Comparison between olfactory bulb and olfactory tract implantations through an endoscopic supraorbital keyhole approach: a cadaveric study - Report - MDSpire
Endoscopic Supraorbital Keyhole Approach for Olfactory Bulb vs Tract Implantation
Overview
This cadaveric study compared the feasibility and technical aspects of implanting electrodes on the olfactory bulb (OB) versus the olfactory tract (OT) using an endoscopic supraorbital keyhole approach (SKA). Implantation on the OT was found to be easier, more stable, and less invasive than on the OB, suggesting the OT as a promising target for future olfactory neurostimulation devices.
Background
Olfactory loss has become increasingly prevalent, especially following the COVID-19 pandemic, significantly impairing quality of life and increasing depression risk. Electrical stimulation of the olfactory system via implants targeting the olfactory mucosa, bulb, or central olfactory networks is an emerging therapeutic strategy. The OB is an attractive target due to its chemotopic organization and surgical accessibility, but electrode placement there is challenging. This study explores the OT as an alternative target for electrode implantation through a minimally invasive SKA.
Data Highlights
Parameter
Olfactory Bulb (OB)
Olfactory Tract (OT)
Number of sides implanted
5
5
Need for orbital roof drilling
Required in all cases
Not required
Electrode stability
Poor; easily displaced
Good; stable placement
Access difficulty
More demanding; variable OB anatomy and CSF flow
Less demanding; straight corridor along lesser wing of sphenoid
Key Findings
Successful electrode placement on both dorsal OB and ventral OT was achieved in all cadaveric specimens.
Orbital roof drilling was necessary for OB implantation but not for OT implantation, simplifying the surgical procedure for OT.
Electrode stability was poor on the OB due to lack of structural support, leading to displacement risk.
OT implantation provided a more stable electrode position with less risk of displacement.
The OT approach avoids detachment of the OB from the cribriform plate, preserving residual olfactory function and future regenerative therapy options.
Endoscopic visualization through the SKA allowed precise electrode placement with minimal invasiveness.
Clinical Implications
The findings suggest that the olfactory tract is a more accessible and stable target for electrode implantation via the supraorbital keyhole approach compared to the olfactory bulb. This approach may reduce operative time and surgical risks, preserve residual olfactory function, and facilitate future clinical trials of olfactory implants. Surgeons developing olfactory neurostimulation devices should consider the OT as a preferred implantation site.
Conclusion
The endoscopic supraorbital keyhole approach enables effective implantation on both the olfactory bulb and tract, but the olfactory tract offers a less invasive, more stable, and technically simpler target. These results support further exploration of OT implantation in clinical olfactory neurostimulation research.
References
Various Authors/Multiple Years -- Olfactory Implantation and Neurostimulation Research
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