THE RETROPERITONEAL INCISION - AN EVALUATION OF POSTOPERATIVE FLANK BULGE

Objectives: To determine if intercostal nerve injury is related to pos toperative flank ''bulge'' and to determine whether the extent of the retroperitoneal incision is related to the incidence of flank bulge fo llowing abdominal aortic aneurysm repair. Design: Bilateral dissection of the 11th intercostal nerve on seven cadavers; neurophysiological e valuation of five patients, three with a flank bulge and two without; and retrospective analysis of the extent of retroperitoneal incision a nd incidence of postoperative flank bulge in 63 consecutive patients. Setting: Urban academic medical center. Patients: Sixty-three consecut ive patients who underwent retroperitoneal repair of an abdominal aort ic aneurysm and neurophysiological evaluation of five volunteer patien ts. Interventions: Retroperitoneal repair of abdominal aortic aneurysm s. Main Outcome Measure: Reduction of injury to the 11th intercostal n erve by avoiding extension of the retroperitoneal incision into the in tercostal space. Results: Of 14 dissections of 11th intercostal nerves , there were bifurcations of the main trunk within the intercostal spa ce in four, at the tip of the 11th rib in seven, and at least 2 cm dis tal to the tip of the rib in three. Neurophysiological evaluation reve aled iterative discharges, polyphasia, fibrillation potentials, and al tered recruitment patterns compatible with intercostal nerve injury in patients with a bulge but not in the opposite abdominal wall musculat ure or in patients without a bulge. Seven (11.11%) of 63 patients had a bulge. Thirty-one of 63 patients had incisions into the 11th interco stal space in which a bulge developed in six (19.35%). Thirty-two pati ents had incisions that avoided extension into the intercostal space; a bulge developed in one (0.03%) (P=.53). Conclusions: Postoperative b ulge is related to intercostal nerve injury with subsequent paralysis of abdominal wall musculature. Intercostal nerve injury can be reduced by avoiding extension of the incision into the 11th intercostal space .