Cavernous venous malformations in and around the central nervous system. Part 1: Dural and extradural.

Cavernous-type malformations are venous lesions that occur in multiple locations throughout the body, and when present in the CNS, they have canonically been referred to as cavernomas, cavernous angiomas, and cerebral cavernous malformations. Herein all these lesions are referred to as "cavernous venous malformations" (CavVMs), which is congruent with the current International Society for the Study of Vascular Anomalies classification system. Even though histologically similar, depending on their location relative to the dura mater, these malformations can have different features. In Part 1 of this review, the authors discuss and review pertinent clinical knowledge with regard to CavVMs as influenced by anatomical location, starting with the dural and extradural malformations. They particularly emphasize dural CavVMs (including those in the cavernous sinus), orbital CavVMs, and spinal CavVMs. The genetic and histopathological features of CavVMs in these locations are reviewed, and commonalities in their presumed mechanisms of pathogenesis support the authors' conceptualization of a spectrum of a single disease entity. Illustrative cases for each subtype are presented, and the pathophysiological and genetic features linking dural and extradural to intradural CavVMs are examined. A new classification is proposed to segregate CavVMs based on the location from which they arise, which guides their natural history and treatment.

Positioning Transclival Tumor-Treating Fields for the Treatment of Diffuse Intrinsic Pontine Gliomas.

Diffuse intrinsic pontine glioma (DIPG) carries an extremely poor prognosis, with 2-year survival rates of <10% despite the maximal radiation therapy. DIPG cells have previously been shown to be sensitive to low-intensity electric fields in vitro. Accordingly, we sought to determine if the endoscopic endonasal (EE) implantation of an electrode array in the clivus would be feasible for the application of tumor-treating fields (TTF) in DIPG. Anatomic constraints are the main limitation in pediatric EE approaches. In our Boston Children's Hospital's DIPG cohort, we measured the average intercarotid distance (1.68 ± 0.36 cm), clival width (1.62 ± 0.19 cm), and clival length from the base of the sella (1.43 ± 0.69 cm). Using a linear regression model, we found that only clival length and sphenoid pneumatization were significantly associated with age (R2 = 0.568, p = 0.005 *; R2 = 0.605, p = 0.0002 *). Critically, neither of these parameters represent limitations to the implantation of a device within the dimensions of those currently available. Our findings confirm that the anatomy present within this age group is amenable to the placement of a 2 × 1 cm electrode array in 94% of patients examined. Our work serves to demonstrate the feasibility of implantable transclival devices for the provision of TTFs as a novel adjunctive therapy for DIPG.

Standard clinical approaches and emerging modalities for glioblastoma imaging.

Glioblastoma (GBM) is the most common primary adult intracranial malignancy and carries a dismal prognosis despite an aggressive multimodal treatment regimen that consists of surgical resection, radiation, and adjuvant chemotherapy. Radiographic evaluation, largely informed by magnetic resonance imaging (MRI), is a critical component of initial diagnosis, surgical planning, and post-treatment monitoring. However, conventional MRI does not provide information regarding tumor microvasculature, necrosis, or neoangiogenesis. In addition, traditional MRI imaging can be further confounded by treatment-related effects such as pseudoprogression, radiation necrosis, and/or pseudoresponse(s) that preclude clinicians from making fully informed decisions when structuring a therapeutic approach. A myriad of novel imaging modalities have been developed to address these deficits. Herein, we provide a clinically oriented review of standard techniques for imaging GBM and highlight emerging technologies utilized in disease characterization and therapeutic development.

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.

Falcotentorial Meningioma Resection Through the Supracerebellar Infratentorial Approach: 2-Dimensional Operative Video.

