Electromyography, also known as needle EMG, is a diagnostic procedure whereby the electrical activity of muscles is recorded using a fine needle electrode to assess muscle and motor neuron function. It is commonly performed as part of an ALS diagnostic work-up.
This article presents real cases of needle EMG in patients that were eventually diagnosed with ALS.
¶ Case 1: 37-year-old male, hand weakness
2022/04/29
Investigation: EMG Nerve Study
INVESTIGATION REPORT:
OUTPATIENT NERVE CONDUCTION STUDY AND EMG
CLINICAL INDICATION:
A 37-year-old gentleman with decrease in strength of thumbs bilaterally. The patient indicates this as an intermittent finding and sometimes not present. Also endorses some tingling in the left pectoralis region and twitching in the muscles of the upper arm.
ELECTRODIAGNOSTIC STUDY:
- Median motor nerve conduction study recording from abductor pollicis brevis was normal bilaterally.
- Ulnar motor nerve conduction study recording from abductor digiti minimi revealed prolongation of the distal motor latency on the left.
- Amplitude was within normal limits; however, there was slowing of nerve conduction across the elbow without conduction block. On the right, latency and amplitude were within normal limits; however again, there was slowing of nerve conduction across the elbow.
- Ulnar motor nerve conduction study recording from first dorsal interosseous revealed slowing of nerve conduction across the elbow bilaterally with intact latencies and amplitudes.
- Median sensory study recording from digit 2 was normal bilaterally.
- Ulnar sensory study recording from digit 5 was normal bilaterally.
- Dorsal ulnar cutaneous sensory response on the left was within normal limits. On the right, there was some slight decrease in amplitude though there was a significant contribution from the radial branch, which is an anatomic variant.
- Mixed palmar studies recording from the wrist did not demonstrate prolongation in the median versus ulnar response.
- Radial sensory study recording from left wrist was normal.
- Monopolar needle EMG of the left deltoid was normal apart from decreased relaxation.
- Monopolar needle EMG of the left biceps brachii demonstrated relatively frequent fasciculation potentials; however, recruitment was normal and motor amplitudes were normal.
- Monopolar needle EMG of the left triceps demonstrated relatively frequent fasciculations; however, again normal recruitment pattern with normal-appearing motor units.
- Monopolar needle EMG of the left brachioradialis demonstrated a few circulation with normal recruitment and normal-appearing motor units.
- Monopolar needle EMG of the left first dorsal interosseous was normal.
- Monopolar needle EMG of the left flexor pollicis longus was normal.
- Monopolar needle EMG of the left abductor pollicis brevis was normal.
ELECTRODIAGNOSTIC INTERPRETATION:
These electrodiagnostic studies are abnormal. There is evidence of slowing of conduction of the ulnar nerve across the elbow bilaterally without conduction block, in keeping with early ulnar neuropathy across the elbow. There was no evidence of denervation changes in ulnar innervated muscle or in the median innervated thumb muscle. There were some scattered fasciculations throughout other muscles in the left upper extremity, both visibly and on electrophysiologically; however, no other abnormalities on the EMG study to suggest acute denervation.
The patient was recommended to pursue positional therapy for his elbows including avoidance of leaning on the elbows, prolonged flexion, or repeated flexion extension. We recommended that he consider wrapping his elbows at night.
If there is persisting concern for progressive weakness, muscle atrophy, or worsening fasciculations, this would require a Neurology consultation, but at this time, no other significant abnormalities were seen on this limited study.
Dictated but not read.
2022/06/21
ASSESSMENT:
INVESTIGATION:
ELECTRODIAGNOSTIC STUDY:
- Median motor nerve conduction study recording from right abductor pollicis brevis was normal.
- Ulnar motor nerve conduction study recording from abductor digiti minimi revealed normal distal motor latency and normal amplitude (though on the low end of normal for a patient of his age) and evidence of slowing across the elbow. There was no conduction block across the elbow.
