title: Neuraxial blockade in patients with preexisting spinal stenosis, lumbar disk disease, or prior spine surgery: efficacy and neurologic complications.
abstract: BACKGROUND
  Patients with spinal canal pathology, including spinal stenosis and lumbar disk disease, are often not considered candidates for neuraxial blockade because of the risk of exacerbating preexisting neurologic deficits or developing new neurologic dysfunction. In contrast, a history of spine surgery is thought to increase the likelihood of difficult or unsuccessful block. In this retrospective study we investigated the risk of neurologic complications and block efficacy in patients with preexisting spinal canal pathology, with or without a history of spine surgery, after neuraxial anesthesia.
  
  
  METHODS
  During the 15-year study period, all patients with a history of spinal stenosis or lumbar radiculopathy undergoing a neuraxial technique were studied. Patient demographics, preoperative neurologic diagnoses and neurologic findings at the time of surgery/neuraxial block, details of the neuraxial block including technique (spinal vs. epidural, single injection vs. continuous), injectate, technical complications (paresthesia elicitation, bloody needle/catheter placement, inability to advance catheter, accidental dural puncture), and block success were noted. New or progressive neurologic deficits were identified. All patients were followed until resolution or last date of evaluation.
  
  
  RESULTS
  There were 937 patients included, 207 (22%) of whom had undergone spinal surgery. A history of spinal stenosis was present in 187 (20%), lumbar radiculopathy in 570 (61%), and peripheral neuropathy in 210 (22%) patients; 180 patients (19%) had multiple neurologic diagnoses. A majority of patients had active but stable neurologic symptoms at the time of surgery. Overall block success was 97.2%. A history of spine surgery did not affect the success rate or frequency of technical complications. Ten (1.1%; 95% confidence interval [CI] 0.5%-2.0%) patients experienced new deficits or worsening of existing symptoms. Three (1.4%) complications occurred in patients with a history of spinal surgery, and the remaining 7 (1.0%) in patients without prior surgical decompression or stabilization (P = NS). Although an orthopedic procedure was not a risk factor, in 5 of the 6 patients in which the surgery was a unilateral lower extremity procedure, the postoperative deficit involved the operative side. Likewise, in both patients undergoing bilateral orthopedic procedures who developed bilateral deficits, the outcome was worse on the previously affected side. A surgical cause was presumed to be the primary etiology in 4 (40%) of 10 patients. The primary etiology of the remaining 6 (60%) complications was judged to be nonsurgical (including anesthetic-related factors). The presence of a preoperative diagnosis of compressive radiculopathy (P = 0.0495) or multiple neurologic diagnoses (P = 0.005) increased the risk of neurologic complications postoperatively.
  
  
  CONCLUSIONS
  We conclude that patients with preexisting spinal canal pathology have a higher incidence of neurologic complications after neuraxial blockade (1.1%; 95% CI 0.5%-2.0%) than that previously reported for patients without such underlying pathology. However, in the absence of a control group of surgical patients with similar anatomic pathology undergoing general anesthesia, we cannot determine whether the higher incidence of neurologic injury is secondary to the surgical procedure, the anesthetic technique, the natural history of spinal pathology, or a combination of factors and the relative contributions of each.
authors.affiliation: Department of Anesthesiology, Mayo Clinic College of Medicine, 200 First Street, SW, Rochester, MN 55905, USA. hebl.james@mayo.edu
authors.forename: James R
authors.initials: JR
authors.lastname: Hebl
authors.forename: Terese T
authors.initials: TT
authors.lastname: Horlocker
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Kopp
authors.forename: Darrell R
authors.initials: DR
authors.lastname: Schroeder
mesh_terms: D015360:Analgesia, Epidural / Q000009:adverse effects; D000767:Anesthesia, Epidural / Q000009:adverse effects; D000775:Anesthesia, Spinal / Q000009:adverse effects; D016009:Chi-Square Distribution; D006801:Humans; D007403:Intervertebral Disc; D008159:Lumbar Vertebrae; D008910:Minnesota; D009407:Nerve Block / Q000009:adverse effects* / Q000379:methods; D019637:Orthopedic Procedures / Q000009:adverse effects*; D011843:Radiculopathy / Q000150:complications*; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013130:Spinal Stenosis / Q000150:complications*; D013131:Spine / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome