Sensory Nerve Action Potentials

2009 ◽  
pp. 239-256
Author(s):  
Eric J. Sorenson
Keyword(s):  
Nerve Conduction ◽  
Action Potentials ◽  
Sensory Nerve ◽  
Nerve Conduction Studies ◽  
Clinical Electrophysiology ◽  
Specific Measure ◽  
Myelinated Axons ◽  
Sensory Pathways ◽  
Sensory Nerve Action ◽  
Peripheral Sensory

Nerve conduction studies are an invaluable addition to clinical electrophysiology testing. SNAPs are a sensitive and specific measure of function in the peripheral sensory pathways. These studies confirm whether large myelinated axons are affected by an underlying abnormality. When an area that is affected is clinically tested, nerve conduction studies can help to distinguish between a preganglionic (i.e., root level or higher) and a postganglionic (i.e., peripheral) process.

Sensory Nerve Conduction Studies

2016 ◽  
pp. 292-311
Author(s):  
Eric J. Sorenson
Keyword(s):  
Nerve Conduction ◽  
Action Potentials ◽  
Sensory Nerve ◽  
Nerve Conduction Studies ◽  
Nerve Action ◽  
Compound Muscle Action Potentials ◽  
Sensory Nerve Action ◽  
Electrical Generator ◽  
Nerve Dysfunction ◽  
Potential Waveform

Sensory nerve action potentials (SNAPs) are an important component of an electrodiagnostic test of peripheral nerves and can localize lesions either proximal or distal to the dorsal root ganglia. They are among the most sensitive measures of peripheral nerve dysfunction, and can provide information about the pathophysiology of the neuropathy, suggesting demyelination or axonal loss in some cases. Because SNAPs are much smaller than compound muscle action potentials, they are technically more difficult to study. Temperature will have a greater impact on SNAPs than motor potentials, with cooler limb temperatures leading to longer latencies, slower conduction velocities, and larger amplitudes. Responses are commonly averaged 3 to 5 times to minimize the effect of the background noise on the waveforms. Distance from the electrical generator and inter-electrode distance will also impact the appearance and size of the nerve potential waveform. This chapter reviews the concepts and applications of sensory nerve action potentials and sensory nerve conduction studies.

scholarly journals Carpal tunnel syndrome: long-term nerve conduction studies in 261 hands

2009 ◽  
Vol 67 (1) ◽  
pp. 69-73 ◽  
Author(s):  
Dante Guilherme Velasco Hardoim ◽  
Guilherme Bueno de Oliveira ◽  
João Aris Kouyoumdjian
Keyword(s):  
Carpal Tunnel Syndrome ◽  
Carpal Tunnel ◽  
Nerve Conduction ◽  
Sensory Nerve ◽  
Nerve Conduction Studies ◽  
Sensory Nerve Action ◽  
Tunnel Syndrome ◽  
The Mean ◽  
Compound Action

OBJECTIVE: To compare a long-term carpal tunnel syndrome (CTS) on nerve conduction studies (NCS) in hands treated non-surgically. METHOD: We retrospectively selected 261 symptomatic CTS hands (166 patients), all of them confirmed by NCS. In all cases, at least 2 NCS were performed in an interval greater than 12 months. Cases with associated polyneuropathy were excluded. NCS parameters for CTS electrodiagnosis included a sensory conduction velocity (SCV) <46.6 m/s (wrist to index finger, 14 cm) and distal motor latency (DML) >4.25 ms (wrist to APB, 8 cm). RESULTS: 92.8% were women; mean age was 49 years (20-76); the mean interval between NCS was 47 months (12-150). In the first exam, the median sensory nerve action potential (SNAP) and the compound action muscular potential were absent in 9.8% and 1.9%, respectively. In the second/last exam, SCV worsened in 54.2%, remained unchanged in 11.6% and improved in 34.2%. SNAP amplitude worsened in 57.7%, remained unchanged in 13.1% and improved in 29.2%. DML worsened in 52.9%, remained unchanged in 7.6% and improved in 39.5%. Overall, NCS parameters worsened in 54.9%, improved in 34.3% and remained unchanged in 10.8%. CONCLUSION: Long-term changing in NCS of CTS hands apparently were not related to clinical symptomatology and could lead to some difficulty in clinical correlation and prognosis. Aging, male gender and absent SNAP were more related to NCS worsening, regardless the mean interval time between the NCS.

