PubMed · 5682199
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W Willgerodt, A Felker. 1968-08-03. [Advances in external tocometry].. https://pubmed.ncbi.nlm.nih.gov/5682199/
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1. We have studied the effects of changes in posture on the motor response to galvanic vestibular stimulation (GVS). The purpose of the experiments was to investigate whether the function of the GVS-evoked response is to stabilize the body or the head in space. Subjects faced forwards with eyes closed standing with various stance widths and sitting. In all cases the GVS-evoked response consisted of a sway of the body towards the anodal ear. 2. In the first set of experiments the response was measured from changes in (i) electromyographic activity of hip and ankle muscles, (ii) the lateral ground reaction force, and (iii) lateral motion of the body at the level of the neck (C7). For all measurements the response became smaller as the feet were placed further apart. 3. In the second set of experiments we measured the GVS-evoked tilts of the head, torso and pelvis. The basic response consisted of a tilt in space (anodal ear down) of all three segments. The head tilted more than the trunk and the trunk tilted more than the pelvis producing a leaning and bending of the body towards the anodal ear. This change in posture was sustained for the duration of the stimulus. 4. The tilt of all three segments was reduced by increasing the stance width. This was due to a reduction in evoked tilt of the pelvis, the bending of the upper body remaining relatively unchanged. Changing from a standing to a sitting posture produced additional reductions in tilt by reducing the degree of upper body bending. 5. The results indicate that the response is organized to stabilize the body rather than the head in space. We suggest that GVS produces a vestibular input akin to that experienced on an inclined support surface and that the function of the response is to counter any threat to balance by keeping the centre of mass of the body within safe limits.
OBJECTIVES: To determine the motor responses resulting from direct electrical stimulation of the hypoglossal (HG) nerve and to correlate these responses to changes in upper airway patency during sleep. DESIGN: The motor effects of direct electrical stimulation of the main trunk of the HG nerve and the branch that supplies the genioglossus muscle during anesthesia and wakefulness were assessed visually. Responses in airflow during sleep to HG nerve stimulation were assessed with standard polysomnographic techniques. SETTING: University medical center. PATIENTS: Fifteen patients undergoing a surgical procedure that involved the neck that exposed the HG nerve and 5 volunteer patients with obstructive sleep apnea constituted the study population. INTERVENTIONS: The main trunk (n = 3) and genioglossus branch (n = 2) of the HG nerve were stimulated electrically with a half-cuff tripolar electrode. RESULTS: Stimulation of the branch of the HG nerve that innervates the genioglossus muscle caused protrusion and contralateral deviation of the tongue. Stimulation of the main trunk of the HG nerve caused slight ipsilateral deviation and retrusion of the tongue. The arousal threshold for stimulation exceeded the motor recruitment threshold by 0.8 +/- 0.4 V. Inspiratory airflow increased in all patients by 184.5 +/- 61.7 mL/s (mean +/- SD; P = .02, analysis of variance) with stimulation. CONCLUSION: Direct HG nerve stimulation below the arousal threshold can improve airflow in patients with obstructive sleep apnea.
Evacuation of urine in paraplegics without the need for catheters would be possible when voiding could be induced by eliciting a bladder contraction. A challenging option to obtain detrusor contraction is electrical stimulation of the detrusor muscle or its motor nerves. This article reviews the 4 possible stimulation sites where stimulation would result in a detrusor contraction: the bladder wall, the pelvic nerves, the sacral roots, and the spinal cord. With respect to electrode application, sacral root stimulation is most attractive. However, in general, sacral root stimulation results in simultaneous activation of both the detrusor muscle and the urethral sphincter, leading to little or no voiding. Several methods are available to overcome the stimulation-induced detrusor-sphincter dyssynergia and allow urine evacuation. These methods, including poststimulus voiding, fatiguing of the sphincter, blocking pudendal nerve transmission, and selective stimulation techniques that allow selective detrusor activation by sacral root stimulation, are reviewed in this paper.