- Ulnar motor nerve conduction study recording from right first dorsal interosseous again revealed slowing of conduction velocity across the elbow without conduction block.
- Peroneal motor nerve conduction study recording from extensor digitorum brevis was normal.
- Tibial motor nerve conduction study recording from right abductor hallucis was normal.
- Median sensory study recording from right digit 2 was normal.
- Ulnar sensory study recording from right digit 5 was normal.
- Superficial peroneal sensory study recording from the right ankle was normal.
- Sural sensory study recording from the right ankle was normal.
- Monopole needle EMG of the right deltoid demonstrated occasional fasciculations, but otherwise normal muscle recruitment and motor units.
- Monopole needle EMG of the right biceps brachii demonstrated relatively frequent fasciculations. The recruitment, however, was normal and the units were normal.
- Monopole needle EMG of the right triceps brachii demonstrated quite frequent fasciculations. Recruitment and motor units were normal.
- Monopolar needle EMG of the right first dorsal interosseous demonstrated abnormal spontaneous activity. There was slightly reduced recruitment in keeping with subacute denervation.
- Monopolar needle EMG of the right flexor pollicis longus demonstrated significant reduction in recruitment with only 2 to 3 units activated with fast firing. This is indicative of more chronic denervation.
- Monopolar needle EMG of the right abductor digiti minim demonstrated a few fasciculations. There were many large amplitude motor units; however, the recruitment was normal.
- Monopolar needle EMG of the right abductor pollicis brevis was within normal limits.
- Monopolar needle EMG of the right extensor digitorum communis demonstrated slight increase in insertional activity, but not sustained abnormal spontaneous activity. There were rare fasciculations.
- Monopolar needle EMG of the right vastus lateralis was normal apart from some fasciculations.
- Monopolar needle EMG of the right tibialis anterior was normal apart from some fasciculations.
- Monopolar needle EMG of the right gastrocnemius medial head was normal apart from fasciculations.
- Monopolar needle EMG of the left first dorsal interosseous demonstrated a few positive sharp waves indicative for abnormal spontaneous activity. There was one-hour large amplitude motor units although the rest of motor units looked appropriate and the recruitment was normal.
- Monopolar needle EMG of the left flexor pollicis longus demonstrated abnormal spontaneous activity. Recruitment was otherwise normal.
- Monopolar needle EMG of the left flexor digitorum profundus digits 4 and 5 was normal.
- Monopolar needle EMG of the left triceps demonstrated relatively frequent fasciculations; however, the recruitment was normal and the motor units appeared normal.
ELECTRODIAGNOSTIC INTERPRETATION:
These electrodiagnostic studies are abnormal.
- There remains an ulnar neuropathy across the right elbow without conduction block.
- There are widespread fasciculations in multiple muscle groups. Most of the muscle groups do not have any associated denervation changes; however, bilateral C8-T1 muscles do have some subtle subacute denervation changes. This is indicative of bilateral C8-T1 radiculopathy, lower trunk plexopathy.
IMPRESSION AND PLAN:
This 37-year-old gentleman notes progressive loss of strength in his hand intrinsics in particular. There definitely are some denervation changes in his distal hand muscles today, largely within the C8-T1 distribution. This is present bilaterally. There is a more widespread process resulting in fasciculations with otherwise normal-appearing motor units. There is based on this study and exam, the possibility for bilateral C8-T1 radiculopathies or lower trunk plexopathy. That would be most in keeping with a thoracic outlet syndrome if that were to be case. There is also an entity called Hirayama disease, which predominantly affects C8-T1 muscles and there is a form of stable motor neuron disease process presenting largely in younger males. The question of a more widespread motor neuron process is still remaining, although I do not see any weakness or denervation of the other muscles or fasciculations, this patient will require ongoing followup. I have recommended an MRI of his cervical spine and brachial plexus to determine if there is any feature of thoracic outlet syndrome or lesions that would explain radiculopathy in those specific regions. If his MRI is negative, I may pursue some antibody testing for his more widespread fasciculations and this can be on a continuation of peripheral nerve hyperexcitability. However, patients with this condition do not typically also have denervation changes in addition to the fasciculations. I will update you on the results of the MRI as soon as it becomes available.
Dictated but not read.
2022/10/04
Investigation; EMG
INVESTIGATION RESULTS:
OUTPATIENT NERVE CONDUCTION STUDY EMG
CLINICAL INDICATION:
A 37-year-old gentleman followed by myself for progressive hand weakness and multifocal fasciculations, for assessment of possible motor neuron disease.
ELECTRODIAGNOSTIC STUDY:
- Median motor nerve conduction study recording from abductor pollicis brevis revealed mild prolongation of the distal motor latency bilaterally. Amplitude on the left was within normal limits; however, lower than that of the previous study in April 2022. On the right, the amplitude was significantly reduced, which is a marked reduction from both April and June studies.
- Ulnar motor nerve conduction study recording from abductor digiti minimi revealed prolongation of the distal motor latencies bilaterally. Amplitudes were reduced bilaterally, further reduced from both the April and June studies. There remained only mild slowing of conduction velocity across the left elbow and mild to moderate slowing across the right elbow. There was no evidence of more proximal conduction slowing or conduction block.
- Ulnar motor nerve conduction study recording from first dorsal interosseous revealed marked reduction in amplitudes bilaterally. There was mild slowing across the elbow. There was no obvious proximal slowing and no conduction block could be proven; however, the amplitudes were already quite low.
- Peroneal motor nerve conduction study recording from extensor digitorum brevis was normal.
- Tibial motor nerve conduction study recording from abductor hallucis was normal.
- Median sensory study recording from digit 2 was normal bilaterally.
- Ulnar sensory study recording from digit 5 was normal apart from very subtle slowing of conduction velocity.
- Dorsal ulnar cutaneous sensory response was again reduced on the right side, although this was improved from previous (there is significant contribution from radial innervation).
- Monopolar needle EMG of the right first dorsal interosseous demonstrated frequent abnormal spontaneous activity. There was a single motor unit activated. This is a marked worsening from previous.
- Monopolar needle EMG of the right flexor pollicis longus demonstrated 2-3 units recruited; however, no abnormal spontaneous activity was recorded. This is the same as previous.
- Monopolar needle EMG of the right extensor indicis proprius demonstrated infrequent abnormal spontaneous activity and fasciculations. Recruitment pattern seemed normal.
- Monopolar needle EMG of the right brachioradialis demonstrated only occasional fasciculations with otherwise normal recruitment.
- Monopolar needle EMG of the right biceps brachii demonstrated relatively frequent fasciculations. However, the recruitment in motor units appeared normal.
- Monopolar needle EMG of the right triceps demonstrated frequent fasciculations; however, normal recruitment otherwise and no other spontaneous activity.
- Monopolar needle EMG of the right deltoid demonstrated relatively frequent fasciculations. These had progressed in frequency from previous. There was slightly reduced recruitment; however, the units still appeared normal.
- Monopolar needle EMG of the right tibialis anterior demonstrated abnormal spontaneous activity by means of occasional positive sharp waves. There were occasional fasciculations. There was slightly reduced recruitment and there were a few large amplitude motor units.
- Monopolar needle EMG of the right gastrocnemius demonstrated increased insertional activity; however, no persistent fibrillation potentials or positive sharp waves. Recruitment pattern appeared normal.
- Monopolar needle EMG of the right vastus lateralis demonstrated frequent fasciculations; however, recruitment was normal and the motor units appeared normal.
- Monopolar needle EMG of the right rectus femoris demonstrated frequent fasciculations. Recruitment pattern was normal and the units appeared normal.
- Monopolar needle EMG of the left deltoid demonstrated a few runs of positive sharp waves. There were frequent fasciculations. Recruitment was normal and the motor units appeared normal.
