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Reappraisal of the anatomy of the frontotemporal branches of the facial nerve

Maximiliano Alberto Nunez, Ahmed Mohyeldin, Dario A. Marotta, Vera Vigo, Karam Asmaro, Yuanzhi Xu, Aaron A. Cohen-Gadol, and Juan C. Fernandez-Miranda

OBJECTIVE

The anatomy of the temporal branches of the facial nerve (FN) has been widely described in the neurosurgical literature because of its relevance in anterolateral approaches to the skull base and implication in frontalis palsies from these approaches. In this study, the authors attempted to describe the anatomy of the temporal branches of the FN and identify whether there are any FN branches that cross the interfascial space of the superficial and deep leaflets of the temporalis fascia.

METHODS

The surgical anatomy of the temporal branches of the FN was studied bilaterally in 5 embalmed heads (n = 10 extracranial FNs). Exquisite dissections were performed to preserve the relationships of the branches of the FN and their relationship to the surrounding fascia of the temporalis muscle, the interfascial fat pad, the surrounding nerve branches, and their final terminal endpoints near the frontalis and temporalis muscles. The authors correlated their findings intraoperatively with 6 consecutive patients with interfascial dissection in which neuromonitoring was performed to stimulate the FN and associated twigs that were observed to be interfascial in 2 of them.

RESULTS

The temporal branches of the FN stay predominantly superficial to the superficial leaflet of the temporal fascia in the loose areolar tissue near the superficial fat pad. As they course over the frontotemporal region, they give off a twig that anastomoses with the zygomaticotemporal branch of the trigeminal nerve, which crosses the superficial layer of the temporalis muscle, spanning the interfascial fat pad, and then pierces the deep temporalis fascial layer. This anatomy was observed in 10 of the 10 FNs dissected. Intraoperatively, stimulation of this interfascial segment yielded no facial muscle response up to 1 mA in any of the patients.

CONCLUSIONS

The temporal branch of the FN gives off a twig that anastomoses with the zygomaticotemporal nerve, which crosses the superficial and deep leaflets of the temporal fascia. Interfascial surgical techniques aimed at protecting the frontalis branch of the FN are safe in their efforts to protect against frontalis palsy with no clinical sequelae when executed properly.

Free access

Pursuing perfect 2D and 3D photography in neuroanatomy: a new paradigm for staying up to date with digital technology

Yuanzhi Xu, Vera Vigo, Joshua Klein, Maximiliano Alberto Nunez, Juan C. Fernandez-Miranda, Aaron A. Cohen-Gadol, and Ying Mao

Free access

Microsurgical anatomy and the importance of the petrosal process of the sphenoid bone in endonasal surgery

Ayoze Doniz-Gonzalez, Vera Vigo, Maximiliano Alberto Nunez, Yuanzhi Xu, Ahmed Mohyeldin, Aaron A. Cohen-Gadol, and Juan C. Fernandez-Miranda

OBJECTIVE

The petrosal process of the sphenoid bone (PPsb) is a relevant skull base osseous prominence present bilaterally that can be used as a key surgical landmark, especially for identifying the abducens nerve. The authors investigated the surgical anatomy of the PPsb, its relationship with adjacent neurovascular structures, and its practical application in endoscopic endonasal surgery.

METHODS

Twenty-one dried skulls were used to analyze the osseous anatomy of the PPsb. A total of 16 fixed silicone-injected postmortem heads were used to expose the PPsb through both endonasal and transcranial approaches. Dimensions and distances of the PPsb from the foramen lacerum (inferiorly) and top of the posterior clinoid process (PCP; superiorly) were measured. Moreover, anatomical variations and the relationship of the PPsb with the surrounding crucial structures were recorded. Three representative cases were selected to illustrate the clinical applications of the findings.

RESULTS

The PPsb presented as a triangular bony prominence, with its base medially adjacent to the dorsum sellae and its apex pointing posterolaterally toward the petrous apex. The mean width of the PPsb was 3.5 ± 1 mm, and the mean distances from the PPsb to the foramen lacerum and the PCP were 5 ± 1 and 11 ± 2.5 mm, respectively. The PPsb is anterior to the petroclival venous confluence, superomedial to the inferior petrosal sinus, and inferomedial to the superior petrosal sinus; constitutes the inferomedial limit of the cavernous sinus; and delimits the upper limit of the paraclival internal carotid artery (ICA) before the artery enters the cavernous sinus. The PPsb is anterior and medial to and below the sixth cranial nerve, forming the floor of Dorello’s canal. During surgery, gentle mobilization of the paraclival ICA reveals the petrosal process, serving as an accurate landmark for the location of the abducens nerve.

CONCLUSIONS

This investigation revealed details of the microsurgical anatomy of the PPsb, its anatomical relationships, and its application as a surgical landmark for identifying the abducens nerve. This novel landmark may help in minimizing the risk of abducens nerve injury during transclival approaches, which extend laterally toward the petrous apex and cavernous sinus region.

