Supracerebellar "Flyover" Approach to Dumbbell Falcotentorial Meningioma Encasing the Galenic Venous System.

Falcotentorial meningiomas involve the tentorial apex and straight sinus, posing challenges when encasing the galenic venous system.1 Microneurosurgery is considered the best treatment option for large falcotentorial meningiomas because it provides a definitive cure.2 In contrast, Gamma Knife surgery mainly allows the control of smaller or residual tumors after microsurgical resection.3 Approach selection between interhemispheric supratentorial versa supracerebellar transtentorial is dictated by the displacement of the Galen vein.1,4-8Video 1 describes the critical surgical steps of the supracerebellar "flyover" approach for a Bassiouni type II dumbbell falcotentorial meningiomas encasing the galenic venous system. Preoperative embolization was ruled out due to potential additional morbidity and mortality risks.9,10 A perimedian supracerebellar infratentorial transtentorial approach was performed with the patient in ¾ prone Concorde position. After early devascularization and division of the tentorium, the meningioma was internally debulked while preserving the arachnoid plane. The posterior choroidal arteries, internal cerebral veins, basal veins of Rosenthal, and vein of Galen were carefully dissected, and the tumor was completely resected. The patient was discharged on postoperative day 3 with no deficits. Postoperative magnetic resonance imaging confirmed a Simpson grade 1 resection. Pathology revealed a grade 2 meningioma. The patient remained asymptomatic with no recurrence at a 10-year follow-up. The reported case demonstrates that the most critical factor in the choice of approach to midline dumbbell falcotentorial meningiomas is the relationship of the tumor to the galenic venous system and its tributaries.

The Party Wall: Redefining the Indications of Transcranial Approaches for Giant Pituitary Adenomas in Endoscopic Era.

The evolution of endoscopic trans-sphenoidal surgery raises the question of the role of transcranial surgery for pituitary tumors, particularly with the effectiveness of adjunct irradiation. This narrative review aims to redefine the current indications for the transcranial approaches for giant pituitary adenomas in the endoscopic era. A critical appraisal of the personal series of the senior author (O.A.-M.) was performed to characterize the patient factors and the tumor's pathological anatomy features that endorse a cranial approach. Traditional indications for transcranial approaches include the absent pneumatization of the sphenoid sinus; kissing/ectatic internal carotid arteries; reduced dimensions of the sella; lateral invasion of the cavernous sinus lateral to the carotid artery; dumbbell-shaped tumors caused by severe diaphragm constriction; fibrous/calcified tumor consistency; wide supra-, para-, and retrosellar extension; arterial encasement; brain invasion; coexisting cerebral aneurysms; and separate coexisting pathologies of the sphenoid sinus, especially infections. Residual/recurrent tumors and postoperative pituitary apoplexy after trans-sphenoidal surgery require individualized considerations. Transcranial approaches still have a critical role in giant and complex pituitary adenomas with wide intracranial extension, brain parenchymal involvement, and the encasement of neurovascular structures.

Fascicular-Sparing Technique for Resection of Cerebellopontine Angle Facial Nerve Schwannoma.

Surgery of cerebellopontine angle (CPA) facial nerve schwannoma (FNS) in patients with good facial nerve function is a challenge.1-10Video 1 highlights the fascicular-sparing technique for resection of a CPA FNS. A 41-year-old male patient symptomatic with persistent headaches and tinnitus underwent a retrosigmoid approach for a right cystic CPA tumor, presumed vestibular schwannoma. Intraoperatively, the facial nerve was identified as fine multiple strands splayed around the perimetry of the tumor, which elicited a motor response at a low threshold stimulation. This finding led to the intraoperative diagnosis of FNS according to the reported criteria.5 Neuromonitoring-assisted fascicular-sparing resection technique was performed. It involved the gradual separation of the uninvolved nerve fibers using a fine-stimulating dissector at a threshold of 0.2 mA. Entry into the tumor was at a stimulation silent cyst. The tumor was debulked with preservation of the endoneurium and pulse irrigation hemostasis. A near-total resection was performed. The patient was discharged on the second postoperative day with a House-Brackman III facial nerve deficit. The deficit remained stable during the following annual follow-up visits. Resection of CPA FNS is indicated at the earliest sign of deficit. However, it might be encountered as masquerading at the surgery of an acoustic tumor. The fascicular-sparing technique is critical in avoiding injuries to the endoneurium during the resection and with the ability to preserve function. The sparing of endoneurium avoids collagenization, fibrosis, and ischemia of the nerve, which are known to be the pathologic substrate of worse functional outcomes.

