Cranial base surgery (acoustic, acoustic neuroma)
The malignancy of cranial base tumours is mostly defined by neuro-anatomical conditions. The most commonly encountered tumours are meningiomas and neuromas. Most of these tumours are acoustic neuromas, trigeminal neuromas and neuromas of the jugular foramen. Neuromas and neurofibromas caused by neurofibromatosa are less common. meningiomas of the posterial cranial fossa, the petrous bone, the clivus and the foramen magnum are categorised in accordance with their anatomical positions. The complex forms of tumour affecting the cranial base include petroclival, sphenoid bone and cavernous sinus meningiomas. Meningiomas of the anterior cranial fossa, such as meningiomas of the nasal apertures (olfactorial meningiomas), the planum sphenoidale, the tuberculum sellae and the lateral spenoid bone, are less complex, but no less complicated. All the above tumours have been classified as benign by the WHO. They respond well to microsurgery and can mostly be removed without loss of function. These types of tumour are rarely malignant. Tumours such as chordomas, chondromas, chondrosarcomas and epidermoid cysts are less frequently encountered cranial base tumours. Here, cranial base surgery plays an important role in the treatment therapy. Interdisciplinary cooperation is required in the case of paranasal carcinomas, esthesioneuroblastomas and interorbital tumours. Metastasis processes are also encountered in the area of the cranial base. New methods of depiction coupled with neuro-navigation and neuro-monitoring options are helping to optimise neurosurgical interventions.