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Ten skull-base neuromas treated at the Otology Group P.C. are presented. Each case is reported in detail. The method by which preoperative diagnosis was made is reviewed. Specific attention is paid to distinguishing these tumors from chemodectomas. Presenting signs and symptoms are enumerated. Operative--especially postoperative--management is discussed in detail.
Tumors at the skull base, usually benign, present diagnostic and therapeutic challenges. Thus they necessitate close cooperation between the departments of otolaryngology, head and neck surgery, neurosurgery, anesthesia and diagnostic radiology. We therefore set up a special team for diagnosis and treatment of such cases. 2 representative cases of benign tumors at the skull base operated through the combined middle cranial fossa--infratemporal fossa approach are presented in detail.
OBJECTIVE: To evaluate the role of bone SPECT in diagnosing metastasis to the skull base in cancer patients. BACKGROUND: Skull base metastasis often causes characteristic clinical syndromes. Antitumor treatment ameliorates or stabilizes symptoms in most patients. Diagnosis may be difficult when neuroimaging studies are negative (as occurs in about one-quarter of patients). Case reports have suggested a role for bone SPECT in these patients. METHODS: We reviewed the charts of all patients (1993-1996) at our institution who had skull base SPECT and at least one neuroimaging study (CT or MRI) for clinically suspected metastasis to the base of the skull. Bone SPECT, CT, and MRI were blindly re-evaluated. RESULTS: We studied 56 patients, of whom 36 had skull base metastasis. Twenty patients had other causes of the clinical syndrome, including leptomeningeal and posterior fossa metastasis, or benign causes. In 29 of 36 patients (81%) with skull base metastasis, CT or MRI clearly demonstrated the lesion. Bone SPECT identified a hot spot in the appropriate region of the skull base in 28 of 36 patients (78%). All seven patients with negative CT or MRI had positive SPECT and four of these had a response to anti-tumor treatment. CONCLUSIONS: SPECT of the skull base can demonstrate lesions not identifiable by CT or MRI. In cancer patients suspected of having skull base metastasis, we recommend SPECT of the skull base when CT or MRI studies are negative.
Two management modal-ities appear to be important in treating skull base chordomas: surgery and radiation therapy. Radical resection of lesions of the distal sacrum (S3-S5) and coccyx may be curative, as total removal is often achieved. In contrast, complete resection of chordomas of the base of the skull is rarely successful because of the inability to achieve a true complete surgical resection. On the other hand, treatment of skull base chordomas by radiation therapy alone is often difficult owing to the large size of the lesion and the dose limitation imposed by the sensitivity of the adjacent structures. Local relapse is the predominant type of treatment failure of skull base chordoma. Skull base surgery and radiation therapy have significantly improved over the last 20 years. The following papers review the most significant recent analyses of therapeutic options in treating skull base chordomas. It seems that the combination of aggressive surgery followed by combined proton-photon radiation therapy offers the best chance of long-term local control to patients harboring cranial chordomas.
Advances in the field of skull base surgery have dramatically reduced the mortality and morbidity of operations on the skull base. Nevertheless, cerebral ischemic events from compromised blood supply to areas of the brain still occur. Although arterial compromise is responsible for a majority of these events, the venous side of the circulation can also play a role in producing cerebral infarctions. A key area of cerebral venous drainage is at the junction of the transverse sinus, sigmoid sinus, and vein of Labbé. Absence of the transverse sinus with the outflow of the vein of Labbé limited to the sigmoid sinus puts these patients at an increased risk for venous infarcts when this area is manipulated during skull base surgery. We have studied 100 consecutive carotid angiograms performed on 50 individuals for carotid artery disease or to rule out aneurysms. We have found that 16.7% of individuals have one atretic transverse sinus. We discuss our results and the implications that they have in skull base surgery. It is our hope that a better understanding of the cerebral venous drainage patterns will help skull base surgeons avoid complications in the future.
