Anesthesia and Neuromonitoring by Reza Gorji, MD

Reza Gorji from University of NY writes at the Neuroanesthesia.net about various neuromonitoring methods and the effect of anesthesia, what types of anesthetic agent is advisable for certain types of EPs and EEGs during surgical procedures.

Anesthesia and Neuromonitoring: Electroencephalography and Evoked Potentials Reza Gorji, MD, Department of Anesthesiology, University Hospital, State University of NY, Syracuse, NY

• Anesthesia and Neuromonitoring (EEG & EP) Patients undergoing neurologic/orthopedic procedures involving the peripheral and central nervous system may be at increased risk from hypoxia/ischemia to vital neurologic structures. Intraoperative neuromonitoring may improve patient outcome by:
  

a. Allowing early detection of ischemia/hypoxia before irreversible damageoccurs

b. Indicating the need for operative intervention (shunts placed in carotid surgery) to minimize nerve damage The role of anesthesiology in neuromonitoring is one of understanding the appropriate anesthetic techniques, applying knowledge of medicine, surgery, physiology and pharmacology to get the best possible outcome.

This monograph will discuss the

various clinically important neuromonitors and offer solutions as they apply to clinical anesthesia.

It is divided in 3 broad sections: Electroencephalography, sensory evoked potentials and motor evoked potentials.

IONM the Gold Standard of Patient Safety? By David J.Anschel, M.D

David J. Anschel, M.D.
Contributing Editor of MedCompare,

David J. Anschel writes about the developments in "Itraoperative Neurophysiological Monitoring and its medical usage:

IONM has become the gold standard for ensuring patient safety while undergoing operations which place the central or peripheral nervous system at risk. Technological advancements within the last few years have allowed monitoring techniques to evolve. The above robust systems are representative of the best that modern medicine has to offer. Allowing neurologists and surgeons to work together to provide better patient outcomes during more complicated procedures in close proximity to vital neurological tissues.

American Society of Anesthesiologissts: Upcoming Conference & Abstracts on Neuromonitoring

Tha annual meeting of American Association of Anesthesiologist will be held during

October 13-17, 2007 San Francisco, CA. There are several interesting research and clinical studies on using neuromonitoring, how different anesthesia affects the intraoperative recording. You can click this highligted assn "Amer Assoc Anesthesiologist Meeting" and read all the important abstracts.

Here is a sample abstrat:

A1 October 13, 2007 9:00 AM - 10:30 PM

Room 301
Somatosensory and Motor Evoked Potentials during Sevoflurane and Propofol Anesthesia

Michael S. Kincaid, M.D., Michael J. Souter, M.D., Patrick D. Bryan, Mark Klein, Arthur M. Lam, M.D.Anesthesiology, University of Washington, Seattle, Washington

Background and Purpose: Transcranial electrical motor evoked potentials (MEP) have joined somatosensory evoked potentials (SSEP) as an important aspect of neurophysiologic monitoring during both intracranial and spine surgery. General anesthesia is known to diminish the quality of signals with SSEP, decreasing amplitude and increasing latency, with volatile anesthesia having a greater effect than intravenous anesthesia. There is little quantitative information on the comparative effect of volatile and intravenous anesthetics on MEP signal quality, however. The purpose of this study is to describe the effects of propofol and sevoflurane on SSEP and MEP in patients undergoing both spine and neurosurgical procedures.

Research & Case Studies using Neuromonitoring!

Years: 2005-2007
Neuromonitoring in Infants:
Motor Evoked Potentials After Transcranial Magnetic Stimulation Support Hypothesis of Coexisting Central Mechanism in Obstetric Brachial Palsy.
Abstract:
Six infants with obstetric brachial palsy, ranging from 4 to 7 months of age, were investigated. One was suspected of having extensive brachial plexus lesions and five were suspected of having a unilateral lesion of both roots C5 and C6. All were referred to our center to investigate the possibility for reconstructive surgery. In all infants, even at this age, transcranial magnetic stimulation resulted in motor evoked potentials (MEP) in the biceps (in one, in the brachioradial) muscles. Averaging could not be done because of the intraindividual variation in latency. The MEP was easier to recognize if evoked when the infant had the arm bent. In all five infants suspected of upper brachial plexus lesion with avulsion of both roots C5 and C6 and/or complete rupture of the upper trunk, proven in four, an MEP on the lesioned side could be evoked. Combined with earlier investigations showing (almost) normal EMG and somatosensory evoked potentials in infants with upper plexus lesion, this leads us to the conclusion that the paralysis of these infants cannot only be attributed to the peripheral axonal damage alone but that central plasticity must also play an important role. As this is a slow process, some infants might not yet be able to use the paralytic muscles. Some theoretic issues are discussed.

