This book is a comprehensive and up-to-date guide to hemifacial spasm, one of the very few neuromuscular disorders that can be treated surgically. All aspects are covered, including classification, pathogenesis, diagnosis and differential diagnosis, surgical principles and practice, medical treatment, the role of botulinum toxin injection, complications, prognosis, and redo surgery. Dr. Kwan Park has performed microvascular decompression surgery, the treatment of choice, in more than 4000 hemifacial spasm patients at Samsung Medical Center in Seoul, Korea. Over the past two decades, important lessons have been learned and new technologies adopted. This book draws together the many scientific contributions of Dr. Park and his team and offers the very latest insights into management of the condition. It will be an excellent guide for young neurosurgeons wishing to master the relevant surgical skills, as well as for all other medical personnel who may encounter patients with involuntary twitching or contraction on one side of the face.