The resection of skull base neoplasms requires an intimate knowledge of basicranial vascular anatomy. Tumor distortion of surgical landmarks may increase the potential for inadvertent vascular injury with life-threatening intraoperative bleeding or delayed neurologic sequelae. Moreover, massive transfusion therapy may significantly alter the hemostatic mechanism in the perioperative period. On the basis of a review of hemorrhagic complications encountered in 154 consecutive skull base procedures, we describe techniques that are designed to avoid or efficiently control venous and arterial bleeding in extended skull base surgery. The management of complications resulting from blood replacement are reviewed.
The surgical anatomy of the skull base is often considered to be complicated. In order to devise a system for organizing the various anatomical relationships into a learnable package, 20 skull base dissections were performed on preserved specimens. The findings from the dissections indicate that it is possible to organize the relationships into a three-dimensional set of coordinates that interrelates nearly all the important structures of the parapharyngeal area of the skull base. This system consists of three vertical and three horizontal planes. It uses the temporomandibular joint (TMJ) as a landmark and as an access pathway to the system. Additionally the findings from the dissections indicate that the classical concept of the parapharyngeal space is not accurate when applied to the skull base.
Summary Chondromas of the skull base are extremely rare cartilaginous tumors. Etiology of chondromas remains unknown. The clinical presentation and radiological findings are not unique and cannot reliably distinguish from other similar lesions in this area. The low frequency of patients with chondromas of the skull base makes it impossible to draw definitive treatment conclusions. Chondromas are benign tumors and have good clinical outcomes. However, follow-up depends on localization of the tumor and neighboring vital structures within a small area. The authors present a case of 16-year-old patient with chondroma of the skull base, followed by a diagnostic evaluation and surgical management. Clinical characteristics of the neoplasm was presented on the basis of literature.
The majority of skull base tumors have been considered inoperable not because of the difficulty of surgical removal, but for lack of reliable methods to reconstruct the skull base following extensive removal of those tumors. In this report a trial fo reconstruction using a transplanted omentum is described. A free sheet of vascularized omentum was taken via laparotomy and transplanted into the skull base in four patients who had undergone extensive resection of skull base tumors. The transplanted omentum served satisfactorily as a barrier to prevent CSF leakage and subsequent infection and was considered to be a reliable material to reconstruct large defects in the skull base. The advantage of the omentum is its applicability in covering defects of all sizes and shapes. The omentum also contains various factors to promote tissue adhesion, such as angiogenic factors and fibroblastic growth factors. Furthermore, it can be expected to prevent secondary infections of the transplanted area, and as being a defense organ in the abdominal cavity. Practical methods to harvest and transplant the free vascularized omentum are described, and four cases of patients who have undergone these procedures are reported.
Basilar skull fractures involving the temporal bone extend through the tympanic part of the temporal bone in two-thirds of cases. The anatomical relationship of this part of the temporal bone and the temporomandibular joint enables air to pass from the auditory canal into the joint. Air in the temporomandibular joint is demonstrated on CT scans as an indirect sign of temporal bone fracture.
STUDY OBJECTIVES: To determine if the complications associated with skull base fractures are increased when nasotracheal intubation is performed in the field. DESIGN: Retrospective, case-control study over a five-year period. SETTING: A helicopter service returning to a Level I trauma center. TYPE OF PARTICIPANTS: All injured patients treated in the field who had either radiographic or clinical evidence of skull base fractures in whom nasotracheal intubation was attempted (38) compared with all patients with skull base fractures in whom nasotracheal intubation was not attempted (48) and a convenience sample of patients without skull base fractures in whom nasotracheal intubation was attempted (45). Patients with obvious midface motion on initial examination were excluded. Complications of skull base fractures were categorized as cerebral spinal fluid leak of longer than 24 hours and/or meningitis, cranial nerve injury, diabetes insipidus, and intracranial placement of the endotracheal tube. INTERVENTIONS: Blind nasotracheal intubation was performed by experienced flight nurses. RESULTS: There were no patients in whom an endotracheal tube was placed intracranially. There was no significant difference in complication rate between the two groups with skull base fractures (with nasotracheal intubation, 24%; 95% confidence interval, 11% to 40%; without nasotracheal intubation, 25%; 95% confidence interval, 14% to 40%). The group without skull base fracture had none of the complications usually associated with skull base fractures. CONCLUSION: Patients with skull base fracture have a significant complication rate (25%). The complications associated with skull base fractures are not markedly increased by attempts at nasotracheal intubation in the field.
