Pankaj A. Gore

The Carotid-oculomotor Window in Exposure of Upper Basilar Artery Aneurysms: A Cadaveric Morphometric Study

OBJECTIVE:The carotid-oculomotor window remains the traditional deep window in the exposure of aneurysms of the upper basilar artery. Although several techniques have been described to expand this window, few morphometric studies document either the degree of its expansion or its contribution to the exposure of the basilar artery. We review the microsurgical anatomy of the carotid-oculomotor window, describe expansion techniques, and analyze morphometrically the contribution of each step (i.e., extradural anterior clinoidectomy, mobilization of the internal carotid artery [ICA], and posterior clinoidectomy) to the expansion of the window and/or exposure of the artery. METHODS:Ten formalin-fixed, alcohol-preserved, cadaver heads injected with pigmented silicone were prepared for bilateral dissection. The vertebrobasilar system was injected with pigmented silicone mixed with barium (1:1), rendering it radiopaque. After completing a frontotemporal-orbitozygomatic craniotomy, we performed dissection in two stages: Stage I consisted of a conventional transsylvian exposure of the upper basilar artery through the carotid-oculomotor window; and Stage II added anterior clinoidectomy, ICA mobilization, and posterior clinoidectomy. A clip was applied to the lowest accessible point of the basilar trunk at each stage. Measurements obtained during each stage included: 1) the transverse carotid-oculomotor distance, that is, anteriorly between the oculomotor foramen and ICA, and posteriorly between the oculomotor nerve and ICA; and 2) the exposed length of the basilar artery, as seen under the microscope and on angiograms. RESULTS:Measurements were obtained before and after the addition of anterior clinoidectomy, mobilization of the ICA, and posterior clinoidectomy. Increases in expansion of the window and exposure of the upper basilar artery were documented as percentages of the control values. The anterior carotid-oculomotor distance averaged 7.1 mm (range, 5–10 mm) and 10.1 mm (range, 7–15 mm) before and after the additional surgical steps to expand the window, respectively. The posterior carotid-oculomotor distance averaged 12.7 mm (range, 9–18 mm) and 16.1 mm (range, 11–22 mm) before and after the additional surgical steps to expand the window, respectively. The exposed length of the basilar artery from the bifurcation to the clip was 4.2 mm (range, 1–13 mm) before expansion and 7 mm (range, 3–15 mm) after expansion. CONCLUSION:Anterior clinoidectomy and ICA mobilization increased the carotid-oculomotor space 44% anteriorly and 28% posteriorly. Posterior clinoidectomy increased the exposed length of the basilar artery by 69%. Superficial wide field exposure, expansion of the carotid-oculomotor window, and increased exposure of the upper basilar artery facilitate both visualization of the aneurysm for clip application and the use of proximal vascular control as an adjunct to basilar aneurysm surgery.

Endoscopic supracerebellar infratentorial approach for pineal cyst resection: technical case report.

OBJECTIVE Accepted surgical strategies to address symptomatic pineal cysts include transventricular flexible or rigid endoscopy and supracerebellar infratentorial or occipital transtentorial microsurgical approaches. We report the first application of the endoscopic supracerebellar infratentorial approach for the complete resection of a pineal cyst. Unlike transventricular endoscopy, this technique poses no risk to the fornices and can be applied independent of ventricular size. CLINICAL PRESENTATION A 37-year-old woman sought treatment for intractable headaches. A thorough evaluation revealed only a pineal cyst exerting mass effect on the tectum but causing no hydrocephalus. A period of nonoperative management was unsuccessful, and the patient was referred for surgery. TECHNIQUE The patient was positioned in the semi-sitting position. The supracerebellar infratentorial corridor was accessed through a burr-hole. The pineal cyst was resected completely via the endoscope. Postoperatively, the patients headaches resolved completely. CONCLUSION The endoscopic supracerebellar infratentorial approach involves minimal brain retraction, poses no risk to the fornices, allows visualization and avoidance of the Galenic veins, and can be performed regardless of the size of the ventricle. Consequently, it is an excellent minimally invasive surgical option for resection or fenestration of symptomatic pineal cysts.

Quantitative comparison of Kawase's approach versus the retrosigmoid approach: implications for tumors involving both middle and posterior fossae.

OBJECTIVE Few quantitative data are available to describe Kawases exposure of the posterior fossa. We used a cadaveric model to compare Kawases and the retrosigmoid approach to the petroclival region. METHODS Eighteen cadaveric specimens were dissected and analyzed (6 retrosigmoid, 6 Kawases, and 6 retrosigmoid intradural suprameatal approaches). Clival and brainstem working areas and surgical freedom were measured. RESULTS The retrosigmoid approach provided a significantly larger clival and brainstem working area than Kawases approach. Surgical freedom at the trigeminal root entry zone, origin of the anterior inferior cerebellar artery, and Dorellos canal was equivalent across approaches. Kawases approach provided the most surgical freedom at the trigeminal porus. However, the addition of a suprameatal extension significantly improved the surgical freedom provided by the retrosigmoid approach. CONCLUSION The retrosigmoid approach is a powerful approach to lesions of the cerebellopontine angle and ventral brainstem. Lesions involving the trigeminal porus and Meckels cave can be approached through Kawases approach or a suprameatal extension of the retrosigmoid approach. Kawases approach is best suited for accessing middle fossa lesions with smaller petroclival components located above the internal auditory canal.

Pediatric cervical spine injuries: a comprehensive review

IntroductionCervical spine injuries can be life-altering issues in the pediatric population. The aim of the present paper was to review this literature.ConclusionsA comprehensive knowledge of the special anatomy and biomechanics of the spine of children is essential in diagnosis and treating issues related to spine injuries.

Endoscopic sublabial transmaxillary approach to the rostral middle fossa.

OBJECTIVE The rostral middle fossa faces the temporal pole and is the endocranial anterosuperior aspect of the greater wing of the sphenoid. Standard approaches to this region, such as the subtemporal, pterional, or orbitozygomatic approaches, require significant brain retraction or manipulation of the temporalis muscle. We report an endoscopic sublabial transmaxillary approach to this cranial base region that avoids the aforementioned pitfalls. METHODS Ten adult cadaveric half heads were used to develop the endoscopic approach and to identify the salient surgical landmarks. RESULTS The approach was divided into three stages: entry into the maxillary sinus, entry into the infratemporal fossa, and entry into the middle fossa. A craniotomy of greater than 20 mm in diameter can be safely created in the rostral middle fossa. When coupled with image guidance, the approach provides the flexibility to tailor the size and location of the middle fossa craniotomy. CONCLUSION Although endonasal endoscopic approaches are increasing in popularity, the middle fossa has not been adequately accessed with these techniques. The endoscopic sublabial transmaxillary approach provides safe and direct access to the rostral middle fossa, eliminating the need for brain retraction, temporalis muscle manipulation, or an external incision. The approach also permits early devascularization of cranial- or dural-based lesions.

JUVENILE INTRADURAL CHORDOMA : CASE REPORT

OBJECTIVE We report the youngest known case of a prepontine intradural chordoma. These tumors are exceedingly rare. Unlike their more common extradural counterparts, no recurrence of an intradural chordoma has been reported. CLINICAL PRESENTATION A 9-year-old boy underwent diagnostic imaging for evaluation of headaches. Although neurologically intact, a magnetic resonance imaging scan revealed a large prepontine mass with focal enhancement. INTERVENTION Endoscopic-assisted gross total resection was attained with staged bilateral retrosigmoid approaches. There were no additional adjuvant therapies. At the time of the 1-year follow-up evaluation, the patient had no recurrence. CONCLUSION By using an endoscopic-assisted procedure, we achieved complete resection of an intradural chordoma offering a potential for surgical cure. Resection is particularly advantageous because it spares the young child the need for radiation treatment. Close follow-up is warranted because we postulate that this tumor exists in a biological continuum between benign notochordal hamartomatous remnants and typical invasive chordomas.

Cervical spine injuries in children: attention to radiographic differences and stability compared to those in the adult patient.

The relative rarity of pediatric cervical spine injuries can impede rapid response and efficient care of this patient population. An understanding of the unique anatomical, radiographic, and biomechanical characteristics of the pediatric cervical spine is essential to the appropriate care of these challenging patients. Patterns of injury, diagnosis, and issues related to operative and nonoperative management are discussed with a focus on the developing spine. Our aim is to improve the understanding of traumatic cervical spine injuries in children for all practitioners involved with their care.

Results with Expanded Endonasal Resection of Skull Base Meningiomas Technical Nuances and Approach Selection Based on an Early Experience.

AIM Reconstruction technique advances have created renewed enthusiasm for the expanded endonasal approach (EEA). However, as with any new technique, early experiences inevitably lead to more selective use of these techniques. We reviewed our experience of the expanded endonasal endoscopic approach for skull base meningiomas and place it in context of the literature. MATERIAL AND METHODS We performed retrospective review of all endonasal cases performed at our center for histologically proven meningioma. Tumor locations in 26 patients included the olfactory groove (n=9), tuberculum sellae (n=7), optic nerve sheath (n=1), planum sphenoidale (n=2), clival (n=1) petroclival (n=3), cavernous sinus (n=2) and extensive pan-basal meningioma (n=1). RESULTS The median follow-up was 38.6 months. Excluding 3 patients with tumors found incidentally, pre-operative symptoms improved in 14 of 23 (61%), were the same in 8 of 23 (35%) and worsened in one of 23 patients (4%) at time of last follow-up. Of all 26 patients, 16 (62%) had complete macroscopic resection of their tumor, 5 (19%) underwent at least 90% resection, and 5 (19%) underwent subtotal resection. There were two neurological complications and one cerebrospinal fluid leak. CONCLUSION This study presents outcomes of patients treated with endonasal endoscopic meningioma surgery. We believe that very low rates of morbidity can be achieved in carefully selected patients, thus avoiding brain manipulation.

Intraosseous spinal glomus tumors: case report.

OBJECTIVEGlomus tumors are rare lesions that can arise intraosseously along the entire spinal axis. Only four cases have been reported, usually manifesting with severe back pain and involving the midthoracic spine or sacrum. The current report describes the largest such lesion reported in the literature to date and summarizes the clinical and pathological characteristics of these rare tumors. METHODSA single, recent case arising from the lumbar vertebra of L3 is described, and the literature of intraosseous spinal glomus tumors is reviewed. RESULTSThe lesion described arose in a 44-year-old man with a 1-year history of neurological symptoms and a large dumbbell-shaped lesion involving the lumbar vertebra, which extended through the neural foramen at L3. The lesion was resected using a two-stage approach. Severe intraoperative hemorrhage necessitated emergent angiographic embolization. Histopathological examination confirmed the presence of a glomus tumor arising from the smooth muscle cells of the glomus body. CONCLUSIONThese rare lesions may extend into the epidural space and through the neural foramina and abdominal compartments; over time, they grow very large. Preoperative embolization may be indicated for large tumors suspected to be glomus tumors.

Management of arteriovenous malformations: a surgical perspective.

The management strategies for arteriovenous malformations (AVMs) continue to evolve, spurred by advancing technology and improved understanding of the natural history of these lesions. In general, intervention is reserved for Spetzler-Martin Grade I-III lesions or for those with certain high-risk features. Grade IV-V AVMs, in contrast, are usually managed conservatively. Although multimodality therapy incorporating endovascular and/or radiosurgical techniques is increasingly common, microsurgical removal remains the definitive form of treatment.