- When determining the location and extent of a peroneal nerve lesion, an important nerve to include in the electrodiagnostic test is:
A) The lateral femoral cutaneous nerve
B) The superfi cial peroneal nerve
C) The lateral peroneal nerve
D) The medial peroneal nerve
- What type of neuropathy is usually seen on electrodiagnostic testing in alcoholic neuropathy?
A) Axonal sensory neuropathy
B) Demyelinating sensory motor neuropathy
C) Axonal and demyelinating sensory motor neuropathy
D) Axonal sensory motor neuropathy
- All of the following can affect H-reflex latency on electrodiagnostic testing except:
A) Demyelinating sensory neuropathy
B) Demyelinating motor neuropathy
- Certain medical conditions predispose a patient to an entrapment neuropathy, such as carpal tunnel syndrome. These include all of the following except:
C) Thyroid disorders
- During electrodiagnostic (EMG) testing, if the patient requests termination of the test:
A) The test should be continued
B) The test should be stopped
C) The test should be paused, and then continued when the patient is more relaxed
D) The patient should be given a sedative to calm him or her down
- A patient presents with weakness in the right hand. Electromyography (EMG)/nerve conduction study (NCS) fi ndings are as follows:
– Right median motor latency = 4.3 msec
– Right ulnar motor latency = 2.2 msec
– Left median motor latency = 3.2 msec
– Right median sensory conduction velocity across the wrist = 36 m/sec
– Right median sensory conduction velocity distally = 44 m/sec
– Needle EMG of the right abductor pollicis brevis (APB) muscle = +3 fi brillation potentials
What would be an appropriate next step?
A) No more testing is indicated
B) Test the left ulnar motor nerve
C) Needle evaluation of the right pronator teres muscle
D) Test the right ulnar sensory nerve
- What would be seen on a needle study in a patient with steroid myopathy?
A) Normal motor units
B) Small amplitude, short duration polyphasic motor units
C) Large amplitude, long duration motor units
D) Small amplitude, long duration polyphasic potentials
- You are performing an electromyography (EMG)/nerve conduction study (NCS) of the upper extremities to evaluate for carpal tunnel syndrome and notice that the sensory and motor, median and ulnar latencies are delayed. Your next steps should be:
A) Test radial sensory nerve
B) Needle testing of bilateral abductor pollicis brevis (APB) muscles
C) Test tibial motor nerve
D) Test the peroneal and sural nerves
- In a patient with an accessory peroneal nerve, stimulation proximally at the fi bular head with pickup over the extensor digitorum brevis (EDB) muscle will lead to:
A) Larger compound motor action potential (CMAP) amplitude than distally at the ankle
B) Increased CMAP conduction velocity proximally
C) Positive defl ection of the CMAP
D) No changes from that of an individual without an accessory peroneal nerve
- Electrodiagnostic findings in a classic radiculopathy will include which of the following? A) Decreased sensory nerve action potential (SNAP) and compound motor action potential (CMAP) amplitudes, with spontaneous potentials seen in the paraspinal muscles
B) Normal SNAP and CMAP amplitudes, with spontaneous potentials from two muscles innervated by the same peripheral nerve
C) Normal SNAP and CMAP amplitudes, with spontaneous potentials in the paraspinal muscles and two muscles from different peripheral nerves innervated by the same affected root
D) Decreased SNAP and CMAP amplitudes, with spontaneous potentials seen in paraspinal muscles and two muscles from different peripheral nerves innervated by the same affected root
- What findings would you expect to see on electrodiagnostic testing in a patient with spinal stenosis?
A) Increased sensory nerve action potential (SNAP) and compound motor action potential
(CMAP) amplitudes with normal conduction velocities
B) Decreased SNAP and CMAP amplitudes with decreased conduction velocities
C) Normal SNAP and CMAP findings with normal needle electromyography (EMG) findings
D) Normal SNAP and CMAP findings with possible abnormal spontaneous potentials at multiple levels
- The most common error in the realm of neurodiagnostic testing is typically related to which of the following?