OBJECTIVE: To review our experience with skull base reconstruction and rehabilitation. METHOD: The clinical data of 30 patients with skull base reconstruction from 200 patients performed skull base surgery were retrospectively reviewed. Bone defect of skull base were repaired in 20 patients and dura defect in 6 patients and soft tissue defect in infratemporal fossa in 8 patients. RESULT: Postoperatively there were transient cerebrospinal leakage in 3 patients, and non-symptom intracranial pneumatosis in 3 patients, and epidural hematoma in 1 patient, and meningitis in 1 patients. CONCLUSION: Immediate reconstruction of skull base with suitable material and surgical technique can prevente complications such as postoperative infection and cerebrospinal leakage brain hernation.
Tumor surgery of the skull base has been increasingly undertaken in recent years. This report involves a series of 18 consecutive patients who have undergone 22 operations at Ohio State University from July 1980 to January 1983 for removal of tumors either adjacent to or through the skull base. A variety of reconstructive techniques such as pericranial flaps, muscle flaps, temporalis fascial grafts, split-rib grafts, fat grafts, and bone grafts have been found to be reliable. This series also included the successful use of a temporalis myocutaneous flap. The conclusion of this study is that these techniques provide a safe approach to the resection of tumors involving the base of skull.
PURPOSE: Patients with skull base lesions present a challenging management problem because of intractable symptoms and limited therapeutic options. In 1989 we began treating selected patients with skull base lesions using linac stereotactic radiosurgery. In this study the efficacy and toxicity of this therapeutic modality is investigated. METHODS AND MATERIALS: Forty-seven patients with 59 malignant skull base lesions were treated with linac radiosurgery between 1989 and 1995. Eleven patients were treated for primary nasopharyngeal carcinoma using radiosurgery as a boost (7 Gy-16 Gy, median: 12 Gy) to the nasopharynx after a course of fractionated radiotherapy (64.8-70 Gy) without chemotherapy. Another 37 patients were treated for 48 skull base metastases or local recurrences from primary head and neck cancers. Eight of these patients had 12 locally recurrent nasopharyngeal carcinoma lesions occuring 6-96 months after standard radiotherapy, including one patient with nasopharyngeal carcinoma who developed a regional relapse after radiotherapy with a stereotactic boost. Lesion volumes by CT or MRI ranged from 0 to 51 cc (median: 8 cc). Radiation doses of 7.0 Gy-35.0 Gy (median: 20.0 Gy) were delivered to recurrent lesions, usually as a single fraction. RESULTS: All 11 patients who received radiosurgery as a nasopharyngeal boost after standard fractionated radiotherapy remain locally controlled (follow-up: 2-34 months, median: 18). However, one patient required a second radiosurgical treatment for regional relapse outside the initial radiosurgery volume. Thirty-three of 48 (69%) recurrent/metastatic lesions have been locally controlled, including 7 of 12 locally recurrent nasopharyngeal lesions. Follow-up for all patients with recurrent lesions ranged from 1 to 60 months (median: 9 months). Local control did not correlate with lesion size (p = 0.80), histology (p = 0.78), or radiosurgical dose (p = 0.44). Major complications developed after 5 of 59 treatments (8.4%), including three cranial nerve palsies, one CSF leak, and one trismus. Complications were not correlated with radiosurgical volume (p = 0.20), prior skull base irradiation (p = 0.90), or radiosurgery dose > 20 Gy (p = 0.49). CONCLUSION: Stereotactic radiosurgery is a reasonable treatment modality for patients with skull base malignancies, including patients with primary and recurrent nasopharyngeal carcinoma. The dose distribution obtained with stereotactic radiosurgery provides better homogeneity than an intracavitary implant when used as a boost for nasopharyngeal lesions, especially lesions which involve areas distant to the nasopharyngeal mucosa.
