Olfactory dysfunction after minor head trauma

Smell deficit is commonly due to head trauma which often causes the shearing of the olfactory nerve axons at the ethmoidal cribriform plate level. Damage to encephalic olfactory structures, however, is also possible. The degree of olfactory function and the influence of age, sex and time since injury are evaluated in patients after trauma. 57 patients with minor head trauma (Glasgow Coma Scale score ≥13) had their medical history reviewed and were given an otorhinolaryngologic examination; a nasal endoscopy; a computerized tomography (CT) scan; a magnetic resonance imaging (MRI); and a smell test to assess odor threshold, discrimination and identification (Sniffin’ Sticks smell test). Imaging did not show any lesions of brain olfactory structures in these patients, but 82.5% of them had anosmia and 12.5% had hyposmia. Females presented a higher means of odor threshold, discrimination and identification than males; young males presented a higher degree of deficit; 60% of the patients were under 40 years of age; and the duration of the smell deficit was reported as occurring from 1 to 288 months in length. Patients reporting minor head trauma presented an associated olfactory dysfunction prevalently caused by fila olfactoria shearing.