Post-traumatic olfactory dysfunction: a cohort study and update.

OBJECTIVES: Post-traumatic olfactory loss (PTOL) is the third most common aetiology for olfactory disorders. Mechanisms that lead to post-traumatic olfactory disorders include sinonasal affections, damage to the olfactory nerve and lesions of the cerebral olfactory centres. The purpose of this review is to present an update of this condition and to present a cohort study of 90 patients. METHODOLOGY: A review of the literature was made on Medline Pubmed up to May 2009 and a review was also conducted of patients with post-traumatic olfactory loss. RESULTS: The degree of olfactory impairment was related to the severity of head trauma and was particularly frequent in cases of occipital impact. Typically, patients experienced a sudden onset of olfactory symptoms and were more severely affected than in other aetiologies. Results from orthonasal and retronasal testing, chemosensory event-related potentials and olfactory bulb (OB) volume confirmed previous findings: patients are usually anosmic, OB volume correlates with the degree of olfactory loss (better correlation with retronasal scores than with orthonasal scores) and olfactory event-related potentials were recorded in only 18 patients. CONCLUSIONS: Accuracy in the evaluation of PTOL patients is based on the expertise and the time spent by the clinician on defining the complaint. Failing treatment, complete evaluation of the PTOL patients may help in counselling for the recovery prognosis, and appropriate counselling must be given to secure the environment and alimentation.