BACKGROUND AND PURPOSE: The developing fetal skull base has previously been studied via dissection and low-resolution CT. Most of the central skull base develops from endochondral ossification through an intermediary chondrocranium. We traced the development of the normal fetal skull base by using plain radiography, MR imaging, and CT. METHODS: Twenty-nine formalin-fixed fetal specimens ranging from 9 to 24 weeks' gestational age were examined with mammographic plain radiography, CT, and MR imaging. Skull base development and ossification were assessed. RESULTS: The postsphenoid cartilages enclose the pituitary and fuse to form the basisphenoid, from which the sella turcica and the posterior body of the sphenoid bone originate. The presphenoid cartilages will form the anterior body of the sphenoid bone. Portions of the presphenoid cartilage give rise to the mesethmoid cartilage, which forms the central portion of the anterior skull base. Ossification begins in the occipital bone (12 weeks) and progresses anteriorly. The postsphenoid (14 weeks) and then the presphenoid portion (17 weeks) of the sphenoid bone ossify. Ossification is seen laterally (16 weeks) in the orbitosphenoid, which contributes to the lesser wing of the sphenoid, and the alisphenoid (15 weeks), which forms the greater wing. CONCLUSION: MR imaging can show early progressive ossification of the cartilaginous skull base and its relation to intracranial structures. The study of fetal developmental anatomy may lead to a better understanding of abnormalities of the skull base.
Most patients with conventional radiotherapy after surgery die with local disease progression. The superior local tumor control and overall survival achieved with fractionated proton RT can be attributed to improved dose localization characteristics of protons, resulting in higher doses delivered. Patients with base of skull neoplasms are increasingly considered for stereotactic radiosurgery. Recently, Muthukumar et al reported for the University of Pittsburgh group on cobalt-60 Gamma Knife (Elekta Instruments, Atlanta, GA) therapy for 15 patients with chordomas or chondrosarcomas of the base of the skull. With tumor volumes ranging between 0.98 and 10.3 mL (mean, 4.6 mL), doses to the tumor margin varying from 12 to 20 Gy (median, 18 Gy) were delivered. Two patients were treated without histologic tumor confirmation. After a median follow-up time of 40 months, 2 patients had died of disease, 2 patients had succumbed to intercurrent disease, and 1 patient surviving at the time of analysis had developed tumor progression. Neither actuarial local control nor actuarial survival data were presented. In the LLUMC series, most tumors exceeded sizes reportedly suitable for radiosurgery or were of a highly irregular configuration. Nevertheless, in 11 patients, tumors less than 15 mL in size remained locally controlled as did tumors sized between 15 and 25 mL in 11 additional patients; these patients were thus potential candidates for stereotactic radiosurgery. At present, too few reports on radiosurgery contain sufficient patient numbers and statistical analyses to permit one to draw conclusions about the feasibility of radiosurgery for chordomas and chondrosarcomas of the base of the skull. A principal difference between proton RT and radiosurgery as currently practiced in most centers concerns target definition. In proton RT, the GTV is treated. In addition, a clinical volume is defined, which is distinctly different from the GTV in size and shape, to include the operative site and other areas of microscopic risk. In many instances, only the GTV is targeted in radiosurgery. Although it is certainly appropriate to explore the role that radiosurgical techniques may have in treating these tumors, results should be evaluated against the excellent outcome that can be achieved with fractionated proton RT, particularly in patients with tumors small enough and of favorable configuration and location to make them candidates for radiosurgery. The present problem of particle therapy is its limited availability. In the United States, only two proton centers can currently provide treatment for base of skull lesions. The HCL is soon to be replaced by a hospital-based facility at the MGH. Several other proton centers in the United