Postoperative cerebrospinal fluid fistula after olfactory groove meningioma surgery

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• Risk factors for postoperative CSF leakage after elective craniotomy and the efficacy of fleece-bound tissue sealing against dural suturing alone: a randomized controlled trial

Postoperative cerebrospinal fluid (CSF) fistula is a known complication after surgical resection of olfactory groove meningiomas (OGMs), primarily due to the proximity to the anterior skull base and potential dural or sinonasal involvement.

• The overall incidence of postoperative cerebrospinal fluid (CSF) fistula following olfactory groove meningioma (OGM) resection ranges between 5% and 25%, depending on surgical technique and skull base reconstruction.
• Higher rates are observed with:
  • Large tumors (>4 cm) with invasion of the cribriform plate or paranasal sinuses
  • Bifrontal craniotomy compared to unilateral or minimally invasive approaches
  • Older surgical series, where vascularized flaps and endoscopic assistance were not routinely used
• Use of vascularized nasoseptal flaps in modern skull base reconstruction has reduced CSF leak rates to <10% in experienced centers.
• Delayed CSF fistula (>5 days post-op) accounts for approximately 30–50% of total leaks.
• CSF fistula is more common in OGM than in other anterior skull base meningiomas due to:
  • Frequent dural and bony erosion
  • Anatomical proximity to ethmoidal and frontal sinuses

The fronto-orbito-basal approach (n = 22) allowed a significantly greater percentage of Simpson I-II removals than the bifrontal (n = 70) and pterional approach (n = 21) (P = 0.0354 and P = 0.0485, respectively). The risk of life-threatening complications trended to be lower in patients operated upon either via the fronto-orbito-basal and via the pterional approach than in those treated via the bifrontal approach. Retraction-related brain swelling did not occur in any case after the fronto-orbito-basal approach (P = 0.0384); however, this approach was associated with a greater rate of cerebrospinal fluid leak (P = 0.0011) ¹⁾.

• OGMs often erode or adhere to the cribriform plate.
• Surgical approach (e.g., subfrontal or bifrontal) may require resection of involved dura and bone.
• Opening of the frontal sinus or ethmoid sinuses increases risk of CSF leak.
• Incomplete closure of the dural or bony defect leads to fistula formation.

• Clear rhinorrhea (usually unilateral)
• Positional headache
• Signs of meningitis (fever, neck stiffness) if infected
• CSF confirmed via β2-transferrin test

• Clinical suspicion: rhinorrhea, wound dehiscence
• β2-transferrin test: specific for CSF
• Imaging:
  • CT: detect skull base defect or pneumocephalus
  • MRI with cisternography: visualize CSF flow

• Bed rest with head elevation
• Lumbar drain placement to divert CSF
• Antibiotics if signs of meningitis

• Indicated for persistent leaks or large defects
• Endoscopic endonasal repair is preferred if sinonasal communication
• Graft materials: fascia lata, fat graft, nasoseptal flap
• Watertight dural closure and skull base reconstruction

• Meticulous closure of the dura
• Skull base reconstruction with vascularized flap when indicated
• Intraoperative use of fluorescein or Valsalva to check for leaks

• Most CSF fistulas resolve with proper management
• Delayed repair increases risk of meningitis and complications
• Long-term prognosis is excellent with successful repair

1. Couldwell WT, et al. Skull base reconstruction after anterior cranial fossa surgery. J Neurosurg.
2. Komotar RJ, et al. Olfactory groove meningiomas: surgical considerations and outcomes. Neurosurg Focus.