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Autonomic Dysreflexia

Prevention of AD During Anorectal Procedures

The second most common cause of AD is pain or irritation within the colorectal area. Constipation, hemorrhoids, and anal fissures, all frequently observed in patients with SCI, contribute to episodes of AD (Teasell et al. 2000McGuire & Kumar 1986Hawkins et al. 1994Teichman et al. 1998). Digital stimulation, a common component of bowel routines in individuals with SCI, can also trigger AD (Furusawa et al. 2007), especially in the presence of hemorrhoids and/or anal fissures. In addition, rectosigmoid distension and anal manipulation are common iatrogenic triggers of AD (Cosman & Vu 2005).

Author Year; Country
Research Design
Sample Size
Methods Outcome
Cosman & Vu 2005; USA




Population: Al l subjects with complete SCI; age 46-49 years; 15-25 years post-injury; level of injury: C4-T1

Treatment: intersphincteric anal block with either: a) 300 mg 1% lidocaine or b) normal saline (placebo) before sigmoidoscopy or anoscopic hemorrhoid ligation procedure.

Outcome Measures: blood pressure.

1.   The mean maximal systolic blood pressure increase for the lidocaine group (22(14) mmHg) was lower than the placebo group (47(31) mmHg) suggesting that AD risk was reduced with lidocaine.
Effect Sizes: Forest plot of standardized mean differences (SMD ± 95%C.I.) as calculated from pre- and post-intervention data

Cosman et al. 2002; USA




Population: 45 patients (44 male, 1 female) with chronic, complete SCI, injury level of T6 or above, undergoing anoscopy and/or flexible sigmoidoscopies.

Treatment: a) 2% topical lidocaine jelly (n=18) or; b) nonmedicated lubricant (control, n=32) just prior to the procedure.

Outcome Measures: blood pressure.

1.   Topical lidocaine had no significant effect on mean maximal systolic blood pressure (increased 35(25) mmHg in the lidocaine group vs. 45(30) mmHg in the control group).

2.   Greater SBP increase with anoscopic procedure compared to sigmoidoscopic procedures (49(29) vs. 25(20) mmHg, respectively).

Effect Sizes: Forest plot of standardized mean differences (SMD ± 95%C.I.) as calculated from pre- and post-intervention data

Furusawa et al. 2009;





Population: 25 cervical SCI subjects (22 men, 3 women); Level of injury: C4-C7; mean(SD) time post-injury: 23.4(36.4), range 3-172 months.

Treatment: 10mL of 2% Lidocaine treatment group (placebo jelly for control group); both groups then underwent digital bowel stimulation to initiate and augment stool flow.

Outcome Measures: blood pressure; heart rate; symptoms of autonomic dysreflexia.

1.   10 subjects in the control group reported symptoms of AD, compared to 4 patients in the treatment group.

2.   Systolic blood pressure was significantly lower in treatment group, compared to the control.

3.   No significant difference in diastolic blood pressure or heart rate.

Effect Sizes: Forest plot of standardized mean differences (SMD ± 95%C.I.) as calculated from pre- and post-intervention data 


In two small RCTs (n=70) (Cosman & Vu 2005Cosman et al. 2002), investigators compared the effect of topical local anesthesia of the anorectal area to a nonmedicated control gel for the prevention of AD during anorectal procedures. They found that anoscopy, which involves stretching the anal sphincters, was a more potent stimulus for AD than flexible sigmoidoscopy, which involves gaseous distention of the rectosigmoid. In one randomized, double-blind, placebo-controlled trial, AD was not abolished by topical lidocaine in the rectum during the anorectal procedure (Cosman et al. 2002). However, the same investigators in a later RCT demonstrated that intersphincteric anal block with lidocaine was effective in limiting anorectal procedure-associated AD (Cosman & Vu 2005). In one small RCT (n=25) (Furusawa et al. 2009) investigators found that topical lidocaine applied to the rectum prior to digital bowel stimulation significantly reduced systolic blood pressure and reports of AD over the duration of the bowel program when compared to the control group.


There is level 1 evidence (from 1 RCT: Cosman & Vu 2005) that lidocaine anal block significantly limits the AD response in susceptible patients undergoing anorectal procedures.

There is level 1 evidence (from 1 RCT: Cosman et al. 2002) that topical lidocaine does not limit or prevent AD in susceptible patients during anorectal procedures.

There is level 1 evidence (from 1 RCT: Furusawa et al. 2009) that topical lidocaine may help to prevent AD during gentle bowel stimulation.

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