Constipation causes

Management

Affects 80% of patients in palliative care and it can be distressing. Under normal

circumstances in a healthy individual, there is peristaltic activity every 90-120 minutes to

propel contents forward in the intestine. This motor activity is increased with gastric,

pancreatic or biliary secretion.

Causes of constipation can be broadly divided into 4 categories;

cancer related,
treatment induced
concurrent disorders
debility related

Cancer related:

Changes in the neural innervations of the GI tract such as compression of spinal cord (SC), narrowing of lumen in the colon, depression and hypercalcaemia( due to increased osteoclast activity and reduced renal excretion) all contribute to constipation.

Tumours can cause compression of the spinal cord due to metastases to the bones and depending on the location of compression this will affect the nerves that are responsible in defecation. On the spinal cord there are sympathetic ( hypogastric nerve arising from thoracic and lumbar region of SC) and parasympathetic nerves (splachnic plevic nerve arising from the sacral region of SC) that function in harmony and send impulses to the intestine, anus muscles and the rectum to control bowel movement. Therefore if cancer cells grow near the spine this results in inflammation which damages the nerves involved in the control of defecation and constipation arises.

The lumen of the colon can narrow as a result of tumour compression and scarring from radiotherapy . This results in difficulty for the passage of stools through the colon in order to reach the rectum and constipation occurs.

Hypercalcaemia can occur as a result of cancer metastases to the bones resulting in increased osteoclast activity. This releases excess calcium into the blood and causes decreased excitability of the muscles of the GI tract and hence less peristaltic contraction to propel food forward.