Middle fossa approach for spontaneous cerebrospinal fluid fistula and encephaloceles Purpose of review The aim of this article is to describe the middle fossa craniotomy (MFC) approach for the repair of cerebrospinal (CSF) fistula and encephaloceles. Recent findings The MFC approach has a greater than 93% success rate for managing CSF fistula and encephaloceles located along the tegmen tympani and tegmen mastoideum. Posterior fossa defects cannot be managed by an MFC approach. Multilayer repair with the combination of soft tissue and durable substances is preferred. Hydroxyapatite bone cement provides a durable repair of thinned or absent areas of bone with a low risk of infection. Concurrent management of symptomatic superior semicircular canal dehiscence may be readily performed. Small keyhole craniotomies with the utilization of the endoscope are possible as a means to minimize temporal lobe retraction. Summary MFC repair of CSF fistula and encephaloceles is a highly effective approach for the repair of tegmen mastoideum and tegmen tympani defects. Correspondence to Joe Walter Kutz, Jr., MD, Department of Otolaryngology, Southwestern Medical Center, University of Texas, 2001 Inwood Road, Dallas, TX 75390, USA. Tel.: +1 214 648 2964;. fax: +1 214 648 9122; e-mail: walter.kutz@utsouthwestern.edu Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

The role of obesity, sleep apnea, and elevated intracranial pressure in spontaneous cerebrospinal fluid leaks Purpose of review Spontaneous cerebrospinal fluid (sCSF) leaks often occurs in middle age, obese females. Here we investigate the role of obesity, idiopathic intracranial hypertension (IIH), and obstructive sleep apnea (OSA) in the pathophysiology of sCSF leaks. Recent findings The association of obesity and sCSF leaks has been well established in many studies. It has now been revealed that sCSF leak patients have thinner calvariums along with the skull base. An intracranial process likely leads to calvarium and skull base thinning in sCSF leaks patients since this occurs independent of extracranial bone thinning and independent of obesity. OSA, which is known to cause spikes in intracranial pressure (ICP), has been found to be significantly prevalent in the sCSF population and has been shown to lead to both calvarial and skull base thinning. Chronically elevated ICP (IIH) has also been shown to impact calvarial and skull base thicknesses. Summary The incidence of sCSF leaks has increased in recent decades along with an increasing rate of obesity. OSA and IIH, which are obesity-related factors and cause transient and chronic elevations in ICP, have now been implicated as critical factors leading to calvarial and skull base thinning and resultant sCSF leaks. Correspondence to Rick F. Nelson, MD, PhD, Indiana University College of Medicine, 355 W. 16th St. Suite 3200, Indianapolis, IN 46202, USA. Tel: +1 317 963 7073; fax: +1 317 963 7085; e-mail: ricnelso@iupui.edu Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

The evolution of presenting signs and symptoms of lateral skull base cerebrospinal fluid leaks Purpose of review To review the presenting signs and symptoms of spontaneous cerebrospinal fluid (CSF) leaks of the lateral skull base. Recent findings Research continues to demonstrate that CSF leaks from the lateral skull base are insidious, and present with subtle signs and symptoms. Patients commonly present with symptoms of aural fullness, middle ear effusion, and otorrhea following tympanostomy tube insertion that can be confused for chronic otitis media. More recently headache, pulsatile tinnitus, and dizziness/vertigo are being recorded as symptoms at presentation, which is likely a reflection of the association of spontaneous CSF leak with obesity, intracranial hypertension, and superior canal dehiscence. The presence of these less common symptoms in the setting of middle ear effusion should raise suspicion for CSF leak. The rate of meningitis in spontaneous CSF leak is not negligible, and patients should be counseled on this life-threatening risk. Summary Spontaneous CSF leak from the lateral skull base presents with subtle signs and symptoms and remains a diagnostic challenge. Less common symptoms may represent associations with underlying comorbidities, and awareness of the increasing coincidence of diseases that accompany spontaneous CSF leak is essential to prompt diagnosis and management. Correspondence to James G. Naples, MD, Division of Otolaryngology, Beth Israel Deaconess Medical Center, 110 Francis St, Suite 6E, Boston, MA 02215, USA. Tel: +1 617 632 7500; e-mail: jnaples513@gmail.com Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.