Types of bowel dysfunction
There are two distinct patterns of bowel dysfunction after spinal cord injury (SCI), depending on whether the sacral reflexes have been affected.
(upper motor neuron [UMn] or reflex) lesion
| Conal or cauda equina|
(lower motor neuron [LMn] or flaccid) lesion
|Injury or damage usually at or above T12 vertebral level1||Injury or damage usually L1 vertebral level and below1|
Testing bulbo-anal and sacral reflexes
Identify if the bulbocavernosus (bulbo-anal) reflex is present by:
- applying pressure to the glans penis or clitoris, to see if a palpable and visible contraction of the anal sphincter occurs1
- applying a gentle tug to the urethral catheter to see if a palpable anal response occurs.
Identify if there is sparing of the sacral reflexes by applying a pinprick to the person’s buttock, just lateral to the anus. If there is a visible contraction of the anal sphincter, this shows that the sacral reflexes have been spared.1
Common issues with defecation
- Difficulty with evacuation
- Faecal incontinence
What causes issues with defecation?
Depending on the level and completeness of injury, SCI can have a number of impacts on defecation, including the following:
Time taken for movement of ingested food and liquids
- Gastric emptying time
- Colonic and whole gut transit time5
Changes in function
- Altered anal sphincter tone
- Altered pelvic floor functioning
- Decreased ability to attain optimum position for defecation due to poor trunk control and balance or equipment available
- Decreased ability to increase intra-abdominal pressure during defecation
- Decreased sitting balance
- Decreased upper limb function
- Decreased ability to transfer
Absence or alteration of reflexes and sensation
- The gastrolic reflex may be absent or reduced
- The ability for a person to sense their rectum is full may be absent or altered
- Anorectal dyssynergy1 (occurs when the muscles and nerves in the pelvic floor, including the anal sphincter fail to coordinate and relax to allow bowel evacuation6)
- Coggrave M, Ash D, Adcock C, et al. Guidelines for management of neurogenic bowel dysfunction in individuals with central neurological conditions. Multidisciplinary Association of Spinal Cord Injured Professionals. 2012.
- Lynch AC, Antony A, Dobbs BR, Frizelle FA. Bowel dysfunction following spinal cord injury. Spinal Cord. 2001;39(4):193-203.
- Krogh K, Christensen P. Neurogenic colorectal and pelvic floor dysfunction. Best Pract Res Cl Ga. 2009;23(4):531-43. DOI: 10.1016/j.bpg.2009.04.012
- Singal AK, Rosman AS, Bauman WA, et al. Recent concepts in the management of bowel problems after spinal cord injury. Adv Med Sci. 2006;51:15-22.
- Williams RE, Bauman WA, Spungen AM, et al. SmartPill technology provides safe and effective assessment of gastrointestinal function in persons with spinal cord injury. Spinal Cord. 2012;50(1):81-4. DOI: 10.1038/sc.2011.92
- Cleveland Clinic. Anismus. Cleveland, Ohio: Cleveland Clinic; 24 May 2022 [cited 8 Nov 2022].