CSF Rhinorrhea

Mrs. Renu Hajaley 48y/F History  Operated for pituitary adenoma in 2002, right frontal craniotomy done.  Received post operative radiotherapy  Admitted on 30.12.2005 with complaints of headache,drowsiness, and intractable vomiting - 1 day.  L.P done was indicative of meningitis  Was started on intravenous antibiotics following which she improved and was discharged on 06.01.2006.  Readmitted on 07.01.2006 with complaints of watery discharge from left nostril, headache and vomiting - since morning  No h/o fever, trauma, altered sensorium, seizures. Examination       Vitals- WNL General -NAD Systemic- NAD Conscious, oriented. Neck rigidity + Active CSF discharge present from left nostril.  No focal neurological deficit. Investigation  CECT head  MRI brain  NCCT PNS CSF Rhinorrhea Introduction  Defects in the floor of the anterior cranial fossa can lead to the leakage of CSF into the nasal cavity.  The term rhinorrhea reflect the site of the drip Problem  The underlying defect responsible for CSF leaks, regardless of the etiology, is the same: disruption in the arachnoid and dura mater coupled with an osseus defect and a CSF pressure gradient that is continuously or intermittently greater than the tensile strength of the disrupted tissue Classification  Traumatic - Accidental / Iatrogenic   Acute: within 1 week of injury delayed: months or years later  Nontraumatic or Spontaneous  High pressure (secondary) • Tumours- Direct/Indirect • Hydrocephalus  Normal pressure (primary) • Congenital anomalies • Focal atrophy- Olfactory/Intrasellar • Osteomyelitic erosion Differences between Traumatic and spontaneous Traumatic Incidence Age/Sex Flow Resolution Side Headache Meningitis Anosmia Common No Low flow Early Constant Uncommon Common Common Spontaneous Uncommon >30, females High flow Late Not constant Common Uncommon Rare Epidemiology  Traumatic: 90%     3% of all head injuries 9% of all high energy penetrating injuries 12-30% of basilar skull fractures In childhood the incidence of traumatic CSF leak is uncommon -1% Epidemiology(Contd)  Spontaneous - Pituitary tumours are the most common cause of spontaneous CSF leaks.  Post operative Leaks  TNTS : most common cause-1.4%-6.4% CP angle: 2%  Pneumocephalus:   Pathognomonic sign of CSF fistula after trauma or spontaneous ( but not after surgery) . 20% of patients with CSF leaks 20% of acute post traumatic and 57% of delayed leaks Post operative leaks- 20%  Meningitis:   Pathophysiology  Immediate leak: a dural tear and a bony defect or fracture has occurred.  Delayed traumatic leak:  Previously intact dural layer that has slowly become herniated through a bony defect, finally tearing the dura and causing the leak. Tear and bony defect are present from the time of the original injury, but the leak occurs only after the masking hematoma dissolves   Spontaneous CSF rhinorrhea usually manifests in adulthood, coinciding with a developmental rise in CSF pressures with maturity.  The dura of the anterior cranial base is subject to wide variations in CSF pressure because of several factors, including normal arterial and respiratory fluctuations. Other stresses on the dura include Valsalva-like actions during nose blowing. This stress can lead to dural injury in areas of abnormalities of the bony floor  Primary nontraumatic CSF leaks :  focal atrophy, rupture of arachnoid projections that accompany the fibers of the olfactory nerve, and persistence of an embryonic olfactory lumen Relevant Anatomy  The most common anatomic sites of CSF leaks are the areas of congenital weakness of the anterior cranial fossa and areas related to the type of surgery performed.  39% - cribriform plate and air cells of the ethmoid sinus 15% of leaks, the fistula extended to the frontal sinus 15% in area of the sella turcica and sphenoid sinus.    Common sites of injury secondary to endoscopic sinus surgery include the lateral lamella of the cribriform plate and the posterior ethmoid roof near the anterior and medial sphenoid wall. In the rare situation, the leak can originate in the middle or posterior cranial fossa and can reach the nasal cavity by way of the middle ear and eustachian tube.  Clinical Signs  Reservoir sign: Ability of a patient to produce CSF at will by positioning the head in a certain way.  Target sign: Differential diffusion of CSF admixed with blood or other sero sanguineous fluid .  Headache : Other confirmatory evidence  Unusually low opening pressure in LP  Unilateral or bilateral anosmia  Optic nerve lesion -Tuberculum sella, sphenoid sinus, and posterior ethmoids Lab studies  Glucose: Concentration of glucose in CSF equals or exceeds 50% of the serum concentration .  Glucose concentration in nasal secretions is 10mg% or less.  Quantitative measurements are diagnostic  Qualitative spot tests not definitive Lab Studies  A rapid but highly unreliable test is glucosecontent determination with the use of glucose oxidase paper. Reducing substances present in the lacrimalgland secretions and nasal mucus may cause false-positive results. Glucose, at a concentration of 5 mg/dL, can lead to a positive result with this test.    Active meningitis can lower the glucose level in the CSF and may lead to false-negative readings.  Immunoelectrophoretic identification of CSFspecific marker proteins is the current standard for identifying CSF. At present, the beta2-transferrin assay is the most widely used test. Beta2-transferrin is a protein that is highly specific for human CSF. It may also be found in the serum of newborns, in vitreous humor, and in patients with liver disease.    The assay has a high sensitivity and specificity, it is performed rapidly, and it is noninvasive. Imaging Studies  Plain radiography  Plain radiographs can demonstrate a fracture of the skull, an air-fluid level in the sinus, or an aerocele in the cranial vault. Air in the subarachnoid space on a plain radiograph is an almost pathognomonic sign of dural injury. It is usually the result of a large tear in the dural envelope. In the absence of a history of trauma, plain radiographs are of little value   CT scan  CT scans can reveal the fracture site that underlies a traumatic leak, reveal an underlying anatomic or developmental abnormality in the case of nontraumatic leak, and provide information on the brain parenchyma in the vicinity of the leak. At present, it is the criterion standard in the evaluation of craniofacial trauma. Thin-section (1-mm) coronal CT scan.   