Intracranial Facial Schwannomas: Multiple Distinct Entities Necessitating Tailored Management.

OBJECTIVE: Facial nerve (FN) schwannomas are extremely rare. According to their origin and involved segment(s), they constitute distinct subtypes. Intact FN function presents a management challenge, particularly in the cerebellopontine angle cisternal subtype that masquerades as a vestibular schwannoma. Fascicular-sparing technique with subtotal resection can maintain a good FN function. This study focuses on management to maintain good FN function. METHODS: A retrospective analysis of a cohort of 13 patients harboring FN schwannoma. Patient demographics, clinical findings, imaging, surgical intervention, and outcomes were analyzed. RESULTS: Five women and 8 men, with an average age of 55.3 years (39-75 years), harbored 6 cisternal, 2 ganglion, and 5 combined tumors. Average tumor size was 28.3 mm (16-50 mm). Eleven patients underwent surgery. Seven patients had fascicle-sparing technique, 5 of whom maintained their preoperative FN function, whereas 2 patients with near-total removal had a deterioration in FN function. Two patients with preoperative complete facial paralysis had gross total removal with interposition nerve graft. CONCLUSIONS: FN schwannomas management is individualized according to the subtype and the FN function at presentation. When FN function is normal, observation can be applied for prolonged period of time. At the early sign of deterioration, sub- or near-total resection with fascicle sparing technique can be performed. The cisternal subtype masquerade as vestibular schwannoma and should be recognized at the initial exposure by the appearance of finely splayed nerve fascicles at the perimetry of the tumor which elicits a motor response at low threshold stimulation.

Preservation of Cranial Nerves Function in Glomus Jugulare Surgery: 2-Dimensional Operative Video.

Owing to their invasive character, extreme vascularity, and critical location, glomus jugulare tumors present a formidable challenge. Techniques have been developed for safe and successful removal of even giant glomus paragangliomas.1-3 Preoperative evaluation including genetic, hormonal, and multiplicity workup4 has enhanced the safety of surgical management, as did modern preoperative embolization by eliminating excessive blood loss.5 Despite these advancements, surgical outcomes of glomus jugulare remain haunted by cranial nerve dysfunction such as facial nerve palsies and hearing loss, with lower cranial nerves dysfunction being the most morbid. These can be avoided by technical maneuvers to preserve the cranial nerves. The external ear canal is not closed to maintain conductive hearing. The facial nerve is not transpositioned and kept inside a bony protective canal. Cranial nerves IX, X, and XI are the most vulnerable because they pass through the jugular foramen ventral to the venous bulb wall. They are preserved by intrabulbar dissection that maintains a protective segment of the venous wall over the nerves. By mastering the anatomy of the upper neck, meticulous dissection is performed to preserve the course of IX, X, XI, and XII.6,7 Ligation of the jugular vein is delayed until the tumor is totally isolated to avoid diffuse bleeding.7 We present the case of a 60-yr-old woman with a glomus jugulare tumor with intradural, extradural, and cervical extension. The technical nuances of cranial nerves preservation are demonstrated. The patient consented to the procedure and publication of her images. Images at 2:12, 2:50, and 3:09 from Al-Mefty and Teixeira,6 with permission from JNSPG.

Resection of Clival Chordoma Through the Anterior Clivectomy: 2-Dimensional Operative Video.

Clival chordomas are rare malignant behaving tumors that grow, locally invade, metastasize, and seed, and they have a high recurrence rate.1,2 The longest disease control is achieved by radical resection followed by high doses of radiation therapy, commonly proton beam.3 To achieve radical tumor removal, multiple surgical procedures through different approaches might be required.4 Since the chordoma's origin is, and remains, extradural, an extradural approach is preferred, and can lead to intradural extension. Anterior approach is frequently utilized to remove the midline-located tumor and the eroded clivus.5 Several midline approaches were utilized, including the transbasal, transfacial, transcervical, open door, and Lefort's maxillotomies1; however, the same tumor removal can be achieved with a simple extension of the trans-sphenoidal approach, by resecting the anterior maxillary wall, of the contralateral to the lesion preponderant side.5 This approach coupled with the use of neuronavigation on mobile head and endoscopic-assisted technique allowed to achieve a wide and direct exposure, with the ability to resect extra- and intradural tumors.2,5 Lately, the endonasal endoscopic technique became popular as an alternative4; however, we found a great advantage in the ability to combine the stereoscopic microsurgical technique with the endoscopic dissection, in addition to avoiding the extensive nasal dissection and its complications. We present a case of a 63-yr old woman with an upper clivus chordoma compressing the brainstem who underwent a gross total resection by endoscopic-assisted microscopic techniques through an anterior clivectomy approach. Patient consented to the procedure and publication of her images.

Resection of Pontine Cavernoma Through the Anterior Transpetrosal Approach: 2-Dimensional Operative Video.

The pons is the most frequent local for brain stem cavernoma.1 Repeated hemorrhage of brainstem cavernoma is associated with significant and accumulative neurological deficits and thus requires treatment. According to the Swedish Karolinska's group of radiosurgery, "it could not be concluded whether GKRS affects the natural course of a CM. The incidence of radiation-induced complications was approximately seven times higher than that expected."2 Thus, microsurgical removal has become the mainstay of treatment. In our experience, the following details assist in obtaining favorable outcomes and avoiding postoperative complications3,4: (a) the entry into the cavernoma based on thorough knowledge of the microanatomy; (b) the detailed study of the images and the presentation of the cavernoma on or near the brain stem surface; (c) the resection of the live cavernous hemangioma and not the mere removal of the multiple aged organized hematomas; (d) the preservation of the associated venous angioma; (e) the direct and shortest access to the lesion provided by a skull base approach; and (f) the use of the available technology, such as intraoperative neuromonitoring and neuroimaging. We present the case of a 54-yr-old male with recent deterioration in year 2001, past repetitive episodes of gait imbalance, and speech difficulty over a 7-yr period from known pontine cavernoma. The anterior petrosal approach provided superb and direct exposure to the entry at the lateral pons and the cavernoma was totally removed with preservation of the venous angioma. His preoperative neurological deficit rapidly recovered. Patient consented to the procedure and photography. Images at 3:15 from Kadri et al, The anatomical basis for surgical presercation of temporal muscle. J Neurosurg. 2004;100:517-522, used with permission from JNSPG. Image at 3:27 from Al-Mefty O, Operative Atlas of Meningiomas, © LWW, 1997, with permission.

The Resection of a Thalamic Pilocytic Astrocytoma Through the Transchoroidal Fissure, Transcallosal Approach: 2-Dimensional Operative Video.

Surgical resection is the primary treatment of pilocytic astrocytomas and total removal can be curative. However, these lesions occur in critical areas, such as the thalamus, being surrounded by critical life neurovascular structures, which imposes a surgical challenge.1-5 Exhaustive acquisition and meticulous interpretation of preoperative radiological exams; reliable surgical orientation based on profound microneurosurgical anatomic knowledge and judicious discernment of the neuroanatomic distortions on the surface and deep-seated structures inflicted by the neuropathological entity; embracing and comprehensive application of the vast scope of available intraoperative guidance imaging and neurophysiological monitoring; in alliance with the mastered carefully microsurgical technique supported by endoscopic visualization are the keystones to the pursed duet "cure with quality of life" in the treatment of these lesions. We present the case of a 17-yr-old young lady with a progressive motor deficit in her right hemibody for over 2 yr. Her radiological investigation demonstrated a left thalamic lesion displacing the projection fibers (corticospinal tract) within the internal capsule laterally. The patient consented to the surgical procedure. The surgical strategy, intraoperative findings, and microsurgical and endoscopic technique, as well as the postoperative radiological and clinical evaluation are presented. The patient gave her informed consent for the publication of the case.

