BMP in Back surgery?:- What and Who?

Bone Morphogenic protein (BMP) is used in certain surgical procedures that involves lower lumbar surgery, but not in other procedures why?. Is BMP good compared to patients own bone transplantation or bone marrow substitute?. Right now it seems lime the FDA has approved BMP to be used only in lower lumbar cases such as L5-S1 procedures?. But, if BMP has anything to do with neurophysiological signals, not sure if there are any reports?.

Brain writes in this column about BMP, it's present usages and more...!. The full article can be read from his original site spine universe, click the topic for the link. 

BMP: The What and the Who

Brian R. Subach, MD, FACS
Neurosurgeon/Spine Surgeon
Virginia Spine Institute
Reston, VA

The title of this article asks two completely different but equally important questions. First, the "what." RhBMP-2 (recombinant bone morphogenetic protein, BMP) is a genetically engineered protein which both recruits bone forming cells to the surgical area and "turns on" local cells to the bone-making process. BMP is used for conditions requiring spinal fusion and stimulation of bone growth.

ABRET changes the Eligibility Requirement for All Exams?

ABRET has announced a major change in the eligibility requirement for exams like CNIM, Long Term Monitoring, EEG and EP technologists.  These news changes will be effective for some exams from Jan 2009 and for others from 2012. The change will apply to all the exams conducted by ABRET.  

The new requirements for CNIM exam is the candidate should undergo prior EEG credentialing???

There are two major requirements, of which the second one is already known to the folks in this area, but the first requirement:

1.An electroneurodiagnostic credential; R. EEG T. or R. EP T. or Canadian equivalent. A copy of current registration must accompany the Application.

For someone with a graduate degree or PhD or MD, if they wanted to be neuromonitoring specialist, they must undergo EEG or EP credentialing through ABRET?, does this makes any sense to those advanced degree holders?. It simply sounds to be ridiculous that ABRET is bent on making such changes as this would drive the PhDs and other advanced degree holders, there are already lots of shortage in neuromonitoring, it is difficult for companies to hire graduates with specialization in neurophysiology or neuroscience, with this new requirements, it is going to get worst to find someone with a credentialing in EEG or EP. 

As of January 1, 2010 the following eligibility requirements will be in effect for the CNIM Examination

The Certification Examination in Neurophysiologic Intraoperative Monitoring is designed and written for the advanced level electroneurodiagnostic professional who is currently practicing in an intraoperative environment.

All candidates must meet the following requirements by the application deadline. There are no alternative routes.

1. An electroneurodiagnostic credential; R. EEG T. or R. EP T. or Canadian equivalent. A copy of current registration must accompany the Application.

Disposable Surgical Face Masks: A Systematic Review

Here is an review on Surgical Masks, a careful review on Masks that looks at all the studies done so far and compares the various usage and it's safety.

Disposable Surgical Face Masks:

A Systematic Review

DISPOSABLE SURGICAL FACE MASKS: A SYSTEMATIC REVIEW

Authors: Allyson Lipp RN DipN RNT MA MSc, Principal Lecturer, School of Care
Sciences, University of Glamorgan, UK.
Peggy Edwards RN Dip Operating
Practice BSc Professional Practice, Welsh Risk Pool Assessor, Pontypridd,
UK
Acknowledgements: Cochrane Collaboration Wounds Group and the Theatre
Nursing Trust Fund. Extracts of systematic review reproduced by kind permission
of: Update Software, Oxford.

ABSTRACT

Surgical face masks were originally developed to contain and
filter droplets of microorganisms expelled from the mouth and nasopharynx of
healthcare workers during surgery, thereby providing protection for the
patient.

However, there are several ways in which surgical face masks could potentially contribute to contamination of the surgical wound. Surgical face masks have recently been advocated as a protective barrier between the surgical team and the patient, but the role of the surgical face mask as an effective measure in preventing surgical wound infections is questionable.
The aim of the systematic review is to identify and review all randomised controlled trials evaluating disposable surgical face masks worn by the surgical team during clean surgery to prevent postoperative surgical wound infection.

