Lateral skull base surgery: the otology group experience

Lateral skull base surgery has remained the surgical frontier of new developments in the treatment of lesions heretofore difficult to access. Examination of surgical results stimulates technical innovation and provides an intervention risk-benefit ratio assessment for particular lesions useful in management planning. With this in mind, we report the updated collective experience with lateral skull base surgery at the Otology Group over the past 20 years. Two hundred ninety-eight patients underwent surgical intervention for lateral skull base lesions. In 81 patients these lesions were malignant; in 217, benign. Of the benign lesions, 165 were glomus tumors: 139 glomus jugulare, 19 glomus vagale, and 7 glomus tympanicum. The remainder comprised 21 menigniomas, 14 neuromas, two neurofibromas, and a small group of much rarer entities. The philosophy of surgical approach, results, and follow-up are discussed.     

Cranial nerve preservation in lesions of the jugular fossa.

The most significant objection to the proposal of lateral transtemporal cranial base surgery for the treatment of jugular foramen tumors is the perceived lasting morbidity attendant to aggregate cranial nerve loss. As techniques become more standardized and earlier diagnosis generates smaller tumors for treatment, outcome has become more predictable. Surgery has become the recognized management preference for these cranial base lesions. The purpose of this article is to assess the role of surgery in the treatment of jugular foramen lesions, as well as to review some of the technical highlights of conservation surgery, its clinical prerequisites, and reasonable expectations. We review 100 lateral skull base surgical cases of lesions involving the jugular foramen. The majority of these lesions--77 of 100--were paragangliomas. For these glomus tumors, cranial nerve preservation correlated well to tumor size and location. The diversity of the remaining 23 cases prevented any substantive conclusions.     

Surgical pathology of the skull base: a 7-year experience

A significant diversity of tissue types interface at the base of the skull and contribute to the diagnostic challenges of skull base surgical pathology. Advances in surgical technique now permit biopsy and resection of lesions previously termed "inoperable." Retrospective review was made of all pathology specimens from skull base surgeries performed at the University of California Davis Medical Center from 1990 to 1996. Surgical biopsies and resections were performed on 186 patients who had 33 distinctive diagnoses. Any preoperative biopsy or tissue from referring institutions was reviewed prior to skull base surgery. One hundred eighteen patients had benign lesions, the most frequent of which were pituitary adenoma (55) and acoustic neuroma (27). Other benign lesions included angiofibroma, meningioma, fibrous dysplasia, and paraganglioma. Sixty-eight patients had malignant tumors, 32 of which were squamous cell earcinoma. Other malignancies included salivary carcinomas, basal cell carcinoma, neuroblastoma, melanoma, and several sarcomas. Unexpected findings were two metastatic carcinomas and five inflammatory lesions. Nearly 1500 intraoperative consultations were performed to establish resection margins and less commonly to confirm the diagnosis. The discrepancy rate between the intraoperative and final diagnosis was 1.8%. Immunohistochemistry and/or electron microscopy was utilized in 44% of the specimens to confirm the diagnosis. Surgical pathology is an essential ingredient to a successful skull base surgery program. Pathologists are involved in both pre- and intraoperative decisions. The diversity of lesions that arise from the skull base often has overlapping histologies that require careful attention to morphology and the use of ancillary studies for accurate diagnosis. The need for frequent intraoperative interpretations contributes to the significant challenge for the surgical pathologist.     

Surgical Pathology of the Skull Base: A 7-Year Experience

A significant diversity of tissue types interface at the base of the skull and contribute to the diagnostic challenges of skull base surgical pathology. Advances in surgical technique now permit biopsy and resection of lesions previously termed “inoperable.” Retrospective review was made of all pathology specimens from skull base surgeries performed at the University of California Davis Medical Center from 1990 to 1996. Surgical biopsies and resections were performed on 186 patients who had 33 distinctive diagnoses. Any preoperative biopsy or tissue from referring institutions was reviewed prior to skull base surgery. One hundred eighteen patients had benign lesions, the most frequent of which were pituitary adenoma (55) and acoustic neuroma (27). Other benign lesions included angiofibroma, meningioma, fibrous dysplasia, and paraganglioma. Sixty-eight patients had malignant tumors, 32 of which were squamous cell earcinoma. Other malignancies included salivary carcinomas, basal cell carcinoma, neuroblastoma, melanoma, and several sarcomas. Unexpected findings were two metastatic carcinomas and five inflammatory lesions. Nearly 1500 intraoperative consultations were performed to establish resection margins and less commonly to confirm the diagnosis. The discrepancy rate between the intraoperative and final diagnosis was 1.8%. Immunohistochemistry and/or electron microscopy was utilized in 44% of the specimens to confirm the diagnosis. Surgical pathology is an essential ingredient to a successful skull base surgery program. Pathologists are involved in both pre- and intraoperative decisions. The diversity of lesions that arise from the skull base often has overlapping histologies that require careful attention to morphology and the use of ancillary studies for accurate diagnosis. The need for frequent intraoperative interpretations contributes to the significant challenge for the surgical pathologist.     

Use of the LandmarX™ Surgical Navigation System in Lateral Skull Base and Temporal Bone Surgery

Despite the widespread availability of surgical navigation devices, their use in lateral skull base and temporal bone surgery has been limited. Problems with current systems include difficulty of use and inadequate accuracy. We present a series of cases using the LandmarXtrade mark surgical navigation system as an adjunct for lateral skull base and temporal bone procedures. This infrared emitting diodes (IRED)-driven system has a post that carries the IREDs and bypasses the need to place the patient in a Mayfield head holder. This configuration allows greater mobility of the surgical field. Registration of the patient can include a combination of fiducial and anatomic landmarks that significantly increase accuracy compared to fiducial calibration alone. We introduced the use of the lateral process of the malleus as a landmark, thereby increasing accuracy within the temporal bone to a range of 0.9 to 1.5 mm. We used the system on encephaloceles, glomus tumors, meningiomas, and schwannomas, and revision surgery for chronic otitis media. It decreased operating time, allowed more effective use of "keyhole" approaches, and increased safety. As the availability and flexibility of these systems increase, their use should become the standard of care in revision temporal bone and lateral skull base procedures.     

Frontal skull base surgery combined with endonasal endoscopic sinus surgery

BACKGROUND: Postoperative infection remains a serious complication after radical resection of anterior skull base lesions because intracranial, nasal, and paranasal cavities are opened during surgery. To prevent complications from postoperative infection, we combined endonasal endoscopic sinus surgery (ESS) with the frontal transbasal approach in patients with skull base lesions. METHODS: Patients (n = 16) with anterior skull base lesions extending to the paranasal or nasal cavity underwent surgical resection via the frontal transbasal approach. After removal of the lesion via the transcranial approach, enlargement of the ostium or sinusotomy was performed bilaterally using our endonasal ESS procedure. The main purpose of ESS is the establishment of a wide drainage route to avoid dead space and postoperative infection. Furthermore, we confirmed the absence of residual lesion and leakage of cerebrospinal fluid (CSF), endoscopically. RESULTS: The frontal transbasal approach combined with endonasal ESS was performed in 16 patients with frontal skull base lesions. There were 8 malignant tumors, 6 benign tumors, and 2 mucoceles. Although 11 patients had preoperative active paranasal sinusitis, most frequently at the ethmoid sinus, none experienced postoperative infection. There was no complication related to ESS procedure. Furthermore, leakage of CSF and extracranial residual tumor were not found. CONCLUSION: Endonasal ESS after frontal skull base surgery is a highly useful technique for preventing postoperative infection, especially for the cases with large skull base tumors extending into other regions involving the paranasal sinuses or nasal cavity and with active paranasal sinusitis.     

The role of digital subtraction angiography in diagnosis of skull-base lesions

Advances in radiographic diagnosis of skull-base lesions have made it possible to approach lesions formerly considered unresectable. The most important of these are the high-resolution computerized tomographic (CT) scanners with bone algorithms. In conjunction with their evaluations it is important to know in detail the vascular structures involved with the skull base. These include not only the jugular vein and bulb and lateral sinus associated with glomus tumor surgery but often the carotid artery associated with lesions of the jugular foramen and petrous apex. Conventional arteriograms have been the best way to evaluate the vascular system but were occasionally associated with some risk and much patient discomfort. New digital subtraction techniques (digital subtraction angiography [DSA] using an intravenous bolus injection of dye) are now yielding x-ray studies equal to or better than conventional arteriography. DSA will be described and the results of these studies of various lesions of the skull base will be presented in conjunction with the results of high-resolution CT scanning to show the complete workup of the skull-base lesion possible for an outpatient.     

