32.1.1 Anatomical Considerations in Pediatric Population

It has been established that most of the growth in the skull base takes place in the first five years of life and continues for at least 10 years after birth. ^{10 , 11} Hence adult surgical approaches to the cranial base require modification when implemented in a child. ¹¹ The smaller size and thinness of the bones of the cranial base requires lesser drilling. It is also well known that the mastoid process is absent at birth and is not fully developed until 3 years of age. This renders the FN, which is more superficial and inferior, vulnerable to surgery. The anatomy of the inner ear, though, once formed, changes little in structure or growth throughout life into adulthood. The effect of extensive bony removal and of ossification centers and unfused suture lines may have an unfavorable effect on the growth of the surrounding structures and it is necessary that further studies are focused on this. ¹

32.1.2 Demography

The occurrence of tumor in the skull base expands itself along the entire growing years from birth to the end of adolescence. The age ranges from 1 year to 18 years in our series (▶ Table 32.1), which was also seen in other series. ^{5 , 12} Although there is a slight male preponderance in some series, small numbers makes this observation inconclusive.

32.1.3 Clinical Features

There is always a delay in diagnosis of skull base pathology, especially in younger children. This apart, unfortunately, the duration between onset of symptoms and intervention in children is also quite long. ^{6 , 9} This is due to multiple factors such as inability of children to express their symptoms adequately, misdiagnosis due to the rarity of pathology of this nature, or reluctance of performing a radical intervention by the treating practitioner because of the tender age of the patients. This is reflected by the fact that prior to surgery at our center, total deafness was seen in 35.4% of cases and a high grade of hearing deterioration in the rest (▶ Table 32.2). After a diagnosis, 32.3% of the cases were treated elsewhere by less extensive procedures before they were referred to our center. Fortunately, the FN function fared better with 83.1% of the cases presenting with an HB grade I or II. Lower cranial nerve dysfunction was noted in 9.2% of cases.

The most common complaints are hearing loss, otalgia, headache, pain over the face, facial weakness, upper neck swelling, epistaxis/nasal obstruction, visual disturbances, nausea, and vomiting. The most common clinical findings are ear discharge, mass in the external auditory canal, hearing loss, facial weakness, decreased facial sensation, decreased visual acuity, and hoarseness/swallowing difficulties. Almost all the cranial nerves from the first to the twelfth can be involved in skull base pathology either individually or with others. Acoustic Neuromas and other lesions involving the cerebellopontine angle (CPA) usually involves the acousticofacial bundle (VII, VIII cranial nerves). Lesions involving the jugular foramen like paragangliomas, schwannomas, meningiomas, and chondrosarcomas usually involve the lower cranial nerves (IX, X, XI, XII cranial nerve). Lesions that involve the temporal bone like petrous bone cholesteatomas (PBCs), cholesterol granulomas, chordomas, etc., can involve the trigeminal nerve and the nerves in the cavernous sinus.

32.1.4 Pathology

There is very little data in the modern English literature on pathologies that involve the skull base in children. However, the spectrum of diseases in children is more or less the same as in adults. However, some tumors are reportedly more common in children, like encephaloceles, fibrous dysplasia, esthesioneuroblastomas, astrocytomas, pituitary adenomas, craniopharyngiomas, hemangiomas, giant cell tumors, malignant fibrous histiocytomas, optic nerve gliomas, osteoblastomas, rhabdomyosarcomas, juvenile nasopharyngeal angiofibromas, and Ewing sarcoma. ¹³ In this chapter we focus on pathologies afflicting the posterior and middle cranial fossa.

The most common tumors arising in children from the posterior cranial fossa and the temporal bone are cholesteatomas, chondrosarcomas, rhabdomyosarcomas, chordomas, vestibular schwannomas (VS), and meningiomas. In our series, ¹ nontumoral pathology (n = 40) exceeded tumoral pathology (n = 25). PBCs were the most common pathology seen in our series, followed by VS. The list of pathologies seen in our series is enlisted in ▶ Table 32.3 along with the surgical approaches. Jackson CG et al ² reported 53.3% of tympanojugular paragangliomas (TJPs) in their series which is contrary to our observation.