severe spinal stenosis c5 c6moderate spinal stenosis c5 c6bilateral foraminal narrowing at c5 c6spinal stenosis c5 c6 c7spinal stenosis c4 c5 c6c5 c6 stenosisc5 c6 degeneration symptomscervical spinal stenosis c5 c6 c7cervical stenosis c5 c6c5 c6 stenosis surgerystenosis c5 c6 neckcanal stenosis c5 c6