Meningiomas are a common pineal region tumor in adults.1 They frequently reach large size with pending serious neurological consequences.1 Although they are more common in women, their presence in men might raise concerns about a higher-grade meningioma. Accordingly, their treatment starts with surgical resection. Their origin is the falcotentorial junction involving the midbrain tectum and the vital deep venous system. The torcular, transverse sinuses, cerebellar veins, straight sinus, internal occipital veins, basal veins, and internal cerebral veins are encountered requiring a cautious fine intra-arachnoidal dissection under high magnification.2 Multiple surgical approaches are described for pineal area tumors with the advantages and disadvantages of each guiding the selection of the approach.3 We believe that the main deciding factor is the relationship of the vein of Galen and its tributaries to the tumor, simply choosing the route that encounters the tumor first and the vein last. We demonstrate the surgical nuances of removing a pineal area meningioma that displaced the vein of Galen superiorly, prompting the resection through a lateral infratentorial supracerebellar approach. We currently prefer the 3/4 concord position because it provides a superb direct exposure over one cerebellar hemisphere, with the cerebellum relaxed downward while the bridging veins are not severely stretched with gravity.4 The sitting surgeon with resting arms in an ergonomic position is able to perform fine microsurgical dissection over extended time.5 The patient was a 57-year-old man with a large falcotentorial meningioma. The patient consented to the surgery and publication of his images.

Multicentric Chordoma With Initial Resection by Bilateral Transcondylar Approach: 2-Dimensional Operative Video.

Chordoma is a rare skull base tumor with malignant behavior.1-3 It invades locally with high recurrences, metastasizes distally, and seeds after interventions.1-4 Chordoma exemplifies the malignant progression doctrine as it accumulated genetic mutations. The natural history of untreated disease is 2.4 yr on average survival.5 Best tumor control is achieved by radical resection, followed by high doses radiation. Multicentric chordoma is an ill-defined challenging entity extremely rare in the literature. However, chordoma is known for distal metastasis, particularly to the lungs, iatrogenic cerebrospinal fluid (CSF) dissemination with drop metastasis, or surgical implantation. A subset of patients present with synchronous or metachronous regional or distal neuraxial lesions associated with the initial chordoma. Patients presenting with multicentric bony axial lesions and no extra-axial metastases point toward the multicentric chordoma concept rather than local, hematogenous, or CSF spread.6-12 Biopsy of these multicentric lesions can show a spectrum of abnormalities ranging from benign notochordal tumor to chordomas confirming the multicentric hypothesis.9 We present a patient who underwent a bilateral transcondylar approach for giant craniovertebral junction chordoma and then treated with radiation and a second lesion at the C6 transverse foramen. Six years later, she presented with a chordoma at the petrous apex. The patient consented to surgery and to the publications of her image. The participants and any identifiable individuals consented to publication of his/her image. Image at 1:39 reprinted with permission from Al-Mefty O, Operative Atlas of Meningiomas. Vol 1, © LWW, 1998.

Microsurgical Resection of a Parasellar Meningioma Invading the Cavernous Sinus, Bone, and Optic Canal: 2-Dimensional Operative Video.

Parasellar meningiomas, regardless of the initial origin, frequently involve the optic canal and cavernous sinus, leading to visual loss and ocular movement dysfunction.1 Hyperostotic bony invasion to the surrounding skull base is common.2 Visual acuity prognosis can be improved by surgical resection through different technical maneuvers, including opening the optic canal and the preservation of the visual apparatus vascular supply by developing the intra-arachnoidal dissection planes.1,3,4 To achieve radical dissection and reduce recurrences, the extradural invaded bone is thoroughly resected. Likewise, the soft and nonadherent invasive tumor around the cavernous carotid can be extensively removed.1,3,4 New or worsening of the ophthalmoplegia is frequent after cavernous sinus exploration and tumor resection. However, it is usually temporary and improves progressively in 80% of patients.1,3,4 Safely approaching these lesions requires extensive anatomic knowledge through cadaveric dissection and training, allowing us to achieve tumor control, preserve or improve visual function, and avoid or delay irradiation therapy.1,3,4 Pituitary function preservation is also possible in many patients through surgery, which is at higher risk with irradiation. We demonstrate the technical maneuvers through a case of a 49-yr-old woman who presented with a parasellar meningioma involving the cavernous sinus, both optic canals, and extensive bony invasion. The patient consented to the surgery and publication of her images. Image at 1:14 and middle and right image at 1:31 reprinted with permission from Al-Mefty O, Operative Atlas of Meningiomas. Vol 1, ©LWW, 1998. Left image at 1:31 reprinted from Arnautovic et al,5 by permission from JNSPG.

