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Diagnosis and medical management of idiopathic intracranial hypertension

Introduction Idiopathic intracranial hypertension (IIH) is a condition defined by increased intracranial pressure without an identifiable cause and its associated symptoms, most notably headache and vision loss. With an estimated incidence of 0.9 per 100,000 in the general population, IIH is primarily observed in overweight women of childbearing age, with an incidence of 7.9 to 20 per 100,000. The diagnosis of IIH requires careful consideration of…

Pathophysiology of spontaneous cerebrospinal fluid leaks and their relationship with idiopathic intracranial hypertension

Introduction The relationship between spontaneous cerebrospinal fluid (CSF) leak and intracranial hypertension has been recognized for nearly two centuries, following the description of a child with hydrocephalus and CSF rhinorrhea in 1826. However, it was not until 1968 when Ommaya et al. suggested a system for classifying nontraumatic spontaneous CSF rhinorrhea that recognized high-pressure leaks as its own category, including known associations with intracranial tumors and…

Postoperative management of traumatic cranial base defects

Introduction The surgeon’s role in repair of a defect causing cerebrospinal fluid (CSF) rhinorrhea does not end with removal of the drapes. Without appropriate postoperative medical and surgical care, the most well-laid surgical repair may ultimately fail with recurrence of CSF leakage. Although little additional postoperative management is required in some simple cases of anterior skull base, low-flow defects without compounding factors that elevate intracranial pressure…

Surgical management of large traumatic anterior cranial base defects via craniotomy

Introduction Major craniofacial trauma can result in numerous comminuted fractures of the frontal and facial bones, and when in-driven, multiple lacerations of the dura mater, laceration and contusion of the underlying frontal lobes, and cerebrospinal fluid (CSF) leak in the form of rhinorrhea, direct leak via open lacerations and tissue defects, or even from the orbit. Surgical management of these injuries requires a thorough understanding of…

Surgical management of iatrogenic cerebrospinal fluid rhinorrhea

Introduction Classification Cerebrospinal fluid (CSF) rhinorrhea results from a breach in the skull base, leading to communication between the subarachnoid space and nasal cavity. The accurate classification of CSF leak etiology is paramount because this information often guides management. An in-depth discussion regarding categorization of CSF rhinorrhea can be found in Chapter 1 , but broadly speaking, there are traumatic and nontraumatic causes. Traumatic causes can…

Imaging of anterior skull base trauma

Introduction Patients with skull base fractures often have accompanying orbital and intracranial injuries, which warrant attention on dedicated imaging evaluation. Computed tomography (CT) is the modality of choice for evaluating anterior skull base fractures and associated intracranial hemorrhage and localizing sites of cerebrospinal fluid (CSF) leakage for surgical repair. Magnetic resonance imaging (MRI) is useful for better delineating potential traumatic cephaloceles and brain injury. Vascular imaging…

Pathophysiology and clinical evaluation of blunt force and penetrating trauma of the anterior cranial base

Introduction Cerebrospinal fluid (CSF) leaks may occur in about 2% to 4% of skull base fractures. , CSF leaks are five to six times more likely to occur in the anterior skull base than the rest of the cranial fossa. Complications such as pneumocephalus, meningitis, or brain abscess can occur. Of these skull base fracture–related CSF leaks, 28% can result in meningitis and have an associated…

Pathophysiology and clinical evaluation of iatrogenic cerebrospinal fluid rhinorrhea after sinus surgery

Introduction Despite significant advances in endoscopic surgical training, technique, and instrumentation, endoscopic sinus and skull base surgery can result in inadvertent skull base injury with subsequent cerebrospinal fluid (CSF) leak a small percentage of the time. Iatrogenic CSF leaks are the most common cause of CSF leak overall in the literature, representing a more frequent cause of CSF rhinorrhea than accidental traumatic injuries. Although traditional endoscopic…

Surgical anatomy of the posterior cranial fossa

Introduction Cerebrospinal fluid (CSF) leaks arising from the posterior fossa are uncommon and are usually a result of abnormal communications between the subarachnoid space and air-containing spaces in the temporal bone. Causes of these abnormal communications include trauma, surgical defects, or spontaneous incidence, often in the setting of some congenital abnormality or predisposing factor. This chapter reviews the surgical anatomy of the posterior cranial fossa and…

Surgical anatomy of the middle cranial fossa

Introduction The skull base represents the inferior segment of the cranium and traditionally is arbitrarily divided into three segments known as the anterior, middle (MCF), and posterior cranial fossae. From a surgical perspective, relevant neurovascular and anatomic functional structures must be recognized and preserved through the different approaches to the MCF to avoid potential complications. , This chapter reviews the surgical anatomy and relevant structures that…

