Anosmia after traumatic brain injury
Most frequently anosmia is an acquired dysfunction and follows traumatic brain injury (TBI), with some studies suggesting that as many as 5% to 20% of individuals suffering from OD had sustained a preceding head trauma 1).
In the largest prospective study of post-TBI anosmia, the incidence increased with TBI severity and other medical illness. The presence of anosmia should also raise the clinical suspicion of depression 2).
Many patients may experience unilateral anosmia, often as a result of minor head trauma. This type of anosmia is normally only detected if both of the nostrils are tested separately. Using this method of testing each nostril separately will often show a reduced or even completely absent sense of smell in either one nostril or both, something which is often not revealed if both nostrils are simultaneously tested.
Olfactory loss due to head trauma is a frequent finding. It is attributed to the tearing or severing of the olfactory fibers at the cribriform plate. In contrast, posttraumatic gustatory loss is observed and reported rarely and the underlying mechanism is less understood. Rahban et al. present a case of a concomitant post-traumatic anosmia and ageusia. Imaging showed a considerable frontobasal brain damage and it is speculated that the gustatory impairment is due to a central injury of the secondary taste cortex. Based on this observation, Rahban et al.we believe that this clinical presentation might be much more frequent than previously reported 3).