A 58-year-old woman presented with a history of right-sided hearing loss and synkinesis following her vestibular schwannoma resection in 2016 elsewhere. She showed some improvement in synkinesis after botulinum toxin treatment. However, on questioning the patient notes that she experienced persistent, clear water-like nasal drainage while bending over, exercising, or doing household work. In 2019, she underwent a right trans-canal cerebrospinal fluid leakage repair with the closure of the Eustachian tube at an outside facility. Eight months later, the symptoms recurred. Her examination showed an obese female (body mass index of 35.1) with clear external auditory canal with tissue behind the tympanic membrane on the right. Nasal exam was normal with no evidence of allergic rhinitis.
DIAGNOSIS: CEREBROSPINAL FLUID LEAK
Negaar Aryan, MD; Karen Tawk, MD; Mehdi Abouzari, MD, PhD; and Hamid R. Djalilian, MD
Clear fluid coming from the nose after a skull base surgery should alarm the clinician of a possible -cerebrospinal fluid (CSF) leak. CSF is a colorless liquid that provides nutrients, hormones, and signaling molecules. It maintains a constant intracranial pressure through production or reabsorption, and clears out unnecessary or toxic metabolic byproducts from the brain. On average, humans have 150 cc of CSF but 450 cc of CSF is produced daily and 450 cc of CSF has to be absorbed. Any imbalances in this equilibrium will lead to excess production of fluid, causing an elevation in intracranial pressure, implicated in idiopathic intracranial hypertension (IIH), hydrocephalus, brain trauma, brain tumors, and stroke. 1,2 CSF leak is a rare but severe condition with serious and potentially fatal outcomes. They are classified into two groups, traumatic and spontaneous. The traumatic group is divided into iatrogenic (related to nasal, ear, or cranial surgery) and non-iatrogenic (related to blunt or penetrating trauma) subgroups. The spontaneous group is further divided into high-pressure and low-pressure subgroups (according to CSF pressure). 3
Idiopathic intracranial hypertension is defined as an increase of CSF pressure inside the skull without any identifier cause. The vast majority of patients (about 90%) are obese women. The pathophysiology of IIH is still unclear, but cerebral venous hypertension is known as the primary underlying cause, which leads to dysfunctional arachnoid granulation, reduced CSF resorption, and elevated intracranial pressure. Patients mostly present with headaches (usually daily, mostly upon waking), vision loss (brief episodic blurring or loss of peripheral vision), and bilateral papilledema. Pulsatile tinnitus and dizziness may also become chief complaints of undiagnosed patients. On the other hand, in patients who have undergone brain surgery, the arachnoid villi (which facilitate reabsorption of CSF) may get clogged up with blood during the surgery, and this may lead to communicating hydrocephalus or decreased absorption, which in the presence of IIH can exacerbate symptoms.
Diagnosis of CSF leaks is still a challenge. Diagnosis of post-traumatic leaks is immediate, whereas in spontaneous leaks it is more difficult since they are characterized by intermittent symptoms, and are dependent on disease etiology, leading to delayed diagnosis. The diagnostic algorithm includes clinical otolaryngology assessment with neurosurgical and ophthalmological consultation, radiological imaging, and laboratory findings of the nasal liquid. In clinical evaluations, performing some maneuvers (e.g., occluding the jugular vein, the Valsalva maneuver or having the patient bend over for a few minutes) can increase the intracranial pressure and reveal the leak. Nasal endoscopy is used to detect bone defects, meningoceles, or meningoencephaloceles in the nose. Neuro-ophthalmologists have an important in the diagnosis of intracranial hypertension. They use fundoscopy and visual field testing to evaluate the retina and optic nerve head and papilledema, and use optical coherence tomography to check the optic nerve changes. Neuro-ophthalmologists are the primary clinicians who treat IIH. Neuroradiological evaluations, including fine cut CT scan and magnetic resonance imaging (MRI), are important for suspected or diagnosed CSF leaks. 5,6
Findings on CT scans, such as bony defect of the skull base (dehiscence in the anterior skull base or and temporal bone) can be helpful in the diagnosis. MRIs can show the presence of meningoceles (dura and CSF outpouching), meningoencephaloceles (brain, dura, and CSF outpouching), and inflammation of the dura in the area in question on post-contrast imaging. MRI also plays an important role in the diagnosis of spontaneous CSF leak in IIH by demonstrating noteworthy signs including an empty sella, flattening of the posterior globes, optic nerve head protrusions, distention of the optic nerve sheaths, tortuosity of the optic nerve, cerebellar tonsillar herniation, meningoceles, CSF leaks, and transverse venous sinus stenosis. The most sensitive and specific laboratory tests for CSF leak diagnosis are beta2-transferrin and beta trace protein which are used on collected nasal secretions. Nasal endoscopy with intrathecal 5% fluorescein is indicated when no signs of leak are found on nasal endoscopy or imaging and when beta2-transferrin and beta trace protein are inconclusive or unavailable. If no CSF leak is found, pseudo-CSF leak diagnosis is made and an intranasal ipratropium trial is indicated. Finally, if the patient shows no improvement, then surgical exploration and treatment are indicated. In addition, screening for medication that can exacerbate IIH, including doxycycline, carbidopa, levodopa, cyclosporine, danazol, lithium, phenytoin, vitamin A, and some contraceptive drugs is also necessary. 3,4
This patient’s imaging showed no leak at the site of the previous craniotomy. Her MRI showed the Eustachian tube packing is still in place (Figures 1 and 2). In addition, contrast concentration (per pixel) in bilateral acoustic meatus or paranasal sinuses measured on radionuclide cisternography did not reveal any rapid or high-flow leak (Figure 3). These findings might be attributable to a very slow-flow and intermittent CSF leakage that cannot be identified using standard imaging—as in this case, the tracer did not have the time to egress the subarachnoid space.