Fiber Microdissection Technique for Demonstrating the Deep Cerebellar Nuclei and Cerebellar Peduncles.

BACKGROUND: The cerebellum is one of the most primitive and complex parts of the human brain. The fiber microdissection technique can be extremely useful for neurosurgeons to understand the topographical organization of the cerebellum's important contents, such as the deep cerebellar nuclei and the cerebellar peduncles, and their relationship with the brain stem. OBJECTIVE: To dissect the deep cerebellar nuclei and the cerebellar peduncles using the fiber microdissection technique. METHODS: Under the operating microscope, 5 previously frozen, formalin-fixed human cerebellums and brain stems were dissected from the superior surface, and 5 were dissected from the inferior surface. Each stage of the process is described. The primary dissection tools were handmade, thin, wooden spatulas with tips of various sizes, toothpicks, and a fine regulated suction. RESULTS: In 15 simplified dissection steps (6 for the superior surface and 9 for the inferior surface), the deep cerebellar nuclei (dentate, interpositus, and fastigial) and the cerebellar peduncles (inferior, middle, and superior) are delineated. Their anatomical relationships with each other and other neighboring structures are demonstrated. CONCLUSION: The anatomy of the deep cerebellar nuclei and the cerebellar peduncles are clearly defined and understood through the use of the fiber microdissection technique. These stepwise dissections will guide the neurosurgeon in acquiring a topographical understanding of these complex and deep structures of the cerebellum. This knowledge, along with radiological information, can help in planning the most appropriate surgical strategy for various lesions of the cerebellum.

Surgical Approaches to the Temporal Horn: An Anatomic Analysis of White Matter Tract Interruption.

BACKGROUND: Surgical access to the temporal horn is necessary to treat tumors and vascular lesions, but is used mainly in patients with mediobasal temporal epilepsy. The surgical approaches to this cavity fall into 3 primary categories: lateral, inferior, and transsylvian. The current neurosurgical literature has underestimated the interruption of involved fiber bundles and the correlated clinical manifestations. OBJECTIVE: To delineate the interruption of fiber bundles during the different approaches to the temporal horn. METHODS: We simulated the lateral (trans-middle temporal gyrus), inferior (transparahippocampal gyrus), and transsylvian approaches in 20 previously frozen, formalin-fixed human brains (40 hemispheres). Fiber dissection was then done along the lateral and inferior aspects under the operating microscope. Each stage of dissection and its respective fiber tract interruption were defined. RESULTS: The lateral (trans-middle temporal gyrus) approach interrupted "U" fibers, the superior longitudinal fasciculus (inferior arm), occipitofrontal fasciculus (ventral segment), uncinate fasciculus (dorsolateral segment), anterior commissure (posterior segment), temporopontine, inferior thalamic peduncle (posterior fibers), posterior thalamic peduncle (anterior portion), and tapetum fibers. The inferior (transparahippocampal gyrus) approach interrupted "U" fibers, the cingulum (inferior arm), and fimbria, and transected the hippocampal formation. The transsylvian approach interrupted "U" fibers (anterobasal region of the extreme capsule), the uncinate fasciculus (ventromedial segment), and anterior commissure (anterior segment), and transected the anterosuperior aspect of the amygdala. CONCLUSION: White matter dissection improves our knowledge of the complex anatomy surrounding the temporal horn. Identifying the fiber bundles at risk during each surgical approach adds important information for choosing the appropriate surgical strategy.

Medial acoustic neuromas: clinical and surgical implications.