- Monopolar needle EMG of the left biceps brachii demonstrated relatively frequent fasciculations. There was moderately reduced recruitment with few large amplitude motor units.
- Monopolar needle EMG of the left first dorsal interosseous demonstrated relatively frequent abnormal spontaneous activity with occasional fasciculations. A single motor unit could be recruited.
- Monopolar needle EMG of the left flexor digitorum profundus digits 4 and 5 demonstrated frequent abnormal spontaneous activity. There was relatively frequent fasciculations. The recruitment appeared normal and the motor units were normal.
- Monopolar needle EMG of the left vastus lateralis demonstrated only fasciculations with normal recruitment and normal-appearing units.
- Monopolar needle EMG of the left tibialis anterior was normal.
- Monopolar needle EMG of the left gastrocnemius was normal.
- Monopolar needle EMG of the left mid-thoracic paraspinal demonstrated occasional fasciculations.
ELECTRODIAGNOSTIC INTERPRETATION:
These electrodiagnostic studies are abnormal. There had been progression of the motor involvement in multiple nerves of the upper and lower extremities. There has been development of some prolongation of the distal motor latencies of the median and ulnar nerves, potentially in response to further reduction in their amplitude; however, no other features consistent with demyelination could be seen. Conduction block could not be proven. Overall, this represents a motor neuropathy affecting upper and lower extremities and sparing sensory responses (I would cite of some mild reduction in the dorsal ulnar cutaneous sensory response, which arguably could be more relayed to partial innervation from the radial nerve rather than true loss).
Taken together, the pattern is in keeping with a motor neuron based process, which is axonal in nature.
I examined the patient today to compare from previous examination. The extraocular movements remained normal and there was no dysarthria or facial weakness. In the limbs, there has been further progression of atrophy, particularly distally in the hands in the thenar eminence and the first dorsal interosseous as well as now more proximally in the upper extremities, in biceps. There were widespread fasciculations more notable than previous. Power was now reduced proximally where had been strong before, at 4+/5 in shoulder abduction, elbow flexion. Elbow extension was 4/5 bilaterally. Finger extension was 4/5 bilaterally, finger abduction was 2 on the right and 3 on the left, flexor pollicis longus 4/5 bilaterally, flexor digitorum profundus full. In the lower extremities, tone was normal. There was, however, weakness of hip flexion at 4/5 bilaterally. Knee extension was questionably weak at 4+/5 bilaterally and ankle dorsiflexion 4+/5 bilaterally. Reflexes were 1+ at brachioradialis and now they were 3+ at the biceps and triceps. At the knee, they were 3+ with some crossed adductor response. I did not elicit any clonus. Plantar responses were mute. He endorsed multiple sensory symptoms, but noting objective on examination.
IMPRESSION AND PLAN:
This 37-year-old gentleman presented initially with hand weakness, largely in the C8-T1 myotomes as well as more widespread fasciculations; however, has had progression in his hand and extremity weakness such that it is beyond just the distribution than it was initially presenting. He is also developing some change in his reflexes to be more hyperreflexic than he was previously. MRI of his cervical spine was nonrevealing and not in keeping with Hirayama disease on the flexion extension views. His lab work including inflammatory markers, CK, autoimmune markers, paraneoplastic markers, voltage-gated potassium channel antibodies, Lyme serology were all unremarkable. Well, I could not find any definitive features of demyelination or conduction block, I have sent him for the neurologic disease profile including GMI and other gangliosides ____ mitogen. Overall, while the progression of sensory sparing weakness and atrophy with ultimate development of some degree of hyperreflexia is quite suspicious for motor neuron disease. The repetitive at which this has progressed is unusual. I am uncertain if it represents other autoimmune or parainfectious phenomenon and whether it might be able to pursue a trial of immune modulating treatment such as IVIG. I will ask a colleague at the Neuromuscular Institute at the [Hospital 2] for a second opinion on this matter as if there are immune modulating treatments of favorable to this patient, they are more available at the [Hospital 2] given access issues here at the [Hospital 1]. I will followup with the patient pending this consultation.