Neuromonitoring in Young Child:
Improvement of Motor-Evoked Potentials by Ketamine and Spatial Facilitation During Spinal Surgery in a Young Child.
Anesth Analg 2005;100:1634-1636© 2005
International Anesthesia Research Society
Monitoring motor evoked potentials is desirable during spine surgery but may be difficult to obtain in small children. In addition, the recording of reliable signals is often hampered by the presence of various anesthetics. We report the case of a young child whose motor evoked potentials were successfully monitored using a ketamine-based anesthesia and a newly introduced stimulation technique consisting of combined spatial and temporal facilitation.






Journal of Clinical Neurophysiology.
24(1):48-51,
February 2007. Colon, A J. *; Vredeveld, J W. *+; Blaauw, G ++

Is MEP monitoring is superior to SSEP in detecting nerve damages?

Our data again confirm that MEP monitoring is superior to SSEP monitoring in detecting impending impairment of the functional integrity of cerebral and spinal cord motor pathways
during surgery. Detection of MEP changes and adjustment of the surgical strategy might allow to prevent irreversible pyramidal tract damage. Stable SSEP/MEP recordings reassure the surgeon that motor function is still intact and surgery can be continued safely. The combined SSEP/ MEP monitoring becomes advantageous, if one modality is not recordable.

Neurosurgical Review
Springer Berlin, Volume 30, Number 2 / April, 2007
M. R. Weinzierl, Email: Martin.Weinzierl@ukaachen.de

Posterior thoracic segmental pedicle screw instrumentation: Evolving methods of safe and effective placement
Intraoperative neuromonitoringIntraoperative neuromonitoring (IONM) has become an integral part of complex spine surgery. The primary objective of IONM is to provide the surgeon with early warning of a potential neurological event. IONM, in the form of somatosensory-evoked potentials (SSEP's), initially gained popularity with deformity surgeons who routinely relied on the Stagnara wake up test to monitor neurologic integrity. Monitoring techniques have become much more sophisticated since their inception affording a higher level of protection to the patient. At present, many centers employ SSEP's, motor-evoked potentials (MEP's), and spontaneous and triggered EMG responses during complex thoracic pedicle screw instrumentation procedures.

Neurology India
Year : 2005 Volume : 53 Issue : 4 Page : 458-465
Philadelphia, 19107 USA
zeiller@comcast.net

Years 2000-2005

Intraoperative Neuromonitoring.
Article Neurologist. 8(4):209-226, July 2002.
Minahan, Robert E. MD
Abstract:
BACKGROUND-: Intraoperative neuromonitoring (IONM) has been a valuable part of surgical procedures for over 25 years. Insight into the nervous system during surgery provides critical information to the surgeon allowing reversal or avoidance of neural insults.

REVIEW SUMMARY-: Electrophysiological tests including electroencephalography, electromyography, and multiple types of evoked potentials (somatosensory, auditory, and motor) are monitored during surgeries that involve risk to the nervous system. Deterioration of signals suggests a surgical insult and is associated with an increased risk of postoperative deficit. Intraoperative identification of this risk allows corrective action. In addition, IONM teams make use of their armamentarium of tests to evaluate anatomy or function of the nervous system in response to specific questions posed by the surgical team.

CONCLUSIONS-: Intraoperative recordings are now a routine part of many surgical procedures. Their correct application leads to improved surgical outcome.
(C) 2002 Lippincott Williams & Wilkins, Inc.



Years 1990- 2000


Years 1980-1990


Years 1970-1980



The Inception of Neuromonitoring: 1960
[1960-1970]