The term 'dystonia' refers to a condition wherein the muscles of various parts of the body are subjected to involuntary contraction. The symptoms could be mild or severe enough to jeopardise daily activities. Generally, the condition has been classified under five categories: generalised, focal, segmental, multifocal, and hemidystonia. In the first type, the condition may strike early, and go on to affect the entire body. This kind is generally considered to be of a genetic nature. The focal type usually occurs in adults and tends to concentrate on localised area such as the neck, face, or arm. Segmental type affects those regions of the body that are connected to each other, whereas multifocal type affects those which are not in connection to each other. In case of hemidystonia, half of the body is affected.
Causes of dystonia
There aren't any specific, identifiable causes of this condition. However, it is believed that this condition might be linked to damage to the basal ganglia, which is the part of the brain that is responsible for muscle contractions.
The symptoms depend upon the area of the body that is affected by involuntary muscle cramp (muscle contraction).
- Eyes: When the condition affects the eyes, the contractions might be so severe that the affected person may start blinking tremendously. This is a focal type of the condition called blepharospasm. Apart from the blinking disorder, one might experience irritation, and develop extreme sensitivity to light. Also, the eyes may be caused to shut down involuntarily. In some cases, the patient might not be able to open his eyes for some time, making him visually impaired temporarily.
- Hands: One classic sign of the condition affecting the hands is the inability to play music on an instrument and worsening of one's handwriting. This is also categorised in the focal type, and is specifically known as writer's cramp. Here, the muscles of the arm suffer involuntary cramps and movements.
- Voice Box: In this case, the part affected is the larynx. The spasms could make the voice sound airy, quiet, or somewhat like strangled. Even this is a kind of focal dystonia.
- Neck: This is also categorised in focal type. It is characterised by intense spasms of the neck muscles. It is also called cervical dystonia. Here the symptoms include twisting and trunking of the head to one side so violently that it may cause tremendous pain. Also, the head might move forward or backward involuntarily.
- Jaw Area: Also known as oromandibular dystonia, this is categorised as a segmental type. This is characterised by forceful contractions of the face, jaw, and/or tongue, which in turn, cause difficulty in opening and closing the mouth. This affects the process of chewing and might cause slurred speech or difficulty in swallowing. This condition is rare.
- Face: When the muscles of one side of the face suffer spasm, the condition is referred to as hemifacial spasm. This is also classified under the focal type. It seems to worsen under stress and fatigue.
There are certain oral medications which aid in improving the function of neurotransmitters that are involved with muscle movement. Apart from these, patients may also be administered with botulinum toxin injections. This agent blocks the release of a chemical messenger that triggers muscle contraction.
Deep brain stimulation is another technique which involves implanting a device in the chest. This device is connected to an electrode implanted in the brain. The device generates electrical pulses that are conveyed to the electrode, which again feeds the signal to a specific region to the brain that controls and reduces muscle contraction.
Sensory trick is another method wherein a physical gesture or position can help reduce the contractions. For instance, placing the hand on the chin or back of the head can help reduce involuntary contractions in case of torticollis.
Surgery is recommended when all the conventional treatment methods fail to produce the desired results. However, it is suitable for eyelid or neck (cervical) dystonia. Here, the surgeons simply remove the nerves that are responsible for causing involuntary contractions.