Causes of constipation

  • All psychoneurological disorders

Diagnosis of constipation

In all patients:

    • Exclude structural/biochemical alterations
      Identify pathophysiological role of slow colonic transit and recto-ano-pelvic dysfunction –
    • Large bowel transit –
    • Anorectal manometry
    • Balloon expulsion test

In neurologic patients

    • Neurophysiologic investigations of the pelvic floor

In specific patients

    • Autonomic test -Defecography
    • Psychiatric assessment

Management of constipation

Slow colonic transit & normal recto-ano-pelvic function

    • High fiber diet± bulk, osmotic, stimulant laxatives, isosmotic PEG electrolyte solution
    • cisapride

If severe & non responding constipation

    • Malone antegrade enema; colectomy

Slow colonic transit and no neurological control of the recto-ano-pelvic function

    • High fiber diet ±bulk laxatives & trigger defecatory reflex with physical maneuvers± glycerin, stimulant laxative suppository, enema
    • Cisapride

Recto-ano-pelvic dysfunction with only partial or no denervation

    • Toilet training
    • Manometry-controlled biofeedback
    • Isosmotic PEG electrolyte solution

Recto-ano-pelvic dysfunction with total denervation

    • Trigger defecatory reflex with physical maneuvers±glycerin, stimulant laxative suppository
    • Electrostimulation of S3-S4 roots
    • Hirschsprung’s d *Surgery


Fecal Incontinence

Causes of fecal incontinence

  • All psychoneurological disorders can cause constipation and thus fecal overflow incontinence for rectal impaction.
  • Neurological disorders affecting at or below the sacral parasympathetic outflow, extrinsic and intrinsic innervation of the recto-ano-pelvic area.

Diagnosis of fecal incontinence

In all patients

    • Exclude structural recto-ano-pelvic alterations and fecal impaction.
    • Evaluate the presence of liquid stools.
    • Anorectal Manometry
    • Neurophysiologic investigations of the pelvic floor

In specific patients

  • Autonomic tests
  • Psychiatric assessment

Management of fecal incontinence

Fecal impaction (see constipation)

Liquid stools (see diarrhea)

Recto-Ano-Pelvic dysfunction with only partial or no denervation

      • *Toilet training
      • *Manometry-controlled biofeedback
      • *Physiotherapy
      • *Electrostimulation
      • *Loperamide

Recto-Ano-Pelvic dysfunction with total denervation

    • *Trigger defecatory reflex with physical maneuvers + glycerin, stimulant laxative suppository *Electrostimulation of S2-S3 roots.
    • *Malone anterograde enema
    • *Colostomy



Causes of diarrhea

  • Autonomic and Enteric Neurological disorders causing intestinal pseudo-obstruction and bacterial overgrowth.
  • Psycho-Functional

Diagnosis of diarrhea

  • Exclude structural and biochemical alterations
  • Breath test

Management of diarrhea

    • *Diet with low fermentable food
    • *Agents to increase stool consistency: Polycarbophyl, Kaolin, Diosmectite (E)
    • *Loperamide
    • *Somatostatin derivatives
    • *5HT3 antagonists

In diabetic neuropathy:

    • *Clonidine
    • *Chelating agents

In breath test positive:

  • *Antibiotic

Visceral Pain

Chronic Visceral Pain and Discomforts

Causes of visceral pain & discomforts

  • Peripheral neuropathy
  • Enteric sensory neurons sensitization
  • Dorsal horn sensory neurons sensitization

Diagnosis of visceral pain & discomforts

  • Exclusion of structural and biochemical alterations
  • Endoluminal distension tests
  • Manometry + provocative tests

Management of visceral pain & discomforts

    • Antispasmodics
    • Drugs acting on the enteric sensory neurons
    • Drugs acting supraspinally
    • Tricyclic antidepressants
    • anxiolytics
    • Liquid levodopa


Other neurological disorders

    • Gastric stasis *



Nervous Regulation of the Gastrointestinal Functions

  • Cranial and sacral parasympathetic outflow is generally excitatory to the GI smooth muscle.
  • Thoracolumbar sympathetic outflow is generally inhibitory to non-sphincteric areas and excitatory to sphincters.
  • Acetylcholine is the neurotransmitter of the parasympathetic system and of the prevertebral sympathetic ganglia; norepinephrine is the neurotransmitter of the postganglionic sympathetic fibers.
  • The interneurons of the ENS elaborate signals, arriving from the ANS, the mucosa, and blood circulating hormones, to coordinate sterotyped response regulating regional gastrointestinal muscular, secretory and blood flow activity, as well as biliary and pancreatic motor-secretory activities. –
  • Visceral afferents:
  • activate viscero-visceral reflexes in the prevertebral ganglia
  • convey gastrointestinal sensations such as hunger, feeling of fulness and distention via vagal fibers and, in part, via fibers of the intermediomedial columns of the spinal cord
  • convey sensation of pain with fibers associated with the sympathetic nervous system to the dorsal root ganglia of the spinal cord.
  • Nervous fibers arising in the cortex and brain stem, pontine locus ceruleus, periacqueductal grey in the midbrain, raphe nuclei, lateral nuclei of the reticular formation, can modulate the peripheral viscero-visceral reflexes and the sensations arising in the gastrointestinal tract.



The Innervation of the Alimentary Canal


Visceral regulatory centers in the cortex, limbic system (olfactory areas, hippocampus, amygdala, cingulate cortex, septal area), hypothalamus, reticular formation.


Parasympathetic neurons are located in the brain stem nuclei, (Superior and inferior salivatory nuclei, lacrimal, and the dorsal nucleus of the vagus) and in the intermediolateral cell columns of the spinal segments S2-S4 and synapse with interneurons of the Enteric nervus system. Preganglionic sympathetic neurons are located in the intermediolateral columns of the spinal segments T1-L3. They synapse in the celiac, superior and inferior mesenteric plexuses with postganglionic neurons the endings of which terminate on axo-axonal synapses on both parasympathetic and ENS intrinsic fibers.


Neurons of the ENS are located in the myenteric and submucosal plexuses of the alimentary canal. The enteric plexuses contain sensory neurons, interneurons, and effector (excitatory and inhibitory) neurons.


Vagal afferent fibers originate in the solitary nucleus of the medulla. –

Splanchnic fibers originate:

      • a) in the intermediomedial cell column of lamina VII in the spinal cord segments T1-L2, and in the segments S2-S4. The ascending fibers are included in the spinoreticular and spinothalamic tracts
      • b) in the neurons located in the dorsal root ganglia which send axons to
        • 1) the prevertebral ganglia
        • 2) a second-order neuron in the dorsal horn of the spinal cord which crosses the spinal cord, ascends in the spino-thalamic and spino-reticular tracts to synapse with a third- order neuron in the thalamus and reticular formation.

From the medulla and spinal cord fibers reach the reticular formation of the brain stem, hypothalamus, and ventral posterior nucleus of the thalamus and from these areas neurons project to the somatosensory cortex and the anterior cingulale gyrus.