Intra-operative neurologic injuries: Avoidance and prompt response

Transcription

1 Intra-operative neurologic injuries: Avoidance and prompt response James S. Harrop MD, FACS Professor Neurological and Orthopedic Surgery Director, Division of Spine and Peripheral Nerve Surgery Nsurg Director Delaware Valley SCI Center Thomas Jefferson University Objectives: To review etiologies of intra-operative neurologic injuries To detail spinal cord anatomy and perfusion To review the strategies to correct and improve neurologic injuries

2 James Harrop MD, FACS DISCLOSURES Company: Ethicon, Inc. AO, DOD, PICORI, NACTN Bioventus, Tejin, Asteria Relationship: Consultant Grant funding Advisory Committee State of the Spine Los Cabos, June 15-17, 2017

3 Overview: Incidence Etiology Treatment/Prevention? Spinal cord perfusion Pharmacology Instrumentation

4 Methodology Searches (1968-Present): Medline/Pubmed Scopus Ovid Cochrane review Reviewed >500 abstracts and articles Conclusion: Very limited material

5 Incidence of intra-operative Neurologic injury: Bridwell K. Major Intraoperative Neurologic Deficits in Pediatric and Adult Spinal Deformity Patients: Incidence and Etiology at One Institution Spine 23(3);324-31: 1998 Retrospective study 1,090 spinal deformity surgery for scoliosis Normal LE and B/B pre-op examinations Results: 0.38% (4/1090) major neurologic deficits post-op All four with deficit had: AP surgery (P = 0.009) Hyperkyphosis (P = ) Unilateral convex segmental vessels ligation 75% (3/4) purely vascular in etiology 25% (¼) Vascular and mechanical etiology All showed marked improvement of motor weakness over time

6 Incidence of intra-operative Neurologic injury: 162 deformity pts [93%(151/162) successfully monitored Electrophysical monitoring (SSEP/MEP) >10% in the latency of SSEP >50% SSEP amplitude loss >75% MEP Loss 8.0% (12/151) new postoperative neurologic deficits 1.3% (2/151) overall permanent deficit Etiology: 66% (8/12) curve/deformity correction 17% (2/12) hypotension 1 direct cord trauma and 1 pedicle screw malposition Electrophysical alerts Higher rate of neurologic events (p < 0.001) Significantly higher in cardiopulmonary comorbidity pts (p = 0.011)

7 Incidence of intra-operative Neurologic injury: 1121 AIS pts (834 female 287 male) 4yr follow-up Intraoperative neurophysiological monitoring (SSEP/MEP) Mean age: 13.9 yrs Relevant neurophysiological change (an alert): Decrease amplitude (unilateral or bilateral) >50% SSEP >65% MEP No latency criteria

8 Etiology of intra-operative Neurologic injury: (0.8%) 9/1121 new deficits 3.4% (38/1121) intraoperative alerts 17 MEP and no SSEP change SSEP lagged behind MEP (5min) Surgical maneuver (26/38) 35% (9/26) instrumentation-related alert 9/9 new deficits Blood vessel (12/38) (9/38) Hypotension All corrected elevating MAP (3/8) Segmental vessel clamping Left T12 segmental vessel

9 Etiology of intra-operative Neurologic injury: CSF PO2 correlation to tcmeps and SCI Methods: Myogenic tcmeps Continuous CSF PO2 via microcatheters Graded lumbar SCI via sequential segmental arteries clamping

10 Reversing intra-operative Neurologic injury: Alert Algorithm: Surgical pause (mean 8.7 minutes)-technical? Increase MAP Alert MAP: 55 mm Hg (desired 65mmHg) Applied correction reduced Anchoring hardware removed Steroid bolus NASCIS II Wake up test Appropriate response to the alert 100% (9/9) Motor or sensory deficit resolved within 90 days

11 Flynn T. 1,445 Neurologic total complications cases of anterior cervical interbody fusion.spine 1982;7: ,000 pts (0.1%) anterior new cervical postoperative operationsneurologic deficit 0.3% Both new corpectomies postoperative neurologic deficit. 267 (18.4%) neurophysiologic alert 35% Minor alerts (i.e.sustained EMG activity) 25% Major alerts

12 Etiology: Summary Intra-Op Neurologic loss: Patient positioning Hypotension Blood flow Deformity correction Instrumentation Operative technique

13 Micro-dissection spine and spinal cord vessels- 35 cadavers 3 longitudinal arterial trunks Medulla oblongata to conus medullarus 1 Ant.- over median sulcus 2 posterolateral- post nerve rootlets Greatest: cerv and lumb enlargement Anterior Posterior

14 Radicular arteries reinforce the longitudinal arterial channels at various levels 8 ant and 12 post feeders (Average) Variability 2-17 Anterior [Kadyi(1889), Suh(1939), Woollam(1958)] 6-25 Posterior Perforating arteries Thoracic cord - too small Cervical note all perforators Thoracic No perforators

15 How many ligations of bilateral segmental arteries cause ischemic spinal cord dysfunction: An experimental study using a dog model: Spine 2006 Interrupted bilaterally segmental arteries in dogs Up to 7 levels ligated Spinal cord blood flow T12 by laser Doppler flowmetry Neurologic function 15 dogs (5 Groups) 10 hours after ligation SC-evoked and motor-evoked potentials Modified Tarlov grading

16 Postoperative neurologic deficit: 2/3 group 4 3/3 group 5 CONCLUSION: 4 consecutive bilateral segmental artery ligation risks SCI RESULTS Group Ligation SC Blood Flow Abn Evoke Abn MEP 1 None 99.3% No No 2 3(T11-13) 80.7% No No 3 4(T10-13) 71.5% No No 4 5(T10-L1) 44.3% 2/3 1/3 5 7(T9-L2) 25.0% 3/3 3/3

17 Secondary Injury: Spinal Cord Hypoperfusion Rubenstein A: Neurosurgery 27(6):882-6, 1990 Prospective database 64 SCI pts MAP > 85 mmhg Crystalloid, blood products, vasopressors Minimum: 7 days post-injury Better neurological recovery than historical control Keep MAP>85-90 mmhg Vale, J. Neurosurg 1997

18 Paraplegia following elective endovascular repair of an infrarenal AAA Lumbar drain immediately inserted Full neurological recovery

19 Treatment with methylprednisolone for either 24 or 48 hours is recommended as an option that should be undertaken only with the knowledge that the evidence suggesting harmful side effects is more consistent than any suggestion of clinical benefit. American Association of Neurological Surgeons & Congress of Neurological Surgeons - March 2002 Stop steroid administration of methylprednisone in patients whose neurologic injury resolved

20 Problem: Instrumentation? When to Remove Pedicle Screw? EMG threshold (<60%) in relation to others are suspect Raynor BL et al: Spine 2002;27: Pedicle screw past vertebral body midline on PA/AP radiograph = medial breach Kim YJ et al: Spine 2005;30:

21 Summary: What to Do? Enhance spinal cord perfusion: Increase MAP Drainage of cerebrospinal fluid Lidocaine, Papaverine? Decrease metabolic rate of ischemic neural tissues Hypothermia Barbiturates Avoidance of hyperglycemia Steroids?

22 Thank You