First Spinal Cord Endoscope Surgery Conducted in Iran

Can you imagine in this 21st century with so much of medical knowledge and medical care a first spinal endoscope surgical procedure is done on Oct 14, 2008?. A first spinal surgery in Iran, wow....finaly a surgical procedure to help patients with back or spinal problems is introduced in Iran by an American spine surgeon?.

Iran News Page One > Iran News First Spinal Cord Endoscope Surgery Conducted in Iran Oct 15, 2008 Iranian.ws The first spinal cord endoscope surgery was conducted in Iran, yesterday morning, by Professor John Chio, head of California Vertebrarium Research Center. Shedding light on details of such a surgery, Chio said: “During this surgery the tissues are not cut and the muscles are placed aside with highly delicate tools in order to reach the spinal cord and to lower disc pressure. Meanwhile, in order to stitch the wound, laser is used.” He added that in this surgery the patient does not bleed and therefore blood transfusion does not take place. The surgeon further underlined that the patient can leave three hours after surgery, resuming his social life within six days and commencing his athletic activities within three weeks. “The operation is also economically justified,” he added. He further said that one of his main goals is to train Iranian physicians, stressing that Iranian physicians are intelligent and can easily learn this operation.

Neuromonitoring:-Failing to be Assertive to communicate the neurophysiological abnormalities will cost you a Lot?

   Josh Colemna's back surgery went wrong during surgical procedure that involved possibly a scoliosis correction or posterior spinal correction, though the exact procedure done and details are not available, it is important to notice the role of neuromonitoring, fialing to do the right thing at right time will not only cost money, job but also someone's life.  
Neuromonitoring companies must make sure they have the competent neurophysiologists with a PhD or MD, or a neurologist is overlooking the technicians or else pay for the mistake. But, a neurophysiologist or neurologist will be able to warn the surgeon and anesthesiologist providing feed back instantly. Why it is so important to have this highly qualified professionals for doing some technical job is that they have the expert knowledge to troubleshoot as well as identify the causes of any changes if takes place, compared to a technician, he/she might be able to perform the technique but will have hard time in interpreting and convince the surgeon of a danger of injury to sensory, motor pathways or spinal cord injuries during back surgery. Anyways, this is an example of how much it will cost and how it will cost you if you fail to alert timely?.

March 24th, 2007 at 9:51 am

$11.7 M verdict against bystander doctor

» by Ted Frank

March 24th, 2007 at 9:51 am

$11.7 M verdict against bystander doctor

» by Ted Frank

A team of doctors at North Fulton Medical Center worked on Josh Coleman’s back surgery in 2003. Dr. Frank Puhalovich had a minor role: “he was only in the operating room for about 10 minutes making sure a technician properly hooked up a monitor that tracks nerve impulses along the spinal [cord] through electrodes attached to Coleman’s head and feet.” But after Puhalovich left, during surgery, the alarm went off: attorneys blame the surgeons’ failure to respond to the alarm in a timely fashion for Coleman’s paralysis. Coleman sued everyone involved, and all the doctors settled, except Puhalovich. So Coleman proceeded to trial against Puhalovich, blamed him also, and a jury awarded $11.7 million. The press coverage gives no indication what the theory of liability is against Puhalovich.

Joshua Coleman, sitting in a wheelchair next to his attorneys, Bill Stone and David Boone, smiled as the verdict was announced after the two-week civil trial.

“Josh is high as a kite right now,” Stone said. “He’s going to have a great weekend.”

(Beth Warren, “Paralyzed man awarded $11.7 million”, Atlanta Journal-Constitution,Mar. 24).

Update: Kevin, MD post with clever title Shotgun yields a jackpot.

 SATURDAY, MARCH 24, 20078

Shotgun yields a jackpot

A neurologist loses a verdict in a back surgery case. He was in the OR for less than 10 minutes, and didn't even operate on the patient. He got caught in the crossfire of a shotgun lawsuit. An unfortunate outcome, but the wrong doctor was targeted.

Cochlear Microphonics & CNAP recording in Neuromonitoring??

