Spontaneous Unilateral Intrasphenoidal Meningocele.

The sphenoid sinus is an uncommon location for protrusion of a meningocele. When this does occur, it nearly always presents with leakage of cerebrospinal fluid through the nasal cavity. We present a case of a 38-year-old female found to have a meningocele protruding into the left sphenoid sinus, who presented with intractable headache but no CSF rhinorrhea. The lesion was discovered on computed tomography angiography, which was performed in order to rule out intracranial pathology as the etiology of her headache. Prior imaging, including pre- and post-contrast MRI, demonstrated the fluid within the sphenoid sinus, but did not reveal the communication through a defect in the base of the skull. Thus, it was assumed to be strictly related to sinus disease in the past. Our case represents a phenomenon whereby meningoceles protruding through the basilar skull into the sphenoid sinus or any other location are potentially misdiagnosed due to poor visualization of the osseous defect and lack of awareness of this entity.