Pathophysiology of neck pain:
Three types of neck pain are usually encountered: Suboccipital neck pain, Sub axial or posterior neck pain and the anterior
Subaxial neck pain is the commonest type of neck pain and is discussed in details as follows,Other subtypes have a similar
etiopathology and follow similar pattern of presentation.
Subaxial or posterior neck pain is usually due to ligamentous or muscular factors. These are secondary to posture, stress,
chronic fatigue and non ergnomically designed work stations.
Muscular pain: Muscles contain un encapsulated free nerve endings which serve as chemosensitive and mechanosenstive
Mechanical stimulus like stretch and pressure stimulates the mechanoreceptors, and chemonociceptors are triggered by
the metabolites that accumulate during anerobic metabolism or by the substances produced after injury or ischemia: the serotonins,
bradykinins, histamine and pottasium ions.
Neck pain in degenerative spine: The primary source of pain in these spines are the disc and facet joints. The
disc which is supplied by sinuvertebral nerve has been shown to produce a consistent pattern of pain when stimulated during
discography. Facet joints that are supplied by posterior primary ramus and contain free nerve endings in capsule have also
shown to produce a reproducibel pattern of neck and shoulder pain when distended during provactive injection studies.
Pathophysiology of Radicular pain and neuro deficit (Radiculopathy):
Radicular pain is the result of irritation of spinal roots by any of following: Soft disc herniations, stenosis, osteophytes,
intrinsic nerve root pathology and trauma. Generation of pain requires two factors: Inflamation of nerve and mechanical deformation.
Inflamation is the result of reaction of nerve roots to the presence of extruded nucleus pulposus. The inflamatory arena resulting
from the above scenario include neuro genic mediators released from cell bodies and non neuro genic mediators of pain
that are released by the disc tissue.