OBJECT: Medial acoustic neuroma is a rare entity that confers a distinct clinical syndrome. It is scarcely discussed in the literature and is associated with adverse features. This study evaluates the clinical and imaging features, pertinent surgical challenges, and treatment outcome in a large series of this variant. The authors postulate that the particular pathological anatomy with its arachnoidal rearrangement has a profound implication on the surgical technique and outcome. METHODS: The authors conducted a retrospective analysis of 52 cases involving 33 women and 19 men who underwent resection of medial acoustic neuromas performed by the senior author (O.A.) over a 20-year period (1993-2013). Clinical, radiological, and operative records were reviewed, with a specific focus on the neurological outcomes and facial nerve function and hearing preservation. Intraoperative findings were analyzed with respect to the effect of arachnoidal arrangement on the surgeon's ability to resect the lesion and the impact on postoperative function. RESULTS: The average tumor size was 34.5 mm (maximum diameter), with over 90% of tumors being 25 mm or larger and 71% being cystic. Cerebellar, trigeminal nerve, and facial nerve dysfunction were common preoperative findings. Hydrocephalus was present in 11 patients. Distinguishing intraoperative findings included marked tumor adherence to the brainstem and frequent hypervascularity, which prompted intracapsular dissection resulting in enhancement on postoperative MRI in 18 cases, with only 3 demonstrating growth on follow-up. There was no mortality or major postoperative neurological deficit. Cerebrospinal fluid leak was encountered in 7 patients, with 4 requiring surgical repair. Among 45 patients who had intact preoperative facial function, only 1 had permanent facial nerve paralysis on extended follow-up. Of the patients with preoperative Grade I-II facial function, 87% continued to have Grade I-II function on follow-up. Of 10 patients who had Class A hearing preoperatively, 5 continued to have Class A or B hearing after surgery. CONCLUSIONS: Medial acoustic neuromas represent a rare subgroup whose site of origin and growth patterns produce a distinct clinical presentation and present specific operative challenges. They reach giant size and are frequently cystic and hypervascular. Their origin and growth pattern lead to arachnoidal rearrangement with marked adherence against the brainstem, which is critical in the surgical management. Excellent surgical outcome is achievable with a high rate of facial nerve function and attainable hearing preservation. These results suggest that similar or better results may be achieved in less complex tumors.

Anterior clivectomy: surgical technique and clinical applications.

OBJECT: Midline clival lesions, whether involving the clivus or simply situated anterior to the brainstem, present a technical challenge for adequate exposure and safe resection. The authors describe, as a minimally invasive technique, an anterior clivectomy performed via an expanded transsphenoidal approach coupled with the use of a neuronavigation on mobile head and endoscopic-assisted technique. Wide and direct exposure, with the ability to resect extra- and intradural tumors, was achieved without mortality and with a low rate of complications. METHODS: Cadaveric dissections were performed to outline the landmarks and measure the window that is created by resecting the clivus anteriorly. The technique was used in 43 patients to resect tumors located at or invading the clivus. The initial exposure of the clivus was obtained via the sublabial transsphenoidal approach. The wall of the anterior maxilla, often on 1 side, was removed to allow a wide side-to-side opening of the nasal speculum. Using neuronavigation, the authors made clivectomy windows by drilling the clivus between anatomical landmarks. Bilateral intraoperative neurophysiological monitoring was used (somatosensory evoked potentials, brainstem auditory evoked responses, and cranial nerves VI-XII). RESULTS: Of the 43 patients, 26 were female and 17 were male, and they ranged in age from 3.5 to 76 years (mean 41.5 years). Thirty-eight patients harbored a chordoma and 5 a giant invasive pituitary adenoma. Gross-total resection of the tumor was achieved in 34 cases (79%). Nine patients (21%) had residual tumor unreachable through the anterior clivectomy, and this required a second-stage resection. Four patients developed new transient extraocular movement deficits. One patient developed a permanent cranial nerve VI palsy. Twenty-seven patients with chordoma underwent postoperative proton-beam radiotherapy. Tumor recurred in 19% of these cases. In 3 patients a cerebrospinal fluid leak developed during hospitalization and was treated successfully. Two other patients presented with a delayed cerebrospinal fluid leak after radiotherapy. Only 1 patient, who had previously undergone Gamma Knife surgery, experienced postoperative hemiparesis. CONCLUSIONS: A complete anterior clivectomy via a simple extension of the transsphenoidal approach allows the surgeon access to different lesions involving the clivus or situated anterior to the brainstem. The exposure is similar to that provided by more extensive transfacial approaches. Instrument manipulation is easy. Neuronavigation, endoscopy, and intraoperative monitoring are easily incorporated and enhance the capability and safety of this approach.

