  To our knowledge, the series of patients presented herein is the largest in the literature to date in which standardized testing methods were used to assess the progression of impaired olfaction. It showed that the rate of improvement of olfactory function was significantly higher in patients with post-URTI dysosmia compared with patients with posttraumatic dysosmia. During an observation period of approximately 1 year, more than 30% of patients with post-URTI olfactory loss experienced improvement, whereas only 10% of patients with posttraumatic olfactory loss experienced improvement. Furthermore, age plays a significant role in the recovery of olfactory function.

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