Spontaneous Skull Base Encephaloceles and Fistulas: Combined Endonasal and Endovascular Techniques

Introduction: Spontaneous skull base encephaloceles and fistulas are considered to result from a multifactorial process and have been postulated to represent a variant of idiopathic intracranial hypertension (IIH), associated to thinning of the cranial base. Treatment is recommended to prevent the occurrence of CNS infections, refractory epilepsy, and neurological sequelae.

Spontaneous skull base encephaloceles and fistulas, that are associated with elevated intracranial pressure, have the highest recurrence rate (25–87%) after surgical repair. Thus, one of the treatment goals must be restoration of normal intracranial pressure, associated to defect correction. Recent literature has suggested that in patients with IIH and documented evidence of venous sinus stenosis with a pressure gradient, venous sinus stenting should be the primary treatment of choice.

Methods: We report a case series of five patients presenting with spontaneous skull base encephaloceles and fistulas who underwent surgical treatment in our neurological surgery department, combining endoscopic endonasal and endovascular techniques.

Magnetic resonance imaging and computed tomography scans were performed and anterior skull base encephaloceles were identified. During investigation, all five patients were also diagnosed with intracranial idiopathic hypertension and venous sinus stenosis.

Results: Four patients were women and the most common clinical presentation was intermittent rhinorrhea. Two patients had already been operated on other hospitals, with recurrence of the encephaloceles. Endoscopic endonasal approaches were performed to correct the skull base defects and surgeries were uneventful. Early in the postoperative period, intracranial pressure was assessed again, and all patients still presented with elevated opening pressure on the lumbar puncture. Venous sinus stenosis was then performed to treat the IIH. The mean follow-up period was of 23 months. One patient presented with a femoral hematoma just after the procedure. There were no intracranial infections or bleeding complications. There was no recurrence of the fistulas or encephaloceles.

Conclusion: Treatment of spontaneous skull base fistulas and encephaloceles may be challenging, due to their multifactorial etiology. In patients with associated intracranial idiopathic hypertension due to venous stenosis, early venous sinus stenting associated to the endoscopic endonasal surgery seems to be a safe option to prevent the fistula recurrence.

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