Abstract
Cerebrospinal fluid rhinorrhea is the result of a pathologic communication between the subarachnoid space and the nasal cavity. This condition most often occurs secondary to an inciting event, but it can also develop unexpectedly. The epidemiology of CSF rhinorrhea has classically been reported in association with its etiology. An initial classification system described by Ommaya in 1968 divided CSF leaks into traumatic and non-traumatic origins [1]. Traumatic leaks were further subdivided into accidental and iatrogenic, and non-traumatic into high pressure (secondary to tumors or hydrocephalus) and normal pressure leaks (such as congenital). Schlosser et al. have more recently defined the five main causes of CSF leaks as: accidental trauma, surgical trauma, tumor related, congenital, and spontaneous [2]. The most common etiology overall is accidental trauma and accounts for 80% of all CSF leaks. Surgical or iatrogenic trauma is the second most common cause and is responsible for 16% of cases. Of note, this includes both otolaryngologic and neurosurgical procedures. The remaining 4% is of non-traumatic origin [3].