Surgery for glomus tumors at the skull base

Glomus tumors of the temporal bone frequently involve the skull base. In the present study, 34% of the tumors occurred with cranial nerve palsies and 15% invaded the CNS. The procedure for surgical resection of glomus tumors of the skull base is described. Results of the procedure included successful surgical resection of 80% of the glomus jugulare tumors and of 94% of the glomus tympanicum tumors. Tumor recurrence and persistence occurred only in the patients with CNS invasion.     

Surgical strategies in the removal of malignant tumors and benign lesions of the anterior skull base

The choice of surgical approaches to the tumors of the anterior skull base is determined by the location, dimensions of such lesions and their relations to the surrounding structures. Furthermore, the need for the reconstruction of the dura and skull base structures has an important influence on the decision about the surgical procedure. Transfacial approaches provide limited exposure, especially when tumors damage the floor of the anterior cranial fossa and involve the frontobasal dura and brain. Transcranial, craniofacial and subcranial approaches in particular may aid a surgeon in the removal of such lesions, and often these surgical procedures are the only beneficial methods. Our study comprised 15 patients. Transcranial approaches were used in ten cases. In five further cases, we adopted craniofacial or subcranial approaches. Total removal of these lesions was possible in 13 cases. Neither important complications nor death after surgery was observed except for two cases (craniofacial/subcranial approach) where the CSF leak and CNS infection were reported. We deem that the transcranial approach creates a good possibility for total removal of anterior skull base tumors, particularly of the benign lesions, and permits reconstruction of the skull base damaged by the tumor. However, in patients with large malignant tumors, the en bloc resection via the combined craniofacial/subcranial approach achieved better outcome.Parts of the materials of this research were presented at the 12th European Congress of Neurosurgery—EANS 2003, 7–12 September, Lisboa, Portugal     

Cranio-facial approaches for tumours involving the anterior half of the skull base

Summary Teamwork between neurosurgeons and head and neck surgeons has increased the possibility of managing tumours involving the skull base.The authors distinguish the anterior half of the skull base into a median and two lateral portions and describe the surgical approaches utilized to expose it.The authors present their clinical experience in 27 patients with extensive lesions of the anterior half of the skull base and their results.     

A New Technique for CT/MR Fusion For Skull Base Imaging

This paper presents our initial experience utilizing a new technique which allows CT and MR image fusion in patients with skull base lesions. Eleven patients with a variety of skull base lesions underwent CT and MR imaging prior to surgery. Both sets of images were coregistered using customized software. The CT and MR data sets were then combined and viewed in a single interactive image formar using a high-speed graphic computing system. Image fusion allowed simultaneous visualization of the bony skull base anatomy (CT) and detailed soft tissue anatomy (MR) using a single image format. Combining both modalities was felt to provide a better assessment of the extent of lesions and improve understanding of their relationship to adjacent bony and neurovascular anatomy. Specifically, image fusion enhanced awareness of location of skill base lesions with respect to the cavernous sinuses. Gasserian ganglia, carotid arteries, and jugular foramina. For tumors arising within the internal auditory canal (IAC), fused images allowed better delineation of the lateral aspect of the lesion with respect to the fundus of the IAC. Thus, fusion of CT and MR studies provides a unique image format which has advantages over single modality display. We believe image fusion is beneficial for surgical planning and for treatment planning of complex skull base malignancies treated with radiotherapy.     

A New Technique for CT/MR Fusion For Skull Base Imaging

This paper presents our initial experience utilizing a new technique which allows CT and MR image fusion in patients with skull base lesions. Eleven patients with a variety of skull base lesions underwent CT and MR imaging prior to surgery. Both sets of images were coregistered using customized software. The CT and MR data sets were then combined and viewed in a single interactive image formar using a high-speed graphic computing system. Image fusion allowed simultaneous visualization of the bony skull base anatomy (CT) and detailed soft tissue anatomy (MR) using a single image format. Combining both modalities was felt to provide a better assessment of the extent of lesions and improve understanding of their relationship to adjacent bony and neurovascular anatomy. Specifically, image fusion enhanced awareness of location of skill base lesions with respect to the cavernous sinuses. Gasserian ganglia, carotid arteries, and jugular foramina. For tumors arising within the internal auditory canal (IAC), fused images allowed better delineation of the lateral aspect of the lesion with respect to the fundus of the IAC. Thus, fusion of CT and MR studies provides a unique image format which has advantages over single modality display. We believe image fusion is beneficial for surgical planning and for treatment planning of complex skull base malignancies treated with radiotherapy.     

