Today, we discussed case of a 64 year old man who presented with anasarca, abdominal distention, and profound hypoalbuminemia, found to have colonic pseudo-obstruction of unclear etiology. Pseudo-obstruction is not an entity that we face frequently, and it turns out that the differential diagnosis for this condition is quite broad and fascinating!
Chronic intestinal pseudo-obstruction
- Syndrome characterized by signs and symptoms of a mechanical obstruction of the small or large bowel, in the absence of an anatomic lesion that obstructs the flow of intestinal contents.
- Pathophysiology: This is a rare disorder that may be due to an underlying 1) neuropathic disorder (enteric nervous system or extrinsic nervous system); 2) myopathic disorder (smooth muscle is affected); or 3) abnormality in the interstitial cell of Cajal (remember, these are the “pacemaker” cells of the gut).
- Degenerative neuropathies: neurologic causes (Parkinson’s Disease, Shy-Drager syndrome) versus metabolic causes (diabetes mellitus) : Affect extrinsic nerve pathways to the gut
- Paraneoplastic immune-mediated pseudo-obstruction: associated with small cell lung cancers and carcinoid tumors : These patients have anti-neuronal nuclear antibodies (anti-Hu) which recognizes an epitope that is shared between neuronal elements within enteric nervous system and underlying malignancy
- Immune-mediated: reported in scleroderma, dermatomyositis, SLE! : antibodies target enteric nerves, smooth muscle cells, and even interstitial cells of Cajal
- Infectious : Chagas disease is the most common infectious cause : viruses can cause inflammatory or functional changes of the enteric nervous system : role of chronic JC virus infection à has been suggested in observational studies
- Radio– and Chemotherapy: especially agents used for gynecological cancer
- Genetic: There are rare familial cases suggesting an underlying genetic bias : Hirschsprung, MELAS (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes), MERRF (myoclonus epilepsy associated with ragged-red fibers)
- Nutritional support
- Prokinetic agents :erythromycin is effective during acute exacerbations; stimulates motilin receptors : metoclopramide is used for those
- Octreotide: shown to be effective patients who have pseudo-obstruction from scleroderma : exact mechanism unclear, but thought to cause changes in the visceral afferent function
- Antibiotics: Not standard of care, but consider in patients who have small intestinal bacterial overgrowth resulting from chronic obstruction
- Immunomodulators?: some case reports have described an association between pseudo-obstruction with lymphocytic infiltration of the myenteric plexus or smooth muscle. Immunomodulatory therapy should be reserved for patients with pseudo-obstruction due to an underlying inflammatory neuropathy that has been confirmed by biopsy or by presence of antineuronal antibodies (anti-Hu)
- Surgery or percutaneous endoscopic colostomy: to provide access to stomach or bowel for decompression to relieve symptoms.
- Intestinal transplantation: indicated in patients whom long-term parenteral nutrition cannot be initiated or continued safely.