Post-traumatic olfactory dysfunction

Objectives: This study demonstrates histopathologic and immunocytochemical changes in the olfactory bulb of a patient with post-traumatic olfactory dy sfunction, These results are analyzed in light of current understanding of the pathophysiology of anosmia and dysosmia following head trauma. Emphasis is placed on potential mechanisms of human regeneration and recovery. Stud y Design: The current study documents the history of a patient with the ini tial complaint of complete anosmia following minor head trauma. Two months after the injury the patient developed persistent, severe dysosmia with deb ilitating weight loss, Neurosurgical treatment, including removal of the ol factory bulbs and tracts, resulted in permanent resolution of dysosmia Meth ods: Histopathologic: and immunocytochemical analysis of the olfactory bulb s was undertaken and compared with age-matched control tissue. Results: Pat hological analysis of the olfactory bulb revealed a marked reduction in the number of nerve processes with few intact olfactory glomeruli compared wit h an age-matched control, Specific immunohistochemical staining for the olf actory neuron-specific protein OMP, however, demonstrated the presence of i ntact axonal projections between the olfactory mucosa and the bulb, Conclus ions: These results support the hypothesis that post-traumatic anosmia invo lves, at least in part, damage to peripheral olfactory nerve fibers with hi stological changes in the olfactory bulb. Potential mechanisms for the deve lopment of post-traumatic dysosmia are also discussed.