The amount of compensatory sweating depends on the patient, the damage that the white rami communicans incurs, and the amount of cell body reorganization in the spinal cord after surgery.
Other potential complications include inadequate resection of the ganglia, gustatory sweating, pneumothorax, cardiac dysfunction, post-operative pain, and finally Horner’s syndrome secondary to resection of the stellate ganglion.
www.ubcmj.com/pdf/ubcmj_2_1_2010_24-29.pdf

After severing the cervical sympathetic trunk, the cells of the cervical sympathetic ganglion undergo transneuronic degeneration
After severing the sympathetic trunk, the cells of its origin undergo complete disintegration within a year.
http://onlinelibrary.wiley.com/doi/10.1111/j.1439-0442.1967.tb00255.x/abstract

Saturday, August 30, 2008

Orthostatic hypotension following sympathectomy can lead to syncope

  1. Describe the reflex compensations when someone suddenly stands up from a supine position. What would happen in a patient who just had a sympathectomy?

    Sudden standing causes pooling of blood in the leg veins. This results in decreased venous return to the heart, which leads to decreased cardiac output (Frank-Starling mechanism), which leads to decreased MAP. This decrease in MAP is detected by the carotid sinus baroreceptors, which relay a message to the medullary cardiovascular control center, which increases sympathetic outflow and decreases parasympathetic outflow, this causes:

  • An increase in HR and myocardial contractility, tending to restore cardiac output.
  • Vasoconstriction in skeletal musculature, skin, kidneys and gut, reducing blood flow to these organs and increasing TPR.
  • Venoconstriction decreasing capacitance and increasing venous return

    A patient with a sympathectomy would experience what's referred to as orthostatic hypotension (which might lead to syncope). Orthostatic hypotension is a decrease in arterial pressure when going from supine to a standing position. A person with a normal baroreceptor mechanism will try to restore MAP. In a person who had a sympathectomy, the sympathetic component of the baroreceptor mechanism is absent.

  1. Will the capillary pressure increase or decrease in the following situations?
  1. Arteriolar vasodilation: increase
  1. Venodilation: decrease (however, Dr. Gray points out that capillary beds of lower extremities will experience an increase in pressure due to back pressure exerted by the column of blood in the dilated veins!)

M.A.S.T.E.R. Learning Program, UC Davis School of Medicine

Date Revised: Jan 16, 2002

Revised by: Gordon Li and Carolyn Nguyen