Free access

Microsurgical anatomy of the dorsal clinoidal space: implications for endoscopic endonasal parasellar surgery

Yuanzhi Xu, Maximiliano Alberto Nunez, Ahmed Mohyeldin, Vera Vigo, Ying Mao, Aaron A. Cohen-Gadol, and Juan C. Fernandez-Miranda

OBJECTIVE

The clinoidal venous space dorsal to the internal carotid artery (ICA) has not been well studied given its inaccessibility due to obstruction by the ICA during transcranial surgery. The evolution of endoscopic endonasal surgery has provided a new perspective into the clinoidal space and a new route for paraclinoidal lesions. Understanding the dorsal clinoidal space (DCS) is vital in planning and performing endoscopic endonasal surgery in the parasellar region. A detailed and precise description of the DCS from the endonasal perspective has not yet been provided. The authors’ goal in this study was to delineate the microsurgical anatomy of the DCS from an endoscopic endonasal perspective, emphasizing its surgical implications when treating invasive pituitary adenomas and other parasellar lesions.

METHODS

An endoscopic endonasal transsellar approach was performed in 15 silicone-injected postmortem heads. Afterward, the sellar region was dissected through a transcranial approach using magnification ×3 to ×40 microscopy. The osseous, dural, and arterial relationships of the DCS and its architecture were investigated. The DCS’s length, width, and depth were measured and its anatomical variations recorded.

RESULTS

The DCS was identified in 90% of the specimens, and in most cases, its shape was a narrow rectangular pyramid, with its base oriented toward the sphenoid sinus and its apex toward the posterior clinoid process. It is delimited superiorly by the distal ring, inferiorly by the medial aspect of the proximal dural ring or caroticoclinoid ligament, laterally by the clinoidal ICA, and medially by the superior continuation of the medial wall of the cavernous sinus. The width, height, and length of the DCS were 4 ± 1, 4.5 ± 1.5, and 7 ± 2 mm, respectively. A fenestrated caroticoclinoid ligament is a potential route for tumor invasion from the cavernous sinus into the DCS.

CONCLUSIONS

This report provides important anatomical descriptions of the DCS from endoscopic endonasal and transcranial perspectives that may facilitate the space’s safe exposure for the removal of invasive adenomas, increasing total resection rates and minimizing the risk of injury to neurovascular structures.

Free access

Microvascular anatomy of the medial temporal region

Yuanzhi Xu, Ahmed Mohyeldin, Maximiliano Alberto Nunez, Ayoze Doniz-Gonzalez, Vera Vigo, Aaron A. Cohen-Gadol, and Juan C. Fernandez-Miranda

OBJECTIVE

The authors investigated the microvascular anatomy of the hippocampus and its implications for medial temporal tumor surgery. They aimed to reveal the anatomical variability of the arterial supply and venous drainage of the hippocampus, emphasizing its clinical implications for the removal of associated tumors.

METHODS

Forty-seven silicon-injected cerebral hemispheres were examined using microscopy. The origin, course, irrigation territory, spatial relationships, and anastomosis of the hippocampal arteries and veins were investigated. Illustrative cases of hippocampectomy for medial temporal tumor surgery are also provided.

RESULTS

The hippocampal arteries can be divided into 3 segments, the anterior (AHA), middle (MHA), and posterior (PHA) hippocampal artery complexes, which correspond to irrigation of the hippocampal head, body, and tail, respectively. The uncal hippocampal and anterior hippocampal-parahippocampal arteries contribute to the AHA complex, the posterior hippocampal-parahippocampal arteries serve as the MHA complex, and the PHA and splenial artery compose the PHA complex. Rich anastomoses between hippocampal arteries were observed, and in 11 (23%) hemispheres, anastomoses between each segment formed a complete vascular arcade at the hippocampal sulcus. Three veins were involved in hippocampal drainage—the anterior hippocampal, anterior longitudinal hippocampal, and posterior longitudinal hippocampal veins—which drain the hippocampal head, body, and tail, respectively, into the basal and internal cerebral veins.

CONCLUSIONS

An understanding of the vascular variability and network of the hippocampus is essential for medial temporal tumor surgery via anterior temporal lobectomy with amygdalohippocampectomy and transsylvian selective amygdalohippocampectomy. Stereotactic procedures in this region should also consider the anatomy of the vascular arcade at the hippocampal sulcus.

Free access

Letter to the Editor. Digitalizing neurosurgical pedagogy

Chidinma M. Wilson, Nolan J. Brown, and Donald K. E. Detchou

Free access

Guidelines for optimal utilization of social media for brain tumor stakeholders

Nima Hamidi, Brij Karmur, Stephanie Sperrazza, Julia Alexieva, Liz Salmi, Brad E. Zacharia, Edjah K. Nduom, Aaron A. Cohen-Gadol, James T. Rutka, and Alireza Mansouri

OBJECTIVE

Effective use of social media (SM) by medical professionals is vital for better connections with patients and dissemination of evidence-based information. A study of SM utilization by different stakeholders in the brain tumor community may help determine guidelines for optimal use.

