Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Volume 1
Evoked Potential Monitoring
| Question | Answer |
|---|---|
| What two tracts make up the dorsal lemniscal sensory system? | cuneatus and gracilis tracts |
| Where are the cuneatus and gracilis tracts of the dorsal lemniscal system located? | in the posterior (dorsal) cord |
| What sensations do the cuneatus and gracilis tracts carry? | sensations of touch, pressure and vibration |
| The integrity of the cuneatus and gracilis tracts is assessed by what? | somatosensory evoked potentials: SSEP |
| Touch, pressure, and vibration sensations are carried into the spinal cord vie the __ __. | dorsal horn |
| Touch, pressure, and vibration asend on the ipsilateral or contralateral side? | ipsilateral |
| Where do the sensations of touch, pressure, and vibration cross over? | the brain stem |
| The sensations of touch, pressure and vibration cross over in the brainstem to which two locations? | contralateral thalamus and primary sensory cortex |
| In addition to traveling directly to the primary sensory cortex, sensory information is also transmitted into the __. | Reticular activating system (RAS) |
| In the RAS what happens to sensory information? | it percolates upward and spreads throughout the cerebral cortex |
| The RAS serves as an ___ route by which sensory information reaches the cerebral cortex | indirect |
| The RAS functions to maintain the ____ state. | alert/awake |
| What happens to the RAS when we go to sleep? | shuts off |
| General Anesthethis produce sedation and hypnosis (sleep) by doing what? | depressing the RAS |
| Complete loss of RAS activity is called __. | coma |
| What is the purpose of SSEP monitoring? | to evaluate the integrity of the brain or spinal cord during certain types of surdery |
| What operations are the gracilis and cuneatus tracts of the posterior spinal cord assessed during? | spine operations, carotid endardarectomy, aortic surgery, or repair of intracranial aneurysms |
| What happens if there is posterior cord ischemia or brain ischemia? | transmission of action potnetials through the posterior cord and/or brain is diminished, thereby reducing the intensity and delaying the arrival of action potentials reaching the cerebral cortex |
| What 3 nerves may be stimulated to elicit somatosensory evoked potentials? | tibial, median, or ulnar nerves |
| Somatosensory evoked potentials are recorded from where? | the scalp |
| The sciatic nerve branches into which two nerves? | common peroneal nerve and the tibial nerve. |
| The tibial nerve at the level of the ___ is usually the site of stimulation for somatosensory evoked potential monitoring. | ankle |
| Besides the tibial nerve, which other two nerves may also be stimulated for somatosensory evoked potential monitoring? | ulnar or median nerves |
| The critical electrode for detecting the evoked potential after stimulation of the tibial nerve must be placed over the primary sensory cortex where on the scalp? | at the midline of the scalp |
| If the median nerve or ulnar nerve is stimulated, the critical recording electrodes must be placed over the primary sensory cortex, where on the scalp? | somewhat laterally from the midline |
| For sensory evoked potentials, the stimulating electrodes are placed ___ and the detecting electrodes are placed ____. (Peripherally or Centrally) | stimulating- peripherally, detecting- centrally |
| List the pathway of action potentials from the right tibial nerve to the sensory cortex. | right tibial nerve to spinal cord via dorsal horn -> right spinal cord (cuneatus and gracilis tracts) -> lef cerebral cortex -> evoked potential recorded from electrodes between ears near midline (over longitudinal fissure) |
| After mild electrical stimulation of the nerve occurs, the electrical information reaches the cortex and what occurs? | a fluctuation in potential, an evoked potential |
| What does the early component or early peak of the evoked potential result from? | action potentials that are carried via the direct route |
| What is the direct route? | action potentials carried to the primary sensory cortex by the cuneatus and gracilis tracts of the dorsal lemniscal system. |
| How many neurons compose the dorsal lemniscal system? | 3 neurons |
| What does the delayed or late peak result from? | the arrival of action potentials that had traversed the reticular activating system |
| Where are electrodes located that receive the late peak? | anywhere on the scalp |
| Which peak is larger is magnitude, the early or late peak? | late peak |
| ___ and ___ are measured in somatosensory evoked potential monitoring. | Latency and amplitude |
| What is latency? | the time it takes for the action potential to traverse the peripheral nerves, spinal cord, and inner brain structures before arriving at the cerebral cortex |
| What is amplitude? | the magnitude or size of the evoked potential |
| What is somatosensory monitoring used to detect? | dorsal spinal cord and brain ischemia |
| The waves that deflect downward are designated ____ and those that deflect upward ___. | downward- P: positive; upward N: negative |
| The latency in milliseconds is indicated by the numbers placed where? | after the P or N |
| An (increase/decrease) in amplitude during evoked potential monitoring suggests that damage is occurring in the neural pathway being monitored. | decrease |
| An (increase/decrease) in latency during evoked potential monitoring suggests that damage is occurring in the neural pathway being monitored. | increase |
| Which nerves are stimulated during spinal scoliosis surgery? | tibial |
| What does increased latency and decreased amplitude of the SSEP with spinal scoliosis surgery indicate? | ischemia of the posterior spinal cord |
| In thoracic and thoracolumbar aortic reconstruction, ____ is one major concern. | spinal cord ischemia |
| During thoracolumbar aortic reconstruction, because ischemia of distal nerves, including posterior tibial nerves, alters conduction and the SSEP, spinal stimulation via a __ ___ electrode may be used. | lumbar epidural |
| Increased latency or decreased amplitude during thoracolumbar surgery indicates what? | ischemia of the posterior cord |
| The incidence of paraplegia following repair of thoracic or thoracolumbar aortic aneurysms varies from __-__%. | 5-40% |
| Since SSEP monitoring assesses the integrity of the __ cord only, monitoring of the __ cord is useful. (Anterior/posterior) | posterior, anterior |
| __ ___ potentials are used to monitor iscemia of the anterior (ventral) columns. | motor evoked |
| What is the most commonly used technique for motor evoked potentials? Stimulation over the __ __ or ___ __ with sensing over the ___ ___. | motor cortex or cervical spine; popliteal nerve |
| The motor cortex or cervical spine is ____ and popliteal nerve is ___. (central/peripheral) | central, peripheral |
| In a carotid endardarterectomy, which nerves are stimulated? | median nerves |
| What do increased latency and decreased amplitude indicated during SSEP of a carotid endarterectomy? | ischemia of deep brain structures and the sensory cortex |
| Why is the usefulness of somatosensory evoked potential monitoring during carotid endarterectomy questionable? | poor outcome changes in SSEP have been noted |
| Somatosensory evoked potentials can be modified by changes in what parameters? | temperature, systemic blood pressure, paCO2, PaO2 |
| SSEP are elicited by repetitive stimulation of what 3 nerves? | tibial, median, or ulnar nerves |
| SSEP is useful for monitoring function of ___ or __ during surgery. | dorsal spinal cord or brain |
| What surgeries is SSEP useful for monitoring? | spinal cord surgery, endarterectomy, aortic surgery, or during repair of intracranial aneurysms |
| Brainstem Auditory Evoked Potentials are elicited by __ ___. | auditory clicks |
| BAEP re useful during operations involving CN ___. | CN VIII |
| Visual evoked potentials are elicited by what? | flashes of light |
| When are visual evoked potentials useful? | if surgery is near the optic nerve |
| Give an example of a surgery that may use visual evoked potentials. | trans-sphenoidal approach to anterior pituitary tumor |
| Visual evoked potentials monitor the integrity of the __ nerve, CN __. | optic nerve, CN II |
| GEneral intravenous anesthetics and volatile inhaltional agents have what effect on evoked potentials? | increase the latency and decrease the amplitude |
| Rank visual, SSEP, and BAEP and their sensitivity to anesthetics. | VEP most, SSEP intermediate, BAEP least |
| How do you remember which is most sensitive? a | VEP: V for Very sensitive; SSEP: S for somewhat sensitive; BAEP: B for Barely sensitive |
| Somatosensory evoked potentials are recorded from electrodes placed over the ___ ___ if the tibial nerve is stimulated bilaterally. | longitudinal sulcus |
| If during a Harrington Rod procedure the amplitude of the SSEP decreases the latency increases, damage to what region of the spinal cord (anterior, posterior, lateral) may have occurred? | The posterior cord may have incurred damage |
Created by:
valleyanesthesia
Popular Nursing sets