Lateral transorbital approach: an alternative microsurgical route for supratentorial cerebral aneurysms

Exo- and endoscopic lateral orbital wall approach for the medial temporal lobe glioma: how I do it

BACKGROUND

The endoscopic transorbital approach provides a direct access to the medial temporal lobe (MTL). However, when excising a highly vascular tumour, a wider access route that enables the concurrent use of standard neurosurgical instruments with both hands is preferable.

METHOD

We described the concept and technique of the lateral orbital wall approach (LOWA), which comprises orbitotomy and mini-craniotomy to treat MTL lesions using an exoscope and endoscope.

CONCLUSION

The LOWA provides a safe and natural surgical corridor to the MTL and enables 2- or 3-hand surgery. Hence, LOWA can potentially improve safety and efficiency to treat MTL lesions.

Revisiting the transorbital approach for emergency external ventricular drainage: an anatomical study of relevant parameters and their effect on the effectiveness of using Tubbs' point

The transorbital approach (TOA) can provide immediate access to the lateral ventricles by piercing the roof of the orbit (ROO) with a spinal needle and without the need of a drill. Reliable external landmarks for the TOA ventriculostomy have been described, however, the necessary spinal needle gauge and other relevant parameters such as the thickness of the ROO have not been evaluated. Nineteen formalin-fixed adult cadaveric heads underwent the TOA. Spinal needles of different gauges were consecutively used in each specimen beginning with the smallest gauge until the ROO was successfully pierced. The thickness of the ROO at the puncture site and around its margins was measured. Other parameters were also measured. The TOA was successfully performed in 14 cases (73.68%), where the most suitable needle gauge was 13 (47.37%), followed by a 10-gauge needle (36.84%). The mean thickness of the ROO at the puncture site, and the mean length of the needle to the puncture site were 1.7 mm (range 0.2-3.4 mm) and 15.5 mm (range 9.2-23.4 mm), respectively. A ROO thickness of greater than 2.0 mm required a 10-gauge needle in seven cases, and in five cases, a 10-gauge needle was not sufficient for piercing the ROO. The presence of hyperostosis frontalis interna (HFI) (21.05%) was related to the failure of this procedure (80%; p < 0.00). Using a 13/10-gauge spinal needle at Tubbs' point for TOA ventriculostomy allowed for external ventricular access in most adult specimens. The presence of HFI can hinder this procedure. These findings are important when TOA ventriculostomy is considered.

Endoscopic transorbital avenue to the skull base: Four-step conceptual analysis of the anatomic journey

Background

In the last decades, skull base surgery had passed through an impressive evolution. The role of neuroanatomic research has been uppermost, and it has played a central role in the development of novel techniques directed to the skull base. Indeed, the deep and comprehensive study of skull base anatomy has been one of the keys of success of the endoscopic endonasal approach to the skull base. In the same way, dedicated efforts expended in the anatomic lab has been a powerful force for the growth of the endoscopic transorbital approach to the lateral skull base.

Therefore, in this conceptual paper, the main steps for the anatomic description of the endoscopic transorbital approach to the skull base have been detailed.

Methods

The anatomic journey for the development of the endoscopic transorbital approach to the skull base has been analyzed, and four “conceptual” steps have been highlighted.

Results

As neurosurgeons, the eyeball has always represented a respectful area: to become familiar with this complex and delicate anatomy, we started by examining the orbital anatomy on a dry skull (step 1). Hence, step 1 is represented by a detailed bone study; step 2 is centered on cadaveric dissection; step 3 consists in 3D quantitative assessment of the novel endoscopic transorbital corridor; and finally, step 4 is the translation of the preclinical data in the real surgical scenario by means of dedicated surgical planning.

Conclusions

The conceptual analysis of the anatomic journey for the description of the endoscopic transorbital approach to the skull base resulted in four main methodological steps that should not be thought strictly consequential but rather interconnected. Indeed, such steps should evolve following the drives that can arise in each specific situation. In conclusion, the four-step anatomic rehearsal can be relevant for the description, diffusion, and development of a novel technique in order to facilitate the application of the endoscopic transorbital approach to the skull base in a real surgical scenario.

Effects of Modified Osteoplastic Pterional Craniotomy on Temporal Muscle Volume and Frontal Muscle Nerve Function

Introduction  Pterional craniotomy is a surgical approach frequently used in aneurysm and skull base surgery. Pterional craniotomy may lead to cosmetic and functional problems, such as eyebrow drop due to facial nerve frontal branch damage, temporal muscle atrophy, and temporomandibular joint pain. The aim was to compare the postoperative effects of our modified osteoplastic craniotomy with classical pterional craniotomy in terms of any change in volume of temporal muscle and in the degree of frontal muscle nerve damage. Materials and Methods  Aneurysm cases were operated with either modified osteoplastic pterional craniotomy or free bone flap pterional craniotomy according to the surgeon's preference. Outcomes were compared in terms of temporal muscle volume and frontal muscle nerve function 6 months postoperatively. Results  Preoperative temporal muscle volume in the modified osteoplastic pterional and free bone flap pterional craniotomy groups were not different ( p  > 0.05). However, significantly less atrophy was observed in the postoperative temporal muscle volume of the osteoplastic group compared with the classical craniotomy group ( p  < 0.001). In addition, when comparing frontal muscle nerve function there was less nerve damage in the modified osteoplastic pterional craniotomy group compared with the classical craniotomy group, although this did not reach significance ( p  > 0.05). Conclusion  Modified osteoplastic pterional craniotomy significantly reduced atrophy of temporal muscle and caused proportionally less frontal muscle nerve damage compared with pterional craniotomy, although this latter outcome was not significant. These findings suggest that osteoplastic craniotomy may be a more advantageous intervention in cosmetic and functional terms compared with classical pterional craniotomy.

The Lateral Orbitotomy Approach for Intraorbital Lesions

The lateral orbitotomy approach (LOA) was first described by Kronlein in 1888 and has since been subject to many modifications and variations. When considering orbital approaches, the location of the pathology is often more important in decision making than the type of pathology. The LOA is best suited for access to intraconal and extraconal lesions lateral to the optic nerve. Pathologies treated via the LOA include primary orbital tumors, extraorbital tumors with local extension into the orbit, and distantly metastatic lesions to the orbit. These all often initially manifest with vision loss, oculomotor deficits, or proptosis. The expertise of a multidisciplinary team is needed to execute safe and effective treatment. Collaboration between many specialties may be required, including ophthalmology, neurosurgery, otolaryngology, plastic surgery, oncology, and anesthesiology. The modern technique involves either a lateral canthotomy or eyelid crease incision with removal of the lateral orbital wall. It affords many advantages over a pterional craniotomy, primarily a lower approach morbidity and superior cosmetic outcomes. Reconstruction is fairly simple and the rate of complications-vision loss and extraocular muscle palsy-are low and infrequently permanent. Deep orbital apex location and intracranial extension have traditionally been considered limitations of this approach. However, with increased surgeon comfort, modern technique, and the adoption of endoscopy, these limits have expanded to even include primarily intracranial pathologies. This review details the LOA, including the general technique, its indications and limitations, reconstruction considerations, complications, and recent data from case series. The focus is on microscopic access to intraorbital lesions.