Studies of the olfactory epithelium in anosmic patients after head trauma Abstract Background An additional diagnostic option for olfactory dysfunction is the study of the olfactory epithelium. Methods Biopsies of the olfactory epithelium were performed under local anaesthesia on five patients with a history of head trauma with anosmic results in the Sniffin Sticks test. The biopsy of a normosmic patient served as a control. Immunochemistry of frozen sections and explant culture studies were made, investigating ability to attach to the culture plate and the outgrowth of neuronal cells after growth-factor stimulation. Results The biopsies were carried out without any complications. All biopsies were positive for neurofilament, a marker for immature neurons. Substantial differences in the explants ability to attach to the culture plate occurred, with a rate of between 25% and 100%. The control showed 67%. After stimulation with growth factors (FGF2), the cultures with more attached cells showed neuronal differentiation with the appearance of bipolar cells. Conclusions The biopsy of the human olfactory epithelium is a minimally invasive procedure which can provide further information on specific changes and possible regenerative ability. Further studies with larger numbers of patients with different causes of an impaired sense of smell are needed to determine specific changes.