Potential contributions of neck muscle dysfunctions to initiation and maintenance of carpal tunnel syndrome.

A biomechanical perspective of the carpal tunnel (CT) is reviewed that lends itself to an understanding of carpal tunnel syndrome (CTS) from a broader pathophysiological perspective than focusing narrowly or solely on nerve disturbance in the extremity. A wider integration of physiological systems in the etiology and maintenance of CTS is proposed that links muscular dysfunction in the neck and possibly elsewhere to dysfunction at the CT. A significant subset of individuals who develop CTS have a primary contribution from muscular dysfunctions rather distal to the CT itself. Neurophysiological dysregulation of normal inhibitory feedback at the level of the motoneuron pool specifically involving gamma motoneuron impulses may be a primary contributing mechanism. Empirical demonstration of amelioration of CTS symptoms by means of surface electromyography (sEMG) retraining of dysfunctional neck muscle patterns is reviewed as support for the hypothesized link. The specific retraining techniques are described. Future conceptual and research directions are noted.

Carpal tunnel syndrome as an expression of muscular dysfunction in the neck.

Carpal tunnel syndrome (CTS) may be a consequence of increased forearm flexor activity secondary to muscle dysfunction in the neck. Eighteen CTS patients, with an average duration of symptoms of 10 months, were studied. Standardized nerve-conduction studies were administered before and after treatment. Surface-EMG techniques measured sternomastoid and cervical paraspinal muscle activity and flexor and extensor muscle activity during head movement. Both sets of neck muscles were found to be asymmetrical when compared side to side. Reduction of the sternomastoid asymmetry decreased forearm flexor EMG activity. Significant decreases in all nerve conduction measures were noted for every subject. Over half reported a loss of symptoms with post hoc analysis suggesting this may be related to the sternomastoid median frequency. It is suggested that increased flexor and/or extensor motor activity is an expression of dysfunctional sternomastoid activity. Possible mechanisms of dysfunction including the tonic neck reflex are discussed.

A randomized crossover investigation of a back pain and disability prevention program: Possible mechanisms of change.

An educational program which emphasized the symmetrical use of back muscles was studied at a health care facility which had extremely high time lost injury rates due to back strains. Participants (N=180) were involved with half studying an educational program entitled "Back to Balance" with the remainder serving as controls. After 3 months, the controls studied the program. All subjects completed psychological tests, received cervical and lumbar paraspinal dynamic EMG evaluations four times (pre-and post-treatment, and after 3 and 12 months). Administrative indices (costs, incidence, and time lost injury rate) were obtained for the 3 years prior to the study and for the 1 year of the study. The 1-year results showed decreased pain, retained knowledge which was generalized to the home, and significantly improved symmetry of both sets of muscles. Administrative data revealed a 72% decrease in the time lost injury rate with reduced costs.

Unexpected brain hemorrhages and the value of computerized tomography.

Intracerebral hemorrhage has been thought in the past to be manifested by sudden onset of hemiplegia, severe headache and deep coma proceeding to death in most cases. There are patients who present with less ominous symptoms who have heretofore been though to have cerebral infarction or transient ischemic attacks who in reality have intracerebral hemorrhages. Computerized tomography has allowed us to identify these patients and to separate them from the large group of patients with ischemic infarcts either due to thromboses or emboli. Six patients were reported with unexpected brain hemorrhages and their good prognosis is emphasized.