Incidence and clinical significance of frontal sinus or orbital entry during pterional (frontotemporal) craniotomy

Frontal sinus entry, orbital entry, or both may occur during pterional craniotomy for microsurgical clipping of aneurysms. We sought to determine the incidence and clinical significance of these findings on postoperative CT scans.

Eighty-two postoperative CT scans of the head obtained from 81 patients (64 women, 17 men; age range, 25-80 years) were retrospectively reviewed over a 1-year period. These scans were reviewed independently by two blinded neuroradiologists for the presence and degree of orbit and frontal sinus entry that may have occurred during craniotomy. Clinical charts, operative notes, and discussions with the patients' neurosurgeons were reviewed to determine the clinical management and significance of these findings.

Of the total 82 craniotomies reviewed, 77 (94%) had been performed via the pterional approach (43 right, 34 left). Twenty-three (30%) of these 77 studies revealed some evidence of penetration into the orbit or frontal sinus (orbit=65.2% [15/23]; frontal sinus=30.4% [7/23]; both=4.4% [1/23]). Only five of 16 patients with radiographic orbital penetration had evidence of involvement of intraorbital contents (ie, thickened lateral rectus, fat herniation, intraorbital air). Chart review revealed no complication or change in management. Of the seven patients with frontal sinus entry, three had mucosal exenteration and packing with antibiotic-coated gelfoam. No delayed complications (ie, persistent fever, mucocele, cerebrospinal fluid leak, air leak, or meningitis) were identified (follow-up period, 18-29 months).

Frontal sinus or orbital entry is not uncommon after pterional craniotomy, but the incidence of immediate complications is rare.