A common cause of neck, shoulder, and arm pain is disc herniation in the lower cervical region; the process is comparable to disc herniation in the lumbar region but gives rise, of course, to a different set of symptoms (Table 10-1). The problem appears most often without a clear and immediate cause, but it may develop after trauma, which may be major or minor (from sudden hyperextension of the neck, falls, diving accidents, forceful manipulations as discussed by Kristoff and Odom). The roots most commonly involved are the seventh (in 70 percent of cases) and the sixth (in 20 percent of cases); fifthand eighth-root compression makes up the remaining 10 percent (Yoss et al). The clinical diagnosis is established by a fairly discrete distribution of pain or paresthesias that corresponds to a single cervical root, reflex loss in the segment of the root, and by elicitation of exaggerated root pain with mechanical tests such as the Spurling maneuver, in which the examiner exerts downward pressure on the top of the head with the patient’s head turned to the affected side and the neck slightly extended. The latter test is not very sensitive but is specific in radiculopathy that has been confirmed by EMG or imaging. It is infrequent that the entire syndrome of pain, motor, reflex and sensory loss corresponding to a root is found and the region of pain is particularly variable in cervical radicular disease by comparison to lumbar root disease.
When the protruded disc lies between the sixth and seventh vertebrae, there is involvement of the seventh cervical root as outlined in Table 10-1. The pain is then in the region of the shoulder blade, or spine of the scapula, and posterolateral upper arm; it may project to the elbow and dorsal forearm, index and middle fingers, or all the fingers. Occasionally discomfort is felt in the pectoral or axillary region. Tenderness is most pronounced over the medial aspect of the shoulder blade opposite the third to fourth thoracic spinous processes and in the supraclavicular area and triceps region. Paresthesia and sensory loss are most evident in the index and middle fingers. Weakness involves the extensors of the forearm and sometimes of the wrist; occasionally the handgrip is weak as well; the triceps may be weak and the triceps reflex is usually diminished or absent; the biceps and supinator reflexes are preserved.
With a laterally situated disc herniation between the fifth and sixth cervical vertebrae, the symptoms and signs are referred to the sixth cervical root. The full syndrome is characterized by pain at the trapezius ridge and tip of the shoulder, with radiation into the anterior-upper part of the arm, radial forearm, often the thumb, and sometimes the index finger as well. There may also be paresthesia and sensory impairment in the same regions; tenderness in the area above the spine of the scapula and in the supraclavicular and biceps regions; weakness in flexion of the forearm (biceps) and in contraction of the deltoid when sustaining arm abduction; and diminished or absent biceps and supinator reflexes (the triceps reflex is retained or sometimes has the appearance of being slightly exaggerated because of flaccidity of the biceps).
The fifth cervical root syndrome, produced by disc herniation between the fourth and fifth vertebral bodies, is characterized by pain in the shoulder and trapezius region and by supraand infraspinatus weakness, manifest by an inability to abduct the arm and rotate it externally with the shoulder adducted (weakness of the supraand infraspinatus muscles). There may be a slight degree of weakness of the biceps and a corresponding reduction in the reflex, but these are inconsistent findings. A small patch of diminished sensation commonly overlies the deltoid muscle.