Pseudo-Cerebrospinal Fluid Rhinorrhea Resulting from Aberrant Cross-Innervation of Trigeminal and Facial Nerves following Skull Base Surgery

Abstract

Objectives Pseudo-cerebrospinal fluid (CSF) rhinorrhea is a rare phenomenon, presumed to result from aberrant autonomic reinnervation of the paranasal mucosa following injury to the greater superficial petrosal nerve or periarterial plexus. In this report, we discuss the case of a postoperative patient with pseudo-CSF rhinorrhea exacerbated by chewing and propose a novel mechanism of pseudo-CSF rhinorrhea. Case Report A 46-year-old man was found to have mastication-induced unilateral clear rhinorrhea following transtemporal resection of a cerebellopontine angle tumor. Computed tomography cisternogram and β-2 transferrin analysis proved negative for any evidence of CSF leak. Conclusions Pseudo-CSF rhinorrhea exacerbated by mastication has not been previously reported in the literature. We propose aberrant cross-innervation of the trigeminal and facial nerves as the mechanism underlying the patient's condition. Pseudo-CSF rhinorrhea is an important entity to identify following skull base surgery because it may spare patients from the unnecessary invasive procedures and morbidity associated with the management of a presumed CSF leak.

Pseudo-Cerebrospinal Fluid Leaks of the Anterior Skull Base: Algorithm for Diagnosis and Management

“…21 Since its first description in 1994, pseudo-CSF leaks have been described in only 24 patients. [6][7][8][9][10][11] The original description proposed a diagnostic criteria on which five features must be present: (1) Skull base procedure involving exposure, manipulation, and/or resection of the petrous or cavernous internal carotid artery and associated autonomic nerves; (2) Rhinorrhea occurs ipsilateral to the surgical procedure, and is typically exacerbated by exertion, increase in room temperature, or intense emotions, and it may begin within months and up to 2 years postoperatively;…”

“…Grannan et al, proposed another hypothesis suggesting an aberrant crossinnervation between the facial and trigeminal nerves. 9 In the end, all theories lead to an increase in parasympathetic innervation of the nasal mucosa, either from removal of sympathetic input, or reinnervation of parasympathetic fibers and hypersensitivity of postganglionic fibers. 6,7 In our cohort, seven patients had some kind of manipulation of the anterior skull base (pituitary surgery, endoscopic sinonasal surgery, transcranial surgery, trauma, or a combination), but there was no direct exposition or manipulation of the carotid artery or the sphenopalatine ganglion.…”

“…1 Early recognition of a CSF leak and subsequent identification of its underlying cause is a basic skill for skull base surgeons, due to the risk of meningitis and intracranial abscess, [2][3][4] which can reach up to 19% in cases of persistent leaks. 5 A rare condition on which unilateral watery rhinorrhea suggestive of CSF occurs in a patient without disruption of the osteodural barrier (pseudo-CSF leak), has been reported after skull base surgery, [6][7][8][9] and following trauma, 8,10,11 and its distinction from a true CSF leak is of uttermost importance to avoid unnecessary procedures, which may cause leaks or other complications by themselves. Therefore, we present our algorithm to rule out CSF leaks in patients with unilateral watery rhinorrhea, based on 10 cases of rhinorrhea feigning CSF leaks we have encountered over the past 20 years.…”