The petrosal approach for the resection of retrochiasmatic craniopharyngiomas.

THE PETROSAL (PRESIGMOID transtentorial) approach has been advocated for resecting retrochiasmatic craniopharyngiomas. The projection of the surgical corridor, posterior to anterior and inferior upward, is particularly valuable in dissecting the upper pole of the tumor, which projects high into the third ventricle. This approach allows direct visualization for dissecting the hypothalamus and the pituitary stalk, and maintaining their blood supply and functional integrity. With a web site video presentation, we demonstrate the operative nuances of the approach to these tumors. We recommend this approach for patients with large and giant retrochiasmatic craniopharyngiomas.

An anatomic mathematical measurement to find an adequate recipient M4 branch for superficial temporal artery to middle cerebral artery bypass surgery.

OBJECTIVE: With the recent interest in superficial temporal artery-middle cerebral artery (MCA) bypass for hemodynamic related ischemia, we performed an anatomic study to find the best possible craniotomy site that will allow finding a suitable recipient cortical artery without compromising the use of the best branch and/or segment of the donor's superficial temporal artery branches. METHODS: Anatomic dissection and measurements were performed in 15 injected cadaveric heads to verify the location of an adequate temporal recipient cortical branch of the MCA. The location of the branch was then correlated with surface anatomic landmarks. Mathematical measurements were then derived. RESULTS: A perpendicular line measuring 5 cm in length is drawn starting from a point two-thirds the distance from the lateral canthus to the tragus, and ending at the center of a circle measuring 3 cm in diameter, which is equivalent to the craniotomy size and site. This craniotomy will expose the posterior aspect of the sylvian fissure and exposes no less than two M4 temporal MCA branches. The diameter of at least one branch is larger than 1 mm in 93% of the specimens. These findings were later successfully applied to several bypass operations. CONCLUSION: This study provides an anatomic and patient-independent mathematical measurement as a way to predictably find an adequate recipient temporal M4 branch for superficial temporal artery-MCA bypass in the majority of patients.

The petrosal approach for the total removal of giant retrochiasmatic craniopharyngiomas in children.

OBJECT: The surgical removal of retrochiasmatic craniopharyngiomas, particularly those of giant size, remains a formidable challenge. The posterior petrosal (or presigmoid transtentorial) approach provides wide, direct exposure of these tumors, which allows safe neurovascular dissection and facilitates their total removal. METHODS: Two patients, one 7-year-old girl and one 4-year-old girl, harboring giant retrochiasmatic craniopharyngiomas underwent total resection via the posterior petrosal approach. Both patients had good outcomes, and no evidence of recurrence was noted in either patient after 3 years of follow up. The surgical technique used in these patients is described. The trajectory of the petrosal approach is posterior-to-anterior and inferior upward. This is particularly valuable for dissecting the upper portion of the tumor, which projects high into the third ventricle. Using this approach, the surgeon can achieve direct visualization for dissection of the hypothalamus and pituitary stalk, while maintaining the blood supply to these structures and preserving their functional integrity. The small and poorly aerated mastoid sinus in children does not contraindicate the use or diminish the advantages of the petrosal approach. CONCLUSIONS: The authors recommend this approach for patients with large or giant retrochiasmatic craniopharyngiomas.

