Laligam N. Sekhar

Chordomas and chondrosarcomas of the cranial base: results and follow-up of 60 patients.

The management of chordomas and chondrosarcomas involving the cranial base remains controversial. The options for therapy include biopsy, partial resection, radical resection, and various forms of radiotherapy. In this article, we analyze the outcome of 60 patients with cranial base chordoma or chondrosarcoma treated with extensive surgical resection between 1984 and 1993. Forty-six patients had chordomas, and 14 had low-grade chondrosarcomas; 50% of these patients had been treated previously. Preoperative studies included computed tomography, magnetic resonance imaging, cerebral angiography, and balloon occlusion test of the internal carotid artery, as indicated. Magnetic resonance imaging was performed on all patients during follow-up. The surgical approaches used for tumor resection were predominantly the following: subtemporal, transzygomatic, transcavernous, and transpetrous apex; subtemporal and infratemporal; extended frontal; and extreme lateral transcondylar. Staged operations with a combination of approaches were used when necessary (52% of cases) to remove a tumor more completely. Statistical analysis was done by the chi 2 test and correlation matrix. Sixty-seven percent of the patients had total or near-total resection. Twenty percent of the patients received postoperative radiotherapy. Eleven patients died during the postoperative follow-up period, nine with chordomas and two with chondrosarcomas. Three patients died because of systemic complications within 3 months after surgery, five died because of tumor recurrence, one died from unrelated causes, and two died from late complications of radiotherapy. The recurrence-free survival rate for all tumors was 80% at 3 years and 76% at 5 years. Chondrosarcomas had a better prognosis than chordomas (recurrence-free survival rates, 90% at 5 years and 65% at 5 years, respectively; P = 0.09). Patients who had undergone previous surgery had a greater risk of recurrence (5-year recurrence-free survival rate, 64%) than did patients who had not undergone previous surgery (5-year recurrence-free survival rate, 93%; P < 0.05). Patients with total or near-total resection had a better 5-year recurrence-free survival rate (84%) than did patients with partial or subtotal resection (64%) (P < 0.05). Postoperative leakage of cerebrospinal fluid was the most frequent complication (30% of patients) and was found to increase the risk of permanent disability. Patients who had undergone previous radiotherapy had a greater risk of death in the postoperative period (within 3 months of their operations) and during follow-up. However, total or near-total resection did not increase the rate of postoperative disability.(ABSTRACT TRUNCATED AT 400 WORDS)

Partial labyrinthectomy petrous apicectomy approach to neoplastic and vascular lesions of the petroclival area

OBJECTIVE: To study the value of an improvement of the presigmoid petrosal approach to the petroclival area by the addition of partial labyrinthectomy and petrous apicectomy and to document hearing and other results. METHODS: Thirty-six consecutive patients treated by this technique during a 2-year period were studied prospectively. The lesions treated included 33 petroclival neoplasms (25 meningiomas, 5 chordomas, 1 chondrosarcoma, 1 trigeminal schwannoma, and 1 epidermoid cyst) and 3 vertebrobasilar aneurysms. The patients underwent clinical, radiological, and neuro-otological examinations. RESULTS: There was no perioperative mortality. Cranial nerve deficits involving Cranial Nerves III, IV, V, and VI occurred in 17 patients (47%) postoperatively. Cerebrospinal fluid leak occurred in 12 patients (33%). Four of these patients were treated by lumbar drainage, two patients were treated by lumboperitoneal shunt, and six patients required reoperation and repacking of the middle ear. Hydrocephalus occurred in five patients (13.9%). There was one case of meningitis and another of systemic sepsis. All 36 patients underwent postoperative audiometric evaluation. When serviceable hearing was present preoperatively (Gardner-Robertson Grades I or II), it was determined to be preserved at postoperative follow-up in 81% of the patients (26 of 32 patients). CONCLUSION: The partial labyrinthectomy petrous apicectomy approach provided improved access to neoplasms of the clivus and petrous apex and the posterior cavernous sinus area and to vertebrobasilar aneurysms in the midclival area. This improvement in access permits more controlled and thorough treatment of these lesions, with reduced brain retraction and acceptable morbidity with respect to auditory function.

