Examination of the hearing, taste and smell function in patients with chronic dizziness following minor trauma

Dizziness and vertigo are common symptoms associated with minor head trauma or whiplash. Although these symptoms improve within a few weeks in many patients, the symptoms can last much longer in some patients. Furthermore, patients with minor trauma often suffer from other symptoms such as hearing loss, tinnitus, olfactory dysfunction, or taste disorder. The aim of the present study was to clarify the process by which dizziness following trauma arises. We investigated 254 patients (115 males and 139 females, with an average age of 44.2 years) who suffered from chronic dizziness following trauma but who did not have any abnormal head CT or MRI findings. In each of the patients, we evaluated the vestibular function and hearing, taste and smell by performing a spontaneous or gaze nystagmus test, an ENG evaluation (eye tracking test, optokinetic nystagmus test, caloric test), a stabilometer test, standard pure tone audiometry, a speech discrimination test, taste test (electrogustometry, filter-paper disk assay using taste solutions), and a smell test (intravenous olfaction test, odor-identification card test for Japanese). Accordingly, we investigated the relation between body sway and other sensory functions. We found a larger sway area than usual in 60% of the patients undergoing a stabilometer test with their eyes open and with their eyes closed. The results of the nystagmus and ENG evaluations suggested a vestibular disorder in 15% to 20% of the patients and a brainstem or cerebellum disorder in 10% or less of the patients. A significant correlation between the body sway area and smell identification was observed. However, smaller correlations were observed between body sway and the hearing threshold, the laterality of the hearing, the taste function, and the smell threshold. According to this study, we speculated that chronic dizziness following minor trauma might arise from related to central nervous system disorders, such as disorders of the hippocampus, hypothalamus, entorhinal cortex or other olfactoryrelated cognitive areas.