Intrasphenoidal encephaloceles represent encephaloceles which extend into the sphenoid sinus yet confined by its floor.
Contributing factors include arachnoid pits/weaknesses in the skull base and intracranial hypertension
- CSF pressures and the hydrostatic pulsative forces may lead to the development of pit holes on the middle fossa at the sites of arachnoid villi with herniation of dura/arachnoid or brain tissue
- If those defects are located over pneumatized lateral extension of the sphenoid sinus, encephalocele can develop and lead to CSF leakage into the sinus.
Patients present with spontaneous cerebral spinal fluid CSF rhinorrhoea.
CT cisternography demonstrate sphenoid sinus pneumatization, and a defect in the superior wall of the left lateral recess of the sphenoid sinus and anteromedial temporal lobe herniating through the bony defect.