Review of skull base surgery approaches: with special reference to pediatric patients

Anatomy of the craniocervical junction - A review

An in-depth understanding of the anatomy of the craniocervical junction (CCJ) is indispensable in skull base neurosurgery. In this paper, we discuss the osteology of the occipital bone, the atlas (C1) and axis (C2), the ligaments and the muscle anatomy of the CCJ region and their relationships with the vertebral artery. We will also discuss the trajectory of the vertebral artery and review the anatomy of the jugular foramen and lower cranial nerves (IX to XII). The most important surgical approaches to the CCJ, including the far lateral approach, the anterolateral approach of Bernard George and the endoscopic endonasal approach, will be discussed to review the surgical anatomy.

Imaging of pediatric nasal masses: A review

Several conditions may present as nasal masses in pediatric age, including congenital and developmental disorders, inflammatory and infectious conditions, neoplastic and neoplastic-like lesions, and other miscellaneous disorders. A confident presurgical diagnosis can be challenging and imaging is often key in the management of these lesions. We provide a pictorial review of pediatric nasal masses and discuss a location-based approach to the diagnosis of these lesions on imaging studies. Acquaintance with the most common pathologies and awareness for its characteristic imaging features can aid the physician in the differential diagnosis. Location and extension of the lesion can be particularly helpful. Midline masses raise suspicion for developmental nasal midline lesions, including frontoethmoidal cephalocele, dermoid/epidermoid cyst, and neuroglial heterotopia. In case of trauma, nasal septum hematoma/abscess should be considered. Developmental or odontogenic cystic lesions and osseous neoplasms and neoplasm-like lesions can originate from the maxilla and palate. Although most nasal tumors show overlapping imaging characteristics, some have suggestive features, such as nasopharyngeal angiofibroma and esthesioneuroblastoma. Malignant tumors tend to be locally aggressive, demonstrating invasive features, bony erosion, intermediate signal on T2-weighted images, and restricted diffusion on diffusion-weighted imaging. In certain cases, a definite diagnosis can only be made histologically. Nonetheless, detailed characterization of the lesion is crucial prior to invasive procedures in order to avoid complications.

Pediatric vestibular schwannomas: case series and a systematic review with meta-analysis

OBJECTIVE

Sporadic unilateral vestibular schwannomas are rare in the pediatric population. Little has been reported in the literature on the presentation, tumor size, response to surgical treatment, and recurrence rates in these younger patients. The authors' goal was to describe their institutional experience with pediatric sporadic vestibular schwannomas and to conduct a meta-analysis of the existing literature to provide further insight into the presentation, tumor characteristics, and surgical outcomes for these rare tumors to help direct future treatment strategies.

METHODS

The authors performed a retrospective review of all patients 21 years of age or younger with unilateral vestibular schwannomas and without neurofibromatosis type 2 who underwent resection by the senior authors between 1997 and 2019. A systematic review of the literature and meta-analysis was also performed by entering the search terms "pediatric" and "vestibular schwannoma" or "acoustic neuroma," as well as "sporadic" into PubMed. Presentation, treatment, clinical outcomes, and follow-up were analyzed.

RESULTS

Fifteen patients were identified at the authors' institution, ranging in age from 12 to 21 years (mean 16.5 years). Common presenting symptoms included hearing loss (87%), headache (40%), vertigo (33%), ataxia (33%), and tinnitus (33%). At the time of surgery, the mean tumor size was 3.4 cm, with four 1-cm tumors. Four patients had residual tumor following their first surgery, 3 (75%) of whom had significant radiographic regrowth that required further treatment. The literature review identified an additional 81 patients from 26 studies with patient-specific clinical data available for analysis. This resulted in a total of 96 reported patients with an overall average age at diagnosis of 12.1 years (range 6-21 years) and an average tumor size of 4.1 cm.

CONCLUSIONS

Pediatric vestibular schwannomas present similarly to those in adults, although symptoms of mass effect are more common, as these tumors tend to be larger at diagnosis. Some children are found to have small tumors and can be successfully treated surgically. Residual tumors in pediatric patients were found to have a higher rate of regrowth than those in their adult counterparts.

Lateral Skull Base Approaches in Pediatric Skull Base Surgery

Lateral skull base pathology is rare in children. Awareness of the potential for lateral skull base lesions in children is imperative for timely identification and appropriate management. Some of the common presentations and pathologies shall be presented, as well as a variety of approaches that may be utilized to access the lateral skull base in the pediatric patient. Although the lateral skull base approaches utilized in adults may also be considered for management of pediatric lesions, some special considerations given the small developing anatomy need to be kept in mind.