Trigeminal schwannomas: experience with 57 cases and a review of the literature

Trigeminal schwannoma is a mostly benign tumor that can be cured by complete resection. Over the last few decades, several pioneers have developed surgical approaches enabling the total removal of such tumors. We analyzed 57 patients who underwent radical surgery, including 45 patients who underwent skull base surgery as their initial treatment, for removal of trigeminal schwannomas. Here, we report the surgical management of these cases. Since 1990, all such patients have been treated using three main types of middle fossa skull base approaches, which minimize the exposure of the brain: the anterior transpetrosal approach, subtemporal interdural approach (Dolenc), or a combination of these approaches. Before 1990, total tumor removal was achieved in only three of eight patients (38%). After 1990, the tumors were totally removed in 43 patients (90%) and were nearly completely removed in an additional three patients (6%). Among the patients who underwent skull base surgery as their initial treatment, a complete resection was achieved in 93% (42/45 patients) of the cases. However, total surgical removal after surgery and Gamma knife surgery was very difficult because of dense adhesions to the brain stem and cranial nerves. No surgery-related mortalities occurred in this series, and the individual KPS scores were more than 90% among the patients who underwent skull base surgery. No recurrences requiring additional surgery have occurred after an average follow-up period of 4.9 years. Most of the trigeminal schwannomas could be removed totally and safely during a single operation after the introduction of skull base surgery. Therefore, radiosurgery should not be applied as the treatment of first choice for younger patients. A correct anatomical knowledge is critical for minimizing brain exposure and avoiding surgical complications.     

Efficacy of navigation in skull base surgery using composite computer graphics of magnetic resonance and computed tomography images

The efficacy of a neurosurgical navigation system using three-dimensional composite computer graphics (CGs) of magnetic resonance (MR) and computed tomography (CT) images was evaluated in skull base surgery. Three-point transformation was used for integration of MR and CT images. MR and CT image data were obtained with three skin markers placed on the patient's scalp. Volume-rendering manipulations of the data produced three-dimensional CGs of the scalp, brain, and lesions from the MR images, and the scalp and skull from the CT. Composite CGs of the scalp, skull, brain, and lesion were created by registering the three markers on the three-dimensional rendered scalp images obtained from MR imaging and CT in the system. This system was used for 14 patients with skull base lesions. Three-point transformation using three-dimensional CGs was easily performed for multimodal registration. Simulation of surgical procedures on composite CGs aided in comprehension of the skull base anatomy and selection of the optimal approaches. Intraoperative navigation aided in determination of actual spatial position in the skull base and the optimal trajectory to the tumor during surgical procedures.     

The role of hair shaving in skull base surgery.

OBJECTIVE: We sought to evaluate surgical wound infection rates in patients undergoing skull base surgery without hair removal. METHODS: We undertook a retrospective study of 175 skull base operations performed without hair removal. Anterior operations were conducted via the subcranial approach (n = 120) and lateral or posterior procedures via various approaches (n = 55). Wounds were examined daily during hospitalization and at routine outpatient follow-up (8 to 45 months) and classified according to the Center for Disease Control and Prevention guidelines. RESULTS: The overall surgical wound infection rate was 1.1% (2 of 175): 0.8% (1 of 120) for anterior and 1.8% (1 of 55) for lateral or posterior procedures. It was similar for clean operations (lateral and posterior) and clean-contaminated (anterior) procedures and was less than or similar to the rates reported for skull base procedures with hair removal. No wound infection occurred among the infected (trauma, fungal infections, and brain abscess) patients. CONCLUSIONS: Skull base surgery without hair removal is safe and not associated with increased risk of wound infection. The method may prevent additional psychologic stress, promote restoration of the patient's self-image, and accelerate his or her return to normal life.     

Superior Turbinectomy: Role for a Two-surgeon Technique in Endoscopic Endonasal Transsphenoidal Surgery—Technical Note

We describe a practical technique of superior turbinectomy followed by posterior ethmoidectomy as a less invasive procedure for two-surgeon technique on endoscopic endonasal transsphenoidal surgery. After identification of the superior turbinate and the sphenoid ostium, the inferior third portion of the superior turbinate was coagulated and resected. This partial superior turbinectomy procedure exposed the posterior ethmoidal sinus. Resection of the bony walls between the sphenoid and posterior ethmoid sinuses provided more lateral and superior exposure of the sphenoid sinus. This technique was performed in 56 patients with midline skull base lesions, including 49 pituitary adenomas and 7 other lesions. Meticulous manipulation of instruments was performed in all cases without surgical complications such as permanent hyposmia/anosmia or nasal bleeding. Our findings suggested that the partial superior turbinectomy followed by retrograde posterior ethmoidectomy is a simple and safe technique providing a sufficient surgical corridor for two-surgeon technique to approaching midline skull base regions, mainly involving pituitary adenomas.     