METHODS

Facebook, Twitter, and YouTube were searched by using the term “Brain Tumor.” Platform-specific metrics were determined, including audience size, as a measure of popularity, and mean annual increase in audience size, as a measure of performance on SM. Accounts were categorized on the basis of apparent ownership and content, with as many as two qualitative themes assigned to each account. Correlations of content themes and posting behavior with popularity and performance metrics were assessed by using the Pearson’s test.

RESULTS

Facebook (67 pages and 304,581 likes) was predominantly used by organizations (64% of pages). Top themes on Facebook, Twitter, and YouTube were charity and fundraising (67% of pages), education and research (72% of accounts), and experience sharing and support seeking (48% of videos, 60% of views, and 82% of user engagement), respectively. On Facebook, only the presence of other concurrent platforms influenced a page’s performance (rho = 0.59) and popularity (rho = 0.61) (p < 0.05). On Twitter, the number of monthly tweets (rho = 0.66) and media utilization (rho = 0.78) were significantly correlated with increased popularity and performance (both p < 0.05). Personal YouTube videos (30% of videos and 61% of views) with the theme of experience sharing and support seeking had the highest level of engagement (60% of views, 70% of comments, and 87% of likes).

CONCLUSIONS

Popularity and prevalence of qualitative themes differ among SM platforms. Thus, optimal audience engagement on each platform can be achieved with thematic considerations. Such considerations, along with optimal SM behavior such as media utilization and multiplatform presence, may help increase content popularity and thus increase community access to neurooncology content provided by medical professionals.

Free access

Guidelines for optimal utilization of social media for brain tumor stakeholders

Nima Hamidi, Brij Karmur, Stephanie Sperrazza, Julia Alexieva, Liz Salmi, Brad E. Zacharia, Edjah K. Nduom, Aaron A. Cohen-Gadol, James T. Rutka, and Alireza Mansouri

OBJECTIVE

Effective use of social media (SM) by medical professionals is vital for better connections with patients and dissemination of evidence-based information. A study of SM utilization by different stakeholders in the brain tumor community may help determine guidelines for optimal use.

METHODS

Facebook, Twitter, and YouTube were searched by using the term “Brain Tumor.” Platform-specific metrics were determined, including audience size, as a measure of popularity, and mean annual increase in audience size, as a measure of performance on SM. Accounts were categorized on the basis of apparent ownership and content, with as many as two qualitative themes assigned to each account. Correlations of content themes and posting behavior with popularity and performance metrics were assessed by using the Pearson’s test.

RESULTS

Facebook (67 pages and 304,581 likes) was predominantly used by organizations (64% of pages). Top themes on Facebook, Twitter, and YouTube were charity and fundraising (67% of pages), education and research (72% of accounts), and experience sharing and support seeking (48% of videos, 60% of views, and 82% of user engagement), respectively. On Facebook, only the presence of other concurrent platforms influenced a page’s performance (rho = 0.59) and popularity (rho = 0.61) (p < 0.05). On Twitter, the number of monthly tweets (rho = 0.66) and media utilization (rho = 0.78) were significantly correlated with increased popularity and performance (both p < 0.05). Personal YouTube videos (30% of videos and 61% of views) with the theme of experience sharing and support seeking had the highest level of engagement (60% of views, 70% of comments, and 87% of likes).

CONCLUSIONS

Popularity and prevalence of qualitative themes differ among SM platforms. Thus, optimal audience engagement on each platform can be achieved with thematic considerations. Such considerations, along with optimal SM behavior such as media utilization and multiplatform presence, may help increase content popularity and thus increase community access to neurooncology content provided by medical professionals.

Open access

Giant diffuse cerebellar AVM: managing ultimate intraoperative challenges

Benjamin K. Hendricks and Aaron A. Cohen-Gadol

Surgery within the posterior cranial fossa uniquely requires excellence in microsurgical technique, given the complexity of the neurovascular structures housed within this region. Arteriovenous malformations (AVMs) within this region represent the greatest surgical challenge because of the difficulty in resecting an AVM completely while preserving the highly eloquent surrounding structures. The AVM in this video exemplifies a surgeon’s “most challenging case,” a surgery that spanned two stages, including 14 hours of resection, but concluded with complete resection despite the complexity of deep arterial and dural feeders.

The video can be found here: https://youtu.be/WNBuwFHSrQ0

Free access

Editorial. Innovations in neurosurgical education during the COVID-19 pandemic: is it time to reexamine our neurosurgical training models?

Samuel B. Tomlinson, Benjamin K. Hendricks, and Aaron A. Cohen-Gadol