Comparative Morphometric Anatomy of the Sphenoid Lateral Wall and Surgical Outcomes of Sphenoid Lateral Wall CSF Leak.

BACKGROUND

Sphenoid sinus lateral wall cerebrospinal fluid (CSF) leaks are rare, with debated anatomical and physiological bases. We evaluated the role of pneumatization in surgical outcomes and compared patient morphometrics with cadaveric specimens.

METHODS

We retrospectively reviewed 11 patients (2017-2025) with lateral sphenoid CSF leaks. The patient characteristics, site of leaks, type of repair done, postclamping opening pressure, surgical approach, reconstruction technique, flap choice, and recurrence were documented. Fine-cut computed tomography (CT) provided morphometrics [foramen rotundum (FR) and vidian canal (VC) diameters, FR-midline, VC-midline, FR-VC distance, and vidian-rotundum angle]. Magnetic resonance imaging assessed markers of intracranial pressure (ICP). Cadaveric measurements (n=17) were compared with patients based on pneumatization type on coronal CT.

RESULTS

Type III pneumatization occurred in 50% of patients; overall, 73% of defects were medial to the FR. In type III, FR was nearly twice the cadaveric value (≈4 mm; P <0.001), while VC metrics and lateral recess width (≈9 mm) were similar. Only one patient showed elevated ICP requiring shunting. Initial recurrence was 27.3%, but overall success reached 100% after the first revision. Recurrences occurred in type III pneumatization with defects lateral to the FR (flap migration or raised ICP). Conchal flaps sufficed for medial defects, whereas nasoseptal flaps were required for lateral type III.

CONCLUSIONS

Larger FR diameters in patients across all pneumatization types, a finding that may reflect remodeling from chronic ICP. However, in type III pneumatization, the defect location lateral to the FR increases technical difficulty. Precise preoperative knowledge of patient-specific anatomy should guide the surgical method and flap selection to ensure durable repair.