title: The outside-in approach to the modified endoscopic Lothrop procedure.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
authors.affiliation: Division of Rhinology, Skull Base Surgery, St. Vincent's Hospital, Sydney, Australia. drdavidchin@gmail.com
authors.forename: David
authors.initials: D
authors.lastname: Chin
authors.forename: Kornkiat
authors.initials: K
authors.lastname: Snidvongs
authors.forename: Larry
authors.initials: L
authors.lastname: Kalish
authors.forename: Raymond
authors.initials: R
authors.lastname: Sacks
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Harvey
mesh_terms: D000328:Adult; D000368:Aged; D004210:Dissection / Q000379:methods*; D004724:Endoscopy / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D005626:Frontal Sinus / Q000601:surgery*; D015522:Frontal Sinusitis / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009298:Nasal Polyps / Q000601:surgery*; D013517:Otorhinolaryngologic Surgical Procedures / Q000379:methods*; D010255:Paranasal Sinus Neoplasms / Q000601:surgery*; D011183:Postoperative Complications / Q000209:etiology* / Q000601:surgery; D012086:Reoperation; D013996:Time and Motion Studies; D014741:Video Recording