Treatment includes conservative and surgical therapies. Conservative therapy is the first choice in patients without an immediate need for intervention. It is recommended for patients to be on bed rest with the head raised by 30 degrees for 1-2 weeks. Medications include antitussives, antiemetics, corticosteroids, and stool softeners. Diuretics such as acetazolamide, reduce the CSF production at the choroid plexus, resulting in lower intracranial (IC) pressure. Lumbar puncture with opening pressure is recommended in patients with high IC pressure. Surgical strategies include wound exploration, mastoid obliteration, Eustachian tube occlusion, and lumboperitoneal shunts placement. Since late-onset CSF leak following a vestibular schwannoma resection can be due to increased intracranial pressure, patient’s evaluation is completed by a referral to a neuro-ophthalmologist.
Since patient workup (nasal endoscopy, CT scan, MRI, radionuclide cisternography) (Figures 4 and 5) showed no sign of CSF leak, an intranasal ipratropium trial (0.03%, twice a day for two weeks) was initiated. In addition, the patient was advised to see a neuro-ophthalmologist for further evaluation of intracranial hypertension. The patient came back after two weeks with no improvement, and therefore, our next step was to discuss surgical options. The two main options included exploration of the previous craniotomy wound versus left-sided transcanal and transnasal endoscopic (transtympanic) CSF leakage control with blockage of the Eustachian tube given the history of multiple late leaks in this patient. Patients with CSF leaks need to be evaluated by a neuro-ophthalmologist after closure of the leak as the closure of the leak can lead to increased intracranial pressure again. The CSF leak creates a pressure valve that will decrease the intracranial pressure while open. However, when the leak is closed, the intracranial pressure can start increasing.
BONUS ONLINE VIDEOS: VISUAL DIAGNOSIS
Read this month’s Clinical Consultation case, then watch the accompanying videos from Hamid R. Djalilian, MD, to review the patient’s imaging for yourself.
Video 1. Axial (horizontal) T1 FLAIR non-enhanced MRI showing the Eustachian tube packing is still in place.
Video 2. Axial (horizontal) CT of temporal bones after contrast injection into the CSF space showing the contrast in the CSF.
Video 3. Coronal (parallel to the face) CT of temporal bones after contrast injection into the CSF space showing no gross contrast in the middle ear indicating not a fast flow leak.
Video 4. Axial (horizontal) T2 MRI demonstrating ischemic changes in middle cerebellar peduncle and cerebellum on left side of image (patient’s right side).
Video 5. Axial (horizontal) CISS MRI showing the different density in the mastoid and middle ear representing scar, fat, and fluid.
Video 6. Coronal (parallel to the face) T1 FLAIR demonstrating the anatomy in the coronal plane.
Watch the patient videos online at thehearingjournal.com.
1. Bothwell SW, Janigro D, Patabendige A 2019 Cerebrospinal fluid dynamics and intracranial pressure elevation in neurological diseases Fluids Barriers of the CNS 16 9 https://doi.org/10.1186/s12987-019-0129-6
2. Miyajima M, Arai H 2015 Evaluation of the production and absorption of cerebrospinal fluid Neurologia Medico-Chirurgica (Tokyo) 55 647 656 https://doi.org/10.2176/nmc.ra.2015-0003
3. Galli J, Morelli F, Rigante M, Paludetti G 2021 Management of cerebrospinal fluid leak: the importance of multidisciplinary approach ACTA Otorhinolaryngologica Italica 41 S18 s29 https://doi.org/10.14639%2F0392-100X-suppl.1-41-2021-02
4. Stevens SM, Rizk HG, Golnik K 2018 Idiopathic intracranial hypertension: contemporary review and implications for the otolaryngologist Laryngoscope 128 248 256 https://doi.org/10.1002/lary.26581
5. Ondik MP, Benson AG, Djalilian H 2006 An unusual site of a CSF leak following resection of a retrosigmoid acoustic neuroma Ear, Nose & Throat Journal 85 164 166-167. https://pubmed.ncbi.nlm.nih.gov/16615598/
6. Oliaei S, Mahboubi H, Djalilian HR 2012 Transmastoid approach to temporal bone cerebrospinal fluid leaks American Journal of Otolaryngology 33 556 561 https://doi.org/10.1016/j.amjoto.2012.01.011