The causes of this disease are 1) idiopathic 2) secondary to surgery or disease (lung disease, thyroid cancer, aortic aneurysm, etc). The symptoms are hoarseness, breathiness or weak voice, which prevent the patients from smooth conversation.
Sometimes spontaneous recovery is expected within 6 months from the onset. However, the surgical treatments are required in unrecovered cases for over 6 months. Thyroplasty type 1 ( Isshiki type 1) is the most common surgery for it.
In addition to type 1 surgery, type 4 thyroplasty or Arytenoid adduction are sometimes performed to obtain the better voices. These surgeries require more fine works and experiences, so these methods might be limited to a few hospitals even in the world.
TP1 + Arytenoid adduction
TP1 + TP4