Dictated but not read.
2022/10/04
Investigation; EMG
INVESTIGATION RESULTS:
OUTPATIENT NERVE CONDUCTION STUDY EMG
CLINICAL INDICATION:
A 37-year-old gentleman followed by myself for progressive hand weakness and multifocal fasciculations, for assessment of possible motor neuron disease.
ELECTRODIAGNOSTIC STUDY:
- Median motor nerve conduction study recording from abductor pollicis brevis revealed mild prolongation of the distal motor latency bilaterally. Amplitude on the left was within normal limits; however, lower than that of the previous study in April 2022. On the right, the amplitude was significantly reduced, which is a marked reduction from both April and June studies.
- Ulnar motor nerve conduction study recording from abductor digiti minimi revealed prolongation of the distal motor latencies bilaterally. Amplitudes were reduced bilaterally, further reduced from both the April and June studies. There remained only mild slowing of conduction velocity across the left elbow and mild to moderate slowing across the right elbow. There was no evidence of more proximal conduction slowing or conduction block.
- Ulnar motor nerve conduction study recording from first dorsal interosseous revealed marked reduction in amplitudes bilaterally. There was mild slowing across the elbow. There was no obvious proximal slowing and no conduction block could be proven; however, the amplitudes were already quite low.
- Peroneal motor nerve conduction study recording from extensor digitorum brevis was normal.
- Tibial motor nerve conduction study recording from abductor hallucis was normal.
- Median sensory study recording from digit 2 was normal bilaterally.
- Ulnar sensory study recording from digit 5 was normal apart from very subtle slowing of conduction velocity.
- Dorsal ulnar cutaneous sensory response was again reduced on the right side, although this was improved from previous (there is significant contribution from radial innervation).
- Monopolar needle EMG of the right first dorsal interosseous demonstrated frequent abnormal spontaneous activity. There was a single motor unit activated. This is a marked worsening from previous.
- Monopolar needle EMG of the right flexor pollicis longus demonstrated 2-3 units recruited; however, no abnormal spontaneous activity was recorded. This is the same as previous.
- Monopolar needle EMG of the right extensor indicis proprius demonstrated infrequent abnormal spontaneous activity and fasciculations. Recruitment pattern seemed normal.
- Monopolar needle EMG of the right brachioradialis demonstrated only occasional fasciculations with otherwise normal recruitment.
- Monopolar needle EMG of the right biceps brachii demonstrated relatively frequent fasciculations. However, the recruitment in motor units appeared normal.
- Monopolar needle EMG of the right triceps demonstrated frequent fasciculations; however, normal recruitment otherwise and no other spontaneous activity.
- Monopolar needle EMG of the right deltoid demonstrated relatively frequent fasciculations. These had progressed in frequency from previous. There was slightly reduced recruitment; however, the units still appeared normal.
- Monopolar needle EMG of the right tibialis anterior demonstrated abnormal spontaneous activity by means of occasional positive sharp waves. There were occasional fasciculations. There was slightly reduced recruitment and there were a few large amplitude motor units.
- Monopolar needle EMG of the right gastrocnemius demonstrated increased insertional activity; however, no persistent fibrillation potentials or positive sharp waves. Recruitment pattern appeared normal.
- Monopolar needle EMG of the right vastus lateralis demonstrated frequent fasciculations; however, recruitment was normal and the motor units appeared normal.
- Monopolar needle EMG of the right rectus femoris demonstrated frequent fasciculations. Recruitment pattern was normal and the units appeared normal.
- Monopolar needle EMG of the left deltoid demonstrated a few runs of positive sharp waves. There were frequent fasciculations. Recruitment was normal and the motor units appeared normal.
- Monopolar needle EMG of the left biceps brachii demonstrated relatively frequent fasciculations. There was moderately reduced recruitment with few large amplitude motor units.
