EMG Case help

[Nimrod123]

A guy in his late 50 to early 60's (protecting his ID) with c/o unstable gait for more than 15 years. Pt hasn't had falls. Takins statins but stopped them (not sure for how long was taking). Pt complains of trouble getting out of the chair. MRI brain shows nonspecific stuff.. Cspine MRI ok. Found clumsy with turns, but negative Romberg. Pt did not have clonus or babinski. Reflexes are obtainable at achilles and patellar. However, decreased vibratory sense. The pt got sent to my EMG lab. Taking biphosphonate, bp med, altose, and Ca/Vit D.

Bilateral peroneal and tibial motor nerves were done which showed normal latencies and conduction velocities. However, the amplitudes were borderline normal low (1.2-1.4 mV for peroneal and 5-6 mV for tibial). The sensory peroneal in 1 leg showed prolonged latency, but borderline normal amplitude (2-4 uV). The bilateral sural showed prolonged pk latency, and borderline normal amplitude (4-8) uV, with normal CV.

I did EMG of bilateral TA, gastroc, and 1st dorsal interossei toe which showed old PSW dennervation and CRD's (<50 uV). The vastus medialis bilaterally were sampled more thoroughly and I couldnt really find CRD's as in the muscle below knees. I also did bilateral lumbar paraspinals at L4/L5/S1 and this lighted up with CRD's bilaterally and old psw's. I also did T paraspinal and proximal deltoid, and both lghted up with CRD's. It sounds like something diffuse. I dont think it is NMJ because he doesnt complain of bulbar symptoms. He didnt have unstable MUAP's which didnt make me think about NMJ. I am not sure if it is myopathic, since the MU's were not small, and I couldnt see an early recruitment pattern.

Thoughts on differential?

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[PMR 4 MSK]

Muscular dystrophy tops my list based on what I'm reading. Other chronic myopathies possible.

ALS also possible. Test UEs and consider CN as well.

 

[Ludicolo]

Does the patient have any actual sensory complaints? What was his motor/strength exam like? Any atrophy? How prolonged were the sensory latencies?

The EMG findings you have right now are rather non-specific. Could be myopathic, could be polyradic. Agree this doesn’t sound like NMJ. And doubt this is ALS, given a >15 year history of symptoms. Are you sure these were CRDs and not myotonic discharges or something else? Any actual fibs or fascics?

And what do you mean by “old PSWs?”

 

[Nimrod123]

I am almost certain they were CRD's, but I may be wrong. You see I didn't see much myotonic discharges during residency. Only from textbook. It didn't sound anything like dive bombers if that is your question. I have heard CRD's before. He denies foot numbness. The latencies were in the high 4's but will have to look it up and post again tomorrrow. His strength was only weak for hip flexors at a 3+ to 4-/5. I didn't test the upper extremities. No fascics. There were sporadic fibs in the lower extremities, particularly distal muscles.


I doubt this is poly radic since he didnt complain of back pain, and the CRD's were alse present in Tspine and Right deltoid.

Olds PSW's = < 50 uV or a little bigger

There was no noticeable atrophy.

 

[RUOkie]

I agree with considering Muscular dystrophies. The age/onset sounds like myotonic dystrophy. Does he have the typical facial characteristics? Myotonic discharges can be mistaken for CRDs in inexperienced electromyographers (I'm sorry but if you have never seen myotonia or myokymia, you are inexperienced)

You should certainly check some cranial muscles and consider genetic testing. Pompe's also needs to be considered