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.

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.

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 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.

Stimulus waveform determines the characteristics of sensory nerve action potentials

2016 ◽  
Vol 127 (3) ◽  
pp. 1879-1885 ◽  
Author(s):  
Pedro Pereira ◽  
João Leote ◽  
Christopher Cabib ◽  
Jordi Casanova-Molla ◽  
Josep Valls-Sole
Keyword(s):  
Action Potentials ◽  
Sensory Nerve ◽  
Stimulus Waveform ◽  
Nerve Action ◽  
Sensory Nerve Action
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