Secondary colonic stent insertion in acute large bowel obstruction following primary stent failure.

INTRODUCTION: Colonic stent insertion has been shown to be an effective treatment for patients with acute large bowel obstruction, either as a bridge to surgery or as definitive treatment. However, little is known of the role of secondary stent insertion following primary stent failure in patients considered inappropriate or high risk for emergency surgery. METHODS: Fourteen patients presenting with acute large bowel obstruction who had previously been treated with colonic stent insertion were studied. All underwent attempted placement of a secondary stent. RESULTS: Technical deployment of the stent was accomplished in 12 patients (86%) but only 9 (64%) achieved clinical decompression. Successful deployment and clinical decompression of a secondary stent was associated with older age (p=0.038). Sex, pathology, site of obstruction, duration of efficacy of initial stent and cause of primary failure were unrelated to outcome. No procedure related morbidity or mortality was noted following repeated intervention. CONCLUSIONS: Secondary colonic stent insertion appears an effective, safe treatment in the majority of patients presenting with acute large bowel obstruction following failure of a primary stent.

Gastrointestinal clear cell sarcoma-like tumour of the ascending colon.

INTRODUCTION: A clear cell sarcoma-like gastrointestinal tumour (CCSLGT) is a rare malignant soft tissue sarcoma. In the literature, they are sometimes referred to as malignant gastrointestinal neuroectodermal tumours, clear cell sarcomas or osteoclast rich tumours of the gastrointestinal tract. CASE HISTORY: We present a case of a CCSLGT arising from the ascending colon of a previously well 22-year-old man presenting with abdominal pain and anaemia. Computed tomography of the abdomen and pelvis showed a 7 cm irregular mass in the right flank that seemed to emerge from the proximal transverse colon. A laparoscopic right hemicolectomy was undertaken to remove the mass. Microscopic pathological examination of the specimen revealed sections of spindle to oval cells with monomorphic nuclei and scant cytoplasm. The cells were arranged in a striking perivascular growth pattern with microcytic breakdown and pseudopapillary formation. Immunohistochemistry analysis showed that the tumour cells removed expressed S100 protein, and were negative for smooth muscle actin, desmin, CD34, CD117, DOG1, HMB-45 and MNF116. Additionally, cytogenetic testing identified EWSR1 gene rearrangement, which was observed by interphase fluorescence in situ hybridisation. CONCLUSIONS: A complex tumour, a CCSLGT can be thought of in simple terms as a gastrointestinal tract tumour that is S100 protein positive, osteoclast rich, HMB-45 negative and compromises a t(12;22)(q13;q12) gene translocation. These simplified CCSLGT characteristics seem to be described and classified under different aliases in the literature, which makes it difficult to accurately predict the appropriate diagnostic and therapeutic modality required to provide the best clinical care. Given that this case report describes the fourth CCSLGT of primary colonic origins, it may aid future targeted therapies as well as offering epidemiological evidence on prevalence and prognosis.

Evacuation proctography: a reappraisal of normal variability.

AIM: Interpretation of evacuation proctography (EP) images is reliant on robust normative data. Previous studies of EP in asymptomatic subjects have been methodologically limited. The aim of this study was to provide parameters of normality for both genders using EP. METHOD: Evacuation proctography was prospectively performed on 46 healthy volunteers (28 women). Proctograms were independently analysed by two reviewers. All established and some new variables of defaecatory structure and function were assessed objectively: anorectal dimensions; anorectal angle changes; evacuation time; percentage contrast evacuated; and incidence of rectal wall morphological 'abnormalities'. RESULTS: Normal ranges were calculated for all main variables. Mean end-evacuation time was 88 s (95% CI: 63-113) in male subjects and 128 s (95% CI: 98-158) in female subjects; percentage contrast evacuated was 71% (95% CI: 63-80) in male subjects and 65% (95% CI: 58-72) in female subjects. Twenty-six (93%) of 28 female subjects had a rectocoele with a mean depth of 2.5 cm (upper limit = 3.9 cm). Recto-rectal intussusception was found in nine subjects (approximately 20% of both genders); however, recto-anal intussusception was not observed. Only rectal diameter differed significantly between genders. Qualitatively, three patterns of evacuation were present. CONCLUSION: This study defines normal ranges for anorectal dimensions and parameters of emptying, as well as the incidence and characteristics of rectal-wall 'abnormalities' observed or derived from EP. These ranges can be applied clinically for subsequent disease comparison.

