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Key Terms

List of Common IOM Terms:

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

  • abnormal – this term applies to baseline responses in which the latency and/or amplitude fall outside of the normal range for the patient’s gender, age, and body type.  In many cases, one side of the body may have “normal” responses while the other side has “abnormal” responses.  In this situation the baselines are termed “asymmetric.”  This interpretation is made by a neurophysiologist.
  • action potential – a momentary change in the electrical potential on the surface of a nerve or muscle cell that occurs when it is stimulated (receives an impulse), resulting in the transmission of an impulse
  • amplitude – the vertical size of a waveform, measured in microVolts.  This varies based on the distance of the signal from the recording electrode.
  • aneurysm – an excessive localized enlargement of a blood vessel caused by disease or weakening of the vessel wall.  It often looks like a berry hanging on a stem.  This is a serious medical condition and must be treated promptly.  Untreated aneurysms have the potential to burst and cause serious injury or death.
  • axon – projection of a neuron that conducts impulses away from the main body of the cell to be transmitted to the next cell
  • baseline – the nerve responses (waveforms) acquired from a patient at a resting state before any surgical manipulation begins.  Sometimes, unstable patients will require baseline response recordings before they are moved or positioned.  These are termed pre-positional baselines.
  • brain waves – visual representation of the brain’s electrical activity recorded using electrodes placed on the scalp, such as in EEG
  • brainstem – connects the cerebrum (brain) with the spinal cord and relays sensory and motor signals between the two.  It also controls autonomic functions (such as heartbeat, digestion, and other automatic body functions).
  • BSER / BAER / BAP / AEP (brainstem auditory evoked potential) – recorded in the brainstem following stimulation of the auditory system using headphones placed in the ears.  These responses help to evaluate the functional integrity of the brainstem and auditory (hearing) system.
  • burst suppression – EEG pattern marked by prolonged periods of silence (no activity) interspersed with brief bursts of activity.  Burst suppression can be observed in an overly-anesthetized patient or in the event of cerebral (brain) ischemia.  This interpretation is made by a neurophysiologist.
  • CAP (compound action potential) – the sum of the activity of multiple nerve fibers (of a single nerve trunk).  When summed, these show the degree of activity in a nerve.
  • cardiothoracic – a medical/surgical specialty having to do with disorders involving the heart, lungs, and great vessels (cardiovascular system)
  • cardiovascular – organ system that functions as a blood distribution network.  The heart supplies the body with frest oxygenated blood via arteries.  De-oxygenated blood is returned to the heart via the veins.
  • central nervous system – the part of the nervous system consisting of the brain and spinal cord
  • cerebral cortex (neocortex) – the outermost sheet of neural tissue in the mammalian brain, made up of gray matter.  It plays a key role in consciousness, awareness, attention, thought, language and memory.
  • cerebral hemorrhage / intracerebral hemorrhage (ICH) / subarachnoid hemorrhage (SAH) – type of bleeding that occurs within the skull, or brain itself.  It can occur due to a trauma or ruptured cerebral aneurysm.  It is a severe condition requiring prompt medical attention.  Outcome is closely related to the size and location of the hemorrhage.
  • cervical vertebrae – “neck” – portion of the spine immediately below the skull.  In general, these vertebrae make up the neck.  There are 7 cervical vertebrae.
  • CMP (compound muscle potential) – recorded from the muscles following direct stimulation of the corresponding nerves and nerve roots.  CDI uses CMP to assist surgeons in identifying nerves in and around the area they are working on and to confirm proper screw placement in spinal fusions.
  • CNIM (Certification Examination in Neurophysiologic Intraoperative Monitoring) – the examination taken by a neurotechnician to become certified in intraoperative monitoring.  Candidates must meet certain education requirements and complete the required amount of intraoperative monitoring training to be eligible to take the exam.  All CDI neurotechnologists maintain CNIM.
  • cranial nerves – nerves that emerge directly from the brain.  Humans have 12 pairs of cranial nerves.  The first 2 pairs emerge from the cerebrum (brain), and the remaining 10 emerge from the brainstem.
  • dermatome – area of skin supplied by a single sensory nerve
  • diagnostics – the process(es) followed to diagnose a patient
  • doppler (direct doppler) – an instrument that uses reflected sound waves to evaluate blood flow rates, particularly in major arteries and veins, and can help doctors ensure proper blood flow or locate clots and blockages.  A handheld probe attached to a box is placed over the vessel and the blood flow is heard as a “wooshing” sound from the box.
  • eChirp – this term is unique to CDI.  It is a signal automatically sent from technologist equipment to the supervising neurophysiologist when the technologist’s machine comes online and again when the technologist begins collecting data.
  • EEG (electroencephalography) – recording of the brain’s spontaneous electrical activity using electrodes placed on the scalp.  EEG is used to evaluate the integrity of brain function, as well as diagnosing brain abnormalities such as epilepsy, comas or strokes.
  • electrode – a solid electric conductor through which an electric current enters or leaves a medium, such as a cell, body, solution or apparatus.  CDI uses 2 types of electrodes; needle electrodes, which are thin needles inserted into the skin, and disc electrodes, which are small metal discs adhered to the skin using a conductive paste.
  • electrophysiology – the study of the electrical properties of biological cells and tissue
  • embolus (pl: emboli) – a detached intravascular mass that may occlude a vessel.  Common pathologic emboli include thromboemboli (a detached blood clot) and cholesterol emboli (a detached portion of arterial plaque).  An embolus may be of solid, liquid or gaseous state.
  • EMG (electromyography) – recording of muscles’ spontaneous electrical activity.  During surgery, EMG helps evaluate nerve/nerve root integrity.  If nerve(s) are being irritated during a surgical procedure, EMG will be seen in the corresponding muscle(s).
  • EOG (electrooculogram) – recorded using electrodes placed around the eye.  It is a technique for measuring the resting (still) state of the retina, recording eye movements, and diagnosing optic issues.
  • epoch – a summary waveform representing the average of a set number of individual waveforms (trials)
  • ERP (event related evoked potential) – a measurable electrophysiologic response that is the direct result of thought, perception or memory in response to a stimulus.  The latency of the these responses can help evaluate the functional integrity of the brain.
  • evoked potential – an electrical signal recorded from the nervous system following the presentation of a stimulus.  CDI performs many forms of evoked potential monitoring (see SEP).
  • FVP (flash visual potential) – recorded from the brain following visual stimulation using a uniform flash of light as the stimulus.  This helps to evaluate the integrity of the visual system.
  • gray matter – consists mainly of neuronal cell bodies and unmyelinated axons.  It is called gray matter because of its gray/brown color caused by capillaries and neuronal cell bodies.  It is found in the brain and spinal cord. 
  • ischemia – restriction or loss of arterial blood supply to a region of the body that can cause damage or dysfunction of the affected tissue.  Correct monitoring can prevent further damage by giving advanced warning of this lack of blood flow.
  • latency – time frame in which a response is observed in relation to its stimulus onset (evoked potential).  Usually measured in milliseconds.
  • lumbar vertebrae – “lower back” – these are the largest vertebrae and make up the portion of the spine located below the thoracic vertebrae down to the tail bone.  This section of the spine contains most of the spine’s natural curvature (lordosis).  There are 5 lumbar vertebrae.
  • MAC (minimum alveolar concentration) – this term applies to inhaled anesthetics.  It is the lung concentration of inhaled anesthetic required to prevent movement in 50% of patients experiencing surgical stimulation/pain.  Inhaled anesthetics have a dramatic effect on cerebral electrophysiology.
  • MEP (motor evoked potential) – recorded from the muscles following stimulation of the motor area of the brain as a way to evaluate the functional integrity of the motor system
  • mini-stroke (transient ischemic attack) (TIA) – brief and transient episode of neurologic (brain) dysfunction caused by temporary ischemia in the brain due to occlusion of a vessel by an emboli.  TIAs have the same symptoms as CVAs, but the symptoms caused by TIAs resolve within minutes to hours and often leave no lingering deficits.
  • montage – defined recording sites and reference pairs used for each modality
  • motor – information relating to the movement of the body.  This information is sent from the brain to various parts of the body via the spinal cord.  CDI monitors motor functions via MEP, as well as EMG and CMP.
  • MSP (median nerve evoked potential) – recorded from the central nervous system following stimulation of the median nerve.  The median nerve exits the spinal cord in the cervical region and runs down through the arm into the first 3 digits of the hand.  MSP is used to evaluate cervical spine and upper extremity function.
  • myelinated – myelin is a white electrical insulating material that wraps around the axon of a neuron and improves the conduction and transmission of nerve impulses.  Cells possessing this insulation are said to be myelinated.
  • myelopathy – pathology (disease or injury) of the spinal cord resulting in chronic ischemia of the cord.  This can have a few possible origins, consisting of trauma to the spinal cord, inflammation of the spinal cord (usually due to disease or infection), or dysfunction of the vascular systems supplying the spinal cord.
  • neuron – “brain cell” – cells that relay electrical impulses in the nervous system.  They are made of 3 parts: dendrites that receive impulses, a cell body, and an axon that transmits impulses.  It should be noted that although these are sometimes referred to as “brain cells”, they are actually found throughout the entire nervous system.
  • neurophysiologist – an individual who has received a doctoral degree (in medicine or a neural science) and has passed the required certification examinations.   Only a neurophysiologist is approved to interpret neurophysiologic data.  CDI’s neurophysiologists are Dr. Robert J. Sclabassi, MD, PhD, and Dr. Vivian Liang, MD, PhD.
  • neurophysiology – the study of the electrical/chemical processes of nervous system function
  • neurophysiology monitoring (neuromonitoring) (clinical neurophysiological monitoring) – the use of electrophysiological modalities to monitor the functional integrity of the nervous system.  It is also used to locate, evaluate and diagnose nervous system disorders and dysfunctions.
  • neuroscience – the scientific study of the nervous system.  It is considered an interdisciplinary science.  This is a general term which encompasses the various scientific disciplines dealing with the structure, development, function, chemistry, pharmacology, and pathology of the nervous system.
  • neurosurgery – the corresponding surgical specialty to neurology utilizing surgery to prevent, diagnose and treat nervous system disorders
  • orthopedic surgery – surgical specialty concerned with disorders of the musculoskeletal system, spine and joints
  • osteoarthritis / degenerative joint disease (DJD) – progressive degeneration of joint cartilage and the underlying bone, most common from middle age onward
  • otolaryngology surgery (ear, nose, and throat) (ENT) – surgical specialty concerned with disorders of the ear, nose, throat, head, face and neck
  • physiology – the study of the functions and activities of living organisms and their parts
  • PSP (peroneal nerve evoked potential) – recorded from the central nervous system following stimulation of the peroneal nerve at the knee.  The peroneal nerve is a branch of the sciatic nerve.  The sciatic nerve exits the spinal cord in the lumbar/sacral region, runs down the hip and leg, and branches into the tibial and peroneal nerves just above the knee.
  • PUP (pudendal nerve evoked potential) – recorded from the stimulation of the pudendal nerve at the penis/vagina.  The pudendal nerve innervates the pelvic area, carrying sensory information from the penis/vagina, urethra and anus.
  • PVP (pattern visual potential) – recorded from the brain following visual stimulation using a patterned stimulus, such as a black and white checkerboard image.  This helps to evaluate the integrity of the visual system.
  • radiculopathy – condition related to pain/weakness in an extremity resulting from compression/trauma to a nerve root.  For example, compression of a nerve root in the cervical spine will cause radiculopathic pain or weakness in the corresponding dermatome/muscle of the upper extremity.
  • remote monitoring – CDI uses a self-developed system, called NeuroNet, that gives a supervising neurophysiologist the ability to see technologists‘ intraoperative data in real time from an off-site location, and communicate with the technologists using a “chat” software known as rtalk.  Technologists can also use rtalk to communicate important information to each other.  (see also telemedicine)
  • sacral vertebrae (sacrum) – “tail bone” – these vertebrae make up the lowest portion of the spine.  In adulthood they fuse together to form the sacrum (tail bone).  There are 5 sacral vertebrae.
  • sensory – information relating to the senses; smell, touch, sight, taste, sound.  This information is sent from the various parts of the body into the brain via the spinal cord.  CDI monitors sensory function via SEP, AEP, and VEP.
