weekly question #2

[RUOkie]

New case from yesterday. I am intentionally witholding information so it is not too easy. Once the right question is asked, I will provide more info.

52 y/o M now 20yrs s/p traumatic L AKA after a farming accident. Never able to use a prosthesis secondary to poor remaining muscle and bad fit. Ambulates with B crutches.

Has 10 yr history of slowly progressive atrophy of the L hand, now with 1yr of worsening function of the hand. He denies sensory changes or pain, just weakness.

1)What would you look for on physical exam.
2)In planning your EMG/NCS are there any studies that you would do that you might not do on a routine study?

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[Taus]

Will write more later when have time..... But my $$ is on ulnar at guyons from 20 years of crutches

 

[fozzy40]

New case from yesterday. I am intentionally witholding information so it is not too easy. Once the right question is asked, I will provide more info.

52 y/o M now 20yrs s/p traumatic L AKA after a farming accident. Never able to use a prosthesis secondary to poor remaining muscle and bad fit. Ambulates with B crutches.

Has 10 yr history of slowly progressive atrophy of the L hand, now with 1yr of worsening function of the hand. He denies sensory changes or pain, just weakness.

1)What would you look for on physical exam.
2)In planning your EMG/NCS are there any studies that you would do that you might not do on a routine study?

1) light touch and pin prick changes, standard manual muscle testing including pincer grip, intrinsic hand atrophy, fasciculations, spasticity, median and ulnar tinels, equal radial and ulnar pulses, Hoffman signs, spurlings test

2) Agree with compressive neuropathies including median mononeuropathy, guyon's canal, UNE, and axillary/radial neuropathy. Could also high median neuropathy like pronator syndrome, ligament of struthers, or AIN involvement. Repetitive crutch trauma can cause brachial plexopathy. Radiculopathy (C8) is always on the table. Painless weakness always makes me think of polyradiculopathy or motor neuron disease.

Atypical sensory studies you may end up doing include radial sensory (radial neuropathy), DUC (guyon's canal), MAC and LAC (UT vs. LT plexopathy). For nerve conduction studies, would do basic median and ulnar motor. Consider F-wave. On EMG, would probably do basic radiculopathy screen but would include EIP, FCU, B-Rad, Pronator to isolate a brachial plexopathy. Would definitely do paraspinals in this case.

 

[Ludicolo]

Good thinking fozzy, considering all possibilities. But try to focus in a little, given the history.

Students/Residents: Let's start thinking like EMGers:

1) Atrophy of the hand: consider the distribution of the atrophy. Partial hand vs. entire hand vs. anywhere else? Think about which individual nerves and which portions of the brachial plexus innervate hand muscles. A helpful tip: on your EMG rotations it’s never enough to just say “brachial plexopathy” as part of your differential diagnosis. I want to know where in the plexus. If an EMG attending asks, “what’s the innervation of the APB?” don’t just answer “median nerve”. That answer is woefully incomplete.

2) No pain or sensory complaints: definitely confirm this on your physical exam, because your DDx changes drastically based on sensory findings. Farmers are kind of stoic – they usually won’t volunteer pain or sensory complaints even if they’re present. Assuming no sensory abnormalities on exam, think about where along the peripheral nervous system (hint: very proximally and very distally) you can see motor without sensory dysfunction.

(Fozzy – points for considering motor neuron dz in your differential. Especially if the patient is a really nice guy.)

3) Based on your DDx: think about which NCS you would perform, and which muscles you would sample on needle EMG. Try to be efficient with your study. You don’t necessarily need to check every nerve and muscle. You’re not looking to screen. You’re looking to confirm your diagnosis.

4) Biomechanics: Think of possible nerve injuries associated with crutch use. Does it matter what kind of crutches the patient uses (axillary or Lofstrand)? Would that change your differential?

 

[fozzy40]

1) Well, with atrophy 2/2 ulnar neuropathy you can see wasting of the FDI, hypothenar eminence, lumbricals. I've also seen wasting of the FCU with UNE. With a distal median nerve compression you would most likely notice wasting of the thenar eminence. With a high median injury, you could see the "hand of benediction" indicating 2nd and 3rd digit weakness with digit flexion. Upper trunk lesions are usually associated with trauma so this would be low on my differential based on history alone. You would see your classic waiter's tip position though. Lower trunk lesions are also associated with trauma and/or radiation or tumor invasion. It would be great to know if he/she has any risk factors for this. I have not seen many posterior cord injuries but I also feel that this is more trauma related which again would be low on my differential. However, an axillary or radial neuropathy is certainly on my list given possibility of repetitive trauma from axillary crutches.

2) Sensory complaints are so subjective so I rely heavily on my physical exam. I've seen people do it many different ways but I always do them with their eyes closed.

With carpal tunnel median mononeuropathy, you would expect sensory changes in the typical digit distribution except for the thenar eminence which is supplied by the superficial branch which does not go through the carpal tunnel. You could see this in a high median neuropathy. Other pure motor neuropathies that could fit this patient include a PIN and AIN injury.