Clipping of Multiple Cerebral Aneurysms Through Cranioorbital Zygomatic Approach: 2-Dimensional Operative Video.

Ruptured cerebral aneurysm is a grave disease, with a high morbidity and mortality, mandating securing the aneurysm to eliminate fatal rebleeding.1 Multiple aneurysms are frequent and may occur in approximately 20% of the cases with female prominence.2 The risk of subarachnoid hemorrhage in unruptured aneurysms is higher in patients who had prior ruptured aneurysms.3 Hence, there is an indication of treating all concomitant aneurysms when one is ruptured. We present the case of clipping of 3 aneurysms via a cranioobritozygomatic (COZ) approach including a middle cerebral artery, anterior choroidal artery, and superior cerebellar artery in a patient presenting with subarachnoid hemorrhage and multiple aneurysms with suboptimal morphology for endovascular coiling. We highlight the advantages of the COZ in the clipping of complex posterior circulation aneurysms and the advantage of mobilization of neural structures to gain wider exposure.4-6 The temporal fossa space provided by zygomatic osteotomy allows the outward mobilization of the temporal lobe after freeing it by splitting the Sylvian fissure. The falciform ligament is opened overlying the optic nerve, allowing for safe dissection within the opticocarotid window. The oculomotor nerve is detethered from the dura surrounding its entry into the cavernous sinus. These maneuvers allow for mobilization of the critical neurovascular structures, which widens the operative corridor without undue traction or retraction. The COZ with clinoidectomy shortens and widens the operative field, allows for enhanced maneuverability, improved visualization, and exposure of the clinoidal carotid, and facilitates the release and mobilization of the optic and third nerve. The patient consented to surgery. Image at 1:40 reprinted with permission from Al-Mefty O, Operative Atlas of Meningiomas. Vol 1, © LWW, 1998.

Giant Ossified Clival Chondrosarcoma Resection: 2-Dimensional Operative Video.

Chondrosarcomas are a spectrum of tumors with variable clinical behavior, histologically classified as grades I, II, and III.1 Maximal surgical resection with adjuvant radiation is the gold standard for grade III malignant tumors.2,3 Lower-grade skull base chondrosarcomas have a slow progressive local growth pattern with an overall benign profile.1,4 In these grade I and II tumors, radical resection can be sufficient in achieving long-term control of the disease without the need for adjuvant therapy, thus avoiding the long-term side effects of irradiation in relatively young patients.4,5 As a slow-growing tumor, skull base chondrosarcoma might reach a giant size with progressive neurological deficits prior to diagnosis. In these cases, to achieve maximal resection, skull base approaches tailored to the patient's anatomy are essential.4,6 Cranial approach is frequently needed due to the calcified nature of part of the tumor that is not amenable to resection through the endonasal approach. The endoscope is extremely helpful combined with the microscopic resection. We demonstrate these techniques through in the surgery of a 39-yr-old female who presented with progressive neurological deficits from a giant ossified chondrosarcoma and underwent a combined petrosal approach for the resection of her tumor. A postoperative small enhancement remained stable on the 4-yr follow-up exam. The pathology confirmed grade II chondrosarcoma, with the patient recovering from her neurological deficit except the third nerve. The patient consented to the surgery and publication of images. Image at 1:36 reprinted with permission from Al-Mefty O, Operative Atlas of Meningiomas. Vol 1, ©LWW, 1998.

Combined Microscopic-Endoscopic Transmastoid Resection of a Petrous Meningioma: 2-Dimensional Operative Video.

Petrous meningiomas are defined as tumors with a basal dural attachment on the posterior surface of the petrous bone.1 Their insertion can be anterior to the meatus (petrous apex meningiomas), or posterior to the meatus, with associated hyperostotic bony invasion either pre- or retro-meatal.2 These meningiomas are amenable to curative surgical removal and have better surgical outcomes than more medially located true petroclival meningiomas that originate medial to the fifth nerve.2-4 They, however, remain challenging because of their close relationship to critical neurovascular structures in the cerebellopontine angle.5 The posterior petrous meningiomas might reach a significant size with compression of the cerebellum, the brainstem, and involvement of the cranial nerves, and extend posteriorly to the transverse sigmoid sinus.2,6 Transmastoid approach with skeletonization and lateral reflection of the transverse sigmoid sinus provides a superb exposure without cerebellar retraction.6,7 The ease and complete resection of the tumor and invaded bone can be facilitated by combined microscopic-endoscopic techniques. We demonstrate these principles through the resection of a petrosal meningioma in a 56-yr-patient who presented with headaches, nystagmus, and mild cerebellar signs. The patient consented to the procedure. Image at 1:36 reprinted with permission from Al-Mefty O, Operative Atlas of Meningiomas. Vol 1, ©LWW, 1998.

Resection of a Dumbbell-Shaped Facial Nerve Schwannoma With Preservation of Facial Nerve Function Through the Extended Middle Fossa Approach: 2-Dimensional Operative Video.

Facial nerve schwannomas are rare and can arise from any segment along the course of the facial nerve.1 Their location and growth patterns present as distinct groups that warrant specific surgical management and approaches.2 The management challenge arises when the facial nerve maintains good function (House-Brackmann grade I-II).3 Hence, a prime goal of management is to maintain good facial animation. In large tumors, however, resection with facial nerve function preservation should be sought and is achievable.4,5 While tumors originating from the geniculate ganglion grow extradural on the floor of the middle fossa, they may extend via an isthmus through the internal auditory canal to the cerebellopontine angle forming a dumbbell-shaped tumor. Despite the large size, they may present with good facial nerve function. These tumors may be resected through an extended middle fossa approach with preservation of facial and vestibulocochlear nerve function. The patient is a 62-yr-old man who presented with mixed sensorineural and conductive hearing loss and normal facial nerve function. Magnetic resonance imaging (MRI) revealed a large tumor involving the middle fossa, internal auditory meatus, and cerebellopontine angle. The tumor was resected through an extended middle fossa approach with a zygomatic osteotomy and anterior petrosectomy.6 A small residual was left at the geniculate ganglion to preserve facial function. The patient did well with hearing preservation and intact facial nerve function. He consented to the procedure and publication of images. Image at 1:30 © Ossama Al-Mefty, used with permission. Images at 2:03 reprinted from Kadri and Al-Mefty,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 a Medulla Oblongata Hemangioblastoma: 2-Dimensional Operative Video.

Hemangioblastomas are benign vascular tumors that can be sporadic or multiple, as part of Von Hippel-Lindau disease. They develop at any level of the central nervous system, with a predilection for the dorsal medulla among brainstem locations. Radical resection of the solid portion of the tumor is the best treatment option.1,2 The resection should be en bloc to avoid uncontrollable intraoperative hemorrhage hindering safe dissection. Preservation of the venous drainage during the progressive dissection of the tumor of the surrounding structures and interruption of numerous small arterial feeders is a tenet for safe surgical resection.3 Once the tumor is completely disconnected, the large draining veins can be coagulated, and the tumor removed. We demonstrate these technical principles in the surgery of a 30-yr-old female with an exophytic hemangioblastoma from the dorsal medulla obstructing the fourth ventricle outflow. We demonstrate the resection of this lesion through a suboccipital craniotomy in a sitting position.4 The patient consented to the surgery and publication of images. Image at 1:26 from Kadri and Al-Mefty,4 by permission from the Congress of Neurological Surgeons.

Nuances of Olfactory Groove Meningioma Surgery: 2-Dimensional Operative Video.

