Spontaneous CSF Leaks and Encephaloceles

Spontaneous cerebrospinal fluid (sCSF) leaks of the temporal bone are an uncommon but important cause of middle ear effusion (Rao et al., Otol Neurotol 26(6):1171-1175, 2005; Leonetti et al., Ear Nose Throat J 84(11):700, 2005; Gubbels et al., Otol Neurotol 28(8):1131-1139, 2007). Because eustachian tube dysfunction and otitis media are more common causes of effusions, the diagnosis of a sCSF leak is often delayed. Fluid suspected to be CSF can be analyzed for beta-2 transferrin, which has 97% sensitivity and 99% specificity for CSF. High-resolution computed topography is the best initial imaging modality. Over 50% of sCSF leaks will have multiple defects, and some defects will be in less common locations such as the posterior fossa or petrous apex, so viewing both axial and coronal scans is essential. MRI is useful to better evaluate for the presence of a meningocele or encephalocele. Obesity, idiopathic intracranial hypertension (IIH), and obstructive sleep apnea (OSA) are associated with sCSF leaks, so these conditions should be investigated. Patients with skull base defects are at a higher risk of meningitis and should undergo appropriate vaccination. Treatment of IIH and OSA is important after surgical repair to prevent recurrent leaks.