– This approach may lead to communication between the nose and the prepontine cistern, resulting in high-flow CSF rhinorrhea.
– Similar to the transtuberculum approach, postoperative CSF rhinorrhea is minimized by multilayered reconstruction and possible addition of a lumbar drain.
– Postoperative CSF rhinorrhea rates as high as 25% to 33% are reported following resection of clival malignancies.
• Prevention and management of CSF leaks
– Useful for small, low-flow defects
– Graft options include bone, cartilage, mucosa, fat, fascia, or acellular tissue matrix.
– The grafts can be used as a simple onlay or as a combined inlay/onlay.
– The gasket seal is a particularly effective combination graft that includes a rigid inlayed buttress with a soft-tissue scaffold. which is itself both an inlay and onlay graft.
2. Vascularized flaps
– Options include the nasoseptal flap, inferior turbinate flap, and the pericranial flap.
– For large or high-flow defects, vascularized flaps decrease postoperative CSF rhinorrhea rate by approximately 50%.
– The nasoseptal flap is the most frequently used vascularized flap, and is based on the septal branch of the sphenopalatine artery.
3. Lumbar drains
– Benefits of lumbar drainage include diversion of CSF away from the repair site, ability to instill fluorescein to look for leak, and access for postoperative intracranial pressure monitoring.
– Risks of lumbar drain include headache, infections (cellulitis, meningitis, ventriculitis), tension pneumocephalus, subdural hemorrhage, and brain herniation.
– Given the risks of lumbar drainage and proven efficacy of current endoscopic skull base repairs such as the nasoseptal flap, routine lumbar drainage following repair of intra-operative CSF leak is not recommended.
– Lumbar drains may be useful as a supplement to multilayered reconstruction in the following circumstances:
a. Early postoperative CSF leak
b. High-flow leak areas such as the clivus
d. Radiation history
e. Large or complex defects
Posterior Septal Artery
• Contributes to the majority of post-operative arterial bleeds
• This branch of the sphenopalatine artery is located inferior to the sphenoid os and splits into an inferior and superior branch prior to entering the septum.
• Prevention of vessel injury:
1. Careful inferior mobilization of this mucosa (rostrum and posterior septum) during sphenoidotomy
2. Prophylactic partial nasoseptal flap elevation (“rescue flap” to prevent injury to the artery during procedure
• Prophylactic cautery of the vessel is not recommended since it is critical for reconstruction of skull base defects.
Anterior and Posterior Ethmoidal Arteries
• Injury to these arteries is most often seen in the transcribriform approach.
• Arterial injury may be followed by retraction into the orbit with resultant rapid development of orbital hematoma, rise in intra-orbital pressure, optic nerve ischemia, and subsequent blindness.
• A slower developing orbital hematoma may also develop from venous bleeding from orbital fat or extra-ocular muscle injury.
• Prevention is accomplished by identification and cautery of arteries during the approach, and extreme care when removing the lamina papyracea or periorbita.
• Early signs of orbital hematoma include preseptal edema, ecchymosis, and proptosis.