Endoscope-assisted microsurgery for intracranial aneurysms

OBJECTIVE We discuss the role of the endoscope in the microsurgical treatment of intracranial aneurysms, analyzing its benefits, risks, and disadvantages. METHODS This was a prospective study of 55 patients with 79 aneurysms, treated between July 1998 and June 2001, for whom the endoscope was used as an adjunct in the microsurgical treatment of their lesions. Seventy-one aneurysms were located in the anterior circulation, and eight were located in the posterior circulation. Thirty-seven patients presented with subarachnoid hemorrhage. Eighteen patients had unruptured aneurysms, of whom 5 presented with mass effect, 2 presented with transient ischemic attacks, and 11 were without symptoms. In all cases, the endoscope was used in addition to microsurgical dissection and clipping (sometimes before clipping, sometimes during clipping, and always after clipping), for observation of the neck anatomic features and perforators and verification of the optimal clip position. Intraoperative angiography was performed for all patients after aneurysm clipping. RESULTS In the majority of cases, the endoscope was very useful for the assessment of regional anatomic features. It allowed better observation of anatomic features, compared with the microscope, for 26 aneurysms; in 15 cases, pertinent anatomic information could be obtained only with the endoscope. The duration of temporary clipping of the parent artery was significantly reduced for two patients. The clip was repositioned because of a residual neck or inclusion of the parent vessel during aneurysm clipping in six cases, and the clip position was readjusted because of compression of the optic nerve in one case. One patient experienced a small aneurysm rupture that was directly related to use of the endoscope, but this was easily controlled, with no sequelae. For many patients, the combination of the neuro-endoscope and the micro-Doppler probe made intraoperative angiography redundant. CONCLUSION “Endoscope-assisted microsurgery” is a major advance in the microsurgical treatment of intracranial aneurysms; the endoscope allows better observation of regional anatomic features because of its magnification, illumination, and ability to “look around corners.”

Vasospasm after cranial base tumor resection: pathogenesis, diagnosis, and therapy

OBJECTIVE Cerebral vasospasm is well known to occur after various cerebral neurosurgical events that cause subarachnoid hemorrhage. However, cerebral vasospasm can occur after cranial base tumor resection. We present a series of nine patients with angiographically evident vasospasm that was clinically symptomatic in eight of them. METHODS A total of 470 consecutive patients with cranial base tumors were operated in our institution between April 1993 and December 1996. Nine had evidence of cerebral vasospasm postoperatively (1.9% of the total population), of whom eight were asymptomatic. There were seven males and two females with an age range of 33 to 65 years (average 48.5 years). There were seven meningiomas, one chordoma, and one trigeminal schwannoma. RESULTS Vasospasm manifested clinically 1 to 30 days postoperatively in eight patients. Most patients were symptomatic within 7 days. In the ninth case, surgery was delayed when asymptomatic vasospasm was noted on an angiogram before second stage surgery. Symptoms included altered mental status in four patients, hemiparesis in three patients (one patient had both hemiparesis and altered mental status), and monoparesis in two patients. Factors that were found to correlate with a higher incidence of vasospasm were tumor size, total operative time, vessel encasement, vessel narrowing, and preoperative embolization. All eight patients with symptomatic vasospasm were treated with hypertensive, hypervolemic, hemodilutional (HHH) therapy. Five patients also underwent intraluminal angioplasty, in conjunction with papaverine in one case. One patient received intraarterial papaverine alone. Angiographic results were good in all patients. Significant clinical improvement was seen in six of the eight symptomatic cases. CONCLUSION Delayed neurological deterioration in a patient who has undergone cranial base tumor surgery not explained by an intracranial mass lesion should be promptly investigated with angiography. If vasospasm is diagnosed, it should be treated aggressively with hypertensive, hypervolemic, hemodilutional therapy and early angioplasty.

Management and long-term outcome of adenoid cystic carcinoma with intracranial extension: a neurosurgical perspective.