Paediatric Chordomas

Paediatric chordomas are rare malignant tumours arising from primitive notochordal remnants with a high rate of recurrence. Only 5 % of them occur in the first two decades such less than 300 paediatric cases have been reported so far in the literature. In children, the average age at diagnosis is 10 years with a male-to-female ratio closed to 1. On the opposite to adults, the majority of paediatric chordomas are intracranial, characteristically centered on the sphenooccipital synchondrosis. Metastatic spread seems to be the prerogative of the under 5-year-old children with more frequent sacro-coccygeal locations and undifferentiated histology. The clinical presentation depends entirely on the tumour location. The most common presenting symptoms are diplopia and signs of raised intracranial pressure. Sacrococcygeal forms may present with an ulcerated subcutaneous mass, radicular pain, bladder and bowel dysfunctions. Diagnosis is suspected on computerised tomography showing the bone destruction and with typically lobulated appearance, hyperintense on T2-weighted magnetic resonance imaging. Today, treatment relies on as complete surgical resection as possible (rarely achieved because of frequent invasiveness of functional structures) followed by adjuvant radiotherapy by proton therapy. The role of chemotherapy has not been proven. Prognosis is better than in adults and depends on the extent of surgical resection, age and histology subgroup. Biological markers are still lacking to improve prognosis by developing targeted therapy.

Endoscopic endonasal surgery for sinonasal and skull base lesions in the pediatric population

Endoscopic endonasal skull base surgical techniques, initially developed in adult patients, are being utilized with increasing frequency in pediatric patients to treat sinonasal and skull base lesions. This article reviews the current state of endoscopic endonasal approaches to the skull base to both treat disease and reconstruct the skull base in pediatric patients. Sinonasal and skull base embryology and anatomy are reviewed as a foundation for understanding the disease processes and surgical techniques. Selected skull base pathologies and conditions that involve the pediatric skull base are also reviewed.

Meningiomas of the pediatric skull base: a review

Pediatric skull base meningiomas are rare and complex clinical entities. Meningioma is a relatively uncommon brain tumor in children, and only ∼ 27% involve the skull base. Some evidence suggests that these tumors are more likely to be atypical or malignant in children than adults. The absence of female preponderance in pediatric meningiomas is reflected in the skull base subpopulation. Skull base meningiomas in children are most likely to be found in the anterior or middle fossa base, or involving the orbit and optic nerve sheath. Petroclival, suprasellar/parasellar, cerebellopontine angle, cavernous sinus, and foramen magnum tumors are very rare. Meningiomas constitute a small proportion of reported cases of pediatric skull base pathology, and they are entirely absent from many case series. Initial gross total resection is consistently associated with superior outcomes. Surgical approaches to the pediatric skull base must take additional factors into consideration including relatively smaller anatomy, immature dentition, incompletely aerated sinuses and air cells, and altered configurations of structures such as the pterional bony complex. Multidisciplinary expertise is essential to optimizing treatment outcomes.

Skull base surgery for tumors in children: long-term clinical and functional outcome

OBJECT

Skull base tumors in children are rare but require complex approaches with potential morbidity to the developing craniofacial skeleton, in addition to tumor-related morbidity. Reports of long-term clinical and functional outcome following skull base approaches in children are scarce. The authors report long-term outcome in children with tumors undergoing multidisciplinary skull base surgery.

METHODS

A retrospective analysis was undertaken of children undergoing surgery at a single institution between 1998 and 2008 for benign and malignant lesions of the anterior, middle, or posterior cranial base. Patients with craniopharyngioma, pituitary tumors, and optic glioma were excluded. Histology, surgical morbidity, length of hospital stay, progression-free survival, and adjuvant therapy were recorded. Functional and cognitive outcome was assessed prospectively using the Late Effects Severity Score (LESS).

RESULTS

Twenty-three children ranging in age from 13 months to 15 years underwent skull base approaches for resection of tumors during the study period. The median follow-up duration was 60 months. Tumor types included meningioma, schwannoma, rhabdomyosarcoma, neuroblastoma, angiofibroma, and chordoma. Complete resection was achieved in 12 patients (52%). Thirteen patients (57%) had benign histology. The median hospital stay was 7 days. There were 3 deaths, 1 perioperative and 2 from tumor progression. Two patients had CSF leakage (9%) and 2 developed meningitis. Two children (9%) had residual neurological deficit at last follow-up evaluation. Thirteen (59%) of 22 surviving patients received adjuvant therapy. The majority of the patients remain in mainstream education and 19 of the 20 surviving children have an LESS of 3 or lower.

