Numb hands

[neglect]

65 yo woman presents to ortho with pain in her hands. He thinks it is not orthopedic, despite her arthritis, so he sends her for a NCV. Unfortunatly she goes to a bad one, who diagnoses her with BL CTS. What the numbers show:
amp
radial sensory: 10R, 8 L
Ulnar sensory: 11R, 9 L
Median sensory: 4R, 8 L

All velocities were normal except into the 40s for the medians.
Median motor: normal but latency high 4's BL.
Ulnar motor: nl.

I see her several months after. She can't feel her fingers at all. Dense glove like decrease in sensation to all modalities, most markedly position and vibration sense. Her legs have what I would say are normal vibration for age.

Is there any other information you want? I'm holding things back.

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[Phantom Spike]

The ulnar sensories are probably normal for age. The radial sensories are slightly diminished in amplitude bilaterally, signifying a mild sensory peripheral neuropathy. The median sensories are clearly diminished in amplitude bilaterally, and if they're slower than the ulnars, that, plus, the prolonged distal median motor latencies, do seem to suggest a superimposed bilateral carpal tunnel syndrome in addition.

Were the lower extremities done? Were sensory responses obtained, and were the tibial and peroneal motor amplitudes normal?

Another possibility, I suppose, that might fit with the patient's clinical findings a bit better, would be a sensory neuronopathy, but the amplitudes of the radial (and ulnar) sensory responses do not seem low enough for that. If that's still a consideration, the study might need to be repeated in a few months. A multilevel radiculopathy (with a superimposed peripheral neuropathy) is another consideration, but would need the needle EMG to prove.

 

[Ludicolo]

If I’m reading correctly, the NCS data is from the first outside suboptimal EMG. Low amplitude radial & median SNAPs. Velocities nl. Motors nl except prolonged median DL. Neglect sees the patient several months later - sensory deficits UE>LE.

Neglect – more info on your exam please. Any atrophy/weakness? Pseudoathetosis? Gait ataxia? Dry eyes? Dry mouth?

I'm assuming you repeated the NCS/EMG... possibly with blinks?

 

[neglect]

I would not have called those ulnar amplitudes as normal, particularly with the rest of the data.

Sural SNAPs were not checked. Although of extreme value, she had nothing in her legs via signs and symptoms.

Reduced reflexes BL arms. She did have pseudochorea, good call. She has mod-severe OA in her hands, and she has some atrophy, but nothing pathologic. No dry eyes, mouth, ataxia, nystagmus, diplopia.

The outside ncv included an emg, for what that's worth, there were minimal abnormalities consistent with mild LMN denervation.

Phantom: I made the diagnosis without another ncv, although I'm going to do that next week. I think you can name the test I obtained.

 

[Phantom Spike]

Phantom: I made the diagnosis without another ncv, although I'm going to do that next week. I think you can name the test I obtained.

An MRI of the cervical spine? To look for a possible cystic cavity?

 

[Phantom Spike]

Of course, if you think about it, a syrinx should give you electrodiagnostic findings similar to a radiculopathy, so the sensory responses should potentially be normal, and the motor responses could be normal as well. The EMG findings of neurogenic changes in the upper extremities would go with it, though. It's clearly not motor neuron disease with the prominent sensory complaints and findings on NCV. I guess you still can't completely rule out a multilevel cervical radiculopathy, though again, the clinical picture with such prominent sensory complaints to the point of pseudochorea, would tend to make that unlikely.

Ludicolo, why were you suggesting the blink reflex? And why the question suggesting autoimmune etiologies ... were you going through a differential diagnosis for a polyneuropathy, or is there a specific disease entity you're thinking about with this case? I know Sjogren's has been known to cause sensory neuronopathies. With no complaints in the legs, a polyneuropathy seems to be unlikely as well.

 

[Ludicolo]

In my experience, if someone presents with a non-length dependent sensory neuropathy (sensory deficits UE >>LE), or demonstrates these findings on NCS, you should think of things like a sensory neuronopathy (or ganglionopathy) as you alluded to. It's actually a well described presentation. A syrinx, being confined to the CNS, shouldn't present with reduced SNAPs.

The DDx for ganglionopathies is fairly narrow. Paraneoplastic syndrome, Sicca complex with or without Sjogrens, idiopathic. Acquired pure sensory neuropathy - think things like Vit B12 deficiency, syphillis, cisplatin or Vit B6 toxicity.

Reasoning for blinks - I went out on a limb thinking Neglect had repeated the NCS (now why would you post if you didn't repeat the study ), and that the patient's UE sensory responses were now absent. Neglect then would have moved to check the sural, but in a 65 year old may not get it anyway. Absent sensories - check blinks.

Now I have a soft spot in my heart for blinks - one of my EMG mentors published a short retrospective study looking at the role of blinks in sensory neuronopathies. Found that the blinks tended to be normal in paraneoplastic causes, and abnormal in sicca and idiopathic cases.

 

[neglect]

I'll cut to the chase and tell you that you're right. And I had much more data than I gave. Unfortunately this lifelong smoker was diagnosed with sclca about 2 weeks before I saw her. Initially I just ordered anti-yo and hu and did nothing further. But based on a phone call later, I did get an MRI, which did not show a syrinx (I would have only posited that based on her exam, not on her ncv). Her anti-yo is positive at high titers. I'm going to repeat the ncv now, and I expect to see progression. Unfortunately, the first ncv predates the diagnosis of lung ca by about 6 months and to my mind it represents a medical error. A neuronopathy should have been on the differential, based on me monday morning quarterbacking the presentation and ncv findings at that time.

So a medically cautionary tale. I'll update as things progress.

 

[Ludicolo]

Nice case. Agree with you - the first EMGer missed it. Think you'll get deposed?

 

[neglect]

Nice case. Agree with you - the first EMGer missed it. Think you'll get deposed?

No. And don't ask me if I think I should be.

I'm uncomfortable making judgments about missing things. With enough scrutiny, some of what I do would break down. But I do it anyway because someone has to make clinical decisions in real time.

How many times have you run up against weird findings on the EMG/NCV that are trivial, and you don't really understand how that could happen, so you think it must be error, but then you repeat and remeasure and it stays? I think I do a good job, but I just did a re-do ncv and couldn't find the Martin Gruber that I myself called! One of those NCVs was wrong and there's no nice way to say it!

Most of the times, these types of things have no bearing (so the velocity is 45 for the ulnar between elbow and wrist that the patient has CTS - this is not a demyelinating case and odds are that you're not going to make it a big deal). Sadly, this one had a lot of bearing. And the error was in not putting together the exam, history, and findings. In retrospect, how can one ignore diffusely low amplitudes? In a prospective case that you're seeing for an hour, different story. I feel lucky to have been the one to see her after the lung data came back, because I think I would have said "axonal sensory neuropathy" and left it at that (although I like to think I wouldn't have).

As I said, a cautionary case.

 

[neglect]

No sensory responses times 8. The median motor nerves were unchanged. So she progressed in a big way.