History
The initial step in the management of neurogenic bowel dysfunction (NBD) is to establish a history of premorbid and current bowel function and patterns. This includes the following:
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Bowel frequency
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Presence of strain
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Presence of hard or lumpy stool
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Presence of incomplete evacuation sensation
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Sensation of anorectal obstruction
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Need for additional manual maneuvers to facilitate defecation
It is important to ascertain whether any gastrointestinal (GI) problems or any other medical conditions (eg, diabetes, irritable bowel syndrome [IBS], lactose intolerance, inflammatory bowel disease [IBD], or rectal bleeding) existed previously. The patient’s functional status should be evaluated. An effort should be made to determine whether the bowel symptoms are affecting the patient’s ability to perform activities of daily living and carry out social and work responsibilities.
Assessment should include the following:
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Ability to learn a bowel program
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Sitting tolerance
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Sitting balance
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Upper-limb strength and proprioception
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Upper-limb function
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Spasticity
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Transfer skills
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Actual and potential risks to skin
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Home accessibility
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Equipment needs
This assessment should involve both the patient and the caregiver.
Symptoms can include the following:
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Abdominal pain
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Abdominal distention
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Early satiety
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Loss of voluntary control over defecation (ie, fecal incontinence)
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Difficulty with evacuation
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Associated neurologic bladder symptoms
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Associated symptoms of autonomic dysreflexia in patients with spinal cord lesions at T6 and above
Physical Examination
The physical examination should include the following:
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Complete abdominal and rectal examination
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Assessment of anal sphincter tone
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Elicitation of anocutaneous and bulbocavernosus reflexes to determine if the patient has upper-motor-neuron (UMN) or lower-motor-neuron (LMN) bowel dysfunction
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Neurologic examination to assess the extent of nerve damage
The abdomen should be inspected for distention, increased abdominal muscle tone indicative of spasticity, and bowel sounds.
The tone of the external anal sphincter is assessed by means of digital examination. The external anal sphincter is normally puckered, with LMN impairment being manifested by flattening or scalloping. Tone is reduced or absent in acute complete spinal cord lesions and LMN impairment. Rectal sensation usually is absent in lesions above L3.
The anocutaneous reflex is assessed by means of stimulation with pinprick in the perianal region, which leads to visible reflexive anal contraction. The anocutaneous reflex is normally present if the S2-4 reflex arc is intact. This reflex does not correlate with internal sphincter function.
The bulbocavernosus reflex is assessed by squeezing the glans penis or clitoris (or applying traction on an indwelling catheter), which results in palpable rectal contraction. This reflex is normally present in most patients. The reflex is brisk with UMN lesions and is absent in LMN lesions or spinal shock.
Sensory examination tests the integrity of sacral dermatomes to light touch and pinprick.
Complications
Autonomic dysreflexia is an abnormal sympathetic nervous system response to a noxious stimulus below the level of injury in individuals with a spinal cord injury (SCI) above T6. An acute episode results in rapidly rising blood pressure with an accompanying risk of brain hemorrhage and death. Symptoms include flushing, sweating and blotchiness above the lesion, chills, nasal congestion, and headache.
Fecal impaction (see the image below) occurs in almost 80% of patients with SCI and can lead to bowel distention, which, if left untreated, may result in perforation and even death.
Abdominal X-ray showing fecal impaction extending from pelvis upward to left subphrenic space and from left toward right flank, measuring over 40 cm in length and 33 cm in width. Image courtesy of Wikimedia Commons
Gastroesophageal reflux results from chronic overdistention of the bowel. Diverticulosis (see the video below) also results from chronic overdistention, as well as from increased intraluminal pressures brought on by fecal impaction.
Rectal prolapse results from repeated passage of large hard stools in patients with a weakened anorectal mechanism, especially in cases involving LMN lesions. Hemorrhoids result from repeated passage of large hard stools as a result of constipation and can lead to chronically high pressures in the anorectal marginal veins. The prevalence of hemorrhoids in this setting may be as high as 76%. Anal fissures may be caused by increased anal tone or by the passage of hard stool; they may manifest as increased spasm of the sphincter and autonomic dysreflexia.
Megacolon is relatively common in patients with NBD, and it may be associated with sigmoid volvulus, fecal impaction, autonomic dysreflexia, dyspnea from diaphragmatic splinting, weight loss, and chronic malnutrition.
Reduced quality of life occurs as a consequence of fear of incontinence and may lead to reduced social activity and isolation, which are associated with depression and anxiety.
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Administration of an enema.
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Illustration of neural control of gut wall by sympathetic, parasympathetic and enteric nervous system. Courtesy of Wikimedia Commons.
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Colonoscopy reveals diverticulosis (pockets within colon that can bleed or become infected). Video courtesy of Dawn Sears, MD, and Dan C Cohen, MD, Division of Gastroenterology, Scott & White Healthcare.
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Abdominal X-ray showing fecal impaction extending from pelvis upward to left subphrenic space and from left toward right flank, measuring over 40 cm in length and 33 cm in width. Image courtesy of Wikimedia Commons