Air-fluid level in the sphenoid sinus. Pneumocephalus on a scan suggests a large dural tear. Deviated crista galli is a radiologic sign in patients presenting with primary CSF rhinorrhea; this finding supports a congenital bony dehiscence as the etiologic basis for this condition.   A modified technique known as digital subtraction cisternography may be useful if CT cisternography does not reveal the leakage site. Omnipaque CT cisternography or metrizamide CT cisternography  The diagnostic yield of CT scan is improved by injecting metrizamide, a water-soluble nonionic tri-iodinated contrast agent. Another option involves the use of iohexol (Omnipaque). These agents are injected intrathecally.  Omnipaque CT cisternography or metrizamide CT cisternography (MCTC) depicts the precise location of CSF leakage in most patients with active leaks. Intermittent or slow leaks may not be identifiable. Magnetic resonance imaging  MRI typically is not recommended in the evaluation of a CSF leak because it does not demonstrate bony defects very well. However, a heavy T2-weighted image can reveal a brisk CSF leak. This modality also can be useful when trying to determine the extent of an encephalocele  Nuclear medicine studies  Radioactive isotopes can be introduced into the CSF by means of lumbar or suboccipital puncture.  The distribution of these agents then can be determined by using serial scanning or scintiphotography.  Another option is to introduce nasal pledgets in various high-risk areas. These pledgets then can be analyzed for the presence of the tracer. Management  Medical therapy: Conservative management consists of a 1- to 2-week trial of bed rest with the patient in a head-up position (15-20º)  Coughing, sneezing, nose blowing should be avoided as much as possible.  Stool softeners or laxatives can be used to decrease the strain and increased ICP associated with bowel movements.  A lumbar drain or repeated lumbar puncture can be used to decrease ICP even further; a rough guideline is the removal of 150 mL of CSF per day. (Not recommended in traumatic fistulas because of high risk of reversing the flow gradient and inducing infection )  Acetazolamide : decreases CSF production by as much as 48%.  Prophylactic antibiotics: controversial. Indications to abort conservative mgt  No decrease in the CSf flow over 6-8 days  Initial decrease followed by continuation of flow for more than 10-12 days.  Presence of intracranial air  Meningitis  Extensive skull fracture involving the sinuses esp frontal sinus. Indications for primary surgical intervention  Proven intermittent or delayed leaks  High pressure leaks acting as safety valve for hydrocephalus  Associated with congenital dysplasias of brain, skull base, orbit  Leaks caused by high energy missile wounds  Post operative cases not controlled by position or drainage esp if air sinuses have been violated during surgery Surgical management  Intracranial  Extracranial Intracranial  Leaks arising from an anterior defect can be approached from a frontal anterior fossa craniotomy.  Different repair techniques have been used, including the use of free or pedicled periosteal or dural flaps, muscle plugs, mobilized portions of the falx cerebri, fascia grafts, and flaps in conjunction with fibrin glue.  Leaks arising from the sphenoid sinus are difficult to reach by means of an intracranial approach.  Advantages :    ability to inspect the adjacent cerebral cortex, direct visualization of the dural defect, and better ability to seal a leak in the presence of increased ICP.  When preoperative localization attempts fail to reveal the site of a leak, intracranial approach with blind repair has been successful. In these situations, the cribriform and the sphenoid area, if necessary, are covered with the repair material.  Disadvantages:    increased morbidity, increased risk of permanent anosmia, trauma related to brain retraction (hematoma, cognitive dysfunction, seizures, edema, hemorrhage), prolonged hospital stays. Failure rates for this approach are 40% for the first attempt and 10% overall.   Extracranial Indications:  Clearly defined spontaneous leaks from anterior fossa, including cribriform fossa and fovea ethmoidalis.  Postoperative CSF leaks after treatment of sellar and parasellar lesions Extracranial External approach  External approaches include the use of an anterior osteoplastic flap through a bicoronal or eyebrow incision, external ethmoidectomy, transethmoidal sphenoidotomy, transseptal sphenoidotomy, and the transantral approach.  Choices of graft material include the fascia lata, temporalis fascia, septal or turbinate mucosa, muscle, fat, and septal cartilage.  For cribriform or fovea ethmoidalis leaks, a transnasal ethmoidectomy is performed, and for sphenoidal leaks, sphenoidotomy is performed as well; graft material is placed over the fistula. If possible, the graft is placed superior to the bony skull base inferior to the dural defect.  Success rates for the extracranial or external approach are 86-100%.  Disadvantages:  inability to treat concomitant intracranial abnormality difficulty with frontal and sphenoid repair with prominent lateral extensions relative ineffectiveness of repairing highpressure leaks from below.   Endoscopic  Advantages:  Better field of vision with enhanced illumination and magnified-angle visualization. Ability to clean the mucosa off the adjacent bone without increasing the size of the defect and accurate positioning of the graft. Lowered morbidity No anosmia.    An overall success rate of 90-95% has been reported with endoscopic repair of CSF leaks.