Anatomy of Ear (pic fromHearing and Hair Cells John S. Oghalai, M.D.Baylor College of Medicine ) (human ear pic: Muni's_neuromonitoring1)Jorge Bohorquez et al describes a system in their recent publication listed below, according to their study one can test both outer hair cell and inner hair cell electrical activity during surgical procedures. Though this work is evaluated in aniamal study, it is pretty interesting if this can be moved to the OR in our neuromonitoring procedures. I am not sure if this is already practiced in the OR by any neuromonitoring companies. It is a very common procedure to do auditory brain stem evoked potentials in tumor resection or craniotomy procedure that might put the 8th nerve in risk, nevertheless, this CM, CAP and CNAP will be a very important approach in certain cases where injury to both IHC and OHCs can be avoided?. 

Neuromonitoring of cochlea and auditory nerve with multiple extracted parameters during induced hypoxia and nerve manipulation

Jorge Bohórquez et al 2005 J. Neural Eng. 2 1-10   doi: 10.1088/1741-2560/2/2/001

Abstract.  A system capable of comprehensive and detailed monitoring of the cochlea and the auditory nerve during intraoperative surgery was developed. Jorge Bohórquez et al 2005 J. Neural Eng. 2 1-10 E-mail: jbohorquez@miami.edu

The cochlear blood flow (CBF) and the

electrocochleogram (ECochGm) were recorded at the round window (RW) niche using a specially designed otic probe.

The ECochGm was further processed to obtain cochlear microphonics (CM) and compound action potentials (CAP). The amplitude and phase of the CM were used to quantify the activity of outer hair cells (OHC); CAP amplitude and latency were used to describe the auditory nerve and the synaptic activity of the inner hair cells (IHC). In addition, concurrent monitoring with

a second electrophysiological channel was achieved by recording compound nerve action potential (CNAP)

obtained directly from the auditory nerve. Stimulation paradigms, instrumentation and signal processing methods were developed to extract and differentiate the activity of the OHC and the IHC in response to three different frequencies. Narrow band acoustical stimuli elicited CM signals indicating mainly nonlinear operation of the mechano-electrical transduction of the OHCs. Special envelope detectors were developed and applied to the ECochGm to extract the CM fundamental component and its harmonics in real time. The system was extensively validated in experimental animal surgeries by performing nerve compressions and manipulations.

Medical & Legal Issues Regarding Brain Injury

What are the medical and legal aspects of Brain Damage or Axonal damage? 

what type of knowledge is neccessary to deal with court cases that may require background knowledge and expertise in looking at the area of brain damage and discuss the intricacies of brain damage and axonal damage to the court officials as well as to the lay people in the jury??. This following article appeared in the latest issue of the newsletter of IBIA (International Brain Injury Association) discusses in detail about what health care professionals should know?.

Medical-Legal Illustration: What Health Care Professionals Should Know

By Robert L. Shepherd, MS, Certified Medical Illustrator, Vice President and Director of Eastern Region Operations, MediVisuals Incorporated

Professionals of numerous medical as well as health care subspecialties are often called upon to provide expert opinions in the context of litigation. Those providing medical-legal opinions may either be called due to their role as a treater of a patient involved in litigation or retained to provide so called “expert witness” testimony because these specialists are recognized as experts in a specific area (even though they may not have treated a patient involved in litigation). In either case, the role of the testifying professional is very important in helping decision makers or triers of fact identify and appreciate the truth in order to achieve just resolution of the contested issue(s). 

For Instance: 

Figure 1:  Example of graphics that can aid expert testimony:  This particular series of illustrations helps demonstrate one of the most difficult concepts for layperson decision makers to appreciate – that is, how brain injuries (traumatic axonal and shear injury) can occur in an individual with only a minor, or sometimes even no significant blow to the head.  The illustrations are also particularly helpful in explaining how an individual can have these injuries, yet the injuries are not evidenced on traditional brain imaging studies such as CT or MRI.   Another very effective animation demonstrating this same phenomenon even more convincingly can be seen at the following link:  http://medivisuals.com/mildtbi

Gray's Anatomy

Gray's Anatomy, the complete Book is available online free at Bartlby.com, this is a treat to medical students, anatomy and physiology students, because it is free online.

