Olfactory dysfunction is often an overlooked consequence of moderate to severe traumatic brain injury, with reported incidence varying from 15 to 60%. The underlying mechanism is likely a combination of shearing of the olfactory nerve at the cribriform plate, disruption of the sinonasal tract, or damage to the central olfactory pathways via secondary brain injury mechanisms. As a heavily under-researched area, evidence for treatment is overall low – however studies suggest earlier implementation of treatment may be associated with better outcomes (hura et.al 2020). This poster summarises key literature and a practical points for olfactory rehabilitation. A review of literature was conducted on June 4 2024 of PubMed, EMBase.
Olfactory training (OT) has increasing evidence as an approach on non-sinonasal related olfactory dysfunction. Initially researched predominantly in post-viral olfactory dysfunction, neurophysiological studies of OT reported increased electrophysiological activity at the level of the olfactory epithelium, increased gray matter volume and regional functional connectivity. In a post-traumatic setting, response to olfactory training has consistently shown greater rates of smell recovery (~36%) compared to non-intervention (18% spontaneous recovery). The most common technique is Olfactory training with four (OT4) or eight key odors (EOT8), which are representative of four main odor categories. Generally, training involves exposure to alternate odorants in typical 5-minute sessions, for over 16 weeks (see diagram).
This poster advocates for early screening of olfactory dysfunction as a common sequela in moderate to severe TBI. Trauma specialists can play a key role in initiating education of OT and prompt early referral to relevant specialist care.