Qotw

[PMR 4 MSK]

I want to get a "Question of the Week" series going, just for fun. I think this could be a good learning opportunity for residents and/or those who are newer to EDx. Attendings can answer, but it'll be more of a learning opportunity of they hold back some.

1st case - A 74 yo male is referred for EMG BLE for right leg numbness and pain, with occasional shooting pains down the left leg. Hx significant for TBI 10 years ago with cognitive defects but no reported hemiparesis. He does not use orthotics.

He had lumbar decompression 6 months ago for "large" lipoma at L4-5. That helped his symptoms of bilateral leg pain for a few months but now they are returning. Repeat MRI shows expected DDD/spondylosis, but no neural compromise.

At the time of his TBI, which required emergent craniotomy, he also had a right ankle dislocation. The right foot now is chronically mildly swollen and he reports it changes colors and temperature easily, but no hyperhydrosis.

PE shows normal strength throughout the LLE, and normal Knee and hip strength on the right, but 4/5 plantar flexors and 2/5 dorsiflexors of the right foot and 0/5 extension of all toes on the right. Sensations diffusely poor throughout the right foot, normal proximal right leg and throughout the left leg. Reflexes 2+ left knee, 1 + right knee, absent at the ankles. Mild pitting edema RLE to 3-4" above ankle. Both feet cooler than lower legs, but good pulses. EDB's both atrophied. No allodynia. He is rather "goofy" and thinks I am the son of the referring doctor, and keeps calling my nurse my "daughter."

As you prepare for the EMG, what would be your expected findings? I.e. what would not surprise you?

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[lobelsteve]

I want to get a "Question of the Week" series going, just for fun. I think this could be a good learning opportunity for residents and/or those who are newer to EDx. Attendings can answer, but it'll be more of a learning opportunity of they hold back some.

1st case - A 74 yo male is referred for EMG BLE for right leg numbness and pain, with occasional shooting pains down the left leg. Hx significant for TBI 10 years ago with cognitive defects but no reported hemiparesis. He does not use orthotics.

He had lumbar decompression 6 months ago for "large" lipoma at L4-5. That helped his symptoms of bilateral leg pain for a few months but now they are returning. Repeat MRI shows expected DDD/spondylosis, but no neural compromise.

At the time of his TBI, which required emergent craniotomy, he also had a right ankle dislocation. The right foot now is chronically mildly swollen and he reports it changes colors and temperature easily, but no hyperhydrosis.

PE shows normal strength throughout the LLE, and normal Knee and hip strength on the right, but 4/5 plantar flexors and 2/5 dorsiflexors of the right foot and 0/5 extension of all toes on the right. Sensations diffusely poor throughout the right foot, normal proximal right leg and throughout the left leg. Reflexes 2+ left knee, 1 + right knee, absent at the ankles. Mild pitting edema RLE to 3-4" above ankle. Both feet cooler than lower legs, but good pulses. EDB's both atrophied. No allodynia. He is rather "goofy" and thinks I am the son of the referring doctor, and keeps calling my nurse my "daughter."

As you prepare for the EMG, what would be your expected findings? I.e. what would not surprise you?

Poorly tolerated and recruitment cannot be adequately performed. Would rather see repeat MRI with contrast than EMG. How is the EMG going to change treatment? Should have both central and peripheral nerve problems based on history- so EMG could be all over the place.

 

[RUOkie]

come on kids!

No other responses other than Steve (who is an attending-I agree with his assessment). This is a great idea PMR4MSK. I am gonna shut up now.

 

[PMR 4 MSK]

Ok, so this is a complex case, but you will encounter things like this.

Lets break it down:

1st, he is 74. What are the expected changes in the lower extremity compared to a young adult? Think of amplitudes, NCV, F-waves, sensories, etc.

2nd - Hx of TBI. He doesn't feel there was any weakness, but there is obvious weakness on exam. How will you differentiate weakness due to TBI from weakness caused by a peripheral process?

3rd - the confounder here is the L4-5 lipoma removed. If it caused any nerve damage, what would you expect to be the findings?

