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Idiopathic dystonia

Idiopathic dystonia represents group of the neuro and degenerative diseases which are mainly characterized by a dystonic hyperkinesia. Dystonia can be shown by the slow (tonic) or repeating stereotypic fast (kloniko-tonic) muscular spasms causing twisting around an axis (from here the term "the torsion dystonia" — from armor. torsio — rotation, twisting), bending or extension of a trunk and extremities. In the beginning dystonia arises only at the movement, then becomes a constant, remaining at rest and leading to forming of a resistant pathological pose. The idiopathic dystonia which is the reason about 90% of all cases of muscular dystonia, as a rule, has hereditary character, but is provided by both family, and sporadic cases. On prevalence dystonia can be generalized or focal.
Idiopathic generalized dystonia (the deforming muscular dystonia) usually begins at children's age (till 15 flyings) with involvement of one of the lower extremities. Within several years the hyperkinesia generalizutsya, extending to muscles of a trunk, a neck, upper extremities. Remissions are sometimes noted, but usually they happen short and incomplete. Idiopathic generalized dystonia is most often inherited on autosomal dominantly type. It is characteristic that disease severity even within one family can be various: at one patients the generalized form of dystonia, at others — a focal form is observed (for example, dystonia of foot or a spastic wryneck). Not less than at 60% of carriers of a pathological gene symptoms of a disease during life are not shown.
At part of patients with generalized dystonia symptoms of parkinsonism are observed (for example, a gipomimiya and a bradykinesia) and high performance even of small doses of drugs of a levodopa is noted (DOFA-zavisimaya dystonia, or Segava's illness). This autosomal and dominant disease which is connected with a mutation of the enzyme catalyzing one of early stages of synthesis of dopamine. The disease most often develops at the age of 4 — 8. Symptoms of parkinsonism and dystonia are to a large extent shown in the lower extremities and lead to the peculiar change of gait reminding gait at a children's cerebral palsy that quite often happens a reason for diagnostic mistakes. The expressed fluctuations of symptoms within a day are characteristic: usually they considerably decrease after a dream, but amplify in the second half of day, especially against an exercise stress. Continuous reception of small doses of drugs of a levodopa (for example, 1/4 or 1/2 tablets of a nakom a day) leads to permanent improvement.
Idiopathic focal dystonia begins after 15 flyings more often and is in most cases provided by sporadic cases. Face muscles (a nictitating spasm, oromandibulyarny dystonia), necks (a spastic wryneck), upper extremities are most often involved.
The idiopathic (essential) nictitating spasm is shown by an involuntary zazhmurivaniye owing to bilateral reduction of a circular muscle of eyes. Usually the nictitating spasm appears after 50 flyings. In the beginning patients complain of frequent blinking and feeling of irritation of eyes, then reductions of a circular muscle of an eye become more and more strong and long because of what patients cannot read, watch TV, cross the street, eat food. The nictitating spasm amplifies at bright light, a flaw and can temporarily decrease at a touch by centuries or a neck, use of dark glasses, closing of one of eyes with a bandage, conversation or singing. In process of progressing of process others are involved mimic and masseters, muscles of language, a throat and a neck. But long stabilization or spontaneous improvement is occasionally noted.
The dystonic nictitating spasm should be differentiated from the reflex nictitating spasm arising at chronic diseases of eyes, especially from irritation of a mucous membrane (for example, at a blepharitis, a keratitis, conjunctivitis, an iritis).
Idiopathic oromandibulyarny dystonia arises at advanced age more often and is shown by a hyperkinesia of muscles of area of a mouth, language, the lower half of mimic muscles, platizm. At patients the forced tightening of jaws with a lockjaw and gnashing by teeth (therefore teeth are gradually erased), broad opