Neurogenic Bowel Flashcards
The amount of waste pads used by incontinent (bowel and bladder) persons in the US each day if stacked and each remaining (1/4) inch thick would be:
1. Higher than commercial jetliners fly
2. taller than mount everest
3. 9 million in number or over 43 miles or over 227000ft high
All of the above.
Which is one of the best predictors for stroke patients to return home
a. urine incontinence
b. frequency of falls
c. bowel incontinence
d dysphagia
bowel incontinence
Definition of neurogenic bowel
results from autonomic and somatic denervation, and preduces fecal incontinence, constipation, and difficulty with evacuation
What defines neurogenic bowel?
a. loss of intrinsic enteric nervous system
b. loss of direct somatic sensory or motor control
c. loss of sympathetic innervation
d. loss of sphincter contraction
loss of somatic sensory or motor control
Bowel management has been found to be one of the areas of _____ among SCI rehab patients
least competence
In a recent study of SCI survivors in sweden, what percentage rated bowel dysfunction as a moderate to severe life-limiting problem?
a. 50%
b. 20%
c. 30%
d. 40%
d. 40%
Prevalence of fecal incontinence and fecal impaction ranges from _____ in general population
0.3% to 5.0%
Prevalence of difficulty with evacution ranges from _____ among hospitalized or institutionalized elderly
10-50%
What percentage of the general population has difficulty with evacuation
3-5%
1/3 of persons with SCI report or exhibit worsening of bowel function after _____ post injury. 33% develop ___
5 years beyond.
megacolon, suggesting inadequate long-term management
IN 1983 report, _____ estimated spent in USA for care of fecally incontinent institutionalized patients
$8 billion/year
Difficulty in bowel evacuation or fecal incontinence
a: affects 90% of SCI persons
b
There are 3 different neuron types in the enteric nervous system based on fuction:
- sensory
- interneurons
- motor neurons.
There is a highly organized intrinsic innervation in 2 layers in enteric system:
- submucosal (meissner’s) plexus
- Intramuscular myenteric (Auerbach’s) plexus
Meissner’s submucosal and intramuscular myenteric (Auerbach’s plexus) have _____ neurons and ______ glial cells/neuron
10-100million neurons
2-3 glial cells/neuron
ENS has its own _____
blood-nerve barrier
The enteric nervous system:
a: consists of submucosal and myenteric plexuses
b. contains more neurons than the spinal cord
c. has its own nerve-blood similar to that of the brain
d all of the above
d. all
GI neurosensory system: Enteric nervous system sensory neurons:
1. ______ -> chemical (mucosal epithelium), thermal & mechanical (intramuscular arrays or intraganglionic) receptors.
2 ______ -> distributed extensively throughout bowel, relaying chemical, thermal & mechanical information.
- Chemical changes creates: (4)_______ that contribute to pain and discomfort
- Vagal afferent nerve endings
- Spinal afferent nerve endings
- injury, ischemia, infection, or inflammation
GI neurosensory system: Enteric nervous system sensory neurons:
- Spinal nerve endings express receptors for (8)
- Mechanoreceptors (derived from 2 ).
3 Vagal afferents are primarily implicated in the ____ response, and spinal afferents are primarily implicated in the _____
- bradykinin, ATP, adenosine, PG, leukotrienes, histamine, mast cell proteases & 5-HT3.
- vagal or spinal afferents
- emetic, sensation of nausea
Sensory pathway for bowel:
Enteric Nervous System Relationship to the Spinal Cord and Brain (Extrinsic Innervation)
Sensory-
1. vagal afferentsin ENS
2. nodose ganglia of vagus
3. nucleus tractus solitarius & area postrema (brainstem)
4. rostral centers in brain.
Describe parasympathetic system of bowel system
Parasympathetic: Vagus- from esophagus to splenic flexure. Pelvic- Nervi erigentes-from S2-S4 to descending colon and rectum
Describe spinal afferents pathway of bowel system:
Spinal afferents(splanchnic & pelvic)
- DRG (or prevertebral sympathetic ganglia)
- dorsal horn (laminae I, II, V, X)
- spinal cord & dorsal column nuclei.
Dorsal columngreater role in nociceptive. Superior/inferior mesenteric (T9-T12) and hypogastric (T12-L3)-Sympathetic
Describe somatics system of bowel
Somatic afferents of pelvic floor-> pudendal n to sacral region of spinal cord. Pudendal N-Somatic (S2-S4) to EAS
_____ travels along bowel wall from esophagus to internal anal sphincter & forms final common pathway to control bowel wall smooth muscle
Enteric nervous system
The inferior splanchnic nerve or nervi erigentes is:
A. the somatic mixed nerve that supplies the pevic floor
B. The parasympathetic nerve that supplies the splenic flexure and descending colon
C The sympathetic nerve that sows colonic peristalsis
D The parasympathetic nerve that modulates small intestine peristalsis to the cecum
B The parasympathetic nerve that supplies the splenic flexure and descending colon
GI neuromotor system:
1. pacemaker & allow propagation of electrical slow waves into circular muscle layer
2. ____ have their own electromechanical automaticity, modulated by ENS.
3. Contraction is mediated by
4. ______ impedes contractile activity
5. ______ enhances colonic motility & its loss is associated with DWE, Ogilvie’s pseudoobstructive syndrome.
6. ____ & ____ postganglionic neurons transmit excitatory or inhibitory messages to secretomotor neurons for modulation of water sodium chloride, bicarbonate, and mucus
- Interstitial cells of Cajal
- Smooth muscles of bowel
- release of excitatory neurotransmitters by vagal afferents at neuromuscular junctions, ACh & substance P.
- Release of NO, ATP, and VIP from inhibitory motor neurons
- Parasympathetic activity
- ENS & sympathetic
The colon functions to:
A. Store waste until convenient to eliminate it
B. Resorb water from chime
C. Expel slid waste products from dietary intake
D All of the above
All
Gastric Motility:
1. _____ has sustained, low-frequency contractions & has tonic pattern.
2. _____ has intermittent, powerful contractions & has phasic pattern. Fundus acts as reservoir
3. ____ is a mixer that generates propulsive waves that accelerate as food is propagated towards pylorus.
- Upper portion (fundus)
- Lower portion (antrum)
- Antrum
Intestinal motility:
1. ___ occurs during fasting in stomach & small intestine. Influenced by hormone motilin.
- Brainstem sends signals that are transmitted to _____, which convert migrating motor complex motility.
- The __________ propel waste through the lumen, particularly in large intestine.
- Interdigestive migrating motor complex pattern
- vagal efferents
- “giant migratory contractions” (GMCs)
What physiologic variable correlates best with the frequency of human defecation?
A. Giant Migratory contraction
B Resting peristaltic waves
C Slow electrical colonic potentials
D Electrical spike burst colonic potentials
A. Giant Migratory contraction
Motility of Anus, Rectum, and Pelvic Floor:
1. Normal defecation& maintenance of fecal continence entail a highly coordinated mechanism involving
2. Pelvic floor is composed of
3. _______ are skeletal muscles that constantly maintain tone & sustain pelvic organs in place against forces of gravity.
- levator ani, puborectalis, & EAS & IAS
- levator ani, underlying sheets of which form a sling.
- Levator ani, puborectalis, & EAS
In the neurally intact state, the early sensory sign of a need for defication comes from:
A. Distension of the cecum
B. Relaxation of internal anal sphincter
C. Stretch of the puborectalis muscle as stool fills the rectum
D External sphincter relaxation
C. Stretch of the puborectalis muscle as stool fills the rectum
Physiology of normal defecation - storage:
1. Colon is reservoir for food waste until it is convenient for elimination. Storesas long as ____
2. Reabsorb
- fluids (_____ can be reabsorbed from large & small bowel walls, with typically ____ of H20 loss in feces)
- gases (___% of 7 to 10 L of gases produced by intracolonic fermentation is absorbed).
Normal defecation begins with reflexes triggered by rectosigmoid distention produced by approximately 200 mL of feces.
Secretes mucus for feces lubrication; supports growth of symbiotic bacteria
- colonic pressure is less than that of anal sphincter mechanism.
- up to 30 L/day; 100 mL; 90%
Fecal Elimination:
A is an unnatural event
B Occurs when colonic pressure exceeds that of the anal sphincter
C Requires 1-2 hours in most persons
D Occurs by resorption of gases created by clonic bacteria
B Occurs when colonic pressure exceeds that of the anal sphincter
- Auerbach and Meissner, as wel as mucosal plexus – which have more ganglia?
- Adrenergic fibers are all ____ & arise from _____. Adrenergic fibers are distributed largely to mesenteric, submucous, & mucosal plexus to blood vessels
- Deep muscular plexus contains a few ganglia, subserosal contains an occasional ganglion, & mucosal plexus shows none.
- extrinsic, prevertebral sympathetic ganglia
Physiology of bowel propulsion
1. Coordinated primarily within the ____, with some ____ reflexes but minimal ____ influence.
- ____ occurs in which bowel proximal to distending bolus contracts & bowel wall distally relaxes, serving to propel bolus further caudal. Reflex relaxation of __ occurs.
- ____ correlates with urge “the call to stool.” Volitional contraction of levator ani to open proximal anal canal & relax EAS & puborectalis muscles.
- Increasing ____ assists bolus elimination.For 90% of normal individuals, only contents of rectum are expulsed, whereas 10% will clear entire contents of left side of colon from splenic flexure distally.
- gut wall, spinal cord, brain
- Rectorectal reflex; IAS
- Rectoanal inhibitory reflex
- intraabdominal pressure (squatting & Valsalva’s maneuver)
Which is a characteristic of the external anal sphincter muscle?
A Autonomic innervation
B Striated muscle
C Continued atonic contraction
D It is smaller than the internal anal sphncter
The external anal sphincter is physically larger than the internal sphincter and is a striated muscle whose normal resting state is tonic contraction (only striated muscle with that).
Physiology - propulsion:
1. One can elect to defer defecation by
2. ___ generally tenses in response to small rectal distention via a spinal reflex, although reflexive relaxation occurs in presence of greater distention.
3. Centered in _____ & are augmented & modulated by higher cortical influences.In SCI, EAS reflexes usually persist & allow spontaneous defection.
4. ____ refers to the increased colonic activity (GMCs & mass movements) in first 30 to 60 mins after a meal.
- volitionally contracting puborectalis muscle & EAS.
- EAS
- conus medullaris
- Gastrocolonic response or Gastrocolic reflex
Chemical control modulates colonic activity
with neurotransmitters and hormones (Bassotti et al.,1995; Sarna, 1991). Local neurogenic control is viathe enteric nervous system, which coordinates all segmentalmotility and some propagated movement (Sarna, 1991). Enteric reflexes do not require extrinsiccolonic innervation (Bayliss and Starling, 1899).When the intestinal wall is stretched or dilated, thenerves in the myenteric plexus cause the musclesabove the dilation to constrict and those below thedilation to relax, propelling the contents caudally.The combined contraction of smooth muscle cells is triggered by electric coupling through gap junctions,which allow myogenic transmission from cell to cell(Christensen, 1991).
Which of the following accurately characterizes the gastricolonic response?
A It is weakest in the morning soon after rising
B It is not affected by atropine
C Peristaltic response is limited to the colon
D It is mediated by hormonal and neural mechanisms
D It is mediated by hormonal and neural mechanisms
Physiology of bowel - propulsion:
1. Hormonal effects, from release of peptides from _____ increase contractility of colonic smooth musculature & by reduction in threshold for spinal cord–mediated vesicovesical reflexes
2. ____ is often used therapeutically, in patients with SCI, to enhance bowel evacuation during this 30 to 60 mins postprandial time frame.