Results of microsurgical clipping of 50 high complexity basilar apex aneurysms.

OBJECTIVE: Complex basilar aneurysms (large size, wide base, low bifurcation, and dysmorphic posteriorly projecting domes) frequently fail endovascular treatment. We report our experience using the pretemporal transzygomatic transcavernous approach with 50 complex basilar aneurysms. METHODS: Using the pretemporal transcavernous route, opening the occulomotor trigone, and removing the anterior clinoid and the posterior clinoid when necessary, a wide exposure of the interpeduncular fossa is achieved. Temporary clips are applied to a perforator-free zone of the basilar trunk, proximal to the superior cerebellar artery. Complexity criteria in the 50 aneurysms included large or giant size in 27 patients, wide dysmorphic base in 18 patients, low bifurcation in 21 patients, posteriorly projecting dome in 11 patients, and dolichoectasia of the apex in three patients. RESULTS: Twenty-five patients presented with subarachnoid hemorrhage. There were 14 men and 36 women between the ages of 32 and 76 years (mean, 52.2 yr). Forty-nine aneurysms (98%) were successfully clipped. There was no procedure-related mortality. Two patients died (one from delayed bowel ischemia and one from a vasospasm-related complication). There were three ischemia-related events, two of which were procedure-related (medial thalamic lacunar infarct, superior cerebellar distribution ischemia) and one which was a third distal middle cerebral cardiac embolus after stopping Coumadin (DuPont Pharmaceuticals, Wilmington, DE) for atrial fibrillation. Transient partial or complete occulomotor palsies occurred in all patients with full recovery as the rule, except in one patient. At discharge, Glascow Outcome Scale scores were 4 or 5 in 88% of the patients. At the 6-month follow-up examination, Rankin Outcome Scale scores were 0 to 2 in 92% of the patients. CONCLUSION: Our experience reintroduces microsurgery as a safe and more durable treatment option for the management of complex basilar apex aneurysms that tend to have a higher rate of failure with endovascular therapy.

Anatomy of the nuchal ligament and its surgical applications.

OBJECTIVE: Although considered a basic maneuver for neurosurgical procedures, dissection of the musculature of the posterior cervical spine can be a source of complications during surgery. These complications include excessive blood loss, a loss of the plane of dissection, and injury to important structures such as the vertebral artery and nerve roots. Inappropriate closing of the muscular plane might also contribute to leakage of spinal fluid and postoperative deformation of the cervical spine. We review the anatomy of the nuchal ligament and describe a technical nuance based on the characteristics of the ligament's components, which can be used to assure the midline for a bloodless and atraumatic dissection. METHODS: We set out to determine whether or not the nuchal ligament could be used as a natural plane of dissection for splitting the posterior cervical musculature. We studied the anatomy of the nuchal ligament in five cadavers. RESULTS: The nuchal ligament extends from the external occipital protuberance to the spinous process of the seventh cervical vertebra (C7). It is covered by layers of cervical fascia and the aponeurosis of the trapezius muscle. It is composed of two portions: 1) the lamellar portion, an anterior double-layered portion with fatty areolar tissue interposed between its layers that inserts into the medial side of the bifid spinous process of the cervical vertebra; and 2) the funicular portion, a posterior fibrous portion that corresponds to the fusion of the layers of the lamellar portion. CONCLUSION: Several steps can assure that the midline plane is respected, thereby decreasing risk and reducing trauma and blood loss during dissection: 1) dissection of the nuchal ligament within the fatty areolar tissue of the lamellar portion, 2) isolation and incision of the funicular portion from inside to outside, and 3) retrograde dissection of the cerviconuchal muscles attached to the occipital bone in a subperiosteal plane.

Surgical clipping of complex basilar apex aneurysms: a strategy for successful outcome using the pretemporal transzygomatic transcavernous approach.

