Multi-modality intraoperative neurophysiological monitoring (IONM) refers to the assessment of neural structures through electrophysiological means during surgery. The document presents 5 case studies demonstrating the use of IONM: Case 1 showed a gradual increase in right Wave V latency during trigeminal nerve decompression, identifying pressure on the VIII nerve. Case 2 showed transient degradation of median SSEPs during insertion of a spinal shunt, but spontaneous return without intervention. Case 3 demonstrated changes in upper extremity MEPs and median SSEPs during cervical laminectomy and shunt placement for C5 tetraplegia. Case 4 assessed sensory and motor function and SSEPs/MEPs before and after

1. University of Florida
Doctor of Audiology Program
SPA7318 - Applied Auditory Electrophysiology
Multi-Modality Intraoperative
Neurophysiologic Monitoring (IONM)
David S. Barnkow, Au.D., D.ABNM, CCC/A
June 11, 2018

2. Multi-Modality IONM refers to
assessment of somatosensory,
motor, auditory or visual neural
structures or function by analyzing
spontaneous or evoked
electrophysiologic activity.

3. Case Study #1
Decompression of Right Cranial
Nerve V
Medical History: Bilateral Trigeminal
Neuralgia and Right Bell’s Palsy
Surgical History: Left Cranial Nerve
V Decompression with Complete
Relief

4. As the cranial nerve decompression progressed a gradual increase in the right Wave
V latency was observed. The change was <1ms latency prolongation and <50%
decrease in amplitude, but the surgeon was advised. A mass of surgical gel was
found to be resting upon the right VIIIth nerve.

5. As the cranial nerve decompression progressed a gradual increase in the right Wave
V latency was observed. The change was <1ms latency prolongation and <50%
decrease in amplitude, but the surgeon was advised. A mass of surgical was found to
be resting upon the right VIIIth nerve.

6. Case Study #2
Cervical Laminectomy, Spinal Cord
Untethering, Expansion Duraplasty,
Subarachnoid Shunt
Medical History: C6 Quadriplegia
Secondary to Cervicothoracic Epidural
Abcess
Surgical History: C7-T2 decompressive
laminectomy and wound irrigation.

7. Case Study #2 – Sensory Assessment

8. Case Study #2 – Motor Assessment

9. Case Study #2 – C6 Quadriplegia
Transient degradation of Median SSEP during insertion of a subarachnoid
shunt into a spinal cord myelocystocele. Repeat testing demonstrated
spontaneous return without surgical intervention.

10. Case Study #2 – C6 Quadriplegia
Right side Motor Evoked Potentials prior to and after placement of
subarachnoid shunt into spinal cord myelocystocele.

11. Case Study #3
Cervical Laminectomy, Subarachnoid
Myelocystocele Shunt Placement
Medical History: C5 Tetraplegia
Secondary to Motorcycle Crash
Chief Complaint: Progressive and
Ascending Motor and Sensory
Neurologic Deficits

12. Case Study #3 – C5 Tetraplegia
Left Side Upper Extremity MEPs

13. Case Study #3 – C5 Tetraplegia
Right Side Upper Extremity MEPs

14. Case Study #3 – C5 Tetraplegia
Left Median Nerve SSEPs

15. Case Study #3 – C5 Tetraplegia
Right Median Nerve SSEPs

16. Case Study #4
hardware removal, thorocolumbar
laminectomy, spinal cord untethering,
expansion duraplasty, subarachnoid
peritoneal shunt
Medical History: 64 y/o male sustained a
T12 spine injury at age 18 y/o resulting in T8
incomplete paraplegia and lumbar syrinx.
Chief Complaint: Left foot drop, loss of
bladder control.

17. Case Study #4 - T8 incomplete paraplegia and lumbar syrinx.
Clinical Sensory Assessment

18. Case Study #4 - T8 incomplete paraplegia and lumbar syrinx.
Clinical Motor Assessment

19. Case Study #4 - T8 incomplete paraplegia and lumbar syrinx.
Left Ulnar SSEP (arm)

20. Case Study #4 - T8 incomplete paraplegia and lumbar syrinx.
Right Ulnar SSEP (arm)

21. Case Study #4 - T8 incomplete paraplegia and lumbar syrinx.
Left Posterior Tibial SSEP (leg)

22. Case Study #4 - T8 incomplete paraplegia and lumbar syrinx.
Right Posterior Tibial Nerve SSEP (leg)

23. Case Study #4 - T8 incomplete paraplegia and lumbar syrinx.
Left Side Motor Evoked Potentials

24. Case Study #4 - T8 incomplete paraplegia and lumbar syrinx.
Right Side Motor Evoked Potentials

25. Case Study #5
Poor Technique Causes Interpretation
Difficulties

26. Left Ulnar SSEP – Poor Subcortical, No Peripheral

27. Right Ulnar SSEP – Reported as degraded. Baseline not representative of
beginning data.

28. Left MEP – illogical muscle order, hand, foot, shoulder, forearm, forearm

29. Left MEP – Reported as degraded. Would represent a very focal left C5 root
compromise

30. Right ABR – Overly processed (smoothed) loosing critical morphology for
waveform identification.

31. The End
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