DURATION OF PAIN AND MUSCULAR ADAPTATIONS IN PATIENTS WITH DYSFUNCTION OF THE CERVICAL-SPINE

Biopsies of the sternocleidomastoid and omohyoid muscle were taken fro m 24 patients who underwent arthrodesis for cervical dysfunction of di fferent etiologies. The two muscles, which are involved differently in movements of the head and cervical spine, were investigated histochem ically. Muscle fibers were classified as type I, IIA, IIB, or IIC (tra nsitional fibers) according to the pH lability of myofibrillar ATPase and calculated relative distribution. In both muscles, fiber transform ations (as evidenced by an increase in the relative amount of type-IIC fibers) were regularly observed within the first 2 years after the on set of the symptoms. The occurrence of the transformation processes wa s independent of the patient's age and sex and was the same for the di fferent etiologies. Since the overall fiber composition of the muscles remained essentially unchanged, the fiber transformations must occur alternatingly in both directions (from ''slow'' to ''fast'' and the re verse). Muscles of patients with a long case history showed no greater signs of fiber transformation. Therefore, fiber transformations in re sponse to cervical dysfunction occur in the initial stage of the disea se and involve different types of muscles. The muscles then return to a ''stable'' condition, independent of the continuation of the dysfunc tion and the chronic neck pain.