Olfactory groove meningiomas frequently present as large or giant-size tumors associated with marked frontal lobe edema and significant frontal lobe dysfunction. Simpson grade I removal was rare in early reports due to their invasion of the ethmoid sinuses and skull base bone,1 which resulted in high recurrence rates.2,3 Indeed, recurrence occurred in the most celebrated case of olfactory groove meningioma.4,5 To achieve Simpson grade I removal (tumor, dura, bone), protect the frontal lobes from additional injury, and provide the best chance for recovery, we demonstrate a few nuances for olfactory groove meningioma surgery: Utilizing a skull base approach with a low dural opening, the frontal veins are preserved, and the frontal lobe is protected from retraction, manipulation, and venous injury. By the time of diagnosis, although the patient's olfaction is often absent, there still remains a role to preserve at least 1 olfactory tract, which might yield some preservation in a limited number of patients. Emphasis has been rightly made on the preservation of the A2 segments, which can be dissected using microsurgical technique. Lastly, multilayer reconstruction of the skull base is required, using an inlay graft, resting on a vascularized pericranial flap, and occlusion of the sinuses with a fat graft. The endonasal endoscopic approach has fallen out of favor due to limitations for complete tumor resection and higher complication rates.6 We present a case of a relatively small olfactory groove meningioma in a 36-yr-old male with partial olfactory loss. The patient consented for surgery. Images at 2:07, 2:29, and 2:54 from Al-Mefty O, Operative Atlas of Meningiomas, © LWW, 1997, with permission. Image at 8:31 public domain by age.

Interposition Grafting of the Facial Nerve After Resection of a Large Facial Nerve Schwannoma: 2-Dimensional Operative Video.

Facial nerve schwannomas can develop at any portion of the facial nerve.1 When arising from the mastoid portion of the facial nerve, the tumor will progressively erode the mastoid, giving the schwannoma an aggressive radiological appearance.1,2 The facial nerve is frequently already paralyzed, or no fascicles can be saved during resection. In these cases, end-to-end interposition grafting is the best option for facial reanimation.1,3-5 The healthy proximal and distal facial nerves are prepared prior to grafting. The great auricular nerve is readily available near the surgical site and represents an excellent graft donor with minimal associated morbidity.4,6 We demonstrate this technique through a case of a 48-yr-old male who presented with a complete right-sided facial nerve palsy due to a large facial schwannoma that invaded the mastoid and extended to the hypoglossal canal, causing hypoglossal nerve paralysis, and petrous carotid canal. His 4-yr follow-up showed no recurrent tumor with restored facial nerve function palsy to a House-Brackman grade III, and full recovery of his hypoglossal nerve function. The patient consented to the surgery and the publication of his image.

Transcondylar Odontoid Resection and Stabilization for Craniovertebral Degenerative Compression: 2-Dimensional Operative Video.

Non-neoplastic craniovertebral junction lesions are well known with various etiologies.1,2 They are frequently associated with craniovertebral junction instability. Many require only stabilization for their management.2 However, when significant irreducible anterior compression is present, surgical decompression becomes necessary.2-4 The traditional decompression route is direct anterior, such as the transoral, transmaxillary, or endoscopic endonasal approaches with a separate posterior stabilization.1,2 The transcondylar approach offers a wide and direct exposure to the anterolateral foramen magnum and atlantoaxial space, allowing extensive decompression, total resection of the odontoid, and associated pannus, even with large lateral extension, as well as fusion in the same surgical setting.5 The surgical manipulation is parallel to the dural sac in the sagittal plane, which could be safer than perpendicular dissection.5 Understanding the regional anatomy allows safe exposure and transposition of the vertebral artery with the surrounding alveolar and venous plexus (suboccipital cavernous sinus).5-7 We present this technique's details in a case of a 72-yr-old female who presented with progressively worsening bilateral upper extremity weakness and significant anterior compression due to irreducible odontoid degenerative changes. We demonstrate the steps necessary to achieve adequate exposure and decompression. The patient agreed to the surgical intervention. Images at 2:46, 3:00, and 3:25 reused from Al-Mefty et al,5 by permission from JNSPG. Images at 9:28 from Symonds et al,3 by permission of Oxford University Press. Image at 2:15, © Ossama Al-Mefty, used with permission.