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[Electromyography in patients with spastic torticollis].

The article describes the results of electromyographic examination of the muscles of the neck in 26 patients with spasmodic torticollis. Electromyography was performed before and after stereotaxic operative interventions on the nucleus of Cajal or in combination with the diencephalic structures. It is shown that electromyographic examination of patients, especially with the use of functional motor and oculomotor tests, widens essentially the possibilities of the diagnosis by facilitating the identification or specification of the predominantly involved group of muscles. The discovery of concurrent oculographic and electromyographic changes in the dominant muscles of the neck during oculomotor tests is evidence of the connection of the system of concurrent movements of the eyes and head with the motor systems participating in the pathology of torticollis. Analysis of the dynamics of electromyographic changes in patients with predominance of the tonic component in the early and late postoperative periods is indicative of gradual increase of positive changes in the motor sphere, which, evidently, is due to the dynamic reorganizations in the previously formed stable pathological system.

Action Potentials↗
PubMed1995

The effects of intrathecally administered baclofen on function in patients with spasticity.

The purpose of this article is to review the literature on the effects of intrathecally administered baclofen on impairment in spasticity and muscle activation patterns, on functional limitations in mobility and self-care, and on disability in daily life roles. We found plentiful evidence of improvement in spasticity, spasms, and bladder function and some reports of improved patterns of muscle activation and kinematics of single-joint movement. Improved ability to accomplish transfers, self-care, and locomotion is less consistently studied but has also been reported in about 60% to 70% of patients. Evidence of improved quality of life is primarily anecdotal but may be found in 10% to 30% of patients. We conclude that research protocols should be developed to clarify effects on control of voluntary movement, functional limitations, and quality of life.

Activities of Daily Living↗
PubMed2001

Evidence for plateau potentials in tail motoneurons of awake chronic spinal rats with spasticity.

Motor units of segmental tail muscles were recorded in awake rats following acute (1-2 days) and chronic (>30 days) sacral spinal cord transection to determine whether plateau potentials contributed to sustained motor-unit discharges after injury. This study was motivated by a companion in vitro study that indicated that after chronic spinal cord injury, the tail motoneurons of the sacrocaudal spinal cord exhibit persistent inward currents (I(PIC)) that cause intrinsically sustained depolarizations (plateau potentials) and firing (self-sustained firing). Importantly, in this companion study, the plateaus were fully activated at recruitment and subsequently helped sustain the firing without causing abrupt nonlinearities in firing. That is, after recruitment and plateau activation, the firing rate was modulated relatively linearly with injected current and therefore provided a good approximation of the input to the motoneuron despite the plateau. Thus in the present study, pairs of motor units were recorded simultaneously from the same muscle, and the firing rate (F) of the lowest-threshold unit (control unit) was used as an estimate of the synaptic input to both units. We then examined whether firing of the higher-threshold unit (test unit) was intrinsically maintained by a plateau, by determining whether more synaptic input was required to recruit the test unit than to maintain its firing. The difference in the estimated synaptic input at recruitment and de-recruitment of the test unit (i.e., change in control unit rate, DeltaF) was taken as an estimate of the plateau current (I(PIC)) that intrinsically sustained the firing. Slowly graded manual skin stimulation was used to recruit and then de-recruit the units. The test unit was recruited when the control unit rate was on average 17.8 and 18.9 Hz in acute and chronic spinal rats, respectively. In chronic spinal rats, the test unit was de-recruited when the control unit rate (re: estimated synaptic input) was significantly reduced, compared with at recruitment (DeltaF = -5.5 Hz), and thus a plateau participated in maintaining the firing. In the lowest-threshold motor units, even a brief stimulation triggered very long-lasting firing (seconds to hours; self-sustained firing). Higher-threshold units required continuous stimulation (or a spontaneous spasm) to cause firing, but again more synaptic input was needed to recruit the unit than to maintain its firing (i.e., plateau present). In contrast, in acute spinal rats, the stimulation did not usually trigger sustained motor-unit firing that could be attributed to plateaus because DeltaF was not significantly different from zero. These results indicate that plateaus play an important role in sustaining motor-unit firing in awake chronic spinal rats and thus contribute to the hyperreflexia and hypertonus associated with chronic injury.

Action Potentials↗