The effects of age and childbirth on anal sphincter function and morphology in 999 symptomatic female patients with colorectal dysfunction.

BACKGROUND AND OBJECTIVES: Conflicting data exist on the contributions of advancing age and childbirth on the structure and function of the anal sphincter. This study aimed to examine the relative contributions of age and childbirth in a large cohort of women referred for investigation of symptoms of colorectal dysfunction (fecal incontinence and constipation). SETTING: This study was conducted at a specialist surgical colorectal investigation unit in a university teaching hospital. PATIENTS: Retrospective analysis was performed on prospectively collected demographic, symptom profile, and physiologic data from 3686 female patients. Strict exclusion criteria were applied, leaving 999 patients for univariate, multivariate, and logistic statistical modeling. MAIN OUTCOME MEASURES: The effects of independent variables alone and in combination on anal sphincter pressures (resting and squeeze increment) and the presence of sphincter defects (internal and external) were expressed as regression coefficients and odds ratios. RESULTS: Median age was 42 years (range, 16-88), and parity was 2 (range, 0-11); 16% were nulliparous. Three hundred sixty patients had fecal incontinence, 352 had constipation, and 287 had combined symptoms. Anal resting tone decreased with age by 0.66 cm H2O per year, and by 4.3 cm H2O per birth, and was associated with both internal and external anal sphincter defects (p = 0.0001 for both). Squeeze increment pressures decreased by 0.3 cm H2O per year, and by 3.8 cm H2O per birth; decreased pressures were, however, only significantly associated with external anal sphincter defects (p = 0.0001) as a result of childbirth. Cesarean delivery was protective against both reduced anal pressures and sphincter defects. Pudendal nerve terminal motor latencies increased bilaterally with age and with vaginal delivery; the impact of both was greater on the left nerve. Rectal sensation was unaffected by age or parity. CONCLUSIONS: Aging predominantly affects anal resting pressures; childbirth, particularly instrumental delivery, is detrimental to the structure and function of the external sphincter.

Short-term outcome following percutaneous tibial nerve stimulation for faecal incontinence: a single-centre prospective study.

AIM: Percutaneous tibial nerve stimulation (PTNS) is increasingly being used as a treatment for faecal incontinence (FI). The evidence for its efficacy is limited to a few studies involving small numbers of patients. The aim of the study was to assess the efficacy of PTNS in patients with urge, passive and mixed FI. METHOD: A prospective cohort of 100 patients with FI was studied. Continence scores were determined before treatment and following 12 sessions of PTNS using a validated questionnaire [Cleveland Clinic Florida (CCF)-FI score]. The deferment time and average number of weekly incontinence episodes before and after 12 sessions of treatment were estimated from a bowel dairy kept by the patient. Quality of life was assessed prior to and on completion of 12 sessions of PTNS using a validated questionnaire [Rockwood Faecal Incontinence Quality of Life (QoL)]. RESULTS: One hundred patients (88 women) of median age of 57 years were included. Patients with urge FI (n=25) and mixed FI (n=60) demonstrated a statistically significant improvement in the mean CCF-FI score (11.0 ± 4.1 to 8.3 ± 4.8 and 12.8 ± 3.7 to 9.1 ± 4.4) with an associated improvement in the QoL score. This effect was not observed in patients with purely passive FI (n=15). CONCLUSION: The study demonstrates that PTNS benefits patients with urge and mixed FI, at least in the short term.

Combined vertical reduction rectoplasty and sacral nerve stimulation for rectal evacuatory dysfunction and faecal incontinence associated with previous anorectal malformation.

Functional outcomes following surgery for anorectal malformation are variable, with many children experiencing persisting anorectal dysfunction. We describe a 34-year-old female with previous vestibular fistula who experienced lifelong rectal evacuatory dysfunction and faecal incontinence; she was treated in a two stage process producing efficient defecation and almost total continence.

Stimulus timing by people with Parkinson's disease.