CONCLUSIONS

Children tolerate complex skull base procedures well, with minimal surgical-related morbidity as well as good long-term tumor control rates and functional outcomes from maximal safe resection combined with adjuvant treatment when required.

Quantitative evaluation of transtemporal and facial translocation approaches to infratemporal fossa

OBJECTIVE

To compare the extent of exposure and surgical maneuverability provided by facial translocation and transtemporal approaches for access to the infratemporal fossa and anterolateral skull base.

MATERIALS AND METHODS

Surgical procedures were performed on five fresh frozen adult cadavers (ten sides) with no known pathology. Facial transfacial approaches with and without a mandibulotomy and transtemporal approaches were evaluated. OBJECTIVE measures were (1) the distance from the surgical plane to designated anatomic landmarks and (2) the surgical angle of exposure.

RESULTS

Distances from the surgical plane to the anatomic reference points were comparable for most of the access procedures (3 to 6 cm). The extended midfacial translocation and bilateral facial translocation approaches did, however, provide a shorter operative distance (1 to 3 cm) for access to the infratemporal fossa and contralateral structures, respectively. The transtemporal approaches facilitate a better angle of exposure (74 to 84 degrees) to the petrotemporal region, while the transfacial approaches were superior for access to the infratemporal structures.

CONCLUSIONS

Based on the results, we propose a clinical algorithm for selecting a surgical approach based on the position and extent of an infratemporal or petrotemporal lesion.

Skull base reconstruction in the pediatric patient

Tumors of the skull base are rare in children and adolescents and present a complicated management problem for oncologists and surgeons alike. Surgical resection is an integral component of the management of many pediatric neoplasms, especially those that are benign or, though not frankly malignant, are locally invasive. The general principles of skull base reconstruction following tumor ablation are applicable to nearly all patients; the reconstructive algorithm, however, is particularly complex in the pediatric population and the potential benefits of therapy must be balanced against the cumulative impact on craniofacial growth and maturity and the donor site morbidity. A retrospective analysis of all patients less than 19 years of age who underwent resection of a skull base tumor was performed. Particular emphasis was placed on the 12 patients who required complex reconstruction by the plastic surgical service. This represents approximately a third of the operated patients. Data were recorded on patient age, tumor pathology and location, prior therapies, surgical approach, extent of resection, margin status, defect components, details of reconstructive methods employed, complications, additional procedures or interventions, and the use and timing of adjuvant therapies. Patient outcome at most recent follow-up was recorded. All patients were followed clinically and by MRI and/or CT scan of the skull base. The reconstructive details recorded included flap choice, recipient vessels, and any concomitant procedures performed. The indications for and details of any staged surgical revisions or prosthetics were also noted. Complications recorded included partial or total flap loss, cerebrospinal fluid leakage, meningitis, infection, abscess, hematoma or seroma formation, delayed healing, and donor site dysfunction. The vertical rectus abdominis myocutaneous free flap was the most common means of reconstruction utilized in this series. Three of 12 patients had reconstruction related complications. Delayed reconstructive procedures or prosthetic interventions have been performed in 6 of the 12 patients who underwent complex reconstructions. On the basis of our experience and previous reports in the literature, we offer the following guidelines for the successful multidisciplinary care of children and adolescents undergoing skull base reconstruction after tumor resection: (1) skull base reconstruction may be safely performed in children and adolescents using free tissue transfer or local flaps; (2) larger defects and those involving more than one anatomic region of the skull base should be repaired with soft-tissue free flaps; and (3) because of the versatility and reliability of free flaps, pedicled flaps should be reserved for limited defects. Because of the potentially synergistic effects of multimodality treatment for skull base malignancies on craniofacial growth and development, we advocate soft-tissue reconstruction as the primary technique, reserving bony flaps for definitive procedures in survivors who have reached skeletal maturity.

Outcome of craniofacial surgery in children and adolescents with malignant tumors involving the skull base: an international collaborative study

BACKGROUND

The aim of the study was to characterize the distribution of anterior skull base (ASB) cancers in the pediatric population and to identify predictors of outcome.

METHODS

This was an international study of 1307 patients undergoing craniofacial surgery for malignant tumors; 6.4% (n = 84) among these were <or=21 years old.

RESULTS

The most common histologic type was sarcoma (40%), followed by squamous cell carcinoma (14%). Higher incidence of tumors was found in older children (7.5-21 years) compared to younger children. The 5-year disease-specific and overall survival rates were 61% and 55%, respectively (median follow-up of 30 months). The best prognosis was associated with low-grade sarcomas and the worst with salivary and squamous cell carcinomas. High-grade sarcoma represented an intermediate risk group. On multivariate analysis, prior radiotherapy and histology were independent predictors of survival.

