Richard Cohen

Royal Free London NHS Foundation Trust, Londinium, England, United Kingdom

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Publications (14)94.12 Total impact

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    ABSTRACT: To investigate the relevance of two dimensional (2D) endoanal ultrasonic (EAUS) assessment of anal sphincter and puborectalis morphology by comparison to functional measures derived from patient symptoms and anorectal physiology.
    Journal of Medical Ultrasound 10/2015; DOI:10.1016/j.jmu.2015.08.004
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    ABSTRACT: Systemic sclerosis (SSc) is a multi-system disorder of unknown aetiology leading to the deposition of excessive connective tissue in the skin, blood vessels and internal organs. Gastrointestinal involvement is present in 90% of cases and the prevalence of faecal incontinence (FI) is 38%. This study comprises the largest case series assessing the efficacy of sacral nerve stimulation (SNS) treatment for incontinence in this patient group. A retrospective analysis on prospectively collected data was performed on all SSc patients from our two centres who had undergone SNS for FI. Ten female patients of mean age of 54 (37-72) years had temporary SNS performed. The mean duration of faecal incontinence was 13 (2-25) years. All had passive faecal incontinence. Each patient had pre-procedure ano-rectal physiology and endoanal ultrasound documenting internal sphincter atrophy/fragmentation or reduced anal resting pressure. Overall there was no statistically significant difference (p=0.57) in the total Wexner incontinence scores before (mean 15.1±SD 2.6) and during temporary SNS procedures (mean 13.1±SD 3.6). Two patients with a significant improvement went on to have permanent SNS with only one achieving a favourable outcome at one year. The study showed that SNS failed to reduce episodes of leakage in nine out of ten patients with systemic sclerosis affected with incontinence. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Colorectal Disease 04/2015; 17(10). DOI:10.1111/codi.12969 · 2.35 Impact Factor
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    ABSTRACT: Fecal incontinence (FI) occurs in 20% of diabetes mellitus (DM) patients. We suspect that gut specific biomarkers would correlate with symptoms of incontinence. The recto-anal inhibitory reflex (RAIR) is an enteric anorectal reflex that reflects the integrity of mechanisms in the physiology of fecal continence. We hypothesised that diabetic patients with FI, not constipation, have prolongation of the RAIR and altered Gut specific autonomic tone. Prospective case matched study recruited: 31 type-I DM (19 FI and 12 constipation); 42 type-II DM (26 FI and 16 constipation); 21 controls were studied. Patients underwent the following assessments: cardiovagal autonomic tone [Modified Mayo CASS score], rectal mucosal blood flow [RMBF] (assessment of gut specific autonomic tone) and RAIR. Three phases of the RAIR and the amplitude of maximal reflex relaxation were compared between groups. All subjects completed symptom scores for FI and constipation. RAIR recovery time back to resting pressure was slower in diabetics with FI than controls (8.7 vs 5.0, p<0.01) and was an independent variable correlating with symptoms of faecal incontinence (p<0.05). RAIR recovery time correlated with RMBF (r=0.58, p=0.04). Parameters of the RAIR correlated with anorectal symptoms of faecal incontinence and was associated with gut specific autonomic neuropathy. This article is protected by copyright. All rights reserved.
    Journal of Digestive Diseases 03/2015; 16(6). DOI:10.1111/1751-2980.12244 · 1.96 Impact Factor
  • Richard Cohen · Justin Stebbing · Alastair Windsor ·

    Future Oncology 09/2009; 5(7):915-7. DOI:10.2217/fon.09.63 · 2.48 Impact Factor
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    ABSTRACT: To validate proposed magnetic resonance (MR) imaging features of Crohn disease activity against a histopathologic reference. Ethical permission was given by the University College London hospital ethics committee, and informed written consent was obtained from all participants. Preoperative MR imaging was performed in 18 consecutive patients with Crohn disease undergoing elective small-bowel resection. The Harvey-Bradshaw index, the C-reactive protein level, and disease chronicity were recorded. The resected bowel was retrospectively identified at preoperative MR imaging, and wall thickness, mural and lymph node/cerebrospinal fluid (CSF) signal intensity ratios on T2-weighted fat-saturated images, gadolinium-based contrast material uptake, enhancement pattern, and mesenteric signal intensity on T2-weighted fat-saturated images were recorded. Precise histologic matching was achieved by imaging the ex vivo surgical specimens. Histopathologic grading of acute inflammation with the acute inflammatory score (AIS) (on the basis of mucosal ulceration, edema, and quantity and depth of neutrophilic infiltration) and the degree of fibrostenosis was performed at each site, and results were compared with MR imaging features. Data were analyzed by using linear regression with robust standard errors of the estimate. AIS was positively correlated with mural thickness and mural/CSF signal intensity ratio on T2-weighted fat-saturated images (P < .001 and P = .003, respectively) but not with mural enhancement at 30 and 70 seconds (P = .50 and P = .73, respectively). AIS was higher with layered mural enhancement (P < .001), a pattern also commonly associated with coexisting fibrostenosis (75%). Mural/CSF signal intensity ratio on T2-weighted fat-saturated images was higher in histologically edematous bowel than in nonedematous bowel (P = .04). There was no correlation between any lymph node characteristic and AIS. Increasing mural thickness, high mural signal intensity on T2-weighted fat-saturated images, and a layered pattern of enhancement reflect histologic features of acute small-bowel inflammation in Crohn disease.
    Radiology 07/2009; 252(3):712-20. DOI:10.1148/radiol.2523082167 · 6.87 Impact Factor

  • Gastroenterology 05/2009; 136(5). DOI:10.1016/S0016-5085(09)60451-0 · 16.72 Impact Factor