The Bartleby.com edition of Gray’s Anatomy of the Human Body features 1,247 vibrant engravings—many in color—from the classic 1918 publication, as well as a subject index with 13,000 entries ranging from the Antrum of Highmore to the Zonule of Zinn.

Henry Gray (1821–1865).  

Anatomy of the Human Body.  1918.

TWENTIETH EDITION
THOROUGHLY REVISED AND RE-EDITED BY WARREN H. LEWIS
ILLUSTRATED WITH 1247 ENGRAVINGS 

PHILADELPHIA: LEA & FEBIGER, 1918
NEW YORK: BARTLEBY.COM, 2000 

Also available free online at

NEUROMONITORING RESEARCH Articles -PubMed

A quick search or  browsing on the PubMed on the subject neuromonitoring produced these results summarised in My NCBI column here.

This is the summary of publications thus far available in the pubmed search. Because of the way the robotic search is conducted using terms/words we "type in", there is a possiblity of exlusion of some related research papers, or inclusion of unrelated papers in the cumulative numbers. But, to the most part I believe these are the numbers reflecting published works on neuromonitoring. 

My NCBI
Welcome drmuni. [Sign Out]
U.S. National Library of Medicine
National Institutes of Health
ePubMedProteinNucleotideGSSESTStructureGenomeBooksCancerChromosomesConserved DomainsdbGaP3D DomainsGeneGenome ProjectGENSATGEO ProfilesGEO DataSetsHomoloGeneJournalsMeSHNCBI Web SiteNLM CatalogOMIAOMIMPMCPopSetProbeProtein ClustersPubChem BioAssayPubChem CompoundPubChem SubstanceSNPTaxonomyToolKitUniGeneUniSTS forSearch term  Items 1 - 20 of 312, of Page 16  Next  ,     Review: 72 forSearch term  Display SummaryBriefAbstractAbstractPlusCitationMEDLINEXMLUI ListLinkOutASN.1Related ArticlesCited in BooksCancerChrom LinksDomain Links3D Domain LinksdbGaP LinksGEO DataSet LinksGene LinksGene (OMIM) LinksGene (GeneRIF) LinksGenome LinksProject LinksGENSAT LinksGEO Profile LinksHomoloGene LinksNucleotide LinksNucleotide (RefSeq) LinksEST LinksEST (RefSeq) LinksGSS LinksGSS (RefSeq) LinksOMIA LinksOMIM (calculated) LinksOMIM (cited) LinksBioAssay LinksCompound LinksCompound (MeSH Keyword)Compound (Publisher) LinksSubstance LinksSubstance (MeSH Keyword)Substance (Publisher) LinksPMC LinksCited in PMCPopSet LinksProbe LinksProtein LinksProtein (RefSeq) LinksProtein (Weighted) LinksProtein Cluster LinksCited ArticlesSNP LinksSNP (Cited)Structure LinksTaxonomy via GenBankUniGene LinksUniSTS LinksAll: 179  of Page 9   Next,     Review: 34

EMG=61225 (3062 Pages), Reviews:3119

EEG=108037 (5402 Pages), Reviews: 7224        
TcMEP=23 (2 Pages), Reviews: 1           
SSEPs (the term SSEP alone does not produce result on somatosensory
but unrelated articles, but SSEPs is the correct term to use)
= 411 (21 Pages), Reviews:18          
Intraoperative, Cortical Mapping= 459 (23 Pages), Reviews:69
Carotid Endarctomy, Neuromonitoring= 28 (2 Pages), Reviews=6               
Scoliosis= 12 (1 Page), Review:1

Pubmed search of the topic Neuromonitoring using words "neuromonitoring, intraoperative neuromonitoring resulted in about 312 research article, 72 reviews for the term neuromonitoring and 179 research article and 34 reviews for the term intraoperative neuromonitoring respectively.

While there are several combination of word search to know the publication lists in this field, the search I posted here pretty much compiles most of them. Some of the other ways to look at the publications in this field using the search words such as "MEP, SSEP, EMG, EEG, Cortical Mapping, Carotid Endarctomy, Scoliosis. Some of the key words required a combination search with the word intraoperative to get specific research articles. In the following section, I will discuss the latest research reports on neuromonitoring comprising works done in 2008.

