The outside-in approach to the modified endoscopic Lothrop procedure.

OBJECTIVES/HYPOTHESIS Drilling in modified endoscopic Lothrop procedure (MELP) is traditionally described as commencing from the frontal recess (FR). This is challenging when the FR is involved by tumor, inflammatory disease, or scarring. The outside-in MELP, where the limits of the sinusotomy are first defined and the FR is addressed last, is described. STUDY DESIGN Case-control study. METHODS Patients undergoing MELP, using the standard or outside-in approach, for inflammatory disease or endoscopic skull base surgery were assessed. Data were collected on demographics, disease characteristics, and FR involvement. Operative time was calculated from intraoperative video recording. Time points recorded were times to frontal sinus and recess connected for outside-in MELP and completion of Lothrop cavity for both groups. Perioperative complications (infection, skin breach or contusion, surgical emphysema, orbital bleeding, cerebrospinal fluid leak, and intracranial complications) were recorded. RESULTS Thirty patients (67% female) with a mean age ± standard deviation of 56.0 ± 10.8 years underwent MELP (24 outside-in, six standard). Time for Lothrop completion was shorter for outside-in MELP (30.60 ± 14.10 minutes vs. 69.66 ± 64.52 minutes, P = .002). Among outside-in MELP, mean time to frontal sinus floor discovery was 8.41 ± 6.29 minutes, to recess connected 26.50 ± 12.45 minutes, and were similar regardless of pathology. The time for Lothrop cavity completion was shorter for tumor cases (24.63 ± 6.49 minutes) than for chronic rhinosinusitis without polyps (35.87 ± 20.18 minutes) and chronic rhinosinusitis with polyps (34.62 ± 11.56 minutes) (P = .05). One patient had skin edema. No other complications were recorded. CONCLUSIONS The outside-in MELP is technically feasible and safe. Its advantage is a wide approach to the frontal sinus with development of the Lothrop cavity en route resulting in short predictable operative times. Defining the limits of the dissection early provides a robust and efficient approach.