Previous literature suggests that Parkinson's disease is marked by deficits in timed behaviour. However, the majority of studies of central timing mechanisms in patients with Parkinson's disease have used timing tasks with a motor component. Since the motor abnormalities are a defining feature of the condition, the status of timing in Parkinson's disease remains uncertain. Data are reported from patients with mild to moderate Parkinson's disease (both on and off medication) and age- and IQ-matched controls on a range of stimulus timing tasks without counting. Tasks used were temporal generalization, bisection, threshold determination, verbal estimation, and a memory for duration task. Performance of patients was generally "normal" on all tasks, but significant differences from performance of controls were found on the memory for duration task. Among the "normal" effects noted were arithmetic mean bisection, asymmetric temporal generalization gradients, and subjective shortening on the memory for duration task. The results suggest (a) that some previous reports of timing "deficits" in Parkinson's patients were possibly due to the use of tasks requiring a timed manual response and (b) small differences between patients and controls may be found on tasks where two stimuli are presented on each trial, whether patients are on medication or off it.

The contribution of non-ocular response inhibition to visual inhibition of return.

Inhibition of return (IOR) refers to slowed responses to targets presented at the same location as a preceding stimulus. IOR is typically investigated using a cue-target design, in which subjects respond only to the second stimulus of a pair. In such tasks, the measurement of 'true' IOR may be confounded by the effect of non-ocular response inhibition, because the participant must suppress any tendency to respond (e.g. key press) to the first stimulus. This confound may be eliminated using a target-target design, in which responses are made to both stimuli. We assessed the contribution of non-ocular response inhibition to visual IOR, measured in a cue-target task, by testing participants on both cue-target and target-target detection tasks, with identical timings and stimuli. Significant IOR was obtained in both tasks but, at a stimulus onset asynchrony (SOA) of 1400 ms, IOR magnitude was significantly greater in the cue-target condition than in the target-target condition. However, at an SOA of 1800 ms, there was no significant difference in the magnitude of IOR between the two tasks. Thus, a proportion of the total IOR effect observed in visual cue-target tasks can be attributed to non-ocular response inhibition, but this process appears to decay more rapidly than does 'true' IOR, having dissipated by 1800 ms following cue onset.

Tactile inhibition of return: non-ocular response inhibition and mode of response.

Inhibition of return (IOR) refers to the slowing of responses to stimuli presented at the same location as a preceding cue. However, the cue-target paradigm used in most previous studies may have overestimated the contribution of eye movement programming to IOR, due to the existence of manual response inhibition effects. This confound can be circumvented by using a target-target paradigm in which participants respond to all stimuli. Here, we compared IOR magnitude from tactile cue-target and target-target tasks involving identical interstimulus intervals of 1,400 and 1,800 ms. Reaction times were measured using a foot pedal toe-lift response and a vocal response. Tactile IOR was observed using both modes of response, demonstrating IOR for the first time using a non-spatial, vocal response. Moreover, IOR effects were significantly smaller in target-target compared to cue-target conditions, thereby confirming the existence of the response inhibition confound.

Effects of a moderate dose of alcohol on simulated laparoscopic surgical performance.

BACKGROUND: In medicine, there is no professional regulation of the drinking of alcohol, nor a body of experimental evidence on which such regulation might be based. Here we report the acute and longer-term ("hangover") effects of a moderate dose of alcohol on performance, as assessed objectively on a laparoscopic surgical simulator. METHODS: In a single-blind, experimental study, medical student subjects were assigned randomly to an alcohol (1.05 mg/kg) or a placebo condition (n = 14 in each). The effects of alcohol on performance on the MIST Virtual Reality surgical simulator were examined 60-90 min and 600-630 min (after a night's sleep) following its ingestion. Measures of the number of errors, time taken, hand movement economy, and excessive use of diathermy were recorded. RESULTS: On each measure, performance was significantly impaired 60-90 min following alcohol ingestion, but there was no hangover effect 600-630 min later, following a night's sleep. This impairment could not be attributed to between-group differences in either predrink performance, expertise or estimated sleep duration during the night preceding the experimental session. CONCLUSIONS: Simulated surgical performance is impaired severely when estimated blood alcohol concentration (BAC) is just above the UK legal limit for driving. These results contribute new, objective and quantitative evidence to the current debate about the use and misuse of alcohol within the medical profession.

A sensorimotor theory of temporal tracking and beat induction.

