Transciliary Supraorbital Approach

Abstract

To the Editor: We read with interest the comments by Dr Balasubramanian.1 The pros and cons that Dr Balasubramanian mentioned are important aspects when neurosurgeons consider these transciliary methods. However, we think it is prudent to stress that the transciliary incision could be used not only for the supraorbital craniotomy but also for the mini-orbitozygomatic craniotomy. With the orbital rim removed, the latter provides increased space for instrument use, minimizes brain retraction, and improves the vertical angle of the corridor to common sites in the anterior circulation aneurysms and anterior skull base lesions (especially in frontobasal or suprasellar tumors).2,3 We find this mini-orbitozygomatic craniotomy especially useful when the endoscope-assisted method is considered (because the increased angle provides a better space to insert the endoscope, which avoids “sword fighting” with the other instruments). In our experience, the prominent frontal sinus is not a contraindication to these approaches. In our patients, the pericranial flap could be harvested and used for reconstruction of the frontal sinus, similar to traditional anterior skull base procedure. In our experience, the initial saline injection to the space above the periosteum is very critical (Figure, A). Immediately after the junction of the orbicularis and frontalis muscle is split, the underlying pericranial (periosteal) flap is harvested (Figure, B; the supraorbital nerve was isolated with a silk). The harvested flap is usually about 3.5 cm in height and 4.5 cm in width, depending on the length of transciliary incision (Figure, C, showing the bony exposure for supraorbital craniotomy [arrow indicates pericranial flap]). If a longer flap is needed (judging from preoperative sagittal imaging), the traction endoscopic method could be used to harvest the flap up to 10 cm. With this traction endoscopic method, the supraorbital nerve (Figure, D) could be preserved after it was isolated up to 5 cm and lateralized to the nasal side during surgery. In our experience, this technique minimizes the postoperative scalp numbness (in both the supraorbital and temporoparietal regions). A similar method is reported by Patel et al4 for repair of the dural defect from an extended endonasal approach. However, they used a median nasion incision and an additional incision behind the hairline to harvest the flap. During surgery, the frontal sinus was entered and the mucosa removed. After irrigation with gentamicin water, the frontal sinus was packed with beta-iodine-soaked gel foam, and the roof was covered with the pericranial flap. With such a method, none of the 23 supraorbital or mini-orbitozygomatic craniotomies that traverse the frontal sinus had postoperative central nervous system or wound infection. Therefore, we do not consider a prominent frontal sinus to be a contraindication to these approaches.FIGURE: The steps and technique used to harvest the pericranial flap in the transciliary approach.When a ventriculostomy is needed, mostly in aneurysm cases, the entry point could be created at the frontal basal region directly under the keyhole. The ventriculostomy catheter was directed at a 45° angle to the midline and a 20° angle up from an imaginary line parallel to the orbitomeatal line.5 The catheter will usually be inserted into the frontal horn at a point 5 cm from the pial surface and may be inserted to 6.5 cm. A subcutaneous tunnel is then created, and the catheter is pulled through another small incision near the pterion behind the hairline. We could not agree more with Dr Balasubramanian that patient selection is the most important step in choosing these minimally invasive techniques. In terms of aneurysmal surgery, traditional craniotomy or even hemicraniectomy was needed in patients with poor-grade subarachnoid hemorrhage or significant brain edema. These cases are apparently poor candidates for supraciliary approach. The approach selection for an anterior skull base tumor is further complicated by the additional option of the extended endonasal approach.6 The tumor size, relationship to optic nerve, surgical experience, and confidence in a watertight reconstruction of dural defect are all important factors to consider. In summary, when minimally invasive approaches are considered, the exposure and angle provided by these approaches are equally important.7 As most experts have mentioned, the most important point is to use the most suitable approach for a particular patient rather than using a one-size-fits-all approach for all patients. Abel Po-Hao Huang Chien-Lian Chen Taipei, Taiwan