scholarly journals Electrophysiological Studies in Five Cases of Abetalipoproteinemia

1984 ◽  
Vol 11 (1) ◽  
pp. 60-63 ◽  
Author(s):  
N.J. Lowry ◽  
M.J. Taylor ◽  
W. Belknapp ◽  
W.J. Logan
Keyword(s):  
Nerve Conduction ◽  
Sensory Nerve ◽  
Auditory Brainstem ◽  
Nerve Conduction Studies ◽  
Auditory Brainstem Responses ◽  
Normal Velocity ◽  
Electrophysiological Studies ◽  
Myelinated Fibres ◽  
Peripheral Motor ◽  
Peripheral Sensory

SUMMARYAuditory brainstem responses (ABRs), visual and somatosensory evoked responses (VEPs and SEPs) and nerve conduction studies were conducted in 5 patients with abetaiipoproteinemia. The ABRs were normal in all cases. The VEPs were of normal amplitude but of increased latencies in two patients. The four eldest patients had delayed cortical SEPs but normal peripheral sensory nerve conduction studies. The peripheral motor conduction velocities were normal in all cases. The peripheral sensory studies showed normal velocity when a response was seen; however, the amplitude of the response was often reduced or it was absent. The electrophysiological studies reported here support a model of axonal loss of large myelinated fibres with secondary demyelination in abetaiipoproteinemia.

scholarly journals Sensory nerve conduction in the caudal nerves of rats with diabetes

2011 ◽  
Vol 26 (2) ◽  
pp. 121-124 ◽  
Author(s):  
Celina Cordeiro de Carvalho ◽  
Juliana Netto Maia ◽  
Otávio Gomes Lins ◽  
Sílvia Regina Arruda de Moraes
Keyword(s):  
Nerve Conduction ◽  
Action Potentials ◽  
Regression Line ◽  
Sensory Nerve ◽  
Diabetic Rats ◽  
Male Rats ◽  
Control Group ◽  
Conduction Velocities ◽  
Sensory Nerve Action ◽  
Diabetes Induction

PURPOSE: To investigate sensory nerve conduction of the caudal nerve in normal and diabetic rats. METHODS: Diabetes was induced in twenty 8-weeks old Wistar male rats. Twenty normal rats served as controls. Caudal nerve conduction studies were made before diabetes induction and the end of each week for six consecutive weeks. The caudal nerve was stimulated distally and nerve potentials were recorded proximally on the animal's tail using common "alligator" clips as surface electrodes. RESULTS: After induction, nerve conduction velocities (NCV) increased slower in the diabetic than in the control group. Sensory nerve action potentials (SNAP) conduction velocities increased slower in the diabetic than in the control group (slope of regression line: 0.5 vs 1.3m/s per week; NCV in the 15th week = 39±3m/s vs 44±4m/s). Tukey's tests showed differences between groups at the 11th, 13th and 15th weeks old. From the 10th week on, SNAP amplitudes increased faster in the diabetic than in the control group (slopes of the regression line: 10 vs 8µV per week; SNAP amplitudes in the 15th week: 107±23µV vs 85±13µV). Differences at the 12th, 13th and 15th weeks were significant. CONCLUSION: In diabetic rats nerve conduction velocities were slower whereas amplitudes were larger than in normal rats.

Reproducibility of sensory nerve conduction studies of the sural nerve using ultrasound-guided needle positioning

2011 ◽  
Vol 44 (6) ◽  
pp. 873-876 ◽  
Author(s):  
Olivier Scheidegger ◽  
Alexander F. Küffer ◽  
Christian P. Kamm ◽  
Kai M. Rösler
Keyword(s):  
Nerve Conduction ◽  
Sural Nerve ◽  
Sensory Nerve ◽  
Nerve Conduction Studies ◽  
Ultrasound Guided

scholarly journals Normal neurophysiologic parameters of the median nerve among adult healthy Sudanese population

2020 ◽  
Vol 10 (4) ◽  
pp. 136-141
Author(s):  
Mohammed Salah Elmagzoub ◽  
Ahmed Hassan Ahmed ◽  
Hussam M A Hameed
Keyword(s):  
Action Potential ◽  
Median Nerve ◽  
Conduction Velocity ◽  
Nerve Conduction ◽  
Compound Muscle Action Potential ◽  
Motor Nerve ◽  
Sensory Nerve ◽  
Peak Latency ◽  
Muscle Action Potential ◽  
Sensory Nerve Action

Background: Nerve conduction studies (NCSs) help in delineating the extent distribution of neural lesion, and the diagnosis of peripheral nerve disorders. Because normative nerve conduction parameters were not yet established in Sudan EMG laboratories, this study aims towards having our own reference values, as we are using the American and British parameters. This will allow avoiding the discrepancies that might be induced by many factors. Methods: NCSs were performed in 200 Median nerves of 100 adult healthy Sudanese subjects using standardized techniques. Results: The median SNAP (sensory nerve action potential) values were as follows: distal latency, 2.6±3 ms with a range of (2.3-2.9); peak latency, 3.5±0.5 ms (3.0-4.0); amplitude, 47.7±18.0μV (29.7-65.7); conduction velocity, 53.0±7.8 m/s (45.2-60.8). The following values were obtained for the Median nerve CMAP (compound muscle action potential) at wrist stimulation: distal latency, 3.5±0.5 ms with a range of (3.0-4.0); peak latency, 9.4± 1.0 ms (8.4-10.4); duration, 5.9±0.9 ms (5.0-6.8); amplitude, 12.3±2.5 mV (9.8-14.8); area, 43.0±10.4 mVms (32.6-53.4); conduction velocity, 63.6±6.2 m/s (57.4-69.8). The F wave was 28.4±1.8 ms (26.6-30.2). Conclusion: The overall mean sensory and motor nerve conduction parameters for the tested nerve compared favorably with the existing literature with some discrepancies that were justified.

scholarly journals Sciatic neuropathy with preserved sensory nerve action potentials, a case series

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Matthew Ritch ◽  
Omer Suhaib ◽  
Yuebing Li
Keyword(s):  
Action Potentials ◽  
Sensory Nerve ◽  
Case Series ◽  
Normal Range ◽  
Single Institution ◽  
Lumbosacral Radiculopathy ◽  
Sciatic Neuropathy ◽  
Nerve Action ◽  
Sensory Nerve Action ◽  
Sensory Fibers

Background: Sciatic neuropathy is differentiated from lumbosacral radiculopathy based on the finding of abnormal sensory nerve action potentials (SNAPs). Cases of sciatic neuropathy with intact SNAPS have not been well described. Methods: A retrospective analysis of 12 patients with sciatic neuropathy in a single institution. Results: We describe 12 patients in whom a sciatic neuropathy was diagnosed based on a combination of history, physical exam, radiological and electrodiagnostic (EDX) findings. Lower extremity SNAPs were found to be within normal range in all patients, although SNAP amplitude asymmetry between both sides was observed in 3. Included patients were young (mean age of 40.3 years) and mostly female (9 patients). Conclusions: Sciatic neuropathy may occur with a relative sparing of sensory fibers. Recognition of this group of patients should help to avoid making a misdiagnosis of lumbosacral radiculopathy.

Sign in / Sign up

Export Citation Format

Share Document