Webster's New World Medical Dictionary

acetylsalicylic acid
See 
aspirin.
achalasia
A disease of the esophagus that mainly
affects young adults. Abnormal function of nerves
and muscles of the esophagus causes difficulty swal-
lowing and sometimes chest pain. Regurgitation of
undigested food can occur, as can coughing or
breathing problems related to entry of food material
into the lungs. The underlying problems are weak-
ness of the lower portion of the esophagus and fail-
ure of the lower esophageal sphincter to open and
allow passage of food. Diagnosis is made by an X-
ray, endoscopy, or esophageal manometry.
Treatment includes medication, dilation (stretch-
ing) to widen the lower part of the esophagus, and
surgery to open the lower esophagus. A fairly recent
approach involves injecting medicines into the
lower esophagus to relax the sphincter.
Achilles tendon
One of the longest tendons in
the body, a tough sinew that attaches the calf muscle
to the back of the heel bone (calcaneus). The name
comes from Greek mythology: The hero Achilles
was invulnerable to injury except for his heel, which
proved his downfall when it was pierced by Paris’s
arrow. It has also proved, literally, to be the down-
fall of many athletes who have experienced the sud-
den pain of its rupture.
Achilles tendonitis
Inflammation in the tendon
of the calf muscle, where it attaches to the heel
bone. Achilles tendonitis causes pain and stiffness at
the back of the leg, near the heel. Achilles tendonitis
can be caused by overuse of the Achilles tendon,
overly tight calf muscles or Achilles tendons, excess
uphill running, a sudden increase in the intensity of
training or the type of shoes worn to run, or wearing
high heels at work and then switching to a lower-
heeled workout shoe. Achilles tendonitis causes
pain, tenderness, and often swelling over the Achilles
tendon. There is pain on rising up on the toes and
pain with stretching of the tendon. The range of
motion of the ankle may be limited. Treatment
includes applying ice packs to the Achilles tendon,
raising the lower leg, and taking an anti-inflamma-
tory medication. In some severe cases of Achilles
tendonitis, a cast may be needed for several weeks.
A heel lift insert may also be used in shoes to prevent
future overstretching of the Achilles tendon. Exerting
rapid stress on the Achilles tendon when it is
inflamed can result in rupture of the tendon.