Anatomic Guidelines for the Repair of CSF Leaks in the Lateral Recess of the Sphenoid Sinus

Objective: Provide anatomic guidelines for choosing the optimal endoscopic endonasal approach (EEA) for the repair of CSF leaks arising in the lateral recess of the sphenoid sinus.

Materials and Methods: IRB approved retrospective chart review to analyze data from patients suffering from CSF leaks in the lateral recess of the sphenoid sinus over a 12-year period. Pre-operative CT and MRI imaging was used to conduct three anatomic measurements that were correlated to the EEA used for leak repair. The vidian-rotundum distance, dimension of the defect, and angle of instrumentation provided guidelines for choosing an extended sphenoidotomy (ES) or a transpterygopalatine fossa (TPPF) approach as seen in Fig. 1.

Results: A cohort of 17 patients was analyzed. The extended sphenoidotomy approach required sphenoid sinus morphology with a tall vertical height and a wide corridor for entry. The transpterygopalatine fossa approach provided access to more extensive lesions in the middle cranial fossa in patients with narrow passageways; thus, was used in the majority of patients. Table 1 shows the anatomic measurements of sphenoid sinus lateral recess defects repaired with the two approaches. Both approaches led to a successful repair in all patients.

Conclusions: Quantitative anatomic measurements provide guidelines that gauge the extent of approach necessary for the repair of CSF leaks in the sphenoid sinus lateral recess. Both the extended sphenoidotomy and transpterygopalatine fossa approaches are effective; however, the extended sphenoidotomy is associated with less post-surgical morbidity than the transpterygopalatine fossa approach. Therefore, the extended sphenoidotomy is the preferred approach in patients with favorable anatomy.

Fig. 1 demonstrates a right-sided lateral recess defect. The vidian-rotundum vertical distance is 6 mm, the lateral recess defect is 20 mm wide, and the angle of instrumentation is 11 degrees.

Table 1 Compares the vertical distance between the vidian and rotundum canals (vidian-rotundum distance), dimensions of the lateral recess defects, and the angle of instrumentation. The extended sphenoidotomy approach is linked to greater measurements in both categories

Measurement	Extended sphenoidotomy approach	Transpterygopalatine fossa approach
Vidian-Rotundum Vertical Distance	12.00 mm	5.78 mm
Lateral Recess Defect	9.67 mm	12.05 mm
Angle of Instrumentation	36.67 mm	8.63 mm