Variations in Lateral Sphenoid Sinus Wall Defects

Defects in the lateral wall of the sphenoid sinus are a rare cause of cerebrospinal fluid (CSF) rhinorrhea. The etiology of these defects may be congenital or acquired. A dehiscent lateral craniopharyngeal canal, or Sternberg canal, arises from a malunion of two parts of the developing sphenoid bone: the greater wing and the basisphenoid.1,2 Originally reported in 4% of healthy adults,3 its true prevalence is not known, as is its relation with adult-onset CSF rhinorrhea and meningoceles of the sphenoid sinus. Acquired conditions probably account for the larger part of lateral sphenoid sinus wall defects, and include trauma, adjacent tumor, idiopathic intracranial hypertension, and iatrogenic damage. Regardless of their cause, large defects in the lateral sphenoid sinus wall are often accompanied by a temporal lobe meningocele or meningoencephalocele. When the defect is small, only CSF would leak, without dural herniation.4 In both cases, the defect should be repaired, achieving high rates of success with both transcranial and endoscopic approaches.5–9 Ongoing pressure plays a role in the pathogenesis of lateral sphenoid sinus wall defects. We hypothesize that apart from complete dehiscence, cases of weakened partially dehiscent walls, bulging into the sphenoid sinus cavity, with micro-tears allowing for CSF leak but without exposed meningeal contents, should also exist. This entity has not been described in the literature so far.