OBJECTIVE: Complex basilar apex aneurysms (large size, wide and complex neck, tortuous parent vessels) continue to pose a challenge in treatment. Endovascular treatment has a high risk of recanalization, and surgical treatment is limited by the space and time necessary to achieve safe clipping. To overcome these obstacles, a modification of previously reported approaches was developed. The pretemporal transzygomatic transcavernous approach and a clipping strategy were used in the treatment of 21 high-complexity basilar apex aneurysms. METHODS: By use of the pretemporal route, the zygomatic notch was widened, the anterior clinoid was removed, the cavernous sinus was partially exposed, and the oculomotor nerve was mobilized. The depth of the field was widened by further cavernous exposure and the removal of the posterior clinoid. Temporary clips were applied to the basilar trunk perforator-free zone to preserve visualization of the aneurysm neck and perforators and to maintain collateral flow to the brainstem. RESULTS: Twenty-one high-complexity basilar apex aneurysms, 11 of which caused subarachnoid hemorrhage, were treated. Twenty (95%) were successfully clipped (Glasgow Outcome Scale scores, 4 or 5 in 90.5% at discharge; Rankin Disability Score, 1 in 90.5% at 1-yr follow-up). Complications were transient oculomotor palsy in all patients, small thalamic infarct in one patient, and cerebrospinal fluid leak in another. There was no surgical mortality. Delayed follow-up angiography in 19 of the 21 patients showed no residual aneurysm. CONCLUSION: We report the largest series of a unique, challenging group of complex basilar apex aneurysms treated with the pretemporal transzygomatic transcavernous approach, which provided improved safety of clipping by 1) increased visualization of the basilar apex and perforator arteries, 2) improved maneuverability of clip application, 3) a safer perforator-free location, and 4) preservation of brainstem collateral flow.

Microsurgery for malignant gliomas.

Reflections directly involving the ongoing, intense research activities in biology, the neurosciences and in neurosurgery are discussed including the evolving diagnostic and treatment modalities of primary and secondary malignant gliomas of the central nervous system. The etiology of this enigmatic disease remains obscure, and a curative therapy is still not available. Nevertheless, as a result of changing paradigms in neuroanatomy, neuropathology, neurophysiology, neuroradiology and in neurosurgery, and taking into account the broader selection of adjuvant therapies available, well circumscribed malignant gliomas, which are in predilected compartments of the brain, can be efficiently resected. Good life quality and a respectable survival time are achieved in the majority of patients.

Surgical treatment of dumbbell-shaped jugular foramen schwannomas.

OBJECT: Schwannomas of the jugular foramen are rare, comprising between 2 and 4% of intracranial schwannomas. The authors retrospectively analyzed their surgical experience with schwannomas of the lower cranial nerves that presented with intra- and extracranial extensions through an enlarged jugular foramen. The transcondylar suprajugular approach was used without sacrificing the labyrinth or the integrity of the jugular bulb. In this report the clinical and radiological features are discussed and complications are analyzed. METHODS: This retrospective study includes six patients (three women and three men, mean age 31.6 years) with dumbbell-shaped jugular foramen schwannomas that were surgically treated by the senior author during a 5.5-year period. One patient had undergone previous surgery elsewhere. Glossopharyngeal and vagal nerve deficits were the most common signs (appearing in all patients), followed by hypoglossal and accessory nerve deficits (66.6%). Two or more signs or symptoms were present in every patient. Three tumors presented with cystic degeneration. In four patients the jugular bulb was not patent on neuroimaging studies. The suprajugular approach was used in five patients; the origin of the tumor from the 10th cranial nerve could be defined in three of them. All lesions were completely resected. No death or additional postoperative cranial nerve deficits occurred in this series. Aspiration pneumonia developed in one patient. Preoperative deficits of the ninth and 10th cranial nerves improved in one third of the patients and half recovered mobility of the tongue. No recurrence was discovered during the mean follow-up period of 32.8 months. CONCLUSIONS: With careful, extensive preoperative evaluation and appropriate planning of the surgical approach, dumbbell-shaped jugular foramen schwannomas can be radically and safely resected without creating additional neurological deficits. Furthermore, recovery of function in the affected cranial nerves can be expected.