Hemihyperhidrosis is excessive sweating on one side of the 
body. This condition is known to occur in some patients who have 
experienced a stroke. A stroke is a burst artery (a type of blood 
vessel that carries blood away from the heart) or a blockage of 
an artery in the brain. Strokes in an area of the lower part of the 
brain known as the medulla have been associated with increased 
sweating on the side of the body that is opposite of the side that 
the stroke occurred in the brain. Specifically, damage to the 
sympathetic nervous system pathways that run through the side 
of the medulla are thought to lead to hemihyperhidrosis. The 
sympathetic nervous system is a network in the body that 
generally excites it by doing things such as increasing the heart 
rate, blood pressure, and perspiration (sweating). 
 
Strokes in another area of the brain called the hypothalamus have also been associated 
with hemihyperhidrosis. The hypothalamus is an area in brain that is important for many 
bodily functions such as sleep, appetite, and temperature control. The easiest way to 
treat excessive sweating is wiith an anti-perspirant, whch can be applied to other parts of 
the body besides the underarms. If this does not work, there are medical treatments that 
can be used such as Botox injections, which block release of a chemical that triggers 
sweating. Surgical removal of sweat glands can be used in severe cases of excessive 
sweating. Hemihyperhidrosis comes from the Greek word "hemi" meaning "half," the 
Greek word "hyper" meaning "above," and the Greek word "hidrosis" meaning "sweating."