Surgical anatomy of the anterior cranial fossa

Introduction It is essential for otolaryngologists and neurosurgeons to have a thorough understanding of the complex anatomy of the anterior skull base. This knowledge allows surgeons to navigate the different intranasal surgical approaches that can be used to manage sinonasal and skull base pathology and to avoid surgical complications. Cerebrospinal fluid (CSF) leaks in the anterior skull base can occur spontaneously or during extended endoscopic endonasal…

Cerebrospinal fluid physiology and dynamics

Introduction The discovery, physiology, and flow of the mysterious “liquor cerebrospinalis” has been an ongoing debate and topic of inquiry which continues in the present time. The great Greek physician Hippocrates (460–370 bc ) embraced the ancient theory of “humoralism” and developed it into a medical theory. It ascribed certain illnesses, emotions, and behavior to an excess or lack of body fluids. This line of thinking…

Role of imaging studies in the evaluation and localization of cerebrospinal fluid leaks

Introduction The radiographic approach to the assessment of skull base cerebrospinal fluid (CSF) leaks, whether traumatic, iatrogenic, congenital, secondary to underlying increased intracranial pressure, or otherwise spontaneous, can be aimed at attempting to initially answer the question of whether a true CSF leak can be detected and then to both localize the site of the leak and to assess the surrounding anatomy for potential preoperative planning…

Confirmatory testing for cerebrospinal fluid rhinorrhea

Introduction Cerebrospinal fluid (CSF) leaks can lead to life-threatening conditions, including meningitis and stroke. Depending on the cause and especially for spontaneous CSF leaks, diagnosis of a CSF leak can be challenging given that nasal mucus can be difficult to distinguish from CSF. Analysis of nasal secretions is frequently used to confirm the presence of a CSF leak when the presence of one is not obvious.…

Evaluation of the patients with cerebrospinal fluid leaks: History and physical examination

Introduction When evaluating a patient for a cranial base cerebrospinal fluid (CSF) leak, the history and physical examination are critical steps to determine the diagnosis, cause, and localization. Establishing the diagnosis of CSF rhinorrhea can be challenging because there is a wide range of causes and presentations, as well as many causes of rhinorrhea that can mimic a CSF leak. CSF rhinorrhea itself is caused by…

Categorizing cerebrospinal fluid leaks: A framework for understanding

Introduction Cerebrospinal fluid (CSF) rhinorrhea is the drainage of spinal fluid from the intracranial space through the nose via the paranasal sinuses. The condition was initially described in the second century by Galen of Pergamon (130–200 ad ), who identified the ventricles to be reservoirs for the animal spirits produced in the brain. He postulated that this liquid carrying the spirits was mixed with air entering…

Osteoplastic Flaps With and Without Obliteration

Introduction ▪ The osteoplastic flap with obliteration of the frontal sinus was considered the mainstay of surgical management of the frontal sinus in the 1950s and 1960s. ▪ The osteoplastic approach to the frontal sinus was first described in 1894 by Schonborn and later modified through the earlier parts of the twentieth century. ▪ Modern concepts of the osteoplastic approach to the frontal sinus stem from…

Frontal Sinus Trephination

Introduction ▪ Modern trephination of the frontal sinus was first described in 1884 by Ogston. ▪ Since the 1980s, endoscopic sinus surgery has been considered the standard of care for the initial surgical management of frontal sinus disease, except in select cases. ▪ Despite endoscopic advancements in the field, frontal trephination is an essential part of a sinus surgeon’s armamentarium. ▪ Trephination provides the surgeon with…

Large Skull Base Defect Reconstruction With and Without Pedicled Flaps

Introduction ▪ Advances in endoscopic sinonasal surgical techniques and instrumentation have led to an expansion in the size and diversity of skull base lesions that are amenable to an entirely endoscopic resection. However, one of the requisites for successful removal of skull base lesions is the ability to repair the resultant defect, as failed reconstructions add significant morbidity. ▪ The ideal endoscopic skull base repair has…

Endoscopic Management of Clival Chordomas and Chondrosarcomas

Introduction ▪ Successful management of malignant clival pathology extending into the posterior fossa continues to be a formidable challenge to the skull base surgeon. ▪ Classically, the clivus and posterior fossa have been approached using lateral and/or transoral-transpalatal routes. ▪ These approaches often lead to collateral/bystander damage to functional tissue structures uninvolved with the primary disease and are commonly associated with cranial nerve deficits and other…