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A Reconstruction Method Using Musculopericranial Flaps that Prevents Cerebrospinal Fluid Rhinorrhea and Intracranial Complications after Extended Anterior Skull Base Resection.

Anterior skull base defects after extended anterior skull base resection including unilateral orbit and the dura were reconstructed using the temporal musculopericranial (TMP) flaps or frontal musculopericranial (FMP) flap in 14 patients. Dural defect was reconstructed with the TMP or FMP flap by making it overlap on the remaining dura around the defects. These flaps were also used, in principle, for the separation of the nasal cavity. For bone defects on the anterior skull base, a bone graft was transplanted in the place between the flap for dural reconstruction and the flap for the separation of the nasal cavity. Bone grafting was nor performed in patients who had an extensive defect and for whom a free flap was used for the separation. After surgery, CSF rhinorrhea did not occur in the 14 patients. Twelve patients did not develop any postoperative complications. Two patients had epidural abscess, but with debridement and the drainage to the nasal cavity, they did not develop severe intracranial complications. We conclude that reconstruction using musculopericranial flaps is a reliable and versatile method with minimum invasion and the shortest operation hours. In particular, musculopericranial flap for dura reconstruction was highly efficacious for the prevention of CSF rhinorrhea.

Journal Article↗

Virtual reality augmentation in skull base surgery.

OBJECTIVE: Skull base anatomy is complex and subject to individual variation. Understanding the complexity of surgical anatomy is faster and easier with virtual models created from primary imaging data of the patient. This study was designed to investigate the usefulness of virtual reality in image guidance for skull base procedures. DESIGN: Primary volumetric image data from 110 patients was acquired using magnetic resonance, computed tomography (CT), and CT angiography. Pathologies included lesions in the anterior, middle, and posterior skull base. The data were transferred to an infrared-based image-guidance system for creation of a virtual operating field (VOF) with translucent surface modulation and optional "fly-through" video mode. During surgery, the target registration error for anatomical landmarks was assessed and the VOF was compared with the patient's anatomy in the operative field. RESULTS: Complex structures like the course of the sigmoid sinus, the carotid artery, and the outline of the paranasal sinuses were well visualized in the VOF and were recognized by the surgeon instantly. Perception was greatly facilitated as compared with routine mental reconstruction of triaxial images. Accurate assessment of the depth of field and very small objects was not possible in VOF images. CONCLUSION: Supported by sound anatomical knowledge, creation of a virtual operating field for a surgical approach in an individual patient offers a déjà vu experience that can enhance the capabilities of a surgical team in skull base approaches. In addition, application of this technique in image-guided procedures assists in targeting or avoiding hidden anatomical structures.

Journal Article↗

Computer-assisted image-guided surgery in pediatric skull-base procedures.

Skull-base surgery is characterized by the variety of important neural and vascular structures within a narrow operating field. Although preoperative imaging by computed tomography (CT) and magnetic resonance imaging (MRI) and the use of microsurgical techniques have improved intraoperative orientation, a large number of complications still are caused by localization problems. Especially in pediatric skull-base surgery, maximum localization accuracy during surgery is required. The authors developed a localizing system based on tomographic imaging (such as CT or MRI) to achieve safer surgery by providing highly accurate location information. The preliminary successful experience in the use of the Aachen computer-assisted surgery device for pediatric skull-base surgery (14 cases) is presented. Indication include juvenile angiofibroma of the nasopharynx, infectious and tumorous diseases of the paranasal sinuses, orbital tumors, foreign bodies, and intracranial abscess formation.

Adolescent↗

Rare tumors of the skull base and temporal bone.

Skull base surgery has advanced significantly in the last decade. Neuro-otologists and neurosurgeons are working together to apply their combined expertise to totally remove skull base lesions with minimal additional neurologic deficit. Standard approaches have been developed for the more common lesions of the skull base, such as the glomus jugular tumor. Rare tumors of the skull base can be removed using the standard skull base surgery techniques. However, there are specific problems with some of these tumors. This article will describe four types of unusual skull base tumors: hyalinized chemodactoma, giant cell tumor of the bone, papillary adenoma of the middle ear, and ganglioneuroma. The unique properties of these tumors and the surgical approach to their removal will be presented and illustrated by case reports.

Adult↗

Radiosurgery for residual or recurrent nonfunctioning pituitary adenoma.

OBJECT: Nonfunctioning pituitary adenomas comprise approximately 30% of all pituitary tumors. The purpose of this retrospective study is to evaluate the efficacy and role of gamma knife radiosurgery (GKS) in the management of residual or recurrent nonfunctioning pituitary adenomas. METHODS: A review was conducted of the data obtained in 42 patients who underwent adjuvant GKS at the University of Pittsburgh between 1987 and 2001. Prior treatments included transsphenoidal resection, craniotomy and resection, or conventional radiotherapy. Endocrinological, ophthalmological, and radiological responses were evaluated. The duration of follow-up review varied from 6 to 102 months (mean 31.2 months). Fifteen patients were observed for more than 40 months. The mean radiation dose to the tumor margin was 16 Gy. Conformal radiosurgery planning was used to restrict the dose to the optic nerve and chiasm. Tumor control after GKS was achieved in 100% of patients with microadenomas and 97% of patients with macroadenomas. Gamma knife radiosurgery was equally effective in controlling adenomas with cavernous sinus invasion and suprasellar extension. No patient developed a new endocrinological deficiency following GKS. One patient's tumor enlarged with an associated decline in visual function. Another patient experienced a deterioration of visual fields despite a decrease in tumor size. CONCLUSIONS: Gamma knife radiosurgery can achieve tumor control in virtually all residual or recurrent nonfunctioning pituitary adenomas. Dose sparing facilitates tumor management even when the adenoma is close to the optic apparatus or invades the cavernous sinus.

