Introduction

Skull base surgeries have evolved over a long period in response to meeting the necessity of treating complex tumors and vascular pathologies while avoiding retraction injuries to normal neurologic structures. Numerous pathologic processes arise within the skull base or extend there by direct growth. The main goal of all skull base approaches, whether microscopic or endoscopic, is to minimize the brain retraction by optimum bone resection. The widespread use of endoscopic surgical techniques in addition to advanced microsurgical skull base techniques in current times has advanced the frontiers of skull base neurosurgery.

The prevention and management of complications are an important cornerstone of skull base surgery. The complications at the skull base may be quite hazardous and usually occur due to errors in choosing the right approach or selecting the patient, or even due to technical gaffes. A myriad of complications can be encountered in skull base surgeries. The common complications are vascular injuries, cerebrospinal fluid (CSF) leak, cranial nerve palsy, wound infection, meningitis, hydrocephalus, vision changes, and cosmetic issues. The breakthroughs in radiologic imaging, advances in neuroanesthesia, and the conceptual progress in surgical techniques and intraoperative monitoring lead to the convergent evolution of this neurosurgical subspecialty. This chapter provides an overview of the major complications encountered in microsurgical and endoscopic skull base surgery and radiosurgery.

Vascular Complications

Vascular complications are the most feared complications of skull base surgeries. They can result from many causes. The infiltration of tumor to the adjacent vasculature, error in surgical technique, prior radiotherapy, inadequate preoperative imaging or interventions like cerebral angiogram or embolization, and nonoptimal use of neuronavigation or micro-Doppler are a few of them. A variety of skull base lesions can encircle the major vascular structures and lead to their narrowing. Cavernous meningioma and petroclival meningioma, which can encircle the internal carotid artery (ICA) and basilar artery, respectively, are classical examples. Pituitary adenoma and chordoma and chondrosarcoma tumors can also invade the major vascular structures like the ICA and basilar artery.

Tumors like the giant medial sphenoid wing meningioma are better evaluated with a preoperative angiogram. It provides information on the course of the ICA in relation to the tumor and associated tumor feeders and offers the opportunity to perform preoperative tumor embolization and collateral circulation assessment. Most patients may be able to tolerate ICA sacrifice based on intraoperative carotid endarterectomy studies. Depending on the possible anticipated complication of the artery/vein, the patient should be well prepared for possible bypass surgery or sinus reconstruction surgery. Knowing the relevant anatomy and the safe handling techniques for the critical neurovascular structures is essential to avoiding such complications.

CSF Leak

CSF leak is a very common complication after skull base surgery due to the close communication of the cisterns with most of the skull base approaches. The incidence of CSF leak in endonasal skull base surgeries ranges from 2% to 64% and ranges from 3% to 26.7% in vestibular schwannoma surgeries. It can range from 4% to 17% in any posterior fossa surgery. The major complications arising as a result of CSF leak are meningitis, ventriculitis, and brain abscess, which may increase the duration of hospital stay, readmission rate, and mortality risk. Craniopharyngioma usually has a higher rate of intraoperative CSF leak relative to other tumor pathologies. The incidence of pseudomeningocele after posterior fossa surgery varies between 15% and 28%. The most common factors associated with such leaks are inadequate dura and wound closure or healing, wound infection, raised intracranial pressure, and opened air petrous cells that have not been occluded. The basic strategies to prevent CSF leak are watertight dural closure and meticulous sealing of opened air cells. Multilayered closure involving fat or muscle patch, along with nasoseptal flap and bony reconstruction with placement of lumbar drain, is helpful in avoiding the postoperative CSF leak in endoscopic skull base surgeries. The Hadad-Bassagasteguy flap (HBF), a neurovascular pedicled flap of the nasal septum mucoperiosteum and mucoperichondrium based on the nasoseptal artery, seems to be advantageous for the reconstruction of the cranial base after endonasal cranial base surgery. The rate of CSF leak can be further reduced by plugging the leaking site with small pieces of fat sealed with fibrin glue. Early detection of CSF leak and avoiding raised intracranial pressure (ICP) are the important precautions to be taken for avoiding this serious complication.