Feel free to comment on any or all of these 3 situations in one patient.

Don't be shy. There is no penalty for being wrong.

 

[Ludicolo]

If nobody steps up, we may need to start calling on people...

 

[latinman]

I am still in training.

I will try to answer these to the best of my abilities, but I think some more information should be provided as part of the vignette.

1st, he is 74. What are the expected changes in the lower extremity compared to a young adult? Think of amplitudes, NCV, F-waves, sensories, etc.

Amplitudes would probably go down with age. Latencies and conduction velocities would also slow down with age. Fwaves are so non-specific that I dont waste my time with them unless I am ruling out Guillan Barre.


2nd - Hx of TBI. He doesn't feel there was any weakness, but there is obvious weakness on exam. How will you differentiate weakness due to TBI from weakness caused by a peripheral process?

Weakness from central process shouild be consistent with somatotropic distribution. Also, with central process you would expect spasticity and brisk reflexes. Peripheral weakness would give u atrophy, and hyporeflexia. He could have physical exam findings showing both? The EDB atrophy speaks for peripheral nerve lesion.

3rd - the confounder here is the L4-5 lipoma removed. If it caused any nerve damage, what would you expect to be the findings?

The EDB atrophy might be explained by this. I am kind of scratching my head as to why the left ankle doesnt have any weakness if it is all a peripheral process.

 

[fozzy40]

Swelling always makes the test technically different in my experience. Not to mention the fact that you state his skin is symmetric cool in which case you have to keep him warm in order to keep your lab norms valid.

On NCV, the pt may or may not have surals present based on age, soft tissue swelling, and/or other comorbidities. However, if it's present on the symptomatic leg and normal that still does fit the radiculopathy picture. With the type of weakness that you describe I would expect to see at least 50% side to side differences in amplitude.

On EMG, he's far enough out that he should not have many/if any denervating potentials that are related to his presumed lipoma causing radiculopathy. Decreased activation may be seen on examination related to the TBI. Likely you would see chronic neurogenic changes (big amplitude, prolonged duration, polyphasia) in L4/5 muscles. I probably wouldn't do paraspinals because the patient did have lumbar surgery which confounds the test.

 

[SSdoc33]

i find in cases where there is significant soft tissue swelling or edema, or if the patient has their AARP card, i tend to rely a bit more on needle EMG findings than NCS. the NCS can be all over the place, but if you know how to read the needle, that should be able to focus your diagnosis

 

[fozzy40]

Thank you by the way for taking an interest!

I want to get a "Question of the Week" series going, just for fun. I think this could be a good learning opportunity for residents and/or those who are newer to EDx. Attendings can answer, but it'll be more of a learning opportunity of they hold back some.

1st case - A 74 yo male is referred for EMG BLE for right leg numbness and pain, with occasional shooting pains down the left leg. Hx significant for TBI 10 years ago with cognitive defects but no reported hemiparesis. He does not use orthotics.

He had lumbar decompression 6 months ago for "large" lipoma at L4-5. That helped his symptoms of bilateral leg pain for a few months but now they are returning. Repeat MRI shows expected DDD/spondylosis, but no neural compromise.

At the time of his TBI, which required emergent craniotomy, he also had a right ankle dislocation. The right foot now is chronically mildly swollen and he reports it changes colors and temperature easily, but no hyperhydrosis.

PE shows normal strength throughout the LLE, and normal Knee and hip strength on the right, but 4/5 plantar flexors and 2/5 dorsiflexors of the right foot and 0/5 extension of all toes on the right. Sensations diffusely poor throughout the right foot, normal proximal right leg and throughout the left leg. Reflexes 2+ left knee, 1 + right knee, absent at the ankles. Mild pitting edema RLE to 3-4" above ankle. Both feet cooler than lower legs, but good pulses. EDB's both atrophied. No allodynia. He is rather "goofy" and thinks I am the son of the referring doctor, and keeps calling my nurse my "daughter."

As you prepare for the EMG, what would be your expected findings? I.e. what would not surprise you?

 

[PMR 4 MSK]

Amplitudes would probably go down with age. Latencies and conduction velocities would also slow down with age. Fwaves are so non-specific that I dont waste my time with them unless I am ruling out Guillan Barre.

Weakness from central process shouild be consistent with somatotropic distribution. Also, with central process you would expect spasticity and brisk reflexes. Peripheral weakness would give u atrophy, and hyporeflexia. He could have physical exam findings showing both? The EDB atrophy speaks for peripheral nerve lesion.

The EDB atrophy might be explained by this. I am kind of scratching my head as to why the left ankle doesnt have any weakness if it is all a peripheral process.

Swelling always makes the test technically different in my experience. Not to mention the fact that you state his skin is symmetric cool in which case you have to keep him warm in order to keep your lab norms valid.

On NCV, the pt may or may not have surals present based on age, soft tissue swelling, and/or other comorbidities. However, if it's present on the symptomatic leg and normal that still does fit the radiculopathy picture. With the type of weakness that you describe I would expect to see at least 50% side to side differences in amplitude.

On EMG, he's far enough out that he should not have many/if any denervating potentials that are related to his presumed lipoma causing radiculopathy. Decreased activation may be seen on examination related to the TBI. Likely you would see chronic neurogenic changes (big amplitude, prolonged duration, polyphasia) in L4/5 muscles. I probably wouldn't do paraspinals because the patient did have lumbar surgery which confounds the test.

Excellent responses. Surals are often absent with advanced age, and the other sensories would almost always be absent (not always, I've seen an 80 year-old with intact sensory responses in the legs). You are spot-on about side-to-side differences.

Motor amplitudes are often lower in older individuals, but whether this is do to age-related atrophy of muscle or nerve (chicken or egg) is uncertain.

F-waves can be an early indicator of peripheral neuropathy. I sometimes see older patients with borderline amplitudes of peroneals, normal tibal amplitudes, normal NCVs, normal surals and other sensories absent. Often, these patients have delayed F-waves, beyond what they should for age. This may be early PPN.

UMN such as TBI should cause hyperreflexia and spasticity, whereas peripheral processes cause hyporeflexivity and flaccidity in muscles. Often, the pattern of paresethesias or numbness is different. Peripheral neuropathies will often disguise central processes, making them harder to diagnose.

EDB atrophy is an easy thing to look for in suspected cases of peripheral neuropathy. A flat EDB almost always correlates with a low amplitude peroneal/fibular motor nerve.

i find in cases where there is significant soft tissue swelling or edema, or if the patient has their AARP card, i tend to rely a bit more on needle EMG findings than NCS. the NCS can be all over the place, but if you know how to read the needle, that should be able to focus your diagnosis

In this case, the bilateral peroneal and tibial motors had low amplitudes: 1.0 - 1.7 mV, and mostly slow conduction in the lower leg: 34 - 42 m/s. The F-waves were all markedly prolonged. Sural sensories were present and normal, peroneals absent.

Needle exam showed 2+ polys and reduced recruitment of the bilateral EDBs and FDIPs, recruitment worse on the right. Left proximal muscles - quads, Tib Ant, Gastroc, were all normal, whereas the right side showed these proximal muscles to also have decreased recruitment, but no polys. NO increased insertional activity, fibs or PSWs observed anywhere. Proximal muscles - gluteals,TFLs normal on both sides, although the rights side recruitment could be borderline. Paraspinals were normal.

I feel in this case the lipoma did not cause appreciable nerve damage (no cauda-equina syndrome was present). He has a classic peripheral polyneuropathy compounded by right hemiparesis. His TBI may alter his perception enough that he doesn't notice it like he would have otherwise. The leg pain may be related to the lipoma, but it cannot be definitively proven.

What would your recommendations be for treatment at this point?

 

[Sivastraba]

What were the patient's risk factors for the polyneuropathy? Diabetes, Throid, EtOH?

 

[PMR 4 MSK]

What were the patient's risk factors for the polyneuropathy? Diabetes, Throid, EtOH?

Good question. We should always ask that one. None that I know of.