In this paper, we develop a theory of the neurobiological basis of temporal tracking and beat induction as a form of sensory-guided action. We propose three principal components for the neurological architecture of temporal tracking: (1) the central auditory system, which represents the temporal information in the input signal in the form of a modulation power spectrum; (2) the musculoskeletal system, which carries out the action and (3) a controller, in the form of a parieto-cerebellar-frontal loop, which carries out the synchronisation between input and output by means of an internal model of the musculoskeletal dynamics. The theory is implemented in the form of a computational algorithm which takes sound samples as input and synchronises a simple linear mass-spring-damper system to simulate audio-motor synchronisation. The model may be applied to both the tracking of isochronous click sequences and beat induction in rhythmic music or speech, and also accounts for the approximate Weberian property of timing.

Human locognosic acuity on the arm varies with explicit and implicit manipulations of attention: implications for interpreting elevated tactile acuity on an amputation stump.

In Experiment 1, normal subjects' ability to localize tactile stimuli (locognosia) delivered to the upper arm was significantly higher when they were instructed explicitly to direct their attention selectively to that segment than when they were instructed explicitly to distribute their attention across the whole arm. This elevation of acuity was eliminated when subjects' attentional resources were divided by superimposition of an effortful, secondary task during stimulation. In Experiment 2, in the absence of explicit attentional instruction, subjects' locognosic acuity on one of three arm segments was significantly higher when stimulation of that segment was 2.5 times more probable than that of stimulation of the other two segments. We surmise that the attentional mechanisms responsible for such modulations of locognosic acuity in normal subjects may contribute to the elevated sensory acuity observed on the stumps of amputees.

Proprioceptive regulation of voluntary ankle movements, demonstrated using muscle vibration, is impaired by Parkinson's disease.

OBJECTIVE: To test the hypothesis that the proprioceptive regulation of voluntary movement is disturbed by Parkinson's disease, the effects of experimental stimulation of proprioceptors, using muscle vibration, on the trajectories of voluntary dorsiflexion movements of the ankle joint were compared between parkinsonian and control subjects. METHODS: Twenty one patients with Parkinson's disease, on routine medication (levodopa in all but one), and an equal number of age matched, neurologically intact controls, were trained initially to make reproducible ankle dorsiflexion movements (20 degrees amplitude with a velocity of 9.7 degrees /s) following a visual "go" cue while movement trajectories were recorded goniometrically. During 50% of the experimental trials, vibration (105 Hz; 0.7 mm peak to peak) was applied to the Achilles tendon during the ankle movement to stimulate antagonist muscle spindles; vibrated and non-vibrated trials were interspersed randomly. Subjects' performance was assessed by measuring end point position-that is, the ankle angle attained 2 seconds after the visual "go" cue, from averaged (20 trials) trajectories. RESULTS: Statistical analysis of the end point amplitudes of movement showed that, whereas the amplitudes of non-vibrated movements did not differ significantly between patients with Parkinson's disease and controls, antagonist muscle vibration produced a highly significant reduction in the amplitudes of ankle dorsiflexion movements in both the patient and control groups. However, the extent of vibration induced undershooting produced in the patients with Parkinson's disease was significantly less than that in the controls; the mean vibrated/non-vibrated ratios were 0.86 and 0.54 for, respectively, the patient and control groups. CONCLUSIONS: The present finding of a reduction of vibration induced ankle movement errors in parkinsonian patients resembles qualitatively previous observations of wrist movements, and suggests that Parkinson's disease may produce a general impairment of proprioceptive guidance.

Abnormalities of motor timing in Huntington's disease.

The ability of patients with Huntington's disease (HD) and control subjects to produce rhythmic finger tapping movements at target frequencies (1-5 Hz) signalled by auditory cues, and to sustain the tapping tempo following sudden withdrawal of cues, was investigated. HD performance, in both the presence and absence of cues, was characterised by, (i) marked irregularity of instantaneous tapping rates and (ii) a tendency to tap too slowly at higher (3-5 Hz) frequency targets and too rapidly at low target frequencies. Analysis of the variability of inter-tap intervals, during uncued tapping at a target rate of 1.8 Hz, using Wing and Kristofferson's model of motor timing (Wing AM, Kristofferson AB. Percept. Psychophys. 1973; 14: 5-12), indicated disturbances of both hypothetical 'clock' and 'motor implementation' systems in HD.

The accuracy and precision of timing of self-paced, repetitive movements in subjects with Parkinson's disease.

