Interventions for Radiating Upper Extremity and Cervical Facet Pain
The evaluation of patients complaining of upper extremity radiating pain must include examination of the head and neck. The first steps are to obtain a careful history and to conduct a systematic physical examination. History of onset, character and location of the pain, helpful medications and ones that aggravate the problem, movement limitation—as well as previous procedures done on the patient—are helpful in the evaluation, diagnosis, and formulation of a treatment plan.
The cervical nerve roots provide innervation to a significant portion of the head. The cranial nerves are also involved in painful conditions of facial structures. The three divisions of the trigeminal nerve innervate the eye and forehead (V1), mid-facial structures (V2), and the lower jaw area (V3). Pain in temporal structures may be referred from the upper cervical area or from injury to second, third, and possibly the fourth, cervical nerves and cervical spinal facet joints. The fourth and fifth cervical nerve roots supply the shoulder area. The thumb area is supplied by C6, and the median nerve which originates from C6-7 supplies the palm and middle fingers. The little finger side is innervated by C8, T1 nerve roots (see Table 1).
|C1-2||Occipital region of head|
|C3||Temporal region of head|
|C6, 7 8, T1||Arm and hand|
Examination of the patient to confirm which nerves are involved in the pain should concentrate on placing gentle pressure along the course of the nerves. Palpation of the second cervical nerve from a posterolateral direction can reproduce pain radiating to the back of the head. Pressure just below this from the side can elicit pain radiating to the temporal area from the C3 distribution. C4 and C5 will possibly refer to the shoulder as well as the side of the head. Spasm of the trapezius muscles and pain invoked by gentle pressure on the anterior border of the trapezius muscle as the examining physician palpates from behind the front edge of the muscle represents pain in the C4 distribution. Pain invoked by palpation a little more posteriorally indicates C5 facet joint distribution. Applying pressure gives a “jump sign” where the patient jumps when pain is elicited. The C6 distribution is more caudal and posterior. In many patients, discogenic referred pain coming from the C5-6 levels is elicited by palpation closer to the spine at a location level with the upper end of the scapula. Palpation behind and inferior to the sternocleidomastoid muscle in patients with cervicogenic facet injury can trigger significant scalene muscle spasm and elicit a jump sign.
Very commonly, physicians taking care of patients fail to examine the anterior and middle scalene muscles. Spasms of these muscles are caused by compression of the brachial plexus between the two muscle groups. The compression can produce significant pain radiating to the arm or shoulder. We have found this to be a useful evaluation, especially in patients who have already had treatment in the form of radiofrequency thermocoagulation of the facet joints but failed to respond. In these patients, the scalene muscle may still be in significant spasm and injection of the interscalene space to free the compression by the two muscle groups can result in significant pain relief and help regain cervical mobility. The interscalene block will reach both the brachial plexus and the cervical sympathetic ganglia.
Evaluation of pain patients with arm pain radiating from the lower cervical nerve roots, C6 and below, is done with a stretching maneuver. The patient’s shoulder and arm are extended horizontally, the shoulder is pushed forward, and the head is tilted in the opposite direction while the patient stabilizes himself/herself by firmly holding on to a structure such as a doorway. This procedure often reproduces the patient’s pain, such as pain radiating to the thumb, the middle of the palm and the little finger along the above outlined dermatomal innervation pattern.
Causes of Cervical Pain
Chronic compression of nerve roots produces radiating pain as will acute, intense compression of normal nerves or compression of injured nerves. Sources of compression include muscle groups in spasm or a bulging intervertebral disc inside the spinal canal, bony outgrowths such as osteophytes due to degenerative processes and spinal lateral recess stenosis near the neuroforamina.1 Other significant causes of pain are degenerative processes of the disc. Leakage of nucleus pulposus material, the soft inner structure of the cervical disc, into the spinal epidural space can produce an inflammatory reaction leading to scar formation similar to scar formation produced by surgery.2-4
Nerve roots move as the human body moves. If the nerves cannot move freely, flexion of the head and neck and movement of the upper extremity often leads to severe radiating pain due to traction in the nerve root. Movement is three times more likely to cause pain when nerve movement is restricted.5
Anterior and middle scalene muscle spasm can lead to significant radiating pain. Interscalene blocks can have rather remarkable long-lasting effect when there is scar formation of the nerve root and spasm of the scalene muscles.
Injury to a nerve can change its normal role of transmitting messages from the periphery to the central nervous system (CNS) and from the CNS to the periphery. An injured nerve may spontaneously generate impulses which produce pain. A cycle develops from the triad of injury leading to pain, leading to muscle spasm and more injury, more pain, and more spasm.
“The challenge for the examining physician is to differentiate pain originating from the different structures of the spinal canal, the muscles or the lateral and anterior structures of the facet joints and discs, or pain due to other pathological processes.”
The challenge for the examining physician is to differentiate pain originating from the different structures of the spinal canal, the muscles or the lateral and anterior structures of the facet joints and discs, or pain due to other pathological processes. Training and experience lead to remarkably accurate presumptive diagnosis but additional diagnostic tools such as flexion-extension x-rays, CT scans and MRIs are important in the complete evaluation.
For interventional pain physicians, there is no substitute for properly supervised training where basic principles must be taught. The training must provide a foundation of clinical experience where supervised procedures are performed with predictable safety and efficacy.