Podcast
Questions and Answers
What is the primary nerve involved in the loss of strength in the finger flexors after a shooting incident?
What is the primary nerve involved in the loss of strength in the finger flexors after a shooting incident?
What does the presence of positive spontaneous activity in m.interosseus dorsalis I indicate?
What does the presence of positive spontaneous activity in m.interosseus dorsalis I indicate?
What complication is indicated by stimulation of the median nerve showing a response in an ulnar muscle during surgery?
What complication is indicated by stimulation of the median nerve showing a response in an ulnar muscle during surgery?
Which type of neuropathy would be indicated by persistent positive sharp waves (PSW) in an electromyography (EMG) test?
Which type of neuropathy would be indicated by persistent positive sharp waves (PSW) in an electromyography (EMG) test?
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What factors can be monitored by electromyographic testing for neuropathy?
What factors can be monitored by electromyographic testing for neuropathy?
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What physiological response is primarily measured in electromyography (EMG)?
What physiological response is primarily measured in electromyography (EMG)?
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Which factor contributes to the increased speed of action potential propagation in nerves?
Which factor contributes to the increased speed of action potential propagation in nerves?
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In the context of nerve conduction, what is the typical latency period for the knee jerk reflex?
In the context of nerve conduction, what is the typical latency period for the knee jerk reflex?
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What is a common clinical presentation of carpal tunnel syndrome?
What is a common clinical presentation of carpal tunnel syndrome?
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Which of the following conditions involves a conduction velocity of 25 m/sec?
Which of the following conditions involves a conduction velocity of 25 m/sec?
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In needle electromyography, what characterizes abnormal motor unit action potentials (MUAPs)?
In needle electromyography, what characterizes abnormal motor unit action potentials (MUAPs)?
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What role does temperature play in nerve conduction?
What role does temperature play in nerve conduction?
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If a patient's finger flexors show loss of strength after an injury, which type of examination would likely provide detailed information about nerve damage?
If a patient's finger flexors show loss of strength after an injury, which type of examination would likely provide detailed information about nerve damage?
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Study Notes
Electromyography
- Electromyography (EMG) is a test for the peripheral nervous system
- Nerves and muscles create electrical current (action potentials, IPSP/EPSP, sodium/potassium pump)
- EMG records electrical current, instantaneously, spontaneously, superficially, and subcutaneously
- Electrical current activates nerves and muscles
- Dr. R Strijers is a neurologist in the Department of Clinical Neurophysiology at VU Medical Center
- A "Surpass II" Quantitative EMG/EP Workstation, made by EMS Biomedical, was used
Neurophysiology
- Nerves and muscles generate electrical current (action potentials, IPSP/EPSP, sodium/potassium pump)
- EEG and EMG are used to record this electrical current
- The methods of recording include instantaneous, spontaneous, superficial, and subcutaneous recording
- Electrical current activates nerves and muscles
- Electromyography is a test used to examine the peripheral nervous system
Primary Afferent Axons
- Propagation speed increases with larger axon diameters and myelination
- Myelinated axons use saltatory conduction (jumping from node to node)
- Different axon types have different diameters and speeds (e.g., Aα, Aβ, Aδ, and C fibers)
Psychogalvanic Response/Lie Detector Test
- Unmyelinated nerves have a latency of 1.8 seconds (1800msec)
Knee Jerk Reflex
- The latency of the patellar tendon reflex is 20 milliseconds
- This reflex is primarily mediated by myelinated nerves
Motor Nerve Conduction
- A schematic diagram shows motor nerve conduction in the hypothenar muscle, with the ulnar nerve
- Measurements, such as distance and time, were taken to determine conduction velocity
- Different sites of stimulation (wrist, below elbow, above elbow, axilla) provide data on conduction velocity through different sections
Sensory Nerve Conduction
- A training video illustrates sensory nerve conduction in the lower arm using the cutaneous nerve
Nerve Conduction Influences
- Temperature and age affect nerve conduction
Motor Nerve Conduction Problems
- Issues like focal partial conduction block, focal total conduction block, fresh transection, and old transections affect motor nerve conduction
- Conditions such as Guillain-Barré syndrome, axonal, and PNP can also affect conduction
Needle Examination
- Needle examination measures electrical activity in muscles and nerves
- This method evaluates motor unit action potentials (MUAPs)
- Normal MUAPs are biphasic or triphasic during muscle contraction
- Abnormal MUAPs can include fibrillation potentials and positive sharp waves at rest, as well as polyphasic potentials with high/low voltage amplitude.
Concentric Needle Examination
- A diagram show the recording of motor unit potentials in a concentric needle examination.
- The major components are SFAP, and MUAP
- These show the amplitude, duration, and number of phases.
Carpal Tunnel Syndrome
- This is a common entrapment syndrome of the median nerve
- Symptoms include numbness, pain, and tingling/paresthesia in the hand, especially at night
- Risk factors include repetitive activities (e.g., typing)
- Treatment options include wrist splints, injections, and surgery (releasing the transverse carpal ligament)
Polyneuropathy
- A case of the condition is where a 31-year-old man has lower leg numbness and walking issues
- Often involves the entire peripheral nervous system (numbness, tingling in hands and feet)
- A variety of causes can lead to polyneuropathy (e.g., diabetes, infections, autoimmune conditions).
Conduction Velocity
- Conduction velocity (measured in m/sec) in different nerves (e.g., right ulnar nerve, left tibial nerve) showed varying values (e.g., 38 m/sec, 25 m/sec, 34 m/sec)
- These values can reflect nerve damage or disease
Intraoperative Nerve Monitoring
- Intraoperative nerve monitoring (IONM) is a technique used during surgery to maintain the health of nerves
Patient with Loss of Strength in Fingerflexors
- A patient who has lost strength in their finger flexors after a hail incident is discussed.
- The nerve damage needs to be diagnosed.
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Description
Test your knowledge on electromyography (EMG) and its significance in studying the peripheral nervous system. This quiz covers the basics of electrical currents generated by nerves and muscles, and recording methods used in neurophysiology, such as EEG and EMG. Perfect for students and professionals in the field of neuroscience!
