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.

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.

Versatile digital data logger: storage of gastrointestinal motility data.

An inexpensive four-channel data logger for recording gastrointestinal potentials is described. A 512 K bytes memory and a sampling speed of 1.25 Hz per channel is adequate for these potentials and permits recordings for up to 27 hours. The small size and light weight allow the device to be carried in a pocket so that recordings can be made while the subject is freely ambulatory. A separate replay unit allows the data stored in the data logger to be presented to a chart recorder or to an interface card in a PC AT. This interface, a Microsoft C vers 5.0 program and the computer display the data as single frames or scrolled, expanded or condensed on either the time or amplitude axis. From the computer the data can be written to a printer and displayed as a chart or to an ASCII format file which can be used for analysis with statistical packages. Examples of recordings from both man and dog are illustrated and the analogue recorded data are compared with data digitally recorded. It is suggested that the data logger has many applications where long-term slow potential changes must be recorded under specially difficult conditions.

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.

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.

Spinal cord stimulation and the relief of chronic pain.

Twenty six patients who had received spinal cord stimulation for chronic pain were evaluated by videotaped structured interviews with staff not directly involved in the patients' care. In addition estimates of pain relief were obtained from clinicians involved in the patients' care and from close relatives and friends. Information about lifestyles and drug usage was also collected and correlated with pain relief. At the time of the interviews half of the patients were receiving 50% or better relief of their pain.

In vivo nuclear magnetic resonance spectroscopy of a transplanted brain tumour.

In vivo nuclear magnetic resonance 31P spectroscopy was used to demonstrate different patterns of high energy phosphate metabolism in a group of malignant tumours of glial origin. In some of the more malignant tumours a decrease in adenylate energy charge was found. This was associated with a decline in phosphocreatine and an increase in sugar phosphate and inorganic phosphorus.

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.

Determination of cerebral blood flow with the EMI CT scanner.

Cerebral blood flow (CBF) detemination were made in seven baboons and two patients with the EMI CT dedicated head scanner. The method for determining the CBF was tested and measurements were made during physiological states elicited by changes in pCO2 and depth of anaesthesia. The method has a number of advantages, particularly for assessing CBF responses to pCO2 changes.

Solar-powered ventilator alarm.

A ventilator alarm device is described with some unique features. It has a very low current consumption. This allows prolonged operation from small batteries which may be recharged from the ambient light in the room. The device is automatically activated and de-activated by the pressure wave from the ventilator. No external switches or other controls are necessary. The very small size means that the device can be directly attached to a ventilator 'in line' with the ventilator circuit. There are no tubing connexions between the ventilator and the alarm device and no separate shelf-space is required.

Results of the use of a new water-soluble contrast medium (metrizamide) in the posterior fossa of the baboon.

An investigation was made of the use of a new water-soluble contrast material (metrizamide) for posterior-fossa radiography in the baboon. The experiments showed that the concentration of metrizamide needed to produce adequate radiographs from sub-occipital injections into the posterior fossa always produced generalized seizures. Intraventricular injection produced excellent radiographs from metrizamide concentrations, which did not result in either clinical or EEG seizure activity. Seizures, when they occurred, were easily controlled with pentobarbitone and phenytoin. In all the experiments, ECG changes were found, which disappeared after some hours.

Sensory innervation of baboon muscle spindles.

The number and distribution of primary and secondary sensory endings has been studied in 52 de-efferentated baboon muscle spindles and the axon diameters of the afferent fibres innervating these endings have been measured. Each spindle contained a single primary sensory ending; most of these endings were supplied by a single afferent nerve fibre. Each primary sensory ending consisted of a multi-branched network distributed on both nuclear bag and nuclear chain fibres. Beaded sensory terminals were prominent in the central part of the ending. Eighty one secondary endings were found in 45 spindles (87% of the number of spindles remained). Of these endings, 70% were found in the S1 position, 25% in the S2 position and 4% in the S3 location. The afferent axons supplying the most equatorial of these endings were of thicker mean diameter than those supplying the most polar endings. In addition, the juxta-equatorial secondary endings were similar in form, although less regularly organized than the primary endings. The more polar secondary endings rarely fromed terminal sensory enlargements and usually took the form of a fine spray of unmyelinated branches. A non-parametric statistical comparison of physiological and anatomical data in baboon spindles has suggested that the demarcation criteria for separation of primary and secondary spindle afferents, using conduction velocity, should be modified. It is suggested that afferent fibres of conduction velocity less than 60 m/sec should be classified as secondary afferents, and fibres of conduction velocity greater than 72 m/sec should be classified as primary afferents.

Muscle spindle afferent studies in the baboon.

1. The muscle spindle afferent conduction velocity and response to muscle twitch and stretch in young baboons has been recorded in order to find a conduction velocity that can be used to separate primary and secondary afferents.2. A number of the features of the response of the spindle afferents to stretch were examined. It was found that none could distinguish between primary and secondary afferents with greater certainty than the conduction velocity.3. Spindle afferents with conduction velocities below 50 m/sec can be classified as secondary and those with conduction velocities above 68 m/sec can be classified as primary with a reasonable degree of certainty.4. The spindle afferents with conduction velocities between 51 and 67 m/sec are most likely not a separate intermediate group but represent a region of overlap between the two groups.5. Comparisons of the difference between the response of primary and secondary afferents to overstretch suggested a mechanism to explain the saturation of the primary afferent response at frequencies far below those at which it is capable of firing.

Thresholds of cortical activation of baboon alpha and gamma-motoneurones during halothane anaesthesia.

1. In the halothane anaesthetized baboon the threshold for cortically elicited primary and secondary spindle afferent discharge was compared to the threshold at the ;best point' for a cortically elicited tibialis anticus tension change.2. The cortical threshold for eliciting a tension change was greater than the cortical threshold for eliciting spindle afferent discharge for some afferents and less for other afferents.3. The pattern of cortically elicited spindle afferent discharge during muscle stretch suggested static gamma-motoneurone activation. No convincing evidence of dynamic gamma-motoneurone activation was seen.4. Inhibition of spindle afferent discharge was occasionally found and the ;best point' was the same as the cortical ;best point' for eliciting monosynaptic alpha-motoneurone activity. This result suggested that the cortical projections which inhibit the pre-existent activity of static gamma-motoneurones are in a close anatomical relation to those cortical projections which elicit activity of alpha- and static gamma-motoneurones.

The response to stretch of muscle spindle afferents of baboon's tibialis anticus and the effect of fusimotor stimulation.

1. Systematic studies of the response of baboon's tibialis anticus muscle spindles to stretch were undertaken. Most of the spindle afferents studied had conduction velocities between 72 and 78 m/sec with a range from 39 to 93 m/sec. There was no clear bimodality in the histogram of the conduction velocity. Measurements were made of the axon diameters of the nerve to tibialis anticus. The largest number of the larger axons had diameters from 11 to 13 mu. The largest axon diameter measured 17 mu and there were very few of these.2. The dynamic index for any given afferent tended to be greater for the more rapidly conducting afferents and lower for the more slowly conducting afferents. However, a statistically significant regression line of this relationship could only be drawn for a stretch velocity of 64 mm/sec.3. The spindle afferent response to stretch was studied from different muscle lengths. It was found that the velocity sensitive portion of the response to phasic stretch decreased when the stretch extended up to or beyond the maximum physiological length of the muscle.4. Dynamic and static fusimotor fibres were isolated. The response of the spindle afferent to stretch, while the dynamic fusimotor fibre was being stimulated, was the same as that reported for the cat by P. B. C. Matthews (1962). During static fusimotor stimulation the response of the spindle afferent to stretch was usually like that reported for the cat. In a single case, however, static fusimotor stimulation resulted in a lowering of the peak frequency of the response of the spindle afferent to the phasic portion of stretch.