Decreased trigeminal sensitivity in anosmia

The present study aimed to investigate intranasal trigeminal sensitivity in a large sample of patients with anosmia due to different etiologies. We in vestigated the trigeminal detection threshold for formic acid in healthy co ntrols (n = 96) and patients with anosmia due to head trauma (n = 18) or si nonasal disease (n = 54). Anosmics exhibited higher thresholds compared wit h normosmics (p < 0.001). In addition, thresholds were found to be higher i n patients with posttraumatic anosmia compared to anosmics with sinonasal d isease (p < 0.001). The data indicate that (1) loss of olfactory sensitivit y in humans may be associated with a decreased sensitivity towards trigemin al stimuli and (2) alteration of intranasal trigeminal function is stronger in patients with posttraumatic anosmia compared to patients with sinonasal disease. This may have implications for the medicolegal investigation of a nosmic patients where trigeminal stimuli are frequently used to assess the patient's response bias. Copyright (C) 2001 S. Karger AG, Basel.