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Biomedical subjects

E S Watkins

Publications and source records attributed to E S Watkins.

17 recordsLinked to original sources
PubMed1991

Development of an electrically stimulated neoanal sphincter.

In early surgical attempts to create a neoanal sphincter for patients who are faecally incontinent, skeletal muscle (usually the gracilis) has been transposed around the anal canal. Despite modifications, such as intermittent electrical stimulation, this procedure is likely to fail because the fast-twitch gracilis muscle is incapable of prolonged contraction without fatigue. Long-term electrical stimulation to convert such a muscle to a slow-twitch, fatigue-resistant muscle, though practicable, has yielded inconsistent results. We describe further modifications of this technique. A neoanal sphincter was constructed with an electrically stimulated transposed gracilis muscle in 20 incontinent patients with a deficient anal sphincter, and as part of a reconstruction in 12 patients in whom the anorectum had been excised or was congenitally absent. A totally implanted stimulator was used to convert the muscle from a fast-twitch to a slow-twitch muscle. Other modifications included vascular delay 4-6 weeks before transposition of the muscle, stimulation of the main nerve to the gracilis rather than its peripheral branches, and intermittent higher frequency stimulation. 2-4 of these modifications gave significantly fewer failures than did 0-1. With the new technique, continence has been restored in patients whose only other treatment option was a permanent stoma.

Adolescent↗
PubMed1991

A case of ocular tilt reaction and torsional nystagmus due to direct stimulation of the midbrain in man.

A case is presented of a patient who underwent insertion of a periaqueductal grey electrode for the relief of chronic pain. Shortly after insertion, the patient developed a left-sided ocular tilt reaction (OTR). The electrode tip, initially to the right of the midline, was then withdrawn slightly so that it was now on the left side. Stimulation at this point gave rise to a worsening of the tilt reaction, in addition to bilateral counter-clockwise torsional nystagmus. Computerized tomography and stereotactic coordinates indicated that the tip of the electrode was finally situated in the region of the left interstitial nucleus of Cajal (INC). The production of an OTR by stimulation in this region is similar to the phenomenon previously reported in monkeys and cats. The side of the OTR is consistent with previous evidence, suggesting that the utricular pathways cross between medulla and midbrain.

Electric Stimulation↗
PubMed1990

Electrically stimulated sartorius neosphincter: canine model of activation and skeletal muscle transformation.

The sartorius muscle was transposed into the abdominal cavity of six dogs, passed around a Thiry-Vella loop and sutured to itself to form a neosphincter. The muscle was activated by electrical stimulation and on contraction the neosphincter stopped or reduced the flow of saline through the Thiry-Vella loop in all animals until the onset of muscle fatigue. Continuous low frequency stimulation was used to transform the skeletal muscle, and when studied after a mean of 8 weeks of stimulation (range 6-11 weeks) the neosphincter stopped the flow for a significantly longer period of time (P = 0.027). Associated with the improved neosphincter function was a significant decrease in the fusion frequency (P = 0.003) and prolongation of the stimulus-peak tension time as assessed by a strain gauge sutured to the neosphincter muscle (P = 0.002). The changes in the contraction properties of the skeletal muscle suggest that continuous low frequency stimulation transformed the muscle fibres from type 2 to type 1, resulting in improved fatigue resistance and potential for continuous sphincter activity.

Animals↗
PubMed1990

Restoration of gastrointestinal continuity and continence after abdominoperineal excision of the rectum using an electrically stimulated neoanal sphincter.

A new operation is described in which a neorectum and neoanal sphincter mechanism have been constructed to restore gastrointestinal continuity and continence in a patient who required abdominoperineal excision of the rectum for a low rectal cancer. The neorectum was constructed by bringing colon down into the pelvis and anastomosing it to the perineal skin. The neoanal sphincter was fashioned from a transposed gracilis muscle and was activated electrically by a totally implanted stimulator. A period of chronic low-frequency stimulation altered the muscle characteristics and enabled the neosphincter to contract continually without fatigue. The patient was continent when the stimulator was turned on and was able to void when the stimulator was turned off.

Abdomen↗
PubMed1990

Construction of a neoanal sphincter by transposition of the gracilis muscle and prolonged neuromuscular stimulation for the treatment of faecal incontinence.

Six patients incapacitating faecal incontinence, in whom conventional treatment had either failed or was contraindicated, were treated by a new technique. A neonanal sphincter was constructed by transposing the gracilis muscle around the anal canal. Chronic neuromuscular stimulation via an implanted electrical stimulator was then used in an attempt to convert the muscle to a slow twitch fatigue resistant muscle. Physiological measurements suggested that this conversion had begun, enabling the neosphincter to mount a sustained contraction. Five patients had their covering stomas closed, and continence was improved in all of them. However, one patient could not cope psychologically with the stimulator, and another patient was continent for long periods only when the neosphincter was used in conjunction with a silastic plug. This new technique may benefit selected patients with incontinence whose only alternative would be a permanent stoma.

Adult↗
PubMed1989

Construction of a neorectum and neoanal sphincter following previous proctocolectomy.

A new operation is described in which a neorectum and neoanal sphincter mechanism have been constructed to restore gastrointestinal continuity and continence in a patient who had previously undergone proctocolectomy and a permanent ileostomy. The neorectum was constructed by forming a triplicated pouch from the distal ileum. The neoanal sphincter was fashioned from a transposed gracilis muscle and was activated electrically by an implanted stimulator. A period of chronic low frequency stimulation altered the muscle characteristics and enabled the neosphincter to contract continually without fatigue. Complete continence was achieved by the neosphincter gripping a Silastic plug inserted within the efferent spout of the pouch. The patient was able to void completely when the stimulator was switched off and the plug removed.

Adult↗
PubMed1989

Idiopathic dystonia and cervical spondylotic myelopathy.

Cervical myelopathy developed in two patients with idiopathic torsion dystonia. There were marked spondylotic changes in both patients, probably attributable to the incessant dystonic movements of the neck. Previous cervical spine surgery may have exacerbated the myelopathy in one of the patients. Cervical myelopathy complicating idiopathic dystonia must be distinguished from other causes of neurological deterioration, since it may be improved by appropriate neurosurgical treatment.

Adult↗
PubMed1987

Microcomputer stereotactic atlas.

A stereotactic atlas to determine thalamic target sites has been incorporated into a microcomputer. Variability studies of the thalamus with mean and standard deviations of nuclear borders are depicted graphically for overlay onto operative images. Internal landmarks traditionally used to reference target points for functional stereotaxis may be determined by conventional ventriculography or derived from magnetic resonance scans. Modeling of polyline vertices established from gray scale contour mapping and atlas reconstructions further enhance the spatial understanding of relationships to midline structures. Computer integration of anatomic reference points, graphically depicted images and stereotactic atlas data into head frame coordinates can be accomplished. This method is consistent with established stereotactic techniques and allows the visual conceptualization of imaged and graphic data for functional stereotaxis.

Brain↗
PubMed1984

Diagnosis and repair of malfunctions of implanted central nervous system stimulators.

Neurostimulator malfunctions must be located and repaired if patients are to receive maximum benefit from central nervous system stimulation. This report lists the problems encountered with the stimulators from four manufacturers. Procedures for locating the source of malfunctions are discussed in some detail.

Central Nervous System Diseases↗
PubMed1983

Three-dimensional stereotactic anatomy of the human trigeminal nerve nuclear complex.

The trigeminal nuclear complex and its spinal tract extend throughout the greater part of the brain-stem and at medullary levels form the target site for producing stereotactic lesions. This paper describes a method for three-dimensional drawings of this nuclear complex. A stereotactic atlas of the human brain-stem and cerebellar nuclei has formed the data base. The two-dimensional composite transverse sections, at 1-mm intervals have been digitized using an X-Y coordinate plotting microscope. Computer programs have been written to generate drawings of a single transverse hemisection as well as regeneration of the opposite hemibrain-stem section. Specific programs were used to reconstruct serial transverse section outlines and incorporate the trigeminal nuclear complex with and without hidden line removal techniques and colour graphic display facilities. Rotation about the x, y and z axes was possible and permits any view of the reconstructed specimen to be computer-generated. A further program for reconstructing structures as stereopairs is presented.

Brain Mapping↗