No abstract

In many centers urethral striated sphincter electromyography has become an essential component of urodynamic testing. The urologist who uses this modality of investigation in an attempt to understand the pathophysiology of striated sphincter dysfunction must have some basic knowledge of electromyography. Attempts have been made to provide such basic information, especially relating to the methods of evaluation and interpretation. We also have incorporated our own views based on our experience with more than 200 subjects with neuropathic vesicourethral dysfunctions.

We investigated 17 spinal shock patients with traumatic complete cord lesions with cystometry, urethral pressure profile, anal and rectal pressure recordings, and electromyography of the pelvic floor sphincters. Bladder filling was accompanied by an elevation of resistance in the bladder neck area, with a concomitant increase of pressure in the external sphincter zone but without a simultaneous increase of the electromyographic activity. These results indicate an increased sympathetic activity in the smooth muscle component of the entire urethra. In the majority of patients the continuous withdrawal pressure profile had higher values in the membranous urethra than the interrupted withdrawal pressure profile had higher values in the membranous urethra than the interrupted withdrawal pressure profile, revealing the importance of sensory afferents from the urethral mucosal receptors in producing artifactual reflex activity in the pelvic floor muscles. In the majority of interrupted withdrawal urethral pressure profiles higher pressures were recorded in the juxtabulbous region than in the mid part of the membranous urethra. A somewhat decreased electromyographic activity was found in the anal and urethral sphincters at rest. It did not often relate to the amount of resistance recorded in either sphincter. High urethral sphincter pressures and somatic activity of the conus medullaris reflexes show that external urethral and anal sphincters escape spinal shock, the primary characteristic of which is areflexia.

Abstract. Patients with spinal cord injur y or multiple sclerosis were surve y ed for the presence of extreme foot deformities and spasticit y . Pes cavus and claw toes were found in eight of 80 spastic spinal cord injury and two of 20 multiple sclerosis patients. Pes cavus and claw toes were not found in 2 9 flaccid spinal cord injury patients.Pes cavus and claw toes were associated with flexor reflexes which could be elicited b y pin prick proximal to the knee, suggesting extreme spasticit y -and b y low excitatory thresholds for the anterior tibialis as indicated electro m y ographicall y .Complications of severe spasticit y associated with spinal cord injur y and multiple sclerosis include pes cavus and claw toes, mediated in part b y spasms of the anterior tibialis.

The purpose of this study was to assess the feasibility of utilizing low-current stimulation for F-wave generation, thereby avoiding the discomfort of repetitive supramaximal stimulation. We employed the same technique as is used for generating F waves in the conventional way, except for using a stimulating current that was just strong enough to evoke a motor response on the oscilloscope. This usually required a stimulus of about 10-15 mA at 0.2-ms duration. Both median nerves of 30 subjects were evaluated with this technique and with F waves generated by the conventional technique in the same subjects. Amplitudes were larger when using supramaximal current stimulation. However, there was no statistical difference between F-wave latencies, chronodispersion, and persistence (penetrance) elicited with maximal and low-current stimulation. This procedure should represent a significant improvement for patient comfort during electrodiagnostic procedures involving F-wave studies.