A) Computer analysis failure
B) Excessive ambient temperature/room temperature
C) Lack of repeat calibration of the testing probe with each measurement
D) Operator error
E) Patient’s inability to fully relax
- What is the only muscle that is innervated exclusively by the C5 nerve root?
B) Levator scapulae
D) Rhomboid (major and minor)
- The X-axis on the oscilloscope (screen) represents:
A) Time in microseconds
B) Time in milliseconds
C) Distance in centimeters
D) Distance in millimeters
- What muscles would be affected in a C6 radiculopathy?
A) Extensor carpi radialis
B) Flexor digitorum superficialis
C) Extensor indicis
D) Rhomboid major
- In the newborn, nerve conduction velocities are approximately what percentage of adult values? A) 50%
C) 100%D) 75%
- On needle electromyographic (EMG) testing, muscles that would be affected in a lesion to the posterior cord include all of the following except:
A) Extensor indicis proprius
C) Pronator teres
- During the needle portion of the examination, when assessing motor unit action potential (MUAP) recruitment:
A) Full recruitment should be attempted
B) Minimal recruitment should be used
C) The muscle should be relaxed
D) Any of the above can be used
- Which of the following can result in a prolongation of the H-reflex?
A) S1 radiculopathy
B) Sacral plexopathy
D) All of the above
- In what condition might you see a potential such as this one?
50 uV 10 ms
A) Normal muscle
D) Disorder of the neuromuscular junction
Electrotherapy diagnostics online multiple choice questions and answers-5
- B) Below the knee, the common peroneal nerve branches into the superficial and deep peroneal nerves. The superficial nerve innervates the peroneus longus and brevis and provides innervation to the lateral aspect of the lower leg as well as the dorsum of the foot (except for the first dorsal web space, which is innervated by the deep peroneal nerve). Nerve conduction study of the superficial peroneal sensory nerve is easy to perform, but often omitted. Just like the dorsal ulnar cutaneous nerve, it can be helpful in determining location and severity of a lesion. It should be noted that the peroneal nerve is also known as the fibular nerve.
- D) The peripheral neuropathy usually seen in alcoholic neuropathy is axonal sensory motor neuropathy. This means that low amplitudes would be seen in the sensory nerve action potentials (SNAPs) and compound motor action potentials (CMAPs) with relative preservation of the velocities (up to 20% decrease in velocity can be seen, as the fastest fibers may be affected).
- D) A demyelinating neuropathy will slow nerves and therefore increase the latency of the H-reflex. Because the pathway of the H-reflex involves both sensory and motor fibers, either type of neuropathy will affect the H-reflex. The height of the person will affect the H-reflex latency because the pathway is longer (it takes a longer time to travel a longer distance).
- D) Diabetes, pregnancy, and thyroid disorders (as well as rheumatoid arthritis, edema, gout, and peripheral neuropathy) can predispose patients to entrapment neuropathies. Psoriasis has not been related to an increase in entrapment neuropathies.
- B) The patient has the right to terminate the test at any point. It is best to explain the benefits of continuing the test and ask the patient whether they are sure that this is what they want. If the patient insists, this should be documented in the EMG report.
- C) Although this appears to be a simple right carpal tunnel syndrome, it is important (especially considering the denervation in the APB muscle) to rule out a median neuropathy more proximally, a double-crush syndrome with cervical radiculopathy, or even an anterior horn cell disorder. Any of these can occur with a carpal tunnel syndrome. It is important to test a more proximal median-innervated muscle (pronator teres) as well as another ulnarly innervated hand muscle. If these are positive, it behooves the electromyographer to continue the needle evaluation.
- A) The motor units in a patient with steroid myopathy would typically have normal-appearing motor units. That is because steroid myopathies typically affect type II fibers. Electromyographic (EMG) testing evaluates type I fibers.
- D) To assess whether a patient has a peripheral neuropathy, it is necessary to test sensory and motor nerves in three limbs. Therefore, the peroneal and sural (or any other sensory and motor nerve in the lower extremity) should be performed.
- A) The accessory peroneal nerve is a branch of the superficial peroneal nerve that innervates the lateral aspect of the EDB. The nerve runs deep to the peroneus brevis and behind the lateral malleolus. The best way to test for this anomalous innervation is to stimulate the peroneal nerve posterior to the lateral malleolus (with pickup over the EDB). The amplitude of the CMAP obtained posterior to the malleolus plus (+) that of the normal ankle peroneal amplitude should summate and equal that of the amplitude proximally at the fibular head.
- C) Radiculopathy is a lesion of a nerve root. Clinically, it may present as sensory, motor, or mixed sensory/motor findings. In radiculopathy, the injury is proximal to the area being stimulated and therefore conduction block or slowing of conduction velocity will not be noted on electrodiagnostic testing. Any damage to the sensory fibers is generally proximal to the dorsal root ganglion (DRG). As there is physical continuity between the sensory nerve cell and the end unit, nerve conduction studies (NCS) will show normal sensory findings. Motor nerve conduction studies will generally be normal too because peripheral nerves contain multiple nerve roots. The classic needle electromyography (EMG) findings in a radiculopathy are abnormal spontaneous potentials (fi bs and positive sharp waves) in the paraspinal muscles of the suspected root level as well as two muscles innervated by different peripheral nerves but the same root level.
- D) In spinal stenosis, there is narrowing of the vertebral canal, which is usually exacerbated by extending the spine (standing) and relieved with flexion of the spine (sitting). Pain may radiate from the back down to the extremities, especially with extension of the spine. SNAPs are normal as the dorsal root ganglion (DRG) is located outside the spinal canal. CMAPs should not be affected as the distal portion of the nerve is not affected. There may be abnormal spontaneous potentials at rest (positive sharp waves [PSW] or fibrillations) or chronic motor unit action potential (MUAP) changes (polyphasic potentials) that are often bilateral. Bilateral paraspinals and extremities should be tested for EMG abnormalities.
- D) Of all of the possible mistakes that can lead to false-positive or false-negative electrodiagnostic results, the most common one is due to the person performing the test. These include not performing the test correctly, not interpreting the test correctly, not testing the appropriate nerves or muscles, failing to account for anomalous innervation, improper technique, or performing the test too early (before findings would be apparent on neurodiagnostic testing).
- D) The dorsal scapular nerve (which innervates the rhomboid muscle) is the first branch of the upper trunk and is usually composed of C5 fibers only.
- B) The X-axis (sweep) represents time, which is usually in milliseconds per division.
- A) The extensor carpi radialis is innervated by the radial nerve C5/6. The flexor digitorum superficialis is via the median nerve C7-T1. The extensor indicis is via the radial nerve C7/8. The rhomboid is innervated by the dorsal scapular nerve, C5.
- A) At birth, most of the myelination is incomplete. Conduction velocities are about half of adult values. By 1 year of age, the velocity is about 75%. Myelination is usually complete by age 3 to 5 years.
- C) The posterior cord includes the axillary nerve (to the deltoid) and the radial nerve (to the triceps and extensor indicis proprius). The pronator teres is innervated through the lateral cord and the median nerve.
- B) When evaluating the recruitment pattern of MUAPs, it is important to use minimal recruitment. Ideally, you would like to see the fi ring rate of one motor unit when a second motor unit is recruited. If maximal recruitment is attempted, individual motor units cannot be assessed and the recruitment frequency cannot be assessed. In addition, there is a risk of the needle breaking in the muscle if the contraction is too strong.
- D) Although the H-reflex is very sensitive, it is not specific. Any of the conditions listed can result in a prolongation of the H-reflex.
- B) Small-amplitude, short-duration polyphasic motor units are often seen in myopathies. In chronic neuropathies, the motor units may be of large amplitude, long duration, and polyphasic.
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