NeuroMonitoring in Epilepsy Related Diseases & Surgeries!?.

Journal of Neurosurgical Focus
In the latest issue of the journal JNS, Scellig S. D. Stone, M.D., and James T. Rutka from The Hospital for Sick Children, and The University of Toronto, Ontario, Canada discuss issues relate to the topic "challenges in Epilepsy related diseases and neurosurgeries in epilepsy patients". 

These challenges can provide great opportunities for neuromonitoring, infact, in this very review you will find that the existing brain mapping and EcoG has been a gold standard to conduct successeful neurosurgeries, it has become an important tool for surgeons to identify and map the areas in epilepsy patients who undergo surgeries to get rid of the epileptic loci in the brain.

The authors described two combined approach that can be used to delineate a possible trajectory for the epilepsy surgeons, such methods may help to relieve the patients from epileptic activities. 

The neuronavigation system and the neuromonitoring approach, I will try to condense the information regarding neuromonitoring here, but one must read the whole article to get a better insight into this field. Three of the exisiting neuromonitoring protocols are discussed,

1.Electrocorticography recording method, using this method one can reliably map the brain areas of interest for surgical removal by directly placing grid electrodes on the surface of brain (invasive), using the method poineered by the Penfield and Jasper [34.Jasper H, Electrocorticography. Penfield W, Jasper H: Epilepsy and the Functional Anatomy of the Human Brain Boston, Little Brown, 1954. 692–738].

2.Depth Electrode Recordings, this method can be combined with the direct mapping of the brain using depth electrode, deep isertion of electrodes into subcortical areas will provide additional information about ictical and interactive epileptic regions, in reality, the DER can be performed outside the OR perioperatively as well as inside the OR intraoperatively, enabling the surgeon to develop a streamlined strategy into the brain area of interest to be lesioned, lesioning brain areas is the surgical procedures carried out to eliminate epileptic activities.

3.Intraoperative EcoG is  yet another recording used widely to operate on interactive epileptic patients, the most important use of EcoG seems to be to during extralesional resections or lesionectomy combined with spike-positive tissue resection procedures. EcoG monitoring seems to have helped reduce the rate of second surgical procedure and reduced epileptic activities significantly in those patients. One of the surgical procedure where EcoG was very useful in the removal of the hippocampal area or mesial temporal or gliosis surgical procedures.

4.Direct Cortical Stimulation method, mostly used in surgeries that involve sensory motor or language areas, a direct application of focal cortical pulses of low voltage current using a hand held bipolar electrode.

So, applying these

techniques in combination as a "multi-model" neuromonitoring procedure

can go long way in safegurding better surgical procedures in epilepsy patients. This is a great review any neurophysiologist or neurosurgeon or neurologist or neuromonitoring personnel must read for better understanding of surgical procedures and neuromonitoring in epilepsy patients.

Ulnar Neuropathy? If the surgery site is lower Lumosacral level, why should you monitor upper limp SSEPs?

This article in the latest Spine Journal (an electronic publication) demonstrates that upper limp SSEP monitoring is quite handy in detecting ulnar nerve neuropathy during lower back surgeries??.

PubMed-NCBI Spine J. 2008 Aug 4. [Epub ahead of print] Upper-limb somatosensory evoked potential monitoring in lumbosacral spine surgery: a prognostic marker for position-related ulnar nerve injury.

BACKGROUND CONTEXT: Somatosensory evoked potential (SSEP) is used to monitor integrity of the brain, spinal cord, and nerve roots during spinal surgery. It records the electrical potentials from the scalp after electrical stimulation of the peripheral nerves of the upper or lower limbs. The standard monitoring modality in lumbosacral spine surgery includes lower-limb SSEP and electromyography (EMG). Upper-limb SSEP monitoring has also been used to detect and prevent brachial plexopathy and peripheral nerve injury in thoracic and lumbosacral spine surgeries. We routinely monitor lower-limb SSEP and EMG in lumbosacral spine procedures at our institution. However, a few patients experienced postoperative numbness and/or pain in their ulnar distribution with uneventful lower-limb SSEP and EMG.

