Transtemporal Mini-trephination Approach: A Novel Corridor to Expose a Septated Lateral Frontal Sinus

Introduction: The lateral frontal sinus is one of the most challenging areas to approach in the paranasal sinuses. Various approaches, such as endoscopic trans-nasal frontal sinusotomy and mini-trephination, fail to completely control this area; thus, we devised a novel transtemporal mini-trephination (TTMT) modification in an attempt to improve exposure.

Method: This cadaveric study used five human heads with ten sides. The external dissection started by drawing a line at the level of the superior orbital rim extending laterally to the temporal fossa ([Fig. 1]). A 2-cm-long curved incision parallel to the zygomatic process of the frontal bone was carried down to the periosteum at the most lateral part of the eyebrow. After exposing the lateral orbital rim, the most lateral aspect of the frontal sinus was opened with a high-speed microdrill equipped with a 4-mm extended-tip straight cutting burr. A surgical navigation system directed the drilling to avoid the anterior cranial fossa or orbital roof. After accessing the frontal sinus lateral recess, larger burrs were used to create an 8 × 10 mm tunnel with a mean length of (8.2 ± 1 mm SD). A standard endoscopic endonasal Draf 3 procedure was then completed to measure maximum lateral accessibility with angled instruments and exposure obtained with the two approaches was compared.

Discussion: This novel transtemporal mini-trephination (TTMT) approach provides an excellent view of the frontal sinus. It is a practical option for far-lateral lesions, such as CSF leaks, or meningoencephalocele. This is particularly useful in well-pneumatized sinuses with multiple septations. Draf procedures ± orbital transposition, external trephination, and external frontoethmoidectomy approaches may not be able to solve this problem, even with the use of angle instrumentation ([Fig. 2]).

Another advantage of the TTMT technique is that it may be used to reach the bilateral frontal sinuses by drilling the interfrontal sinus septum. Conversely, the most significant disadvantage of this method is that its use is limited to well-pneumatized frontal sinuses. We compared the main pros and cons in a table ([Fig. 3]).

In the absence of a navigation system, one of the benefits of integrating the Draf 3 approach is the ability to transilluminate the frontal sinus, which helps outline the frontal sinus boundaries and guides the drilling.

Conclusion: This study describes a novel approach to the frontal sinus with the ability to afford bilateral access and offers a considerable advantage when facing septated sinuses; however, it is exclusively limited to well-pneumatized frontal sinuses. This approach enables an open access with sufficient space for bimanual dissection, avoiding the need for angulated instruments. Combining the transtemporal mini-trephination technique with Draf sinusotomies ± orbital transposition may amplify the utility and accessibility to all frontal sinus regions.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
01 February 2023