Delayed postoperative cerebrospinal fluid leaks are uncommon and largely unstudied complications. In a study, London et al. aimed to identify they're etiology and understand the efficacy of various reconstruction strategies.

A retrospective chart analysis of 1017 endonasal skull base surgeries performed by a single neurosurgeon was completed identifying delayed CSF leaks (occurring >1 week after surgery).

Seventeen cases of early (1-2 weeks after surgery) or delayed (>2 weeks after surgery) postoperative CSF leak were identified. The most common reconstruction during the initial surgery consisted of an inlay or gasket seal collagen matrix (82.4% of patients) with an onlay pedicled flap (76.5% of patients). Presenting symptoms of delayed CSF leak included rhinorrhea (82.4%), headache (41.2%), and meningitis (23.5%). The most common causes included flap dehiscence (17.6%); provoking events such as emesis, sneezing, or fall (17.6%); flap necrosis (11.8%); flap displacement (11.8%); and inadequate apposition of the flap, that is, folded flap (11.8%). Reconstructive techniques of the delayed CSF leak included fortification of the initial reconstruction with free fat grafts (29.4% of patients), combined collagen matrix with a fat graft (23.5% of patients), repositioning of the previous flap (11.8% of patients), and repair with a new flap (11.8% of patients). CSF diversion (spinal/ventricular drain or shunt) was used in 17.6% of patients.

This study identifies the most common etiologic factors leading to a delayed CSF leak and its initial symptoms. Furthermore, it serves as the foundation for a reconstructive algorithm based on reinforcement of the initial repair with free abdominal fat graft with or without collagen matrix ¹⁾.