Causes of dystonia

What is Dystonia?

Dystonia is a loss of the muscle tone and muscle tension. It involves involuntary hyperkinetic movements. This disease is characterized by continuously or periodically repeated muscle contractions. Dystonia causes deflection or abnormal positions of the body. This disables patients or leads to inappropriate position of body parts or the whole body. Sometimes, pain occurs and various complications arise.

In extremely severe cases, the deflection of the whole body or appearance of dystonic status when medical procedures aren’t able to prevent such movements can cause damage to the muscle structure.

Classification of Dystonia

Dystonia include a very diverse group of diseases that can be classified according to age of disease appearance, localization of dystonic movements, etiology and so on.

According to dystonia movements localization there are focal, segmental and generalized dystonia.

Focal dystonia includes: blepharospasm, oromandibular dystonia, spasmodic dystonia and cervical dystonia.

Cervical dystonia is characterized by muscle cramps that cause moving of the neck to the side, forward or backward. Also, a shoulder may be raised to an inclined head. Besides that, head tremor may be present. Movements may be painful. Blepharospasm is reluctantly frequent blinking, glimmering or closing the eyes. It also includes eyes and eyelids irritability and sensitivity to light and wind.

Oromandibular dystonia includes muscle spasms that cause the opening and closing of the mouth, distorted speech and dysphagia.

Writer's hand is characterized by difficulty in writing, muscle cramps in hand and wrist while trying to write and presence of pain.

Spastic dysphonia manifests as difficult straining speech, sometimes with shortness of breath and whispering speech which is sometimes impossible. Generalized dystonia usually occurs in childhood on the arm or leg which later spreads on the trunk.

Symptoms

Dystonic involuntary movements are relatively slow and long-lasting causing abnormal position of extremities (twisting). Trunk and limbs musculature are affected by these movements. The movements are often repetitive. The most common initial symptom is action leg dystonia superimposed with willing movement. Child occasionally twists legs and feet in unnatural ways. Sometimes, shoulder convulsions or grimacing may occur. Later on, the muscles of the trunk, shoulders and pelvic girdle are included too. In the beginning, spasms (cramps) occur rarely, then more and more frequent until they become permanent. Head muscles are also affected and speech and swallowing function can be disordered. In some cases generalized dystonic symptoms become very frequent and difficult. This condition is called dystonic status. Some of these patients require mouth to mouth reanimation and in some cases this stage has lethal outcome.

Causes

Primary dystonia is a hereditary disease which can be autosomal- recessively transmitted. It occurs in early childhood, rapidly progresses and appears only in the Jews. Also, it may be dominantly transmitted. Such condition starts later, often in adolescence, progresses slowly and its occurrence is not linked to nationality.

Symptomatic dystonia can be seen in Wilson's disease, Huntington's disease, Hallervorden-Spatz’s disease, birth trauma, application of various neuroleptics and basal ganglia damages.