CONCLUSION

Surgery for malignant tumors involving the ASB is feasible and safe in children. Histology is significant determinant of poor outcome in this population.

Spectrum of skull base tumors in children and adolescents: a series of 42 patients and review of the literature

OBJECTIVE

This study aims to contribute to the collective experience with the treatment of those skull base tumors exceptionally arising in children and adolescents.

MATERIALS AND METHODS

We retrospectively reviewed 42 patients younger than 19 years and operated on for a skull base tumor between 1992 and 2002. We analyzed data regarding patient age, histology, tumor location, extent of resection, postoperative complications, and adjuvant therapies. Long-term outcomes were also tracked (functional sequelae, recurrence, mortality).

CONCLUSION

The median age was 13.75 years. Twenty-two patients harbored a malignant tumor. Gross total resection was achieved for 78% of cases. Transient postoperative cerebrospinal fluid leak or infection affected ten patients, suggesting the need for reconstructive techniques. Nineteen patients received adjuvant therapy. Recurrence rate was 47%. At the end of the follow-up (median = 63 months), 14% of patients had a neurological deficit and 30% were dead. Middle cranial base tumors were associated with a poor prognosis.

Cancer of the nasal cavity in the pediatric population

OBJECTIVE

The purpose of this work was to investigate the clinical manifestations and diagnostic range of malignant entities presenting as a nasal mass in the pediatric population.

PATIENTS AND METHODS

A retrospective cohort analysis was conducted at a specialty hospital and a tertiary care university hospital. Patients aged between birth and 18 years and diagnosed with a malignancy that arose within the nasal cavity between the years 1991 and 2006 were included. This institution-specific patient group was compared with a similar cohort of patients extracted from the national Surveillance Epidemiology and End Results database. The main outcome measures were the incidence, presentation, and diagnoses of nasal cancer presenting in this population.

RESULTS

Sixteen patients with nasal malignancies presented institutionally in the defined pediatric age group. Patient age at the time of diagnosis ranged from 7 months to 17 years, with a slight male predominance. The main presenting symptoms were unilateral nasal congestion and ophthalmologic complaints. The median time from presentation to diagnosis was 7 weeks; patients who presented with nonspecific complaints, such as nasal obstruction, headache, and fatigue, were given a diagnosis, on average, later than those who presented with focal manifestations. Nationwide, 47 patients were identified from the Surveillance Epidemiology and End Results database. In both subject groups, the most common diagnoses were rhabdomyosarcoma (37.5% institutionally and 23% in the Surveillance Epidemiology and End Results group) and esthesioneuroblastoma (25% institutionally and 28% Surveillance Epidemiology and End Results). In the Surveillance Epidemiology and End Results cohort, the overall mean survival rate was 188 months.

CONCLUSIONS

Nasal cancer in the pediatric population often presents with nonspecific signs and symptoms, and a high index of suspicion is necessary for a timely diagnosis. Soft tissue sarcomas are expectedly common. The relative high frequency of esthesioneuroblastoma is particularly noteworthy.

Transnasal Endoscopic Resection of Juvenile Nasopharyngeal Angiofibroma without Preoperative Embolization

Juvenile nasopharyngeal angiofibroma (JNA) is a benign, highly vascular, and locally invasive tumor. Because the location of these tumors makes conventional surgery difficult, interest in endoscopic resection is increasing, particularly for the treatment of lesions that do not extend laterally into the infratemporal fossa. We report the results of our series of 23 patients with JNA (stage IIB or lower) who underwent transnasal endoscopic resection under hypotensive general anesthesia without preoperative embolization of the tumor. All tumors were successfully excised. The amount of intraoperative blood loss was acceptable. We observed only 1 recurrence, which was diagnosed 19 months postoperatively in a patient with a stage IIB primary tumor. We observed only 3 complications during follow-up—all synechia. We conclude that endoscopic resection of JNAs is safe and effective. The low incidence of recurrence and complications in this series indicates that preoperative embolization may not be necessary for lesions that have not undergone extensive spread; instead, intraoperative bleeding can be adequately controlled with good hypotensive general anesthesia.

Infantile clivus chordoma without clivus involvement: case report and review of the literature

BACKGROUND

We present a giant clival chordoma with disseminated disease but without involvement of the clivus. To our knowledge, this is the youngest child and only the second case, presenting without base of skull involvement, in paediatric literature and the fourth reported case of a chordoma in a patient with tuberous sclerosis.

DISCUSSION

We discuss the subtle presentation, difficulties in diagnosis and management and also review the literature.

