Mohamed A. Labib

A Road Map to the Internal Carotid Artery in Expanded Endoscopic Endonasal Approaches to the Ventral Cranial Base

BACKGROUND: Injuring the internal carotid artery (ICA) is a feared complication of endoscopic endonasal approaches. OBJECTIVE: To introduce a comprehensive ICA classification scheme pertinent to safe endoscopic endonasal cranial base surgery. METHODS: Anatomic dissections were performed in 33 cadaveric specimens (bilateral). Anatomic correlations were analyzed. RESULTS: Based on anatomic correlations, the ICA may be described as 6 distinct segments: (1) parapharyngeal (common carotid bifurcation to ICA foramen); (2) petrous (carotid canal to posterolateral aspect of foramen lacerum); (3) paraclival (posterolateral foramen lacerum to the superomedial aspect of the petrous apex); (4) parasellar (superomedial petrous apex to the proximal dural ring); (5) paraclinoid (from the proximal to the distal dural rings); and (6) intradural (distal ring to ICA bifurcation). Corresponding surgical landmarks included the Eustachian tube, the fossa of Rosenmüller, and levator veli palatini for the parapharyngeal segment; the vidian canal and V3 for the petrous segment; the fibrocartilage of foramen lacerum, foramen rotundum, maxillary strut, lingular process of the sphenoid bone, and paraclival protuberance for the paraclival segment; the sellar floor and petrous apex for the parasellar segment; and the medial and lateral opticocarotid and lateral tubercular recesses, as well as the distal osseous arch of the carotid sulcus for the paraclinoid segment. CONCLUSION: The proposed endoscopic classification outlines key anatomic reference points independent of the vessels geometry or the sinonasal pneumatization, thus serving as (1) a practical guide to navigate the ventral cranial base while avoiding injury to the ICA and (2) further foundation for a modular access system. ABBREVIATIONS: DOA, distal osseous arch EEA, expanded endoscopic approach ICA, internal carotid artery LOCR, lateral opticocarotid recess LTR, lateral tubercular recess MOCR, medial opticocarotid recess SOF, superior orbital fissure

The medial opticocarotid recess: an anatomic study of an endoscopic "key landmark" for the ventral cranial base.

BACKGROUND: The medial opticocarotid recess (MOCR) has become an important landmark for endoscopic approaches to the cranial base. OBJECTIVE: To examine the anatomy of the MOCR and outline its role as a “key landmark” for approaches to the sellar and suprasellar regions. METHODS: Ten silicone-injected cadaveric specimens and 96 dry crania were examined. Dissections were done endoscopically and microscopically. RESULTS: The lateral tubercular recess is an osseous depression located at the lateral edge of the tuberculum when viewed from the sphenoid sinus. Intracranially, it corresponds to the lateral tubercular crest (LTC), a ridge situated at the superomedial aspect of the carotid sulcus. The MOCR is a teardrop-shaped osseous indentation formed at the medial junction of the paraclinoid carotid canal and the optic canal. Dorsally, it is represented by a teardrop-shaped area with vertices at the inferior aspect of the LTC, the medial aspect of the junction of the superior and posterior surfaces of the optic strut, and the superolateral aspect of the tuberculum. The middle clinoid process is situated inferior to the LTC. The distal osseous arch of the carotid sulcus connects the lateral opticocarotid recess to the lateral tubercular recess and is a landmark for the paraclinoid internal carotid artery. Only 44% of the specimens had middle clinoid processes. CONCLUSION: The MOCR and middle clinoid process are distinct structures. Because of its location at the confluence of the optic canal, the carotid canal, the sella, and the anterior cranial base, the MOCR is a key landmark for endoscopic approaches. ABBREVIATIONS: DOA, distal osseous arch ICA, internal carotid artery LOCR, lateral opticocarotid recess LTC, lateral tubercular crest LTR, lateral tubercular recess MOCR, medial opticocarotid recess

Temporal lobe arteriovenous malformations: surgical outcomes with a focus on visual field defects and epilepsy.

