Dystonia is a disorder of the nerves which causes various muscles undergo sudden and abnormal contractions which results in repetitive and abnormal movements. Sometimes, the body gets distorted into abnormal postures for certain intervals of time due to the twisting movements caused by such muscular contractions. Focal dystonia is a type of dystonia where such abrupt and unnatural muscular contractions are focused at a single or a cluster of muscles in a particular area of the body.
For instance, focal hand dystonia is characterized by uncontrolled, involuntary, sudden and spasmodic closing in and opening out of the fingers of the hands. In focal dystonia of the hand, the inward curling and outward opening motions of the fingers take place in sudden, uncontrolled spasms rather than intentional or voluntary contraction of the muscles of the hands. So, what causes focal dystonia? What are the symptoms and how can this neurological condition be treated? Let's proceed upon finding out the answers to these questions.
So, what exactly causes focal dystonia and what are the mechanics behind this condition? Well, the sudden, spasmodic muscle twitching takes place when the neurons that are present in the thin nervous tissue layer enclosing the brain (sensorimotor cortex) misfire. The sensorimotor cortex can be equated with a neurological map of the entire human body and each part of the body, its functions and movements, are represented upon this map. When a representation of a certain body part becomes blurred or distorted upon this neural map, the neurons that carry message to such a body part get confused causing them to misfire. This induces the uncontrolled, sudden twitches and abnormal muscular contractions that are characteristic of focal dystonia.
Another reason behind the dystonia of a particular body part, or a specific muscle region thereof, is different areas of this neural map getting cross connected. This leads to the wrong neural signals being sent to the wrong areas. It's very similar to telephone line cross connections where your phone rings for the wrong reasons and you may be able to listen to the conversation of other people without being able to do much about it. Both these reasons lead to either loss of motor control or distorted motor functions of the affected cluster or group of muscles.
Any uncontrolled and sustained contraction of a single or a group of muscles in any part of the body may indicate towards possible focal dystonia. Also, any sudden case of postural distortion of any part of the body is a common dystonia symptom and may be indicative of focal dystonia. The most common cases of this type of dystonia occur in the eyelids (Blepharospasm which is characterized by either an increase in blinking or persistent closure of the eyelids causing functional blindness), the head and neck (cervical dystonia which is characterized by muscular spasms in these areas and may even result in the neck assuming twisted or other abnormal postures), the lower part of the face and lower jaw (Oromandibular and lingual dystonia which are symptomized by forceful opening and closing of the mouth caused by strong contraction of the local muscles), larynx (spasmodic dystonia which is indicated by the affected individual having difficulty with his/her vocal cord functions) and limbs.
The most common treatment of this condition is botox. This is a symptomatic treatment and botox injections only serve to alleviate the muscular spasms. These injections do not cure the condition at the neurological level. The only way to eradicate this disorder from its roots is to retrain the sensorimotor to enable the misrepresented or affected body part to be better identified upon this neural map. This is like re-wiring the brain and remapping the sensorimotor cortex.
Many a time, musicians and instrumentalists develop focal dystonia of the hands, mouth and fingers as an overuse or overtraining of certain muscles has shown to cause a representative distortion of that muscle upon the cortical map. Leon Fleisher, Alex Klein, Ernestine Whitman, Keith Emerson and Gary Graffman are such notable musicians who have been diagnosed with dystonia of various muscles, depending upon their mode of creating music. Dilbert comic strip creator Scott Adams also suffers from dystonia of the hand.