3) Could you give me some more hints on the physical exam to help me design a study?

4) The type of crutches and whether he/she is using them correctly absolutely makes a difference. Axillary crutches can certainly cause an axillary or radial neuropathy. With lofstrands, you can have a median, ulnar, or PIN injury because of the stabilizing force proximally. Both can cause a median or ulnar wrist neuropathy because of the position of the wrist, the force being loaded, and the repetitive nature.

Good thinking fozzy, considering all possibilities. But try to focus in a little, given the history.

Students/Residents: Let's start thinking like EMGers:

1) Atrophy of the hand: consider the distribution of the atrophy. Partial hand vs. entire hand vs. anywhere else? Think about which individual nerves and which portions of the brachial plexus innervate hand muscles. A helpful tip: on your EMG rotations it’s never enough to just say “brachial plexopathy” as part of your differential diagnosis. I want to know where in the plexus. If an EMG attending asks, “what’s the innervation of the APB?” don’t just answer “median nerve”. That answer is woefully incomplete.

2) No pain or sensory complaints: definitely confirm this on your physical exam, because your DDx changes drastically based on sensory findings. Farmers are kind of stoic – they usually won’t volunteer pain or sensory complaints even if they’re present. Assuming no sensory abnormalities on exam, think about where along the peripheral nervous system (hint: very proximally and very distally) you can see motor without sensory dysfunction.

(Fozzy – points for considering motor neuron dz in your differential. Especially if the patient is a really nice guy.)

3) Based on your DDx: think about which NCS you would perform, and which muscles you would sample on needle EMG. Try to be efficient with your study. You don’t necessarily need to check every nerve and muscle. You’re not looking to screen. You’re looking to confirm your diagnosis.

4) Biomechanics: Think of possible nerve injuries associated with crutch use. Does it matter what kind of crutches the patient uses (axillary or Lofstrand)? Would that change your differential?

 

[RUOkie]

Will write more later when have time..... But my $$ is on ulnar at guyons from 20 years of crutches

OK, you jumped a little ahead there.

WHAT would you do to confirm this?

 

[RUOkie]

1) Well, with atrophy 2/2 ulnar neuropathy you can see wasting of the FDI, hypothenar eminence, lumbricals. I've also seen wasting of the FCU with UNE. With a distal median nerve compression you would most likely notice wasting of the thenar eminence. With a high median injury, you could see the "hand of benediction" indicating 2nd and 3rd digit weakness with digit flexion. Upper trunk lesions are usually associated with trauma so this would be low on my differential based on history alone. You would see your classic waiter's tip position though. Lower trunk lesions are also associated with trauma and/or radiation or tumor invasion. It would be great to know if he/she has any risk factors for this. I have not seen many posterior cord injuries but I also feel that this is more trauma related which again would be low on my differential. However, an axillary or radial neuropathy is certainly on my list given possibility of repetitive trauma from axillary crutches.

2) Sensory complaints are so subjective so I rely heavily on my physical exam. I've seen people do it many different ways but I always do them with their eyes closed.

With carpal tunnel median mononeuropathy, you would expect sensory changes in the typical digit distribution except for the thenar eminence which is supplied by the superficial branch which does not go through the carpal tunnel. You could see this in a high median neuropathy. Other pure motor neuropathies that could fit this patient include a PIN and AIN injury.

3) Could you give me some more hints on the physical exam to help me design a study?

4) The type of crutches and whether he/she is using them correctly absolutely makes a difference. Axillary crutches can certainly cause an axillary or radial neuropathy. With lofstrands, you can have a median, ulnar, or PIN injury because of the stabilizing force proximally. Both can cause a median or ulnar wrist neuropathy because of the position of the wrist, the force being loaded, and the repetitive nature.

Much better.

Thanks Ludicolo for guiding them a little and not just taking over.

OK more info.

On exam, he has severe atrophy of the FDI, normal bulk of the Thenar, and hypothenar muscles. Sensation was completely normal to LT/PP (I did not use monofillament though) He uses axillary crutches that are very old and in disrepair, but he does not place any pressure on the axilla (he uses them properly, but there is no padding). He has a large callus on the palm just radial to the hypothenar eminence. Tinnels are negative over both the Median and Ulnar nerves including over the callus. Reflexes are normal. No fasiculations seen anywhere.


NOW PLAN YOUR STUDY

 

[RUOkie]

(Fozzy – points for considering motor neuron dz in your differential. Especially if the patient is a really nice guy.)

Ain't that always the case.

