To determine the extent to which olfactory function can improve after loss induced by head trauma or a previous upper respiratory tract infection (URI) and the time for this improvement for more effective patient counseling.
Patients initially evaluated at the University of Cincinnati (Ohio) Taste and Smell Center were reevaluated for olfactory loss with the University of Pennsylvania (Philadelphia) Smell Identification Test 1 to 5 years after initial testing. Changes in score on this test were used to indicate improvement in sensory function. Subjective information on olfactory ability and olfactory symptoms was also collected.
University-based tertiary care center.
Patients and Other Participants:
Forty-one patients with olfactory loss induced by head trauma (20) or previous URI (21).
Seven (35%) of 20 patients with head trauma improved on the smell test by 4 points or more. Fourteen of 21 (67%) patients with a previous URI had improved scores of this magnitude or more. A statistically significant correlation was noted between the amount of improvement and length of follow-up for URI patients. Thirteen of these patients also reported improved olfactory function.
These findings for patients with head trauma are consistent with other reports of recovery of (or improvement in) olfactory function after trauma-induced loss. For patients with previous URI, these data indicate that improvement in olfactory function occurs, but the improvement may take several years.(Arch Otolaryngol Head Neck Surg. 1995;121:1183-1187)
Duncan HJ, Seiden AM. Long-term Follow-up of Olfactory Loss Secondary to Head Trauma and Upper Respiratory Tract Infection. Arch Otolaryngol Head Neck Surg. 1995;121(10):1183–1187. doi:10.1001/archotol.1995.01890100087015