The Spread of Somatosensory-Evoked Potentials Within the Nervous System

1985 ◽  
Vol 48 (1-6) ◽  
pp. 222-225
Author(s):  
A. Sólyom ◽  
S. Tóth ◽  
I. Holczinger ◽  
J. Vajda ◽  
Z. Tóth ◽  
...  
Keyword(s):  
Nervous System ◽  
Evoked Potentials ◽  
Somatosensory Evoked Potentials

Somatosensory Evoked Potentials

2016 ◽  
pp. 539-566 ◽  
Author(s):  
James C. Watson ◽  
Jonathan L. Carter
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Evoked Potentials ◽  
Somatosensory Evoked Potentials ◽  
Dorsal Column ◽  
Medial Lemniscus ◽  
Prognostic Information ◽  
Technical Aspects ◽  
Non Invasive ◽  
Anoxic Coma

Somatosensory evoked potentials (SEPs) provide a non-invasive, sensitive, and quantitative way of assessing the functional integrity of the peripheral and central proprioceptive, dorsal column–medial lemniscus somatosensory conduction pathways. SEPs can be used to localize lesions in the nervous system, to identify objectively abnormalities in patients with few sensory manifestations or none at all, to determine whether a process potentially affecting the spinal cord is functionally impairing, and to provide prognostic information in the context of post-anoxic coma. This chapter discusses the technical aspects, limitations, and roles of SEPs in the evaluation of neurologic symptoms, and provides examples of SEPs in different diseases.

Impairment Tutorial: Rating Sensory and Motor Deficits of the Upper Extremity

2000 ◽  
Vol 5 (2) ◽  
pp. 5-7
Author(s):  
Charles N. Brooks
Keyword(s):  
Nervous System ◽  
Evoked Potentials ◽  
Peripheral Nervous System ◽  
Conduction Velocity ◽  
Motor Neurons ◽  
Somatosensory Evoked Potentials ◽  
Nerve Conduction ◽  
Nerve Fibers ◽  
Nerve Conduction Studies ◽  
Electrical Potentials

Abstract The three components of electrodiagnosis useful in evaluation of the peripheral nervous system and spinal cord include electromyography (EMG), electroneurography (nerve conduction studies), and somatosensory evoked potentials. EMG examination involves introduction of a special recording needle into a muscle belly. Electrical potentials located within a few millimeters of the needle are picked up by an electrode and are transmitted from the muscle to amplifiers that filter and display results visually for the electromyographer. Three types of spontaneous activity in electrical potentials are of the greatest relevance: positive sharp waves, fibrillation potentials, and fasciculations (fasciculation potentials on the EMG result from irregular firing of motor units). Electromyography can help assess the status of nerve fibers indirectly, but the integrity of large myelinated sensory and motor neurons can be evaluated directly by nerve conduction studies (NCS), also known as electroneurography. NCS can assess motor neurons, sensory neurons, or mixed nerve trunks. Sensory nerve conduction velocity can be studied in a manner analogous to motor conduction velocity: sensory fibers can be directly stimulated, and the evoked response can be measured at the wrist and elbow. Somatosensory evoked potentials occasionally are useful as an adjunct to EMG and NCS in the diagnosis of peripheral nervous system pathology. These tests also are useful when it is unclear whether an individual has a true radiculopathy.

Electrodiagnosis of the Peripheral Nervous System: An Introduction

2014 ◽  
Vol 19 (3) ◽  
pp. 10-14
Author(s):  
Richard T. Katz
Keyword(s):  
Nervous System ◽  
Evoked Potentials ◽  
Spontaneous Activity ◽  
Peripheral Nervous System ◽  
Motor Neurons ◽  
Somatosensory Evoked Potentials ◽  
Nerve Conduction ◽  
Nerve Fibers ◽  
Nerve Conduction Studies ◽  
Mixed Nerve

Abstract This article is an introduction to electrodiagnosis of the peripheral nervous system, including electromyography, electroneurography (nerve conduction studies), and somatosensory evoked potentials. Electromyography involves the introduction of a special recording needle into a muscle body in search of spontaneous activity (electrical potentials that occur while the muscle is at rest). Three types of spontaneous activity are of greatest relevance: positive sharp waves, fibrillation potentials, and fasciculations. Electromyography can help assess the status of nerve fibers indirectly, but the integrity of large myelinated sensory and motor neurons can be evaluated directly by nerve conduction studies (NCS), also known as electroneurography. NCS involves the introduction of an electrical stimulus, either by surface electrode or needle, and recording an evoked response. NCS can assess motor neurons, sensory neurons, or mixed nerve trunks, depending on the strategy employed. Somatosensory evoked potentials (SSEP) sometimes are useful as an adjunct to EMG and NCS in the diagnosis of peripheral nervous system pathology and are obtained by stimulating a peripheral mixed nerve at a frequency of approximately 2-5 Hz. Several manufacturers have created automated, hand-held units for performing nerve conduction studies, and neuromuscular ultrasound is noninvasive and painless, and ultrasound of nerve entrapment has identified nerve enlargement just proximal to the site of entrapment. Physicians should know or learn the qualifications of the physician to whom they refer their patients for electrodiagnostic assessment.

scholarly journals Spinal Cord Stimulation Inhibits Cortical Somatosensory Evoked Potentials Significantly Stronger than Transcutaneous Electrical Nerve Stimulation

2013 ◽  
Vol 4;16 (4;7) ◽  
pp. 405-414
Author(s):  
Tilman Wolter
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Pain Relief ◽  
Evoked Potentials ◽  
Nerve Stimulation ◽  
Somatosensory Evoked Potentials ◽  
Spinal Cord Stimulation ◽  
Transcutaneous Electrical Nerve Stimulation ◽  
Dose Dependency ◽  
Electrical Nerve Stimulation

Background: Despite the good clinical results elicited by spinal cord stimulation (SCS), the physiological basis of action of SCS is widely unknown. Inhibition of somatosensory evoked potential (SEP) amplitudes by SCS has been described, but it is unclear whether this displays dose dependency. Moreover, it is unknown whether the pain-relieving effect elicited by SCS correlates with the inhibition of SEPs. Finally, this study aimed to answer the question whether there is a difference in the effect on SEPs between SCS and transcutaneous electrical nerve stimulation (TENS), thus between central nervous system stimulation and peripheral nervous system stimulation. Methods: Ten patients (4 men and 6 women, age range 40-77 years) with neuropathic lower limb pain were included in the study. All patients had implanted SCS systems with percutaneous type electrodes. Cortical SEPs under SCS and TENS were measured without stimulation, under stimulation at perception threshold (PT), and at maximal threshold (MT) in a crossover design. Results: Cortical SEP amplitudes were significantly inhibited by SCS. Stimulation at PT and at MT both led to a statistically significant inhibition of the SEP amplitude. The difference between amplitude reduction at PT and MT showed a tendency towards significance. The degree of SEP amplitude inhibition did not correlate with pain relief. Inhibition of SEP amplitudes by TENS was weaker than that elicited by SCS. The average percentage of amplitude reduction at MT was twice as high under SCS as it was under TENS. No effects on SEP latencies were seen. Conclusions: SCS exerts a significantly stronger inhibition of SEP amplitudes than TENS. The data hint at a dose dependency of SCS-induced SEP amplitude inhibition. No correlation between SEP amplitude inhibition and pain relief was found. Key words: spinal cord stimulation, SCS, transcutaneous electrical nerve stimulation, TENS, neuropathic pain, somatosensory evoked potentials, SEP

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