Cerebrospinal Fluid (CSF) Leaks


Cerebrospinal fluid (CSF) is constantly made by the brain and reabsorbed into the blood system. On occasion, as a result of a skull fracture, weakness of the brain covering (dura), intracranial surgery or growth of a brain tumor, CSF may leak through the brain covering. This is a potentially dangerous condition that can lead to an infection of the CSF (meningitis) or of the brain itself (brain abscess).

One of the more common complications of endonasal transsphenoidal surgery is a post-operative CSF leak. CSF leaks that occur at the time of surgery require careful repair to avoid a post-operative CSF leak. The extent and type of skull base repair depends on the size and location of the defect. Using a graded repair methodology, the chance of a post-operative CSF leak is generally 1% or less for standard endonasal removal of pituitary adenomas and other sellar tumors (Grade 1 and 2 CSF leaks and skull base defects) but is increased to 3-5% for large skull base defects (Grade 3) associated with endonasal endoscopic removal of brain tumors such as craniopharyngiomas, meningiomas and some very large invasive pituitary adenomas.  


A CSF leak is usually associated with watery clear drainage out of the nose (after endonasal surgery or retromastoid surgery) or out of a surgical incision. If there is persistent drainage occurring within the first 1-2 weeks after surgery, you should contact your surgeon promptly. If meningitis has occurred, headache, stiff neck, fever and photophobia (sensitivity to light) may occur; other symptoms such as weakness, in-coordination and confusion may occur 


The diagnosis of a post-operative CSF leak is made by noting watery drainage out of the nose or a surgical incision. A brain MRI or CT scan may also show from where the CSF leak is originating and may reveal intracranial air (pneumocephalus). A CT scan with injection of a contrast agent through the lumbar spine (a spinal tap) can also be helpful in localizing the origin of a CSF leak and dural defect. In some instances, it may be difficult to determine if fluid from the nose or ear is actually CSF. To help determine this, a sample of the fluid can be collected and tested for a compound found only in the CSF called Beta-2 transferrin. If you have endonasal endoscopic surgery or a retromastoid craniotomy, you will be assessed for a post-operative CSF leak prior to discharge home. 


Treatment of a CSF leak requires either direct surgical repair or in some instances use of temporary diversion of CSF through a lumbar drain or a ventriculostomy (a catheter placed in the ventricle of the brain). In some instances, both surgical repair and CSF diversion are required to effectively seal a CSF leak. More recently, for repair of large (Grade 3) anterior skull base defects associated with endonasal surgery, we have begun selective use of a pedicled naso-septal flap as part of the multi-layered repair.