Guidance for a patient with complicated symptoms and EDX and imaging findings Stephan Pirnie 5/15/24 11:19 AM (CDT) 67F
Patient with right-hand weakness and numbness/pain over the past year. She reports it started in digit 5, now, has it in digit 4 and her numb (D1) of the same hand. She is having progressive difficulty with gripping things, flexing her fingers and thumb, but also has some weakness with extending her wrist and thumb. She has history of stroke with right-sided residual deficits a few years ago, but those were improving until the last year.
Her exam is notable for 4/5 RUE shoulder abduction, elbow flexion, elbow extension; 3/5 RUE wrist extension, finger extension, DIP flexion, thumb opposition, and 2nd/5th digit abduction. 5/5 throughout the LUE. Decreased sensation in right D4 and D5 digits. MSR: 3+ reflex throughout the RUE. Has a positive Tinel's at the elbow but also positive Spurling and Adson + Roos test (she really reported symptoms with any movement of that arm).
Sensory NCS:
NCS notable for absent right ulnar SNAP with robust median, radial, and contralateral ulnar signals.
Motor NCS:
Very low amplitude right ulnar CMAP (0.2 mV) and slowing across the elbow (59 m/s to 48 m/s) without conduction block. Also slowing of the right median SNAP at D2 (4.4 ms), with normal right median CMAP.
nEE:
EMG with neurogentic changes in FDIH, OP, EIP (p waves, fibs, large polyphasic units with markedly reduced recruitment, with most spontaneous activity at FDIH).
Normal biceps, triceps.
The lesion seems to be post ganglionic, and with pattern of numbness and weakness, the most parsimonious location would be inferior trunk. No trauma, no cancer history. However, she also has slowing across the elbow, so considered separate severe ulnar neuropathy and a cervical (C8?) radiculopathy.
I sent for an MRI brachial plexus with contrast, which returned as essentially normal. Then got an MRI C-spine with findings of "Severe right foraminal zone stenosis C6- C7 due to uncinate osteoarthropathy and moderate degenerative disc disease. Tiny right paramedian disc protrusion C5-C6. There is no central canal compromise at any level". Nothing notable at C7/T1.
I've referred her to both a hand surgeon to discuss her ulnar elbow, and a spine neurosurgeon for her neck.
Any suggestions on interpretation of localization in this patient? Things that would have helped electrodiagnostically to point in the right direction for management? Looking back I probably should have done a MABC.
Responses:
Channarayapatna Sridhara 5/16/24 9:00 AM (CDT).
Thank you Dr. Pirnie for posting this interesting and challenging patient history and the findings. Clearly the previous UMN lesion poses a challenge in using the strength examination as an adjudicator.
The normal CMAP of the median nerve is difficult to explain if it was purely a lower trunk or C8-T1 root pathology, especially in the presence of severe loss of ulnar CMAP and unobtainable ulnar SNAP. However, there are abnormalities in the EI that may localize the lesion at these levels.
My thought processes in the presence of weakness of wrist extension and finger extension are PIN (in the presence of normal radial SNAP), CTS (in the presence of prolonged peak latency of the median sensory), and severe ulnar neuropathy.
I agree that MABC would have helped with the localization but having normal imaging studies makes this point mute. Additional radial innervated muscle study to confirm PIN, motor latency comparison between lumbrical, palmar interosseous, radial motor conduction study would be benefit to assess this patient. These studies may help with the appropriate management of the patient.
Sandra Hearn 5/17/24 4:42 PM (CDT)
Hey Steve! It's great to hear from you.
I agree with Dr. Sridhara that the discordance between the median motor CMAP and the [clinical weakness + EMG findings] is odd here! The presence of multiple disorders in the mix (CNS cause of weakness, ulnar neuropathy, and broader distal upper limb weakness) forces a look at relative differences/severities. The 3 things I would revisit with history/exam and the EDX data are:
Is the median motor CMAP truly normal, or could reflect some axonal loss, aligning with your EMG? (How does it measure up against the contralateral?)
Conversely, on EMG, are the recruitment abnormalities different between ulnar innervation and the other C8/T1 muscles examined (EI, OP)?
If the patient had significant hemiparesis at some point, there can be lower motor neuron dysfunction (apparent on EDX as some fibrillations and some reinnervation changes), but I think you are suggesting dysfunction beyond this.
Evidence of peripheral sensory deficit beyond the ulnar nerve, either clinically or EDXically? MABC territory.
