Deciphering NCV/EMG/EP Test Reports & PN Types
 

Hi folks, how did you come to understand details about the type of PN you have? I’ve looked at the diagnostic flowcharts and seen all manner of categories – small fiber, large fiber, non-length dependent, focal, multifocal, diffuse, symmetric, proximal, distal, demyelenating, axonal, etc. etc. etc. My current neurologist just says that I have generalized sensory (mainly) neuropathy and that a latent autoimmune disease is the likely cause.

My first neurologist – the one who did my electrodiagnostic tests several years ago – was tight-lipped and kept his cards close to his chest. He said only that I might have MS. We were talking about my MRI results when he said it (there were two tiny WMLs on my brain scan), but since he never told me that any of my other test results were abnormal, I assumed MS was his working theory for me. When I was switching neurologists, I formally requested copies of the tests he performed on me and learned for the first time that my EMG, NCV, and EP studies were abnormal.

Here are the first neurologist’s conclusions on those test reports:

UPPER EMG: “This study is abnormal”; “mostly consistent with a C6 and C7 radiculopathy.” In the details section, he talks about “significant fibrillation potentials and prolonged insertional activity,” as well as “spontaneous activity on left paraspinal musculature.”

UPPER NCV: “median and ulnar sensory nerves had somewhat reduced velocities”; “mild sensory polyneuropathy evident.”

LOWER EMG: “Bilateral L5 and left S1 chronic radiculitis.” “The study demonstrated bilateral EDB muscles to have enlarged and polyphasic motor unit potentials with reduced recruitment.” He also mentions “prolonged insertional activity at L5-S1 bilaterally.”

LOWER NCV: “Right posterior tarsal tunnel syndrome”; “prolongation of H-reflex on left side.”

Is it just me, or does it sound like my EMG results were worse than my NC results? What does that say about the kind of PN I have? Now here is the test result that scares me:

LOWER EVOKED POTENTIAL: “Prolongation of interpeak latencies is consistent with sensory fiber lesion at or above L1 and C5 spinal level. Prolongation of N45z latency suggests subcortical pathology.” :( :confused: :(

I know no one can diagnose me, but many of you sound like you have a detailed understanding of the type of PN you have. I am trying to find my way in to understanding my case better, but I don’t match up well with the most common type of PN, and I don’t have the right language to locate myself on the flowcharts, so to speak. I am wondering if anyone can gather any tidbits from the key words in the test reports above.

Thanks for listening. :Thanx:

Well--
 

--at least you know, through the abnormal results of the NCV/EMG studies, that there is a problem with at least some of the large fiber nerves--the ones that have myelin sheathings and which involve sensory nerves that sense mechanical touch, vibration, and position, and all motor nerves that enervate musculature. Small-fiber nerves do not have myelin sheathings and subsume the sensory processes of pain and temperature, as well as most autonomic functions.

The NCV/EMG results point to radiculopathy, which involves the spinal nerve roots next to the spinal cord itself (radic is root in Latin). This is most often the result of mechanical compressive forces--disc bulging, bone overgrowth in the spinal vertebrae, and the like.

The other result you mention is from a completely different test. Evoked potential testing is designed to measure the conductivity and responsivity of the central nervous system (brain and spinal cord), not the peripheral nervous system. And yes, that result bears looking into, though it can be caused by compressive forces in the spine, impinging the spinal cord in the same way these can impinge nerve roots. "Suggests subcortical pathology" means it is likely this is coming from below the level of the brain, though what you quoted really doesn't narrow much down--I'm not sure what it means to say "at or above the C5 or L1 spinal level", as the fifth cervical level and the first lumbar level are quite far apart--a few feet in fact (C5 is in the neck and L1 lower back).

The small brain spots notwithstanding, I think your back needs to be imaged much more closely--have you ever had MRI's on a high Tesla unit of your cervical, thoracic, and lumbosacral spines?

Good point!
 

Hi glenntaj, thank you for your comments. No, I have not had my back properly imaged. I had a 1.5T C-spine MRI done at the same time as my first brain scan, but it was unremarkable.

My first neurologist seemed confused about my case IMHO. He kept asking me questions about where the pain is in my back and neck, and I kept responding that I don't have chronic pain in my back and neck. When I tried to explain my symptoms to him, he always seemed to be looking for their precise location on my body as if they were localized when actually I experience most of my symptoms in a bilateral, diffuse, and/or generalized manner. When my second brain scan came back unchanged from the first, I asked him to send me for spinal MRIs. Weirdly enough, he declined saying, "Why, your back doesn't hurt, right?" And he was right--my back didn't hurt--but that was probably the first time he remembered that it didn't hurt!

My current neurologist doesn't seem to put much stock in the first neurologist's specific conclusions. He thinks that I have a latent autoimmune disease and we have to watch and continue to do blood work annually and when new symptoms appear. But you raise a compelling point: the original electrodiagnostic test reports point to my back and neck and those areas are mostly untested. I will try to raise this with my current neurologist at my next appointment.

This stuff is so hard. I am struggling with my basic coordination and balance, but my case continues to be a question mark. I have seen folks on this board saying that you need to be your own detective because medical specialists are so pressed for time and no one is looking at your case closely enough to figure out complicated presentations. I GREATLY appreciate your help in understanding these reports better. :Thank you: