Spinal arterial anatomy and risk factors for lower extremity weakness following endovascular thoracoabdominal aortic aneurysm repair with branched stent-grafts

Purpose: To evaluate spinal arterial anatomy and identify risk factors for lower extremity weakness (LEW) following endovascular thoracoabdominal aortic aneurysm (TAAA) repair. Methods: A retrospective review was conducted of 37 patients (27 men; mean age 74.8±7.1 years, range 58-86) undergoing endovascular TAAA repair with branched stent-grafts at a single academic institution from July 2005 to December 2007. Data were collected on preoperative comorbidities, duration of operation, blood loss, type of anesthesia, extent of aortic coverage, blood pressure, cerebrospinal fluid (CSF) pressure and drainage, and postoperative development of LEW. Pre- and postoperative contrast-enhanced computed tomographic angiograms (CTA) in a 26-patient subset were analyzed to evaluate the number of patent intercostal and lumbar arteries before and after repair. Results: All patients were neurologically intact at the end of the operation. Seven (19%) patients developed LEW postoperatively: 6 perioperatively and 1 after discharge. LEW was associated with postoperative hypotension, internal iliac artery (MA) occlusion, and fewer patent segmental arteries on preoperative CTA. Lowest mean systolic blood pressure was <90 mmHg in all 6 (100%) patients who developed LEW in hospital compared to 12 (44%) of the 27 patients who did not develop LEW (p=0.02). Complete resolution of LEW (n=4) followed prompt measures to raise blood pressure and lower CSF pressure. Persistent LEW (n=3) was associated with sustained hypotension from sepsis, postoperative bleeding, and hemodialysis, respectively. Two (29%) of 7 patients with LEW either lost prograde flow to an HA during repair or had bilaterally occluded IIAs preoperatively compared to 2 (7%) of 30 patients without LEW (p=0.16). Comparison of pre- and postoperative CTAs showed no reduction in the mean number of patent segmental arteries in patients with or without LEW. Conclusion: Endovascular TAAA repair inevitably occludes direct inflow to lumbar and intercostal arteries. The distal segments of these arteries to the spine, however, are seen to remain patent through collaterals. Measures to preserve collateral pathways and increase perfusion pressure may help prevent or treat LEW.