Orbitozygomatic craniotomy. Technical note

Anterior communicating artery aneurysms

ANTERIOR COMMUNICATING ARTERY aneurysms are complex lesions for which surgical success requires extensive preoperative and intraoperative planning. Adherence to the tenets of aneurysm surgery, including vascular control and preservation of perforating arteries, is essential for their exclusion from the circulation.

Cosmetic considerations in cranial base surgery

Recent advances in the surgical techniques for the resection of cranial base tumors have allowed for improved degrees of tumor resection, functional outcomes, and esthetic results. If the resection and functional results are not compromised by procedures providing excellent cosmetic outcomes, there is no reason to ignore or compromise the esthetic aspect with regard to technical execution and planning. A thorough assessment of the patient's preoperative deficits and tumor anatomy and a working knowledge of the available cranial base approaches and their combinations permit the surgeon to design an approach that allows for optimal tumor resection with the best possible cosmetic result. In a time when alternative treatment options like radiosurgery exist for cranial base tumors, esthetic outcome is a significant quality-of-life issue that patients consider in their decision to choose surgery versus an alternative treatment.

Anatomical study of the orbitozygomatic transsellar-transcavernous-transclinoidal approach to the basilar artery bifurcation

OBJECT

An anatomical study in which measurements were obtained was undertaken to demonstrate that the orbitozygomatic transcavernous-transclinoidal approach provides excellent exposure of the trunk of the basilar artery (BA) and its bifurcation.

METHODS

Bilateral stepwise dissections were performed on 10 fixed cadaver heads with the aid of x 3 to x 40 magnifications. A frontotemporal craniotomy was made, followed by an orbitozygomatic osteotomy. After the dura mater had been opened, the sylvian fissure was widely separated. The anteromedial triangle of the cavernous sinus was opened to mobilize the internal carotid artery medially. The sella turcica and the dorsum sellae were exposed. The posterior clinoid process and the dorsum sellae were drilled to expose a length of BA that included its bifurcation. Measurements were obtained following the frontotemporal craniotomy, orbitozygomatic osteotomy, and drilling of the posterior clinoid process to quantify the exposures provided by these procedures. Excellent exposure of the trunk of the BA and its bifurcation was achieved. The structures in the interpeduncular cistern and the prepontine cistern were also exposed. There was an average gain of a 13.4-mm-long segment of the BA, which in some surgeries can be invaluable. The angle of exposure that was achieved with the BA bifurcation located at the apex increased markedly. Moreover, this method widened the oculomotor nerve-carotid artery corridor for easier access to the BA bifurcation region.

CONCLUSIONS

This approach combines the advantages granted by most conventional approaches to aneurysms of the BA bifurcation. The approach is suitable for aneurysms situated at a high, normal, or low position on the BA bifurcation. It exposes a sufficient length of the BA trunk to place a temporary clip.

Cosmetic and functional reconstruction achieved using a split myofascial bone flap for pterional craniotomy. Technical note

Cosmetic deformities that appear following pterional craniotomy are usually caused by temporal muscle atrophy, injury to the frontotemporal branch of the facial nerve, or bone pits in the craniotomy line. To resolve these problems during pterional craniotomy, an alternative method was developed in which a split myofascial bone flap and a free bone flap are used. The authors have used this method in the treatment of 40 patients over the last 3 years. Excellent cosmetic and functional results have been obtained. This method can provide wide exposure similar to that achieved using Yaşargil's interfascial pterional craniotomy, without limiting the operative field with a bulky temporal muscle flap.

Transorbital keyhole approach to anterior communicating artery aneurysms

OBJECTIVE

The transorbital keyhole approach to anterior communicating artery aneurysms was developed as a minimally invasive method for safe control of the anterior communicating artery complex. This approach does not necessitate resection of the gyrus rectus.

METHODS

The technique is described in detail. The transorbital keyhole approach provides more ventral access than the supraorbital approaches, and the anterior communicating artery complex can be controlled by splitting the basal aspect of the interhemispheric fissure.