In separate experiments, we studied the temporal accuracy and precision of self-paced, repetitive finger-tapping in two groups of 12 patients with Parkinson's disease and a group of 12 controls matched to the patients with respect to age and general cognitive state. One group (I) of patients was studied initially following 12-15 h abstinence from normal levodopa medication ('off') and again, subsequently, approximately 1 h after ingestion of a single normal dose ('on'). A second group (II) of patients, each of whom had bilaterally asymmetrical neurological signs, was tested using 'worse' and 'better' hands separately. Within each session, subjects were tested repeatedly on a tapping task during which they were required to produce a regular series of self-timed inter-tap intervals, the target duration (550 ms) of which had been established previously during an initial period of tapping in synchrony with the beats of a regular metronome. We employed Wing and Kristofferson's (1973) model of control of motor timing to partition the total variance (TV) about the mean inter-response interval (IRI) produced during the self-paced phase of each run into separate components ['clock' variance (CV) and 'motor-delay' variance (MDV)] attributable to hypothetical 'clock' and 'motor-implementation' processes. Although the mean self-paced IRI of parkinsonian patients was generally shorter than that of controls, only during the 'on' medication condition (Group I) was it significantly so. By comparison with control values, and those observed during the 'on' medication condition, values of TV, CV and MDV in Group I were all significantly higher when subjects were 'off' medication. During the 'on' medication condition, only CV was significantly higher than the control value. In Group II, values of TV, CV and MDV associated with use of the 'worse' hand were all significantly higher than both control values and those associated with use of the 'better' hand. Values of these variables when subjects used the 'better' hand did not, however, differ significantly from control values. The theoretical import of these results is discussed in the light of several important procedural, statistical and computational issues and we conclude that TV, CV, and MDV may all vary significantly as a function of the efficacy of dopaminergic transmission in the basal ganglia.

Generalized versus spouse-specific anger/hostility and men's violence against intimates.

The present study examined the extent to which generalized versus spouse-specific anger/hostility was associated with partner violence in 263 men seeking conjoint marital therapy. Clinic men were classified as nonviolent (NV), moderately violent (MV), and severely violent (SV). A community comparison group of relationship-satisfied, non-violent men (CO) was also included. All clinic men reported higher levels of generalized and spouse-specific anger, spouse-specific aggression/hostility, depressive symptomatology and lower spouse-specific assertiveness than community men. SV men reported higher levels of spouse-specific anger/hostility, relationship discord, depressive symptomatology, and lower general problem-solving ability than NV men. Regression analyses confirmed that spouse-specific anger/hostility, low problem-solving ability, and relationship discord were significant predictors of men's violence. Overall, generalized anger and hostility were not unique predictors of men's violence against intimates.

Effects of alcohol, at two times of day, on EEG-derived indices of physiological arousal.

Effects of alcohol consumption (0.8 ml/kg) on sleep propensity, spectral characteristics of the EEG and self-rated activation in 16 young male subjects, were investigated during sessions at each of two times of day (08.00 and 16.00). Within-session, time-related changes in the pattern of stage-1 sleep occurrence, and of spectral power in different EEG bands indicated that, irrespective of time of day, physiological arousal increased as estimated blood alcohol concentration (BAC) was rising, and decreased as BAC was falling. Subjective activation was reduced by alcohol during both phases of the BAC curve. A pattern of reduced stage-1 sleep occurrence, higher absolute high alpha power and higher ratings of activation suggested that, irrespective of alcohol condition, physiological and subjective arousal was higher during sessions starting at 16.00 than during those starting at 08.00. There were no significant interactions between alcohol and time of day in respect of any dependent variable. However, the degree to which effects reflecting circadian variation may have been masked by effects of limited sleep restriction prior to morning sessions remains unclear. Subjects reported having slept on only 23.5% of occasions when sleep was scored. Comparison of patterns of statistically significant changes in absolute and relative power in different bands indicated that the two indices do not provide exactly equivalent information about changes in the EEG.

Effects of alcohol on the sleep-stage structure of a nap in the afternoon.

The effects of the ingestion of 0.8 ml/kg alcohol on the sleep-stage structure of nap sleep were compared with those of a non-alcoholic drink in 8 young male subjects napping between 14.00 h and 15.00 h. During nights immediately preceding experimental sessions, time to bed and time in bed (hence, sleep duration) were controlled. While not affecting total nap sleep duration, alcohol significantly increased time in stage 4 sleep, primarily at the expense of time in stage 2.