A Review of Stereotactic Radiosurgery Practice in the Management of Skull Base Meningiomas

Gross total resection of skull base meningiomas poses a surgical challenge due to their proximity to neurovascular structures. Once the gold standard therapy for skull base meningiomas, microsurgery has been gradually replaced by or used in combination with stereotactic radiosurgery (SRS). This review surveys the safety and efficacy of SRS in the treatment of cranial base meningiomas including 36 articles from 1991 to 2010. SRS produces excellent tumor control with low morbidity rates compared with surgery alone for asymptomatic small skull base meningiomas, patients with risk factors precluding conventional surgery, and as adjuvant therapy for recurrent or residual lesions.     

Image-guided surgery of the skull base using a novel miniature position sensor

Image-guided navigational systems have been a useful adjunct for minimally invasive surgery of the skull base. A novel miniature position sensor has been developed that uses a low magnetic field for real-time tracking of surgical instruments. The 1.7-mm-diameter sensor attached to the position and orientation system (Magellan(R), Biosense, Inc., Johnson and Johnson Co., Baldwin Park, CA) was deployed through various surgical instruments or used in a hand-held fashion with a malleable shaft probe. We report on our experience using this electromagnetic system in a series of lesions of the sella and clivus. After patient/image registration, the system was consistently accurate to within 2 mm. We have found this system to be particularly advantageous in endoscopic surgery of cystic lesions of the skull base, where access is limited and anatomy may be distorted. In three patients, this device obviated the need for an extensive external surgical approach. Case histories are presented, which illustrate the specific advantages this miniature system provides during skull base surgery.     

Image-Guided Surgery of the Skull Base Using a Novel Miniature Position Sensor

Image-guided navigational systems have been a useful adjunct for minimally invasive surgery of the skull base. A novel miniature position sensor has been developed that uses a low magnetic field for real-time tracking of surgical instruments. The 1.7-mm-diameter sensor attached to the position and orientation system (Magellan®, Biosense, Inc., Johnson and Johnson Co., Baldwin Park, CA) was deployed through various surgical instruments or used in a hand-held fashion with a malleable shaft probe. We report on our experience using this electromagnetic system in a series of lesions of the sella and clivus. After patient/image registration, the system was consistently accurate to within 2 mm. We have found this system to be particularly advantageous in endoscopic surgery of cystic lesions of the skull base, where access is limited and anatomy may be distorted. In three patients, this device obviated the need for an extensive external surgical approach. Case histories are presented, which illustrate the specific advantages this miniature system provides during skull base surgery.     

鼻内镜治疗颅底疾病112例报告

目的探讨鼻内镜径路治疗颅底疾病的价值。方法2002年5月~2006年12月,对112例颅底疾病行鼻内镜径路手术,其中脑脊液鼻漏39例,垂体瘤4例,脑膜膨出或脑膜脑膨出3例,蝶筛囊肿9例,蝶窦炎伴息肉2例,真菌性蝶窦炎12例,内翻性乳头状瘤11例,鼻咽纤维血管瘤6例,骨化纤维瘤2例,骨纤维异常增殖2例,脊索瘤7例,颅咽管瘤2例,鳞癌10例,未分化癌1例,乳头状瘤癌变2例。结果全组均在鼻内镜下处理,其中20例病变为次全切除,包括鳞癌8例、未分化癌1例、脊索瘤7例、颅咽管瘤2例、骨纤维异常增殖2例。脑脊液鼻漏1次手术成功31例(79.5%),2次成功4例,3次成功4例,最终成功率100%。1例脑膜脑膨出术后2个月复发并伴脑脊液漏,内镜下再次手术成功。1例内翻性乳头状瘤术后11个月复发,改行鼻侧切开术。1例真菌性蝶窦炎术后4个月复发行再次内镜手术。1例脑脊液鼻漏术后颅内感染。结论鼻内镜径路可以处理多种颅底疾病,是一种安全、有效、微创的手术方式,但仍需严格掌握手术适应证,特别是恶性肿瘤。