Adenoid cystic carcinoma is a tumor of minor and major salivary glands that often invades the cranial base and intracranial cavity via local and perineural spread. In the past, the role of neurosurgeons in managing these tumors has been limited. The growth of interdisciplinary cranial base surgical approaches has now increased the involvement of neurosurgeons in the management of these tumors. We present a series of 16 patients with adenoid cystic carcinomas with cranial base and intracranial extension, the largest series reported in the neurosurgical literature. We have focused our approach on a neurosurgical perspective and made recommendations for the treatment of these tumors in relation to the following specific aspects of this disease. 1) The management of the carotid artery: In our experience, when the carotid artery is involved by tumor, a preliminary cerebral revascularization procedure with a cervical carotid to middle cerebral artery vein bypass graft should be performed before tumor resection. 2) The management of the cavernous sinus and orbit: Cavernous sinus tumor should be removed as fully as possible, but every effort should be made to preserve the IIIrd and IVth cranial nerves to achieve optimal functional and cosmetic results. The orbit should be exenterated when there is intraconal involvement; otherwise, intraorbital tumor can be removed with orbital preservation. 3) The use of palliative surgery: We have found that the use of palliative surgery can be considered even in patients whose extent of local disease precludes a surgical cure. The slow progression of the disease allows for long-term survival of many patients with advanced local disease and even of those with metastatic disease. 4) The long-term survival of these patients: In our series, six patients had no evidence of local disease and a mean survival of 72 months, one living patient had evidence of local disease and has survived 56 months, eight patients died of disease, with a mean survival of 137 months, and one patient died of complications after surviving for 63 months.

Surgical Anatomy of the Infratemporal Fossa: The Styloid Diaphragm Revisited

INTRODUCTION The infratemporal fossa (ITF) gives passage to most major cerebral vessels and cranial nerves. Dissection of the ITF is essential in many of the lateral cranial base approaches and in exposure of the high cervical internal carotid artery (ICA). We reviewed the surgical anatomy of this region. METHODS Direct foraminal measurements were made in seven dry skulls (14 sides), and the relationship of these foramina to each other and various landmarks were determined. Ten ITF dissections were performed using a preauricular subtemporal-infratemporal approach. Preliminary dissections of the extracranial great vessels and structures larger than 1 cm were performed using standard macroscopic surgical techniques. Dissection of all structures less than 1 cm was conducted using microsurgical techniques and instruments, including the operating microscope. The anatomic relationships of the muscles, nerves, arteries, and veins were carefully recorded, with special emphasis regarding the relationship of these structures to the styloid diaphragm. The dissection was purely extradural. RESULTS The styloid diaphragm was identified in all specimens. It divides the ITF into the prestyloid region and the retrostyloid region. The prestyloid region contains the parotid gland and associated structures, including the facial nerve and external carotid artery. The retrostyloid region contains major vascular structures (ICA, internal jugular vein) and the initial exocranial portion of the lower Cranial Nerves IX through XII. Landmarks were identified for the different cranial nerves. The bifurcation of the main trunk of the facial nerve was an average of 21 mm medial to the cartilaginous pointer and an average of 31 mm medial to the tragus of the ear. The glossopharyngeal nerve was found posterior and lateral to stylopharyngeus muscle in nine cases and medial in only one. The vagus nerve was consistently found in the angle formed posteriorly by the ICA and the internal jugular vein. The spinal accessory nerve crossed anterior to the internal jugular vein in five cases and posterior in another five cases. It could be located as it entered the medial surface of the sternocleidomastoid muscle 28 mm (mean) below the mastoid tip. The hypoglossal nerve was most consistently identified as it crossed under the sternocleidomastoid branch of the occipital artery 25 mm posterior to the angle of the mandible and 52 mm anterior and inferior to the mastoid tip. CONCLUSION The styloid diaphragm divides the ITF into prestyloid and retrostyloid regions and covers the high cervical ICA. Using landmarks for the exocranial portion of the lower cranial nerves is useful it identifying them and avoiding injury during approaches to the high cervical ICA, the upper cervical spine, and the ITF.

Saphenous vein graft reconstruction of an unclippable giant basilar artery aneurysm performed with the patient under deep hypothermic circulatory arrest: technical case report.

