Dystonia is a neurological movement disorder characterized by involuntary, repetitive muscle contractions that cause twisting and abnormal postures. Dystonia can be classified into different types according to the part of the body it affects. One of the dystonia types is focal dystonia which we will explain in this article.
Focal Dystonia Introduction
Focal dystonia is a type of adult-onset dystonia. It affects specific parts of the body such as the hands, arms, neck, mouth, jaw, eyes and vocal cords. Focal dystonia of the hands is featured by a sudden and abnormal muscular contraction in the hands that may cause involuntary, spasmodic closing and opening of the fingers of the hands. In focal dystonia the fingers suddenly extend outwardly or curl into the palm.
Causes of Focal Dystonia
Abrupt and uncontrollable muscle contractions and twisting in focal dystonia occur due to malfunctioning of the neurons located in the sensorimotor cortex of the brain. The sensorimotor cortex is a thin layer of nervous tissue that surrounds the brain and regulates muscle coordination. It can be compared to a neural chart of the entire body and its functions and movements. If a specific part of the body is not correctly drawn into this chart, the neurons that transmit messages to that body part may send out wrong signals. This will lead to loss of regulation of coordinated movements and result in involuntary, sudden and abnormal twitching and contractions of muscles.
Symptoms of Focal Dystonia
Focal dystonia can manifest as any uncontrolled and sustained contraction of a muscle or a group of muscles in any body part. A common dystonia symptom, that is also associated with focal dystonia, is sudden abnormal posture. Tremors are also common for focal dystonia.
The symptoms may vary depending on the type of focal dystonia. Blepharospasm is the focal dystonia that affects the eyelids. It causes uncontrollable blinking and closure of the eyelids and may lead to functional blindness. Cervical dystonia or spasmodic torticollis is a type of focal dystonia that affects muscles of the neck and shoulders. It causes uncontrollable turning of the head and abnormal postures. Oromandibular dystonia affects the face, mouth and jaw and causes tongue twisting and forceful opening and shutting of the jaw. Spasmodic dystonia or laryngeal dystonia affects the vocal cords and causes broken speech pattern and strained and strangled voice quality.
Treatment for Focal Dystonia
Treatment for focal dystonia aims to relieve the symptoms but the disorder cannot be reversed. Focal dystonia is most commonly treated with botox injections which prevent or reduce muscle contractions and twitching. Medications can be also used in treatment of focal dystonia in order to regulate release or production of chemical messengers in the brain.