Neuromonitoring Signal Changes during Spinal Epidural Hematoma?

Are there non-surgical factors that can cause spinal cord damage???......,

oh yes, 

there are few non-surgically induced damages that might go unnoticed in the absence of intraoperative neuromonitoring such as ischaemia, hematoma, stroke and so on...?.

 The following work demonstrates the timely detection of epidural hematoma by neurophysiological wave form changes.

the disappearance of evoked potentials and the subsequent appearance of paraplegia in our patient was unlikely to be caused by the epidural LA, but probably by the occurrence of the spinal epidural hematoma as a complication of epidural catheterization.

Acute spinal cord dysfunction was revealed by INM, then elucidated by imaging of the spine. The whole sequence of events led to timely urgent neurosurgical intervention which resulted in complete restoration of motor and sensory functions.

Our patient’s case supports the value of evoked-potential monitoring during spinal surgery.

This case and previous work offer arguments that evoked potentials are relatively insensitive to epidural LAs, but nevertheless we suggest that neuraxial LAs better be avoided in cases in which INM is used.

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.

Nerve Conduction Study & Needle Electromyography

Nerve Conduction Technology News:- NeuroMetrix completes CE Technical File and Achieves CE Marking for its ADVANCE(TM) System allowing Marketing in the European Union

Last update: 7:30 a.m. EDT July 29, 2008

WALTHAM, Mass., Jul 29, 2008 (BUSINESS WIRE) -- NeuroMetrix, Inc. (NURO:

neurometrix inc com

NURO 1.39, -0.02, -1.4%) today announced that it has completed the CE technical file for its ADVANCE System ("ADVANCE"). With this regulatory step, NeuroMetrix intends to begin marketing ADVANCE to neurologists, clinical neurophysiologists, hand surgeons, and other specialists in the EU.

ADVANCE is a comprehensive platform for the performance of traditional nerve conduction studies and needle electromyography procedures. The technical specifications include a precision electrical stimulator and dual recording channels for acquiring nerve conduction responses. A third channel is available for recording needle electromyography signals. ADVANCE introduces several important technological improvements.

SOURCE: NeuroMetrix, Inc.

NeuroMetrix, Inc.
Jessica Borchetta, 781-314-2725
Administrative Assistant
neurometrix.ir@neurometrix.com

65,000 Peers, Doctors Online Network!

BUSINESS AMNews articles linked to Sermo's online physician forum

Doctors can join 30,000??? (it is 65,000 now!) peers to comment on stories and initiate discussions.

By AMNews staff. Oct. 15, 2007.

---

Doctors now can share their views on American Medical News articles with thousands of their colleagues on Sermo, an online community for physicians only.

Current and recent articles in the American Medical News online edition -- amednews.com -- carry links that instantly connect readers to the free Sermo site (www.sermo.com). Established Sermo member physicians then need only log in. First-time physician users can access the Sermo community after a simple registration procedure, taking about two minutes, that includes verification of their MD or DO degree.

Spinal cord tumor removal & Neuromonitoring

Spinal cord tumor resection can pose serious risks of
surgical
induced sensory or motor deficits, intraoperative neuromonitoring
of
combined sensory and motor pathways can be useful to prevent potential
damages. Here are some collective articles related to spinal cord tumor resection.

http://www.doaj.org/doaj?func=abstract&id=198856

Spinal Cord integerity risk & Tibial single Trial SSEP?

Single trial Tibial Somatosensory SSEP along with H-reflex can be used to monitor the spinal cord integerity and function during surgical procedures that put the cord in risk. The following article
describes how this combination of a single trial SSEP can be
useful?.

When spinal cord functional integrity is at risk during surgery, intraoperative neuromonitoring is recommended.

Tibial Single Trial Somatosensory Evoked Potentials (SEPs) and H-reflex are here used in a combined neuromonitoring method: both signals monitor the spinal cord status, though involving different nervous pathways.

However, SEPs express a trial-to-trial variability that is difficult to track because of the intrinsic low signal-to-noise ratio. For this reason single trial techniques are needed to extract SEPs from the background EEG.