Anterior cervical discectomy with intraoperative neuromonitoring changes

1. ACDF for stenosis with
intraoperative neuromonitoring
changes
Spine Conference
June 11, 2019

2. 84-year-old woman chief complaint neck and left upper extremity
pain.
Symptom onset March 26, 2019,Patient has pain in her neck that
radiates down her left arm left ulnar forearm into her left thumb
index finger. She has no right-sided symptoms. 18 years ago she
had a similar problem that was treated with traction. She saw her
primary care physician who ordered 2 rounds of steroid packs and
Dilaudid. Patient still has severe pain.
Past medical history: D&C 1954, ruptured ectopic pregnancy 54,
cystocele rectocele repair 1976, right leg vein stripping 1976,
hysterectomy 1976, left knee surgery 1976, left heel spur surgery
1992, left ankle stabilization 922, umbilical hernia repair 1995,
laparoscopic cholecystectomy 1995, incisional hernia repair 2003,
hemorrhoidectomy 2005, right carpal tunnel release 2006, eye
surgery bilateral 2000-08-15, history of gout, hypertension, kidney
disease, blood transfusion, bilateral knee arthritis
Social history: She retired as a nursing assistant years ago. She
lives alone, has supportive son and daughter accompying patient.
Has a groceries delivered. She does her own cooking and cleaning.
She is right-hand dominant. He has used a wheeled walker for the
last 5-6 years and walks with a bent forward posture. She has 7
grown children she is a widow. Her children's ages are 68, 67, 63,
56, 59. She is a non-smoker no alcohol.
EXAM: keeps neck in flexed, position5 feet tall 210 pounds. The
patient is in some distress today. She walks with a bent forward
posture using a wheeled walker. She does have left grip weakness
4 out of 5 motor left wrist flexion extension left elbow flexion
extension and deltoids are 5 out of 5 motor. Left shoulder is stiff
she cannot flex much past 120 degrees. She has severe pain in her
left shoulder when a 4 mm left shoulder. Rotator cuff external
rotation L but the side strength is 5 out of 5 motor on the left. Full
range of motion of her neck. Decreased sensation in her left thumb
left index finger left radial forearm. Deep tendon reflexes 0 out of 4
patellar Achilles tendons brachialis biceps triceps tendons.

3. Patient kept her neck flexed at all times
because it was more comfortable

14. c7t1

15. c6c7

16. C5C6

17. c5

18. C4C5

19. C3C4

20. C2C3

21. 84 woman severe L UE pain
thumb IF
Stenosis C5C7
Thoracic kyphosis
Cervical spine kept flexed

35. ExampIe IONM

41. Neuronfrom Gk. neuro-, comb. form of neuron "nerve," originally "sinew, tendon, cord, bowstring," also
"strength, vigor," from PIE *(s)neu- "tendon, sinew" (see nerve
 Axons have terminal
endings
 Synapse
 Axonal signals are
electrical and need
insulation like wires
made by supporting
cells
 Axons are white
 Glial cells support
axons

43. SSEP

44. TcMEP

45. Etiology SSEP changes
• Technical (needles, technical)
• Physiological (low BP, anemia, O2 sat, hypothermia)
• Pharmacological (halogens)
• Positional (head, shoulders, extremity)
• Surgical (implant, trauma, reperfusion)

50. Rapid forced dorsiflexion
with slight tension
loss of central inhibition
1006 patients PSF for
scoliosis
6 deficits
positive=no clonus
no false negatives
3 false positive
personal experience: many
patients woke up before
clonus was obtained ie many
false positives

51. GOAL: review of literature to answer 2 questions: 1. Do IONM abnormalities
predict postop deficits? 2. Does IONM increase safety or efficacy of surgery?
1966-2007 review, 868 papers down to 39 references
adjustments: anesthesia, hypothermia, hypotension
SSEP are sensitive but no specific
no information on efficacy of intervention

52. • IONM is a valid diagnostic adjunct to assess spinal cord integrity BUT there is no
therapeutic relationship and it’s use does not improve neurological outcome; no
therapeutic benefit during intramedullar tumor resections
• False positives exceed true positives 3:1
• No evidence that IONM can avoid postop neurological injury and paralysis once
an injury has been detected by modifying the operative procedure to reduce or
eliminate the injurious threat

54. Evidence Based Level 1 randomized (big)
trial: In every other helicopter ride the
pilot does not know the findings of the
safety gauges that measure performance
and the co-pilot who does see the
gauges cannot say anything to the pilot;
was there a difference in outcome?

56. Spinal cord plaintiff median: award $2.9M, settlement $1.45M
Standard of Care: Skill, knowledge, and care most people would
exercise under the same or similar circumstances
Examples of Intraoperative monitoring: Electronic Fetal
Monitoring and CO2 monitoring

57. Wash Univ experience St Louis, MO
from 1985 to 2010
23% cervical
instrumentation (screws) 131
positioning 85
correction 56
systemic 49
unknown 24
focal cord compression 15

58. • Journal of Neurosurgery 2019
• Retrospective National Inpatient Sample
• 141,007 ACDF cases 2009-2013 and 9,540 cases of IONM 7%
• No association between neurological complications and IONM
• Risk factors: age>65, multilevel fusion, CCI score>0, and nonelective admission were a/w neuro complication
• Neuro complications IONM group 0.17% and non-IONM group 0.22%
• Use of IONM a/w an additional $7k charges

59. 50% loss TcMEP or SSEP; 3 busy pediatric spine deformity centers
prospective 452 patients, 7% IONM changes, 20% had improvement
after increasing MAP from 72 to 86 mm Hg. Mean time to
improvement was 37 min but most had improvement in 15 min.
Recommendation: step one is increase MAP to 85mm Hg.
STEPS FOR IONM changes:
increasing mean arterial pressure
removal of traction
removal compression/distraction from implants
loosening set screws
bending of rods to lessen correction
removal of rods
removal of screws
probing for breeches
steroid administration
lidocaine administration
distribution of warm saline
transfusion
Stagnara wake-up test

60. Singapore, 128 patients, 10% alerts, 53% decompression, effective

61. Assuta medical center Tel Aviv
468 patients cervical 2006-2013 SSEP, tcMEP, EMG
2% deltoid weakness
Timing of changes: 47% during decomp, 36% head positioning
Poor outcome greater if signal change was permanent 42% v transient 11%
18 cases of false negatives; specificity 97%, neg pred value 96%, sensitivity 37%

62. C5

67. thanks