OBJECTIVE AND IMPORTANCE Effective treatment for unclippable giant vertebrobasilar aneurysms remains unclear. We present the first reported case of a giant vertebrobasilar aneurysm being successfully treated with trapping of the aneurysm and internal carotid artery to basilar artery bypass with a saphenous vein graft that was performed with the patient under hypothermic circulatory arrest. CLINICAL PRESENTATION A 15-year-old female patient with a history of probable subarachnoid hemorrhage and chronic headaches presented with a relatively acute exacerbation of her headache, nausea, vomiting, and weakness. Imaging studies revealed a 4 x 4 x 3-cm vertebrobasilar aneurysm, supplied by an angiographically dominant right vertebral artery and causing significant brain stem compression. INTERVENTION Initially, a petrosal approach with a hearing-preserving partial labyrinthectomy was used to perform a right external carotid artery to posterior cerebral artery bypass with saphenous vein. Delayed occlusion of the right vertebral artery with an intraluminal balloon was planned; however, intraoperative angiography revealed poor graft flow, presumably because of the small size of the posterior cerebral artery. Postoperative graft occlusion was anticipated. During this same time interval, the patient deteriorated neurologically. Brain imaging failed to reveal evidence of cerebral infarction. The patient underwent subsequent surgery. After a total petrosectomy, the aneurysm was trapped, an aneurysmectomy was performed, and, with the patient under deep hypothermic circulatory arrest, a new interposition saphenous vein graft was inserted between the internal carotid and basilar arteries. Excellent flow was observed angiographically. At her 4-month follow-up examination, the patient had improved to near baseline. CONCLUSION We present a technically challenging but safe and definitive treatment option for an unclippable giant vertebrobasilar aneurysm. Using cranial base approaches and hypothermic circulatory arrest techniques, aneurysmal trapping and successful bypass grafting directly into the basilar artery was performed.

Subtonsillar-transcerebellomedullary approach to lesions involving the fourth ventricle, the cerebellomedullary fissure and the lateral brainstem

We describe the use of the subtonsillar-transcerebellomedullary approach to laterally placed fourth ventricle and brain-stem lesions. The subtonsillar-transcerebellomedullary approach to the fourth ventricle and the lateral brainstem was used in six patients: three patients with tumours of the fourth ventricle and brainstem (two ependymomas and one papillary thyroid carcinoma metastasis), two patients with cavernous angiomas of the brainstem and one patient with a distal posterior inferior cerebellar artery (PICA) aneurysm. The microsurgical anatomy of this approach was studied in five cadaveric head specimens. The tumours and cavernous angiomas were removed and the distal PICA aneurysm was clipped successfully. In all patients the Karnofsky performance scale (KPS) was equal to or better than the preoperative status on follow-up examinations. The anatomical studies also revealed the extensive exposure provided with this approach. The subtonsillar-transcerebellomedullary approach is recommended for lesions occupying the cerebellomedullary fissure, and the lateral aspect of the fourth ventricle.

Early Arytenoid Adduction for Vagal Paralysis After Skull Base Surgery

Objectives To evaluate the efficacy of early arytenoid adduction in the management of vagal paralysis after skull base surgery.

Extradural origin of the posteroinferior cerebellar artery

OBJECTIVE: The posteroinferior cerebellar artery (PICA) usually arises from the intradural segment of the vertebral artery (VA). The extradural origin of the PICA is infrequent. Its preoperatory identification is important in surgical strategy during the exposure of the VA. METHODS: During an anatomic prosection, the VA was exposed at the craniocervical junction in cadaveric adult specimens. The extradural origin of the PICA was encountered bilaterally in one specimen and on one side in a second specimen. An anatomic study with histological and radiographic correlation was performed. RESULTS: Perforating branches originate from the PICA. They supply the middle and inferior third of the olive and the lateral aspect of the medulla. The PICA has cortical branches that lead to the cerebellum. Injury to the PICA can produce an infarction of these neural structures that can be asymptomatic or cause major neurological deficits. Radiographic results obtained using a lateral projection provided the most reliable delineation of the extradural origin of the PICA. When this artery originates at, or posterior to, the posterior aspect of the occipital condyle, an extradural origin is likely. CONCLUSION: Bilateral selective vertebral angiography should be performed with special attention to the relationships of PICA origins before any surgical exposure of the VA at the craniocervical junction, unless magnetic resonance angiography provides this information without question. A thorough understanding of the relative dominance of the VAs and PICAs, the location of the PICA origin, and the collateral circulation of the posterior fossa are prerequisites to surgery in this region. The preoperative identification of an extradural PICA is important in planning surgical strategy and in avoiding complications during operations near the foramen magnum.