Skull base approaches in the pediatric population

BACKGROUND

This study aimed to examine the surgical, oncologic, and developmental results of infants and children undergoing extirpation of skull base tumors.

METHODS

Sixty-seven children aged 0.5 to 18 years (mean, 11 years) who were operated on during a 6-year period made up the study cohort. Eighteen cases (27%) involved malignant tumors, and 49 (73%) involved benign tumors. The most common benign tumors were craniopharyngioma (n = 10) and juvenile nasopharyngeal angiofibroma (n = 8). The most common malignant tumor was sarcoma (n = 5). Thirty-six tumors (55%) involved the anterior skull base, and the rest involved the lateral (n = 24) and posterior (n = 7) skull base. Subcranial, transfacial, and subfrontal approaches were used for extirpation of anterior skull base tumors. Voluminous or malignant tumors were excised by use of combined approaches (subcranial-transfacial, subcranial-degloving, or pterional-degloving). Twenty-two children underwent adjuvant therapy (chemotherapy, radiation, or both). Postoperative follow-up was 3 to 60 months.

RESULTS

No severe postoperative complications (ie, meningitis, cerebrospinal fluid leak, tension pneumocephalus) and no perioperative mortality occurred. Two and a half years later, 54 of the children (80%) are alive and well. Five children, two with optic glioma and one each with squamous cell carcinoma, ependymoma, and germinoma, have died of their disease. The subcranial approach had no cosmetic impact on the craniofacial development of the patients.

CONCLUSION

The extirpation of skull base tumors by use of conventional surgical techniques is feasible and safe among infants and children. The complication and mortality rates are lower than those in adults. The long-term cosmetic effect of the subcranial approach is negligible.

Cosmetic considerations in cranial base surgery

Recent advances in the surgical techniques for the resection of cranial base tumors have allowed for improved degrees of tumor resection, functional outcomes, and esthetic results. If the resection and functional results are not compromised by procedures providing excellent cosmetic outcomes, there is no reason to ignore or compromise the esthetic aspect with regard to technical execution and planning. A thorough assessment of the patient's preoperative deficits and tumor anatomy and a working knowledge of the available cranial base approaches and their combinations permit the surgeon to design an approach that allows for optimal tumor resection with the best possible cosmetic result. In a time when alternative treatment options like radiosurgery exist for cranial base tumors, esthetic outcome is a significant quality-of-life issue that patients consider in their decision to choose surgery versus an alternative treatment.

Tumors of the skull base in children: review of tumor types and management strategies

Although many treatment strategies for skull base tumors in adults have been reported, relatively little has been reported regarding such therapies in the pediatric population. Skull base tumors in children present a therapeutic challenge because of their unique pathological composition, the constraints of the maturing skull and brain, and the small size of the patients. In this review, the authors examine the pediatric skull base lesions that occur in the anterior, middle, and posterior cranial base, focusing on unique pediatric tumors such as encepahalocele, fibrous dysplasia, esthesioneuroblastoma, craniopharyngioma, juvenile nasopharyngeal angiofibroma, cholesteatoma, chordoma, chondrosarcoma, and Ewing sarcoma. They review management strategies that include radio- and chemotherapy, as well as surgical approaches with emphasis on the modifications and complications associated with the procedures as they apply in children. Evidence for the advantages and limitations of radiotherapy, chemotherapy, and surgery as it pertains to the pediatric population will be examined. With a working knowledge of skull base anatomy and special considerations of the developing craniofacial skeleton, neurosurgeons can treat skull base lesions in children with acceptable morbidity and mortality rates. Outcomes in this population may be better than those in adults, in part because of the benign histopathology that frequently affects the pediatric skull base, as well as the plasticity of the maturing nervous system.

Cerebellopontine angle tumors: role of magnetic resonance imaging

The cerebellopontine (CP) angle is bound anterolaterally by the posterior aspect of the petrous temporal bone and posteromedially by the cerebellum and pons. It contains important vascular structures and cranial nerves and is subject to a certain gamut of lesions, notably tumors with interesting radiological manifestations. Radiological investigation of these lesions has seen significant improvement in recent decades. Magnetic resonance is the imaging modality of choice for lesions of the CP angle and internal auditory canal. Lesions of the CP angles usually are divided into those native to the angle (vestibular schwannoma, meningioma, epidermoid, arachnoid cyst, metastases, lipoma, etc.) and those extending to the angle from adjacent structures (gliomas, ependymomas, choroid plexus papillomas, vascular malformations). Vestibular schwannomas are by far the most important lesion of the CP angle.