Chemosensory Function in Congenitally Blind or Deaf Teenagers

Introduction It may be assumed that congenital absence of a certain sensory function would affect the processing of remaining sensory processes. The purpose of the present study was to evaluate chemosensory brain responsiveness both electrophysiologically and psychophysically in congenitally blind or deaf individuals. Methods Fourteen blind, 13 deaf, and 10 control subjects were recruited to this study. Psychophysical assessment of olfactory function was performed via "Sniffin' Sticks" test. In this test, olfactory threshold, discrimination, identification, and total scores were compared between blind, deaf, and control subjects. In addition, electrophysiological assessment of olfactory function was performed via event-related potentials to olfactory and trigeminal stimuli. Results The "Sniffin' Sticks" test indicated frequent hyposmia in the deaf group. Discrimination and total scores of the deaf group were significantly lower than the control group. On the other hand, there were no significant differences between blind and control groups. Threshold and total scores of the deaf group were significantly lower than the blind group. There were no significant differences in amplitudes and latencies of any chemosensory-evoked potential components for both stimuli between the groups. Conclusions The deaf subjects appear to have lower olfactory test scores than blind and control subjects. Application of stimulants in a more complex setup may help to disentangle the various changes in chemosensory processing in the absence of other sensory channels.