Can C8 radiculopathy be confirmed by EMG but not in MRI?

Question

Hello doctor,

I am a female, 30 years old.

Questions: 1) How and why do I have all symptoms of c8 radiculopathy confirmed by EMG but not reflective of MRI- c7/t1 normal? 2) What else if anything could cause c8 radiculopathy in last 2 digits per my imaging that would explain this medically? 3) What is your final assessment and why?

To date: Undergone much PT and recieved facet injections at 2 sites: above and below ACDF. Persistent neck pain into scalpula and upper extremity unilateral hand numbness especially D4, D5. Now with new weakness in opposite hand.

History/background/ diagnostics: Former ACDF at c5/6 labeled degenerative disk in mid/late 20's. Resulted in great sucess post-surgery. Several years later- accident occurs: results multiple levels damaged, cervical spondylosis. Imaging reports:

MRI findings:

no cord/ vertebral lesion and multi DDD below above acdf. C4/5 herniation and degeneration and cord encroachment. C5/C6- bony overgrowth causes cord encroachment. C6/C7 herniation degeneration but without any encroachment. C7/T1- unremarkable. Myelo gram- showed small extradural lesion at C5/6 with thecal sac compression. A spur projecting from posterior border of C6, small ventral defect.

EMG- (left- UE) Neuro exam: weakness ADM, APB, 1st D1. Decreased sensation digits 3,4,5 clawing in 5th digit. DTR 1+. NCV: left ulnar sensory nerve decreased conduction veloc (wrist-5th digit, 42/s) Polyphasic Volition 1st D1 and ADM. No acute radiculopathy, plexopathy, peripheral neuropathy. Final: Abnormal test concluded Chronic C8 radiculopathy.

Answer 1

Hi,

Welcome to icliniq.com.

You do have chronic C8 radiculopathy from your detailed description. The reason for mismatch between NCV / EMG findings and MRI can be explained on the basis of a pre-fixed or a post-fixed brachial plexus where in the nerve exiting the C7-T1 inter space is actually carrying nerve fibres from the space below; that will show up normal on MRI. The actual C8 fibres are going out at a space above ie C6-C7 or higher where they are getting compressed. Spur and compression exists at a higher level.

The second possibility is that there is arachnoiditis but that should show up on MRI, however, I have not seen the MRI myself and have to rely on the report (attachment removed to protect patient identity). The third explanation is possible injuries scarring at the time of ACDF or after less likely as you would have known the temporal sequence of symptoms. By APB you mean adductor and not abductor pollicus brevis - that is median nerve. Appearance of new symptoms and persisting neck pain afert ACDF suggests instability at another level which unfortunately can happen and is a collateral effect of fusion in spine. Get flexion extension X-rays and dynamic contrast MRI.