Adenoma↗

The challenges of revision skull base surgery.

Because the skull base is an anatomically complex structure, skull base tumors can hide easily in the crevices that interconnect the intra- and extracranial spaces and intermingle with important neurovascular structures. Often, total surgical resection of these tumors is not possible, and even with postoperative adjuvant radiotherapy, some recurrences after treatment are inevitable. Early detection of recurrent skull base tumors requires clinical vigilance and periodic imaging studies. The management of recurrent skull base tumors presents many challenges beyond those associated with primary procedures. A multidisciplinary setting that includes modern microsurgery and stereotactic radiation therapy provides patients with optimal care.

Chondrosarcoma↗

Linear accelerator based radiosurgery as a salvage treatment for skull base and intracranial invasion of recurrent nasopharyngeal carcinomas.

Nasopharyngeal carcinoma is a common disease entity in Taiwan. It can spread in the prestyloid, retrostyloid compartments, parapharyngeal space, and skull base, and induce paralysis of cranial nerves. We have treated more than 1,500 cases in the past 14 years. Since 1994, we have treated 11 cases of nasopharyngeal carcinomas with skull base invasion by linear accelerator-based stereotactic radiosurgery. There were six male and five female patients. The mean age was 48.4 years. Seven patients had symptoms of low cranial nerves. For these patients, conformal radiotherapy plus brachytherapy was used for the masses beyond the skull base. Stereotactic radiosurgery with a dose of 10 Gy to 19 Gy for one treatment was used for the masses invading the skull base. Eight patients died in follow-up periods from 5 months to 2 years 7 months. Approximately half of patients revealed good response of tumor to radiosurgery. Two patients demonstrated no response of tumors to radiosurgery. Stereotactic radiosurgery may be an adjuvant treatment for recurrent nasopharyngeal carcinomas with skull base and intracranial invasion.

Adult↗

Skull base trauma: diagnosis and management.

The singular anatomical relationship of the base of the skull is responsible for the particular problems that may arise after injury. Extensive dural laceration and severe neurovascular damage may accompany skull base injuries. Trauma to the anterior skull base is frequently related to the paranasal sinuses, and trauma to the middle and the posterior skull base usually affects the petrous bone. Injury to the anterior fossa including the paranasal sinuses may produce CSF leakage, damage the olfactory nerves, optic nerves, and orbita contents. Fractures may affect the carotid canal, injure the internal carotid artery and result in carotid-cavernous fistula. Trauma to the petrous bone may cause facial palsy and deafness, and CSF leakage with otorrhoea or paradoxal rhinoliquorrhoea. Trauma to the posterior fossa may lacerate the major venous sinuses, and affect the cranio-cervical stability. Each one of these injuries will need a particular strategy. Decision making for management as a whole must consider all aspects, including the fact that these injuries frequently involve polytraumatized patients. Decisions regarding the timing of surgery and the sequence of the surgical procedures must be made with great care. Modern surgical techniques and recent technologies including functional preservation of the olfactory nerves in frontobasal trauma, visual evoked potentials, assisted optic nerve decompression, facial nerve reconstruction, interventional technique for intravascular repair of vascular injuries, and recent developments in cochlea implants and brain stem implants, all contributed significantly to improve outcome and enhance the quality of life of patients. This article reviews basic principles of management of skull base trauma stressing the role of these advanced techniques.

Cerebrospinal Fluid Otorrhea↗

Posttreatment imaging of the skull base.

Imaging the skull base after surgery can be challenging because anatomic structures may have been destroyed by an underlying process or removed at surgery. Foreign substances may be introduced to fill a void left by tumor resection, for hemostasis, and to repair dural defects. Previous imaging studies must be available for comparison to understand the characteristics of an underlying lesion. By following the progression of a lesion on subsequent imaging studies, the nature of treatment-related changes and residual or recurrent pathology is best realized.

Angiography↗

[Imaging of skull base tumors in adults].

The skull base is divided into three parts: anterior, central and posterior. Numerous foramina are located in the skull base and transmit important neurovascular structures. Numerous types of tumor can be observed at the skull base. They are classified as anterior, central and posterior skull base tumors. They are also divided into three groups according to their origin: tumors arising from the skull base itself, intracranial tumors and extracranial tumors invading the skull base. Imaging is very important for diagnosis, treatment and follow-up of patients with skull base tumors. Magnetic resonance imaging is the most useful modality as it visualizes the lesion on different planes and permits the planning of therapy. Computed tomography depicts the osseous lesions more precisely and may be necessary before surgery. Catheter angiography is now in most cases replaced by magnetic resonance angiography. Interventional neuroradiology is necessary if the lesion is highly vascularized or if a vessel is encased in the tumor.

Adult↗

[The latest innovations in the operation of en-bloc resection on the frontal skull base].

We have organized skull base surgery teams with otolaryngologists, neurosurgeons and plastic surgeons since 1993 and managed frontal skull base malignancies by a combined transbasal and transfacial approach. However, in the maneuvers, several problems are yet to be solved in minimizing tumor recurrence and postoperative complications. We have recently developed a microscopic en-bloc resection method assisted by an endoscope, and VFOT flap (vascularized frontal outer table flap) for the reconstruction on the frontal skull base. The VFOT flap can be elevated simultaneously with bifrontal craniotomy. The pedicled calvarian bone is split, and the frontal outer table with the pericranium is placed on the frontal base defect caused by the tumor resections. Those procedures seem to be useful for skull base surgery, and easy to perform for neurosurgeons.

Adult↗

Complications of skull base surgery.

As skull base resections have increased in complexity and magnitude, so have the complications associated with the procedures. In this paper, we have reviewed the major complications of skull base surgery, including CSF leak, bleeding, stroke, meningitis, cranial nerve deficits and recurrent disease. This report summarizes the factors that lead to these complications, as well as measures to prevent them. We have also discussed our approach to the management of these complications, with particular emphasis on CSF leak and vagal nerve paralysis.

Head and Neck Neoplasms↗

Management of malignant schwannomas of the paranasal sinuses and anterior skull base.

The evolution of skull base surgery has facilitated the extirpation of previously unresectable tumors. As experience with skull base surgery increases, the feasibility of resection and long-term outcomes is becoming apparent for the more common lesions. Neoplasms such as malignant schwannomas are rare and, therefore, defy single-institution analysis. The treatment and four-year follow-up of a malignant paranasal sinus and anterior skull base schwannoma is described. Analysis of the literature confirms the low incidence of this tumor and supports the efficacy of skull base surgery in its treatment.

Aged↗

Anterior skull base fractures.

Anterior skull base trauma evaluation and management has historically been difficult to systematically study secondary to the relative rarity of its occurrence, associated major morbidity and high mortality, and poor radiographic techniques. It has only been recently that improved care has allowed for decreased morbidity and mortality. The advent of computed tomography imaging techniques has led to anatomic characterization and detailed study of injury patterns. This article reviews current techniques for evaluation and management of the associated sinonasal, orbital, and neurologic sequelae of anterior skull base injuries.

Ethmoid Bone↗

Skull base reconstruction.

Reconstruction of skull base defects following tumor resection is of paramount importance in avoiding serious and life-threatening complications. Cranial base surgery has evolved and outcomes have steadily improved as increasingly reliable reconstructive techniques have been adapted to repair the challenging wounds in this complex anatomic region. The most significant development has been the introduction and refinement of microvascular free tissue transfer to the skull base over the past 15 to 20 years. Free flaps can reliably provide the requisite tissue to not only seal the intracranial space from the subjacent cavities, but also to restore complex craniofacial defects that often result from skull base tumor excision. Advances in alloplast technology have also expanded the armamentarium available to the reconstructive surgeon. In particular, bone substitutes, titanium hardware, and resorbable plate fixation have been shown to be very efficacious when used in carefully selected situations. Finally, tissue sealants and adhesives have become widely used as an adjunctive method to achieve a water-tight dural repair.

Biomedical and Dental Materials↗

Chondrosarcoma of the skull base.

Chondrosarcoma of the skull base is an uncommon neoplasm that comprises 0.15% of all intracranial tumors and 6% of skull base lesions. Compression of vital neurologic structures by tumor expansion as well as the histologic characteristics contribute to the malignant potential of these neoplasms. Tumor recurrence has been associated with incomplete resection in this traditionally surgically inaccessible region. This review of five cases of chondrosarcoma of the skull base examines the surgical approaches to resection in a chronologic fashion to emphasize that total gross resection of these lesions has become possible through the evolution of lateral skull base techniques. The difficulty in pathologic diagnosis and the efficacy of postoperative radiotherapy in enhancing survival are also addressed.

Adult↗

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.

Journal Article↗

Complication avoidance in the treatment of malignant tumors of the skull base.

The treatment of malignant skull base tumors has improved with the development of skull base surgical approaches that allow en bloc resection of a lesion and increase the efficacy of adjuvant therapies. The anatomical complexity of these lesions and their surroundings has led to a relatively high complication rate. Infection and cerebrospinal fluid fistulas are the most common serious procedure-related complications. They result from the frequent necessity of working in a contaminated space such as the paranasal sinuses as well as from the creation of large dural and skull base defects. The authors have reviewed the literature regarding complications of surgery for malignant skull base lesions and present several techniques and strategies for minimizing their incidence by performing the craniofacial approach to anterior skull base lesions.

Bone Transplantation↗