These 3 questions would help identify if there is a unifying focal peripheral lesion driving the functional decline (and whether it is largely ulnar vs more C8/T1/L-trunk). Then:
Are the wrist extensors (C6-7) truly getting weaker, or is this weakness part of her stroke deficit? If they are getting weaker, do EMG findings support a peripheral nervous system etiology of this component? If these look like the hand muscles, this is a broader pathophysiologic process.
Early motor neuron disease plus ulnar neuropathy is a possibility with the data presented, especially if the EMG abnormalities beyond the ulnar nerve are substantial and the sensory piece is focal. If the EMG abnormalities are milder and the patient’s new functional loss could actually be mainly driven by ulnar neuropathy, then I wonder about stroke sequelae muddying the waters here.
Richard Ball, 5/18/24 11:22 AM (CDT)
In a patient like this, there are almost certainly multiple etiologies. You are not likely to define them all.
Sometimes you have to compromise and figure out what is most reasonable for the patient, even if there is uncertainty in the situation.
The one thing I would ask with this patient given the overall findings, "What are the chances that she does NOT have an ulnar neuropathy at the elbow?".
A significant ulnar neuropathy at any level is devastating to hand function from both a motor and sensory standpoint. I'm assuming that she is right-hand hand dominant and she is using the right upper extremity functionally, which it sounds like she is. I'd therefore be inclined, if there were no contraindications, to decompress her ulnar nerve at the elbow. Even if this were her only problem, her prognosis following surgical decompression probably isn't good given the severity of her electrodiagnostic findings. But, you might just give her enough improvement in hand function that it would be worth doing and the relative risk is low. I hesitate to treat minor ulnar neuropathies surgically, but this one is not minor. A diagnostic ultrasound of the ulnar nerve at the elbow might add some certainty to what you were dealing with.
You will have to analyze everything about her situation, but an ulnar nerve decompression at the elbow might be a very reasonable thing to do, even if all of the lectrodiagnostic findings cannot be explained on that basis alone.
Stephan Pirnie 5/23/24 10:26 AM (CDT)
Thank you all for the helpful input! This patient was scheduled to follow up with me on Tuesday but unfortunately did not show up for her appointment. I'll need to chat with her to see if she'll tolerate more studies to further define what is going on.
Any thoughts about whether cervical paraspinal could be helpful here? I have certainly used paraspinal EMG more than I did in residency, mainly in the lumbosacral region. I don't find them terribly helpful for localizing a lesion to a specific nerve root, but can be helpful to correlate with limb myotomal abnormalities.
Channarayapatna Sridhara 5/30/24 12:22 PM (CDT)
There is some wonderful discussion from Drs Ball, Hearn. Hope the following addsto the discussion and diagnosis in this patient based on the last question Dr. Pirniehas raised.
Another muscle that may be helpful in making a diagnosis of a proximal lesion is the Lower part of the pectoralis major that is only derived from C8-T1. If this muscle is abnormal, especially in the presence of a normal MRI of the plexus the lesion is likely in the root level. Additional MABC comparing to the opposite side will help. If the amplitude is normal and symmetrical that will help to diagnose a preganglionic root pathology. As you note I am shying away from the paraspinal examination as this gets innervated the earliest and presence of abnormal spontaneous activity is less prevalent after 8-12 weeks after development of a radiculopathy.
Stephanie Jackson 5/30/24 12:24 PM (CDT)
I'd also like to hear more opinions about the possible radiculopathy. Doing paraspinals was controversial during residency and fellowship due to lack of reliability, so they stopped doing them. Especially with so many people with previous surgery or injury. I wonder how much is being missed or overread due to paraspinals.
Was the MRI spine personally reviewed? The report didn't state it was normal and our standard supine MRI miss about 30% of radiculopathies. We need more upright stress MRIs that show the patient turned upright with GRAVITY and the change is remarkable. Watching it in person is something everyone needs to see. I assume the patient is also diabetic since she's of the demographic, so another factor that complicates the findings.
Sandra Hearn, 5/31/24 7:09 PM (CDT)
To Dr. Pirnie’s question about the paraspinals. In this case with clear clinical neurological deficits & active denervation in the limb, I think findings of significant active denervation in the paraspinals would adjust my differential, raising likely hoodof an intraspinal or an early diffuse process. Conversely, scant abnormalities or normal findings would not change my impression (I would not rule out radiculopathy for the reason Dr. Sridhara stated).
A priori, we don't know what we’ll find! So, I think they are worthwhile to study, while interpreting cautiously—but the studies and other components already mentioned may turn out to be higher yield.
Dr. Sridhara - what is your localization for the lower portion of pectoralis major specifically? Is this anterior and medial to the axillary fold, or would I need to go even more caudally to ensure I get the lower portion? Thanks for teaching me this one!