INTRAOPERATIVE NEUROMONITORING IN POSTERIOR FOSSA TUMORS AND SPINAL CORD SURGERY: ENHANCING SURGICAL PRECISION AND PATIENT SAFETY
Ovidiu C. Banea, MD, PhD
Clinical Neurophysiology
Hospital Sant Rafael Barcelona
HM Nou Delfos Barcelona
2024 © NEUROPHYSIOLOGY PLUS
PEDIATRIC NEUROSURGERY SYMPOSIUM
Marie Curie Children´s Hospital Bucharest, Romania
May 19th, 2024
SUMMARY
IONM BASIS
IONM BASIS
IONM is safe!
TEAM: Surgeon, Clinical Neurophysiologist and Anesthesiologist
Deletis V , 2007
METHODS OF IONM
MONITORING TECHNIQUES (continuous surveillance of neurophysiological status)
MAPPING TECHNIQUES (identifying of structures)
e.g. Hypoglossal mapping
Duque et al. 2013 http://www.wjso.com/content/11/1/225
SSEP
SOMATOSENSORY SYSTEM
TC MEP
Motor Pathways
STIMULATION site
Cortical
(debate, experience):
C1, C2
Upper extremities
C3,C4
Lower extremities
Recording: Muscles
Stecker et al, 2012
METHODS OF IONM
Spontaneous Electromyography
Provides information on the state of the peripheral nerve that innervates the muscle
To differentiate new activity and acute injuries as fibrillations and fasciculations of muscle fibers is important to registered and be aware to previous activity (before surgery).
ROMSTOCK has classified spontaneous activity in trains A, B, C.
The high frequency activity A is suggestive of acute nerve injury (in Stecker et al 2013).
ADVANTAGE shows spontaneous damage
LIMITS
METHODS OF IONM
Triggered Electromyography
Its main use is to check if a screw already placed is correctly located
Deletis V, 2007
METHODS OF IONM
Triggered Electromyography
MONOPOLAR ELECTRODE (PROBE) MORE sensible, less specific
- WIDER spreading electric field
- LOWER motor threshold at the same distance
METHODS OF IONM
Triggered Electromyography
BIPOLAR ELECTRODE (PROBE) less sensible, more specific
-FOCAL
-HIGHER motor threshold at same distance (<2mA probably over nerve)
BRAINSTEM 0.16 mA
BAEPS AND VEPS
SENSORY SYSTEMS
Visual cortex N70, P100
Intraoperative recordings from the optic nerve shows an early positive deflection with a latency of 75 ms, followed by a broad negative potential with a latency of approx. 55 ms in response to short light flashes
IONM AND ANAESTHESIA
Mechanism
The major target of anaesthetic agents is GABA and NMDA receptors mediating electrolyte channels (Na, Cl, Ca) at synapses, with consequent synapses transmission loss.
Halogenated inhalational agents and ketamine appear to decrease axonal conduction
D response recorded from the epidural space is highly resistant
INHALATIONAL AGENTS
EFFECT
Synaptic Inhibition on alpha motoneuron until EEG electrocerebral silence
Case: During a surgery on cervical myelopathy anaesthesia with Sevoflurane set by anaesthesist produced abolition of all potentials during 15 minutes with consequent unmonitored time.
IONM AND ANAESTHESIA
NITROUS OXIDE
Produces depression of myogenic
TC MEP
INTRAVENOUS ANALGESIC AGENTS
Most favourable for IONM
Barbiturates and BDZ similar to INH AG
ETOMIDATE
THIOPENTAL, MIDAZOLAM & PROPOFOL produce marked depression in bolus doses.
MUSCLE RELAXANTS
PROBLEM ELECTROPHYSIOLOGIST vs CLINICAL NEUROPHYSIOLOGY
PROBLEM ELECTROPHYSIOLOGIST vs CLINICAL NEUROPHYSIOLOGY
Dr Martin U Schuhmann
IONM in Romania
Multimodal approach
23rd of November 2013 Dr Claudiu Matei invited H del Mar / 3 LECTURES
Dr Jesús Lafuente Baraza (Neurosurgery)
Dr Alba Leon Jorba (Clinical Neurophysiology)
Dr Ovidiu Banea (Clinical Neurophysiology Resident) “General Aspects of IONM”
IONM
Sibiu EXPERIENCE
Dr. Claudiu Matei Dr. Dan Filip
Since 2014:
330 cases with IONM at the beginning selective cases, now almost all pediatric patients
IONM
Marie Curie Children’s Hospital
Photo: Dr Sorin Târnoveanu
POSTERIOR FOSSA TUMORS
multimodal approach
CPA TUMOR
MEP AND COMEP CORTICOGENICULATE OR CORTICOBULBAR CZ-C3 AND CZ-C4
CPA TUMOR
MEP AND COMEP CORTICOGENICULATE OR CORTICOBULBAR CZ-C3 AND CZ-C4
MAPPING EMG UP TO 0.4-06 MA
IONM BRAINSTEAM TUMOR REFLEX V-VII
BLINK V-VII AND TRIGEMINO-TRIGEMINAL (MASS) V-V REFLEXES
V-VII and TRIGEMINO-VAGAL V-X REFLEX ?
PREOPERATIVE very important even if no apparent deficits
V-VII and TRIGEMINO-VAGAL V-X REFLEX ?
TRIGEMINO-VAGAL REFLEX TO ASSESS PALATOGLOSSAL STATUS?
DELAYED R1 right Orbicularis oculi
TRIGEMINO-VAGAL REFLEX not published
Spontaneous EMG with “A TRAINS”
VIDEO HERE
National University Hospital of Iceland
SURGICAL INSTRUMENT ARTIFACT
SPINAL CORD phase reversal
Mirela Simon (Massachusets General Hospital)
Mirela Simon, 2012
SPINAL CORD phase reversal
Moritz Ueberschaer et al, 2023
SPINAL CORD TUMOR C6-T8
Ingvar Hákon Ólafsson & Haldor Skúlasson
SPINAL CORD TUMOR C6-T8 CASE HERE
208 © Neurophysiology Plus
**Proposed and performed M.I.O.N. methods:**
1. **Motor Evoked Potentials (TcMEP):** Indirect electrical transcranial stimulation using 4 electrodes (C1-C2 and/or C3-C4) applied to the scalp with the usual 10-20 EEG montage. Stimulation: Train of five at > 200 Hz. Recording at the level of APB (right), bilateral anal sphincter, bilateral VM, bilateral TA, bilateral GM, and bilateral AH.
2. **Somatosensory Evoked Potentials (SSEP):** Stimulation at the level of the bilateral posterior tibial nerve and the right median nerve. Recording at Cz’-FPz for lower limbs and C3’-FPz for the median nerve. Control was done at the popliteal fossa and spinal C7.
3. **Pudendo-Anal Reflex (direct evaluation of S2-S4):** Squared stimuli applied to the clitoral area with amplification from both anal sphincter muscles. Double stimuli of 0.2 ms duration and a stimulation rate of 0.5-2 Hz.
. **Direct Electromyography:** Continuous recording from all myotomes described in "1".
5. **Proximity topological mapping method for all nerve roots at the tumor level (bilateral, levels L3, L4, L5, S1, S2):** Two types of probes were used for this purpose: Monopolar with stimulation up to 20 mA and specific bipolar with reduced stimulation of 0.1-3 mA.
6. **"TIVA" anesthesia control with 3 EEG channels and repetitive stimulation for the neuromuscular block (TOF).**
VA MULTUMESC PENTRU ATENTIE!
Thank you!