BACKGROUND Temporal lobe arteriovenous malformations (AVMs) represent a subgroup of intracranial AVMs with particular characteristics and management issues. OBJECTIVE To characterize the surgical outcomes of temporal lobe AVMs with emphasis on visual field deficits (VFDs) and seizures. METHODS Between 1992 and 2008, 29 patients were operated on for temporal lobe AVMs. Patient data were retrospectively collected and analyzed. RESULTS Twelve of 29 patients (41.4%) presented with seizures and 4 (13.7%) presented with VFDs. Postoperatively, 6 patients (24%) showed new VFDs and 2 improved, with a rate of preservation of full visual fields of 84%. Larger AVMs (> 3 cm) were significantly associated with postoperative VFD (P = .008). Epilepsy outcomes assessed by the Engel scale were as follows: 9 patients (75%) were in class I (seizure free), 1 patient (8.3%) was in class III, and 2 patients (16.6%) were in class IV (no change or worsening). Postoperative modified Rankin Scale outcomes were excellent (grade 0-1) in 18 patients, good (grade 2) in 7, and poor (grade 3-4) in 4. Older age at diagnosis correlated with a worse functional outcome (Spearman ρ = 0.369; P = .049). AVMs were totally removed in 27 of 29 patients (93.1%). Complete surgical excision was confirmed with angiography. Two patients needed reoperation for AVM remnant. Three patients had persistent hemiparesis (10.3% permanent morbidity). There was no mortality. CONCLUSION Seizure control is usually underappreciated in the surgical management of AVMs. However, in temporal lobe AVMs, good outcomes with low morbidity and good visual field preservation can be accomplished.

Flow diversion in the treatment of carotid injury and carotid-cavernous fistula after transsphenoidal surgery:

We describe a case of iatrogenic carotid injury with secondary carotid-cavernous fistula (CCF) treated with a silk flow diverter stent placed within the injured internal carotid artery and coils placed within the cavernous sinus. Flow diverters may offer a simple and potentially safe vessel-sparing option in this rare complication of transsphenoidal surgery. The management options are discussed and the relevant literature is reviewed.

Part I: The challenge of functional preservation: an integrated systems approach using diffusion-weighted, image-guided, exoscopic-assisted, transulcal radial corridors

Abstract Surgical access to subcortical lesions in the sensorimotor area can lead to a high degree of cognitive and functional morbidity through injury to white matter fiber tracts. Inherent technological challenges limit resection of lesions in the sensorimotor area. A systematic and integrated approach to address these challenges termed the six-pillar approach has been developed. While individual elements of these pillars have been reported elsewhere, the authors hypothesize that the consistent adoption of standardized imaging, navigation, access, optics and resection technologies as a system identifies and protects eloquent tissue. In addition, this approach allows for the targeted harvest of viable cells to serve as the substrate for molecular regenerative therapy. An illustrative case with resection of a low-grade glioma in the sensorimotor region using the six-pillar approach is included to highlight the strengths of this approach.

Part II: an evaluation of an integrated systems approach using diffusion-weighted, image-guided, exoscopic-assisted, transulcal radial corridors

Abstract Background: Subcortical injury resulting from the surgical access and management of lesions in the sensorimotor area is associated with a high degree of cognitive and functional morbidity. Methods: We used a systems approach integrating the six core competencies of the 6 Pillar approach: 1) image interpretation and trajectory planning; 2) dynamic navigation; 3) radial transulcal access and cannulation; 4) exoscopic high-definition optics; 5) resection with automated nonthermal mechanical instrumentation; and 6) regenerative medicine. We describe the application of the 6 Pillar approach to 13 consecutive patients with lesions in the sensorimotor area. Results: Eight females and five males with lesions in the sensorimotor area were treated using the 6 Pillar approach. There were eight tumors, one abscess, and four primary intracranial hemorrhages. Fifteen procedures were performed. Postoperatively, seven patients improved neurologically (three tumors, one abscess, and three ICHs), five remained unchanged, and one patient died. There was no worsening of pre-existing deficits. Conclusion: The integration of the 6 Pillar approach provides a safe and effective parafascicular minimally invasive corridor to subcortical lesions involving the sensorimotor area. Future studies will be needed to determine long-term efficacy, durability, and degree of resection within each category.

“Pushing the envelope in neurosurgery”: dilemma of the appropriate indications

We reviewed the case report of a 68-year-old man who harbored two distinct meningiomas located in the parasagittal and falcine regions. The patient had a past history of scalp irradiation for tinea capitis, which was complicated with severe skin atrophy of the scalp. His parasagittal meningioma was managed previously with surgery and radiation therapy, in which histopathological examination revealed an atypical WHO II meningioma. The surgery was complicated by partial wound dehiscence and cerebrospinal fluid (CSF) leak, which were managed successfully. Despite surgery and radiation, the parasagittal meningioma recurred and the authors performed a subtotal resection of the lesion via a purely endoscopic parafalcine interhemispheric approach due to unsuitable skin condition at the site of the previous surgery. The authors are to be commended for their brave attempt at removing the tumors via a distant purely endoscopic approach as well as on their technical dexterity. We would like to point out a few concerns. First, a multidisciplinary approach involving vascular and plastic surgeons could have been planned in order to allow optimal surgical resection of the tumor through the traditional approach. Desai et al. [1] have performed a systematic review and developed an algorithm for optimal scalp reconstruction. Although the exact size of the atrophic scalp was not reported in this patient, Desai et al. have found that patients with large defects and a history of radiation will likely benefit from free tissue transfer. Therefore, this management strategy should have been considered for a safer access to the tumor. Second, the effectiveness of a subtotal removal via endoscopic surgery in this particular situation is debatable. Such resection is associated with 44 % recurrence risk at 10 years [2]. The patient in this case harbored a more aggressive tumor (WHO II) and surgery alone (subtotal resection) without radiation might not be enough to control the tumor growth. Although a gross total resection might mandate the resection of the encased/infiltrated superior sagittal sinus, no information about the sinus patency (magnetic resonance venography or angiography) was provided. Other factors (e.g., MIB-1 index) are also important, particularly in grades II-III like the one observed in the authors’ patient [3]. The authors, however, did not report the MIB-1 index (Ki-67) for their patients, making the estimation of the efficacy of the procedure and risk of recurrence rather difficult. Although no reports exist on the optimal treatment modality for recurrent aggressive parasagittal meningiomas, many therapeutic modalities have been reported in the literature with variable outcomes, including repeat surgery, re-irradiation, brachytherapy, or a combination between them [4, 5]. Recently, Abou Al-Shaar et al. [4] reported two patients with aggressive falcine meningiomas, which recurred despite receiving multiple surgeries and radiation therapy. Both patients harbored WHO II meningioma with a MIB-1 index (Ki-67) of 30 % and 7.8 %, respectively. The patients underwent resection of their tumors and permanent implantation of brachytherapy seeds along the resection site. Both patients were doing well with no recurrence at 31 and 10 months after brachytherapy. Others achieved tumor control with permanent or temporary placement of brachytherapy seeds without resecting the recurrent tumor [6]. Although the efficacy of these treatments is very debatable, they could have been * Amir R. Dehdashti Adehdashti@NSHS.edu

Glomangiopericytoma simulating an intracavernous meningioma.

Background: Glomangiopericytoma is an uncommonly encountered tumor of the nose and paranasal sinuses, accounting for <0.5% of all sinonasal tumors. Extension of these lesions to the anterior or middle cranial fossa is rare. When this occurs, diagnosing glomangiopericytoma is extremely challenging, as it is often confused with other anterior skull base tumors. Case Description: We report a case of a giant glomangiopericytoma localizing into the cavernous sinus in a 48-year-old female who presented with mild left-sided ptosis for 48 months. The lesion simulated an intracavernous meningioma on preoperative imaging. An expanded endoscopic endonasal approach was used to debulk the portion of the lesion in the medial compartment of the cavernous sinus. Postoperatively, the patients ptosis resolved completely, and no new deficits were sustained. Conclusion: This is the only case of glomangiopericytoma localizing solely to the cavernous sinus reported to date.