3. In neurally intact state, colonic transport takes_____ from the ileocecal valve to the rectum
- upper GIT (gastrin, motilin, cholecystokinin)
- Gastrocolonic response
- 12 to 30 hours
Extrinsic reflex pathways from the central nervous system to the intestine and colon both facilitate and inhibit motility. Vagal reflexes increase propulsive peristalsis of the small intestine down through the transverse colon. Sacral parasympathetic reflexesare excitatory and are relayed from the colon tosacral spinal cord segments within the conusmedullaris and back along the pelvic nerve. Spinalcord-mediated reflexes via the pelvic nerve are initiatedfrom enteric circuits in response to colonic dilationand serve to reinforce colonic-initiatedpropulsive activity in defecation (Sarna, 1991). Therectocolic reflex is a pelvic nerve-mediated pathwaythat produces propulsive colonic peristalsis inresponse to chemical or mechanical stimulation ofthe rectum and anal canal. Stimulation of theparasympathetic pelvic splanchnic nerve canincrease motility of the entire colon.Colonic movements can be individual segmentalcontractions, organized groups (colonic migrating ornonmigrating), and special propulsive (giant migratingcontractions, or GMC) (Sarna, 1991) waves ofperistalsis that propel stool over long distances. Inthe neurally intact state, colonic transport takes 12 to30 hours from the ileocecal valve to the rectum
(Menardo et al., 1987).
The external anal sphincter is innervated by:
A L2 and L5 nerve roots
B L5 and S1 nerve roots
C S2 through S4 nerve roots
D Inferior splanchnic nerve
C S2 through S4 nerve roots
Physiology of bowel - propulsion:
1. Resting anal canal pressure is determined by: (2)
2. ___ are only striated skeletal muscles whose normal resting state is tonic contraction & these muscles consist mainly of _____ fibers
3. EAS is ______ than IAS has reflex & volitional control
4. EAS is innervated by _____, & puborectalis muscle is innervated by branches from
- angulation & pressure at anorectal junction by puborectalis sling & smooth muscle IAS tone
- EAS & puborectalis muscle; slow-twitch, fatigue-resistant type I\
- physically larger
- S2 to S4 nerve roots via pudendal nerve; S1 to S5 roots
The act of defecation involve contracting which muscles?
A Levator Ani
B Puborectalis
C External anal sphincter
D All of the above
B Puborectalis
Physiology of bowel - continence
1. 2 things in resting state:
2. ____ via lumbar colonic nerves increases IAS tone
3. IAS tone is lowered by
- Closed IAS and acute angle of anorectal canal by puborectalis sling
- Sympathetic (L1-L2)
- rectal dilation from stool or digital stimulation
Continence
In the resting state, fecal continence is maintained by a closed IAS and by the acute angle of theanorectal canal produced by the puborectalis sling. Sympathetic (L1-L2) discharges via the lumbar colonic nerve increases IAS tone. IAS tone is inhibited
with rectal dilatation by stool (rectalanal inhibitory reflex) or digital stimulation.
Name stage of normal defecation:
Puborectais, external and internal anal sphincters contracted
Holding
Name stage of normal defecation:
Puborectalis and external anal sphincter reax
Levator ani, abdominals and diaphragm contract
Initiation
Name the stage of normal defecation
Internal anal and external anal sphincters relax. Rectum contracts
Completion
Defecation:
describe sequence of defecation 3)
- Spontaneous, involuntary advancement of stool stretches rectum & puborectalis
- Temporary retain stool by voluntary contraction of EAS
- Voluntary relaxation of EAS & puborectalis straightens anorectal for stool passage & augmented by peristalsis & valsalva of abdominal musculature
Compared with the external anal sphincter, the internal anal sphincter is:
1. Larger and maintains 80% of the resting anal canal pressure
2. Smaller and maintains 80% of the resting anal canal pressure
3. Larger and maintains 20% of the resting anal canal pressure
4. Smaller and maintains 20% of the resting anal canal pressure
- Smaller and maintains 80% of the resting anal canal pressure
Pathophysiology of GI dysfunction:
bowel Dysfunction:
1. Normal:
2. UMNB:
3. UMNB and posterior rhizotomy:
4. LMNB:
- Normal colon activity and defecation
- Chronic intractable constipation, fecal impaction, reflex defecation with or without incontinence
- Chronic constipation, no reflex defecation
- Chronic constipation; fecal impaction maximal in the rectum
Pathophysiology of GI dysfunction:
Transit time (cecum to anus)
1. Normal:
2. UMNB:
3. UMNB and posterior rhizotomy:
4. LMNB:
- 12-48h
- prolonged >72h
- Very prolonged unless sacral nerve stimulator used
- Prolonged >6 days especially left side of colon
Pathophysiology of GI dysfunction:
Colonic motility at rest
1. Normal:
2. UMNB:
3. UMNB and posterior rhizotomy:
4. LMNB:
- GMCs aproximatel 4per 24h
- GMCs might be reduced in frequency
- Reduced GMCs
- Reduced GMCS
Pathophysiology of GI dysfunction:
Colonic motility in response to stimuli
1. Normal:
2. UMNB:
3. UMNB and posterior rhizotomy:
4. LMNB:
- GMCs facilitated by defecation, exercise, and food ingestion
- Less GMC facilitation by defecation, exercise, or food ingestion
- Less GMC facilitation by defecation, exercise, or food ingestion
- Less GMC facilitation by defecatin, exercise, or food ingestion
Pathophysiology of GI dysfunction:
Anal Sphincter Pressure Resting tone(mmHg)
1. Normal:
2. UMNB:
3. UMNB and posterior rhizotomy:
4. LMNB:
- > 30
- > 30
- Normal
- Reduced
Pathophysiology of GI dysfunction:
Anal Sphincter Pressure volitional squeeze
1. Normal:
2. UMNB:
3. UMNB and posterior rhizotomy:
4. LMNB:
- > 30 (up to 1800)
- absent
- absent
- absent
Pathophysiology of GI dysfunction:
Anal Sphincter Pressure (rectal compliance)
1. Normal:
2. UMNB:
3. UMNB and posterior rhizotomy:
4. LMNB:
- normal
- normal but sigmoid compliance decreased
- Normal or increased
- rectum dilated; increased distension volume; increased compliance
What triggers normal defecation?
A a thought
B Food in stomach
C Dilatation of the rectosigmoid by 200mL of feces
D Valsalva inhibitory maneuver
Normal defecation begins with reflexes triggered by rectosigmoid distension of approximately 200 mL of feces. A rectoreflex occurs in which the bowel proximal to the bolus contracts and the bowel wall distally relaxes, serving to propel the bolus.
Pathophysiology of GI dysfunction:
Rectal balloon distension effect on EAS
1. Normal:
2. UMNB:
3. UMNB and posterior rhizotomy:
4. LMNB:
- Causes contraction
- Causes contraction
- No contraction
- No contraction
Pathophysiology of GI dysfunction:
Rectal balloon distension effect on IAS
1. Normal:
2. UMNB:
3. UMNB and posterior rhizotomy:
4. LMNB:
- normal recto anal inhibitory reflex
- Normal recto anal inhibitory reflex
- normal recto anal inhibitory reflex
- normal recto anal inhibitory reflex
Pathophysiology of GI dysfunction:
Sensory perception threshold
1. Normal:
2. UMNB:
3. UMNB and posterior rhizotomy:
4. LMNB:
- < 20ml volume
- none
- none
4 none