States are currently under active consideration. Proton RT is an evolutionary process. Recent developments in proton RT include intensity modulated therapy and improvements in beam delivery systems, namely, the introduction of active beam scanning. These should further increase the degree of dose conformity. In addition, other heavy particles are also being investigated so as to combine the physical advantages of protons with the differential increased biologic effectiveness of particles in tumor as compared to normal tissues. A report from the Heavy Ion Research Facility in Darmstadt, Germany, has not revealed any increased acute toxicities in the first 13 patients with skull base chordomas or chondrosarcomas treated using carbon ions. Several important factors have emerged from recently published results: Patients with low-grade chondrosarcomas and male patients with chordomas have an excellent chance of durable tumor control and long-term survival after proton RT. Severe complications are within the acceptable range considering the high doses delivered and given the major morbidity associated with uncontrollable tumor growth in such patients. Female patients with chordomas experience increased early and late failures
OBJECTIVE: Although anterior skull base surgery has become a relatively safe and effective procedure, postoperative complications remain a serious problem. One of the most devastating complications of anterior skull base procedures is tension pneumocephalus (TP). In order to prevent TP, authors have recommended the use of prophylactic airway diversion procedures, such as prolonged endotracheal intubation or prophylactic tracheostomy. However, these procedures may mask neurologic deterioration, delay treatment, and prolong rehabilitation. The purpose of this study was to determine the need for airway diversion procedures in anterior skull base surgery. STUDY DESIGN: Eighty-five patients underwent anterior skull base operations through the subcranial approach without prophylactic airway diversion. Sixty-four patients underwent resection of tumors, 12 patients underwent repair of cerebrospinal fluid leak, 6 patients underwent surgery due to anterior skull base fungal infections, and 3 patients underwent anterior skull base reconstruction procedures. RESULTS: The complication rate of TP was 1.2% (1/85). This complication rate is similar to that previously reported for operations performed with airway diversion procedures. CONCLUSION: Prophylactic airway diversion procedures are unnecessary in routine anterior skull base operations. Airway diversion should be indicated only when factors that might predispose the patient to risk of TP have been identified (ie, chronic cough or obstructive pulmonary diseases).
UNLABELLED: Skull-base invasions of head and neck tumors were examined by simultaneous bone and tumor dual-isotope SPECT (S-SPECT) with 99mTc-hydroxy-methylene-diphosphonate (99mTc-HMDP) and 201Tl-chloride. The effectiveness and reliability of tumor diagnosis by this method was the primary interest in this study. METHODS: Before S-SPECT imaging, a phantom experiment using dried skull-bone specimens was performed to establish anatomical details of the skull base with the SPECT camera. Radionuclide crosstalk, window widths and control patients were also examined prior to S-SPECT imaging. Twenty patients with suspected tumor invasion of the skull base underwent S-SPECT. RESULTS: Preliminary experiments revealed that crosstalk effects could be disregarded with adequate window width and routine administrative doses of the radionuclides. S-SPECT detected bone destruction and the extent of tumor invasion for all 12 patients in whom skull-base involvement was diagnosed by CT or MRI. For the three patients in whom CT or MRI revealed no tumor invasion, the S-SPECT images did not show any abnormal accumulation in similar regions. In the remaining five patients without CT and MRI confirmation of skull-base invasion, the S-SPECT findings showed skull-base abnormalities in three. Tumor invasion was confirmed surgically or by clinical follow-up. The remaining two patients had negative S-SPECT images. CONCLUSION: S-SPECT is an effective and reliable diagnostic technique for detecting tumor invasion in the complex bony regions of the skull base.