 

[latinman]

I would start with some sensory screening. I know there is no sensory deficit on physical exam, but for completeness sake I would do at least a median sensory recording from the 3rd finger, ulnar sensory recording from 5th finger, an MABC to r/o lower trunk plexus (the MABC might be debatable for some of you), and a DUC comparing side to side. I would then proceed to motor NCS studies. I would get median motor studies recording from APB's and ulnar motor studies recording from ADM and FDI. Sometimes with ulnar neuropathies the FDI fibers will be affected, but not the ADM fibers. Depending on what I see on the ulnar motor studies at the wrist, below elbow and above elbow stimulation points; I might consider inching study. You could also record from the FDI and stimulate at the wrist and midpalm to r/u compression at the wrist (ie., conduction block will be seen). EMG would consist of sampling mainly C8-T1 muscles from different peripheral nerve and cord innervation. EIP, FCU, FDP, FDI, ADM, APB are definitely fair game. Some of you might like to sample the FPL but this is close to the radial artery. Other muscles from middle and upper trunk to consider include the Deltoid, biceps, PT, Triceps. Some of you might think that this is an overkill, but I rather sample more if I have the time. This is probably too ambitious to be done in 1 hour...

 

[Ludicolo]

I would start with some sensory screening. I know there is no sensory deficit on physical exam, but for completeness sake I would do at least a median sensory recording from the 3rd finger, ulnar sensory recording from 5th finger, an MABC to r/o lower trunk plexus (the MABC might be debatable for some of you), and a DUC comparing side to side. I would then proceed to motor NCS studies. I would get median motor studies recording from APB's and ulnar motor studies recording from ADM and FDI. Sometimes with ulnar neuropathies the FDI fibers will be affected, but not the ADM fibers. Depending on what I see on the ulnar motor studies at the wrist, below elbow and above elbow stimulation points; I might consider inching study. You could also record from the FDI and stimulate at the wrist and midpalm to r/u compression at the wrist (ie., conduction block will be seen). EMG would consist of sampling mainly C8-T1 muscles from different peripheral nerve and cord innervation. EIP, FCU, FDP, FDI, ADM, APB are definitely fair game. Some of you might like to sample the FPL but this is close to the radial artery. Other muscles from middle and upper trunk to consider include the Deltoid, biceps, PT, Triceps. Some of you might think that this is an overkill, but I rather sample more if I have the time. This is probably too ambitious to be done in 1 hour...

RUOkie, this is an excellent teaching case. If I may…

latinman - what’s your ddx, in order of likelihood? If you’re thinking compression, where exactly do you think this patient is being compressed? Be detailed and specific as possible. Let’s see who really knows their anatomy.

Then design and streamline your study. I’m of the opinion that less is more. Reconsider which NCS you would perform and which muscles you would check. And think about what you would expect to see during the study. Based on #1 of your differential, what should you see on each of the above studies you mentioned?

 

[RUOkie]

RUOkie, this is an excellent teaching case. If I may…

latinman - what’s your ddx, in order of likelihood? If you’re thinking compression, where exactly do you think this patient is being compressed? Be detailed and specific as possible. Let’s see who really knows their anatomy.

Then design and streamline your study. I’m of the opinion that less is more. Reconsider which NCS you would perform and which muscles you would check. And think about what you would expect to see during the study. Based on #1 of your differential, what should you see on each of the above studies you mentioned?

I appreciate your stepping in. I was at the US course in Vegas and did not log on for the past week. THAT is exactly what I wanted people to do.

 

[PMR 4 MSK]

I appreciate your stepping in. I was at the US course in Vegas and did not log on for the past week. THAT is exactly what I wanted people to do.

OT, I was there, too in Vegas. Best course AAPM&R has ever put on, IMHO. Everyone should do it.

 

[PMR 4 MSK]

I saw this guy today. 66 yo male, referred by spine surgeon for LUE numbness. Has cervical stenosis C5-6 and C6-7, with left C6 nerve root displacement. Surgeon wisely wants EMG LUE as the numbness is "whole hand."

Symptoms present > 1 year, neck pain, pain in left arm, N/T as above. Also right hand numbness x 2 or more months. On questioning, says he does have foot numbness as well.

Exam shows good strength throughout BUE except 4+ left finger abduction, diffuse 1+ reflexes, normal sensation to soft touch. Some left hand intrinsic atrophy noted, specifically 1st webspace. No thenar atrophy.

Study shows left median motor latency 6.1 (<4.2), amplitude 5.5 (>5), NCV 38 (>50). Left ulnar motor latency 4.8 (<3.2), amplitude 3.6 (>30), NCV forearm 33, across elbow 39 (>50). No F-wave responses median or ulnar.

Left orthodromic sensories median 2.8, ulnar NR, radial 2.7 (<2.5).

Needle exam normal left Deltoid, tricep, bicep and PT. FDIM shows 1+polys, slightly reduced recuitment. APB shows 1+ PSWs and a few fibs.

At this point I had to move on, pt had been 15 minutes late and I was well into my next appt slot. Pt to be rescheduled to do f/u studies.

You now know as much about him as I do.

So in planning the follow-up, what specific studies would you do? This is Medicare, so they limit what they will pay for (they go by AANEM recommendations). Think about what your working diagnosis is/are and how you would proceed with the minimal number studies you would need to fully diagnose. It is ok to do studies you might not get paid for.

 

[RUOkie]

OT, I was there, too in Vegas. Best course AAPM&R has ever put on, IMHO. Everyone should do it.

threadjack: I agree completely. Mentally draining, but awsomme course. My brain is still fried from the pace of those 5 days.