May 13, 2025
Skull base cerebrospinal fluid (CSF) leaks arising over the ear can cause bothersome symptoms of hearing loss, ear fullness, and popping and crackling in the ear and also may put people at risk of meningitis. The exact underlying cause of skull base CSF leaks is not fully understood, but obesity and elevated intracranial hypertension are often associated with them. Skull base CSF leaks can be fixed with surgery to improve symptoms and reduce the risk of meningitis.
The incidence of CSF leaks has increased in recent decades, alongside rising levels of obesity. Mayo Clinic in Jacksonville, Florida, is taking a comprehensive and holistic approach to surgical repair to avoid recurrences and manage the potential underlying causes.
"We are interested in helping people long term, which includes reducing the risk for CSF leak recurrence," says Mallory J. Raymond, M.D., a neurotologist at Mayo Clinic in Jacksonville, Florida. "Rather than simply offering a quick repair for skull base CSF leaks, we also treat the risk factors that might predispose that person to a CSF leak."
Mayo Clinic's comprehensive approach to skull base CSF leaks relies on four key factors.
Multidisciplinary strategy for managing skull base CSF leaks
As a neurotologist, Dr. Raymond specializes in ear and lateral skull base surgery. She is often the first point of contact for patients presenting with a possible CSF leak. Initial symptoms of a skull base CSF leak may include:
- Clear drainage from one nostril or ear.
- Ear fullness.
- Hearing loss.
- Metallic taste.
- Sounds of fluid under the eardrum.
"Primary care doctors and general otolaryngologists often struggle with diagnosing skull base CSF leaks," Dr. Raymond says. "It overlaps in presentation with many other conditions, most commonly fluid behind the ear caused by chronic otitis media or eustachian tube dysfunction."
The neurotologists at Mayo Clinic in Florida work as the central spoke in a wheel of multidisciplinary specialists associated with the Cerebrospinal Fluid Dynamics Clinic that includes:
- Neurologists who evaluate for elevated intracranial hypertension.
- Neuroradiologists who conduct advanced imaging and interpretation.
- Neurosurgeons who perform complex CSF leak repairs.
- Neuro-ophthalmologists who assess for papilledema and possible vision loss.
The evaluation and treatment of skull base CSF leaks are part of a comprehensive plan that addresses underlying conditions and risks, such as obesity, intracranial pressure and obstructive sleep apnea (OSA), as evidenced by a study published in Laryngoscope.
"Depending on the risk factors involved, we might work closely with specialists from the Bariatric Center," says Dr. Raymond. "Addressing underlying issues helps us improve outcomes."
Advanced imaging guides precise skull base CSF leak diagnosis and repair
Repairing a skull base CSF leak requires a complex surgical approach that depends on the location and size of the leak. Brain MRI and temporal bone scans obtained with a photon-counting CT scanner help identify the source of the leak. Compared with traditional CT scans, photon-counting CT scans provide higher resolution and better visualization of anatomical structures using a lower radiation dose, as cited in the American Journal of Neuroradiology. Neuroradiologists also evaluate for encephaloceles. An encephalocele is an outpouching of the brain that is essentially squeezed through a defect in the skull base and ends up surrounding or sitting on top of ossicles, known as hearing bones.
"The protocols we use for MRI and photon-counting CT are integral," says Dr. Raymond. "They enable us to precisely identify the leak source."
Evidenced-based practices and surgical expertise yield superior outcomes for skull base CSF leak repair
The treatment team takes a nuanced, evidence-based approach to CSF leak treatment that is personalized to each patient.
"We don't yet have enough evidence to suggest that by managing intracranial pressure, we can get the leaks to stop or reduce the risk of meningitis without surgery," says Dr. Raymond. "That's why I don't routinely recommend medication or venous sinus stenting as an alternative."
The primary treatment for skull base CSF leaks at Mayo Clinic is surgery, guided by advanced imaging to ensure precise repairs. Depending on the leak location, neurotologists and neurosurgeons repair the leak from below through the mastoid at the base of the skull or with a combined approach from below and above using a craniotomy or middle fossa approach.
Mayo Clinic maintains low recurrence rates, around 5%, because of its dual approach: repairing the leak and addressing underlying issues. Follow-up after CSF leak repair and ongoing risk management help with early detection of any future issues. Communication with the referring physician ensures all clinicians involved understand what caused the leak and how it is being managed.
Leaders in improving skull base CSF leak management
Looking ahead, the Mayo Clinic team is working to answer important questions in managing skull base CSF leaks. The team conducts ongoing research addressing current topics, such as:
- The risk of meningitis. Skull base CSF leaks and surgery increase the risk of meningitis. Which risk is more concerning and how does that finding affect treatment protocols?
- The impact of medications on recurrence risk. Can medication reduce the risk of recurrence after a skull base CSF leak repair?
- Understanding the venous drainage system. The flow dynamics within this system may be related to elevated intracranial pressure. Could changes in these dynamics bring about a skull base CSF leak?
For more information
Yancy KL, et al. Impact of obesity and obstructive sleep apnea in lateral skull base cerebrospinal fluid leak repair. Laryngoscope. 2019;130:2234.
Benson JC, et al. A new frontier in temporal bone imaging: Photon-counting detector CT demonstrates superior visualization of critical anatomic structures at reduced radiation dose. American Journal of Neuroradiology. 2022;43:579.
Refer a patient to Mayo Clinic.