  • spinal nerves – nerves that emerge from the spinal cord (as opposed to directly from the brain like the cranial nerves).  There are 31 pairs of spinal nerves that contain both sensory and motor fibers.
  • spondylosis – osteoarthritic degeneration of spinal vertebrae joints causing narrowing of the space between two adjacent vertebrae.  This may lead to the compression of spinal nerve roots, ultimately causing radiculopathy and vertebral instability.
  • stenosis – an abnormal narrowing in a tubular structure of the body.  In vascular medicine, blood vessels become stenotic due to a buildup of plaque inside.  In neurology, spinal stenosis occurs due to osteoarthritic degeneration of the vertebrae, causing the central canal to become narrower and compress the spinal cord.
  • stimulation (of a nerve) – applying an electrical current (measured in milliAmps) to a nerve using an electrode placed on or under the skin.  This stimulation will create a signal to be transmitted to and recorded in the brain.  For some systems (visual and auditory), the stimulus is not an electric current but rather something presented to the patient to evoke a response from that system (such as a flash of light or a click tone).
  • stroke (cerebrovascular accident) (CVA) – ischemia of neural (brain) tissue caused by occlusion of blood flow by an embolus or hemorrhage.  Patients may experience long-lasting or permanent deficits related to the location and amount of neural tissue affected by the CVA.
  • symptomatic / asymptomatic – these terms refer to the state of the patient.  If a patient is still currently experiencing the symptoms caused by their injury/disease they are deemed symptomatic.  If the patient never had symptoms of their injury/disease or the symptoms have resolved they are deemed asymptomatic.
  • telemedicine – healthcare provided by a physician at a distance using information technologies and telecommunications.  Examples are images (such as x-rays) or videos received in real time by an off-site physician and his/her ability to communicate back in real time.  At CDI, a supervising neurophysiologist is able to see a technologist‘s data and communicate with said technologist in real time using their self-developed NeuroNet system.  This allows for immediate relay of the neurophysiologist’s interpretation to the surgeon, and immediate action can be taken by the surgeon if necessary.  (see also remote monitoring)
  • thoracic vertebrae – “mid back” – these vertebrae attach the ribs to the spine.  There are 12 thoracic vertebrae and they are located between the cervical and lumbar vertebrae.
  • TIVA (total intravenous anesthesia) – an anesthetic regimen administered during surgery comprised solely of intravenous medications and no inhaled agents.  This type of anesthesia is preferable for MEP monitoring.
  • transcranial doppler – testing device that measures the velocity of blood flow through the brain’s blood vessels (see also doppler)
  • TSP (tibial nerve evoked potential) – recorded from the central nervous system following stimulation of the tibial nerve.  The tibial nerve is a branch of the sciatic nerve.  The sciatic nerve exits the spinal cord in the lumbar/sacral region, runs down the hip and leg, and branches into the tibial and peroneal nerves just above the knee.
  • USP (ulnar nerve evoked potential) – recorded from the central nervous system following stimulation of the ulnar nerve.  The ulnar nerve exits the spinal cord in the cervical region and runs down through the arm into the last 2 digits of the hand.  USP is used to evaluate cervical spine and upper extremity function.
  • vertebra (pl. vertebrae) – the individual bones that make up the spine (backbone).  There are 33 spinal vertebrae, which are divided and grouped into cervical, thoracic, lumbar, sacral, and coccygeal.
  • VEP (visual evoked potential) – recorded from the brain, using EEG, following the presentation of a stimulus to the visual system.  This helps to evaluate the functional integrity of the visual system.
  • waveform – a curve showing the shape of a wave at a given time, supplying a visual representation of electrophysiological activity.  It is formed by amplitude (vertical axis) vs. time (horizontal axis).
  • white matter – consists mainly myelinated axons.  It is called white matter because of its pink/white color caused by the white color of myelin and red capillaries.  It is found in the brain and spinal cord.
  • within normal limits – this term applies to baseline responses in which the latency and amplitude fall within a normal range for the patient’s gender, age and body type.  This interpretation is made by a neurophysiologist.

 

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