RESULTS

Since late 1998, the authors have used the transorbital keyhole approach routinely. During the initial experience with 33 patients, the only observed complication specific to this approach was transient diplopia in one patient. At follow-up examinations 2 to 15 months after surgery, the cosmetic results were favorable as compared with those of standard pterional craniotomy.

CONCLUSION

We have designed a small, custom-tailored approach to the anterior communicating artery complex for routine use. The small orbitocranial approach is a step toward the ideal of purely extra-axial safe control of anterior communicating artery aneurysms. The orbitocranial keyhole approach seems to be substantially better than the craniotomy, although it requires additional effort and time.

Subfascial and submuscular methods of temporal muscle dissection and their relationship to the frontal branch of the facial nerve. Technical note

The microsurgical anatomy of the temporal and zygomatic branches of the facial nerve are presented along with related local vasculature (frontal and parietal branches of the superficial temporal artery [STA]) as encountered when using subfascial and submuscular temporal muscle dissection techniques for anterolateral craniotomies. Twenty sides were studied in 10 cadaveric specimens that had been previously injected with latex. The rami of the temporal and zygomatic branches of the facial nerve and branches of the STA were dissected out through pterional and orbitozygomatic approaches by using a submuscular or subfascial temporal muscle dissection technique. The three rami of the temporal branch of the facial nerve (the auricularis, frontalis, and orbicularis) were found to run within the galeal plane of the scalp. The zygomatic branch of the facial nerve was found to course deeper than the most caudal extension of the galea, known as the superficial musculoaponeurotic layer. The frontal branch of the STA served as an important landmark for the subfascial or submuscular dissections because excessive reflection of the scalp flap inferior to the level of this vessel would inadvertently injure the frontalis branch of the facial nerve. Subfascial and submuscular dissections of the temporal muscle offer an alternative to the interfascial technique during anterolateral craniotomies. Scalp and temporal dissection performed with careful attention to anatomical landmarks (frontal branch of the STA and the suprafascial fat pad) provides a safe and expeditious alternative to the traditional interfascial technique.

Transciliary subfrontal craniotomy for anterior skull base lesions. Technical note

Microsurgical approaches are the procedures of choice for high-risk patients with lesions requiring surgical treatment. The use of a microscope reduces the extent of the surgical invasion, thus minimizing the handling of healthy tissues. The authors present a surgical approach described for the first time in 1981, which has been used for the past 17 years in more than 260 patients with different tumors and vascular lesions of the anterior cranial fossa. The modification set forth in this article makes better exposure possible, allows more space for instrument handling, and improves cosmetic results. This particular report was based on the treatment of 41 patients who were observed for longer than 3 months. All of the patients were satisfied with the cosmetic result.

[An en bloc cranio-orbitozygomatic approach: surgical technique and results]

An en bloc cranio-orbitozygomatic approach is described. This technique was applied in seven patients (five basilar artery aneurysms, a trigeminal neuroma, a meningioma of the lesser sphenoid wing). The follow-up period ranged from 3 to 50 months. The patients were retrospectively analyzed from the cosmetic point of view, and submitted to computerized tomography with three dimensional and multiplanar reconstructions. The access provided a wider operative field with a shorter distance to the pathology and possibility of increased angulation of the microscope. The aneurysms could be clipped and the tumors completely removed in all cases. A frontalis muscle paralysis occurred in two cases, as well as a temporalis muscle atrophy in another two patients. There were no enophthalmos or bone flap displacements. The surgical technique is simple and do not require drills, electric saws and mini-plates.

Anchoring the detached temporalis muscle in craniofacial surgery

The temporalis muscle is often detached to enable craniofacial tumour and trauma access surgery. Failure to carefully handle and reattach the muscle often leads to a cosmetic and functional deformity. The authors discuss the principles of elevation of the whole temporal muscle within its surrounding fascia to reduce atrophy. The temporalis muscle is then reattached to its point of origin, using suspensory absorbable sutures attached to 3 mm titanium microscrews placed inferior to the limits of the muscle, to make them non-palpable. The aim is to reduce the postoperative temporal hollowing often seen when these principles are not observed. A series of cases using this technique are reported.