Dynamic Foraminal Stenosis
Positional Neuropathy While Standing?
How often have you heard someone say that when he stands up he experiences focal pain, numbness or weakness in a particular nerve root distribution that is relieved by lying down. The positional nature of the symptoms and the neural dysfunction suggest that there is nerve root compression or irritation while standing and relived while supine (non-wright bearing). It should not be surprising that MRI imaging performed in supine position would fail to demonstrate the nerve root compression that is only present when the individual is supine.
The sagittal T2-weighted image on the left was obtained in the supine position through the right L4-5 neural foramen and shows fat surrounding the right L4 nerve root. The sagittal image on the right was obtained while standing and shows loss of vertical disc height, overriding of the fact joints and an intraforaminal disc herniation with positional dynamic nerve root compression.
These images display the importance of weight-bearing MRI imaging for the evaluation of patients with positional pain or neuropathy that is worse when standing or weight-bearing.