  • Gastroenterology 05/2009; 136(5). DOI:10.1016/S0016-5085(09)60983-5 · 16.72 Impact Factor
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    ABSTRACT: To determine mural perfusion dynamics in Crohn disease by using dynamic contrast material-enhanced magnetic resonance (MR) imaging and to correlate these with histopathologic markers of inflammation and angiogenesis. Ethical permission was given by the University College London Hospital ethics committee, and informed consent was obtained from all participants. Eleven consecutive patients with Crohn disease (eight female patients, three men; mean age, 39.5 years; range, 16.4-66.6 years) undergoing elective small-bowel resection were recruited between July 2006 and December 2007. Harvey-Bradshaw index, C-reactive protein (CRP) level, and disease chronicity were recorded. Preoperatively, dynamic contrast-enhanced MR imaging was performed through the section of bowel destined for resection, and slope of enhancement, time to maximum enhancement, enhancement ratio, the volume transfer coefficient K(trans), and the extracellular volume fraction v(e) were calculated for the affected segment. Ex vivo surgical specimens were imaged to facilitate imaging-pathologic correlation. Histopathologic sampling of the specimen was performed through the imaged tissue, and microvascular density (MVD) was determined, together with acute and chronic inflammation scores. Correlations between clinical, MR imaging, and histopathologic data were made by using the Kendall rank correlation and linear regression. Disease chronicity was positively correlated with enhancement ratio (correlation coefficient, 0.82; P = .002). Slope of enhancement demonstrated a significant negative correlation with MVD (correlation coefficient, -0.86; P < .001). There was a negative correlation between CRP level and slope of enhancement (correlation coefficient, -0.77; P = .006). Neither acute nor chronic inflammation score correlated with any other parameter. Certain MR imaging-derived mural hemodynamic parameters correlate with disease chronicity and angiogenesis in Crohn disease, but not with histologic and clinical markers of inflammation. Data support the working hypothesis that microvessel permeability increases with disease chronicity and that tissue MVD is actually inversely related to mural blood flow.
    Radiology 03/2009; 251(2):369-79. DOI:10.1148/radiol.2512081292 · 6.87 Impact Factor
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    ABSTRACT: The vascular type of Ehlers-Danlos syndrome, type IV, is associated with severe complications, including arterial rupture and visceral perforation. However, to our knowledge, there has been only one previous report of splenic rupture caused by a spontaneous hemorrhage in type IV Ehlers-Danlos syndrome. We report another case of this uncommon complication, occurring in a 35-year-old woman who presented after the sudden onset of acute abdominal pain. Patients should be stabilized quickly in the intensive care unit and the most timesaving surgical techniques used. Moreover, tissues must be handled with great care intraoperatively in view of their extreme fragility. Despite prompt and appropriate treatment, the prognosis is often dismal.
    Surgery Today 02/2009; 39(1):52-4. DOI:10.1007/s00595-007-3782-3 · 1.53 Impact Factor
  • Richard Cohen · Alastair Windsor · Kumaran Thiruppathy ·
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    ABSTRACT: Pearls and PitfallsRectovaginal fistulas cause an underappreciated morbidity to affected women.The incidence of these fistulas in underdeveloped countries is underappreciated.The most common causes are traumatic obstetrical injuries during childbirth, postoperative causes, radiation therapy, invasive malignancies, and diverticulitis.Rectovaginal fistulas are classified as simple or complex and involve either the upper, middle, or lower third of the rectovaginal septum.Etiology and techniques of repair depend on location of the fistula.Lower third rectovaginal fistulas are usually repaired by a perineal approach, either transanal or transvaginal.Upper third rectovaginal fistulas are approached trans-abdominally.Approach to middle third rectovaginal fistulas depends on etiology; some can be repaired via a perineal approach, others require a trans-abdominal approach.Complex rectovaginal fistulas often require temporary or permanent proximal colonic diversion. ...
    General Surgery, 01/2009: pages 809-818; , ISBN: 978-1-84628-832-6

  • Future Oncology 01/2009; 4(6):741-4. DOI:10.2217/14796694.4.6.741 · 2.48 Impact Factor

  • Gastroenterology 04/2008; 134(4). DOI:10.1016/S0016-5085(08)61528-0 · 16.72 Impact Factor

  • Gastroenterology 04/2008; 134(4). DOI:10.1016/S0016-5085(08)62705-5 · 16.72 Impact Factor
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    ABSTRACT: Preoperative MRI of fistula in ano is becoming more common. This prospective study aimed to determine if a significant difference occurred in interpretation between one expert and one novice observer and to assess inter- and intraobserver agreement after both observers underwent a period of directed education. SUBJECTS AND METHODS. An outcome-derived reference standard was defined in 100 patients with suspected fistula in ano via a combination of preoperative MRI, surgical findings, and clinical outcome. The performances of a single expert and a single novice interpreter were compared with this reference standard both before and after a period of directed education, and inter- and intraobserver agreement was determined. Initially the expert correctly classified significantly more fistulas than the novice (85% vs 63%, p = 0.024), but after directed education there was no significant difference, with good agreement for both the classification of the primary track (kappa = 0.71) and identification of extensions (k = 0.61). Intraobserver agreement was very good for the expert (kappa = 0.92) and novice (kappa = 0.88) for classification of the primary track and good (kappa = 0.64 and 0.74, respectively) for identification of extensions. The diagnostic accuracy for fistula in ano classification using MRI was significantly higher for one expert than for one novice, though this was rectified by a short period of directed education.
    American Journal of Roentgenology 08/2004; 183(1):135-40. DOI:10.2214/ajr.183.1.1830135 · 2.73 Impact Factor