- Monopolar needle EMG of the left first dorsal interosseous demonstrated relatively frequent abnormal spontaneous activity with occasional fasciculations. A single motor unit could be recruited.
- Monopolar needle EMG of the left flexor digitorum profundus digits 4 and 5 demonstrated frequent abnormal spontaneous activity. There was relatively frequent fasciculations. The recruitment appeared normal and the motor units were normal.
- Monopolar needle EMG of the left vastus lateralis demonstrated only fasciculations with normal recruitment and normal-appearing units.
- Monopolar needle EMG of the left tibialis anterior was normal.
- Monopolar needle EMG of the left gastrocnemius was normal.
- Monopolar needle EMG of the left mid-thoracic paraspinal demonstrated occasional fasciculations.
ELECTRODIAGNOSTIC INTERPRETATION:
These electrodiagnostic studies are abnormal. There had been progression of the motor involvement in multiple nerves of the upper and lower extremities. There has been development of some prolongation of the distal motor latencies of the median and ulnar nerves, potentially in response to further reduction in their amplitude; however, no other features consistent with demyelination could be seen. Conduction block could not be proven. Overall, this represents a motor neuropathy affecting upper and lower extremities and sparing sensory responses (I would cite of some mild reduction in the dorsal ulnar cutaneous sensory response, which arguably could be more relayed to partial innervation from the radial nerve rather than true loss).
Taken together, the pattern is in keeping with a motor neuron based process, which is axonal in nature.
I examined the patient today to compare from previous examination. The extraocular movements remained normal and there was no dysarthria or facial weakness. In the limbs, there has been further progression of atrophy, particularly distally in the hands in the thenar eminence and the first dorsal interosseous as well as now more proximally in the upper extremities, in biceps. There were widespread fasciculations more notable than previous. Power was now reduced proximally where had been strong before, at 4+/5 in shoulder abduction, elbow flexion. Elbow extension was 4/5 bilaterally. Finger extension was 4/5 bilaterally, finger abduction was 2 on the right and 3 on the left, flexor pollicis longus 4/5 bilaterally, flexor digitorum profundus full. In the lower extremities, tone was normal. There was, however, weakness of hip flexion at 4/5 bilaterally. Knee extension was questionably weak at 4+/5 bilaterally and ankle dorsiflexion 4+/5 bilaterally. Reflexes were 1+ at brachioradialis and now they were 3+ at the biceps and triceps. At the knee, they were 3+ with some crossed adductor response. I did not elicit any clonus. Plantar responses were mute. He endorsed multiple sensory symptoms, but noting objective on examination.
IMPRESSION AND PLAN:
This 37-year-old gentleman presented initially with hand weakness, largely in the C8-T1 myotomes as well as more widespread fasciculations; however, has had progression in his hand and extremity weakness such that it is beyond just the distribution than it was initially presenting. He is also developing some change in his reflexes to be more hyperreflexic than he was previously. MRI of his cervical spine was nonrevealing and not in keeping with Hirayama disease on the flexion extension views. His lab work including inflammatory markers, CK, autoimmune markers, paraneoplastic markers, voltage-gated potassium channel antibodies, Lyme serology were all unremarkable. Well, I could not find any definitive features of demyelination or conduction block, I have sent him for the neurologic disease profile including GMI and other gangliosides ____ mitogen. Overall, while the progression of sensory sparing weakness and atrophy with ultimate development of some degree of hyperreflexia is quite suspicious for motor neuron disease. The repetitive at which this has progressed is unusual. I am uncertain if it represents other autoimmune or parainfectious phenomenon and whether it might be able to pursue a trial of immune modulating treatment such as IVIG. I will ask a colleague at the Neuromuscular Institute at the [Hospital 2] for a second opinion on this matter as if there are immune modulating treatments of favorable to this patient, they are more available at the [Hospital 2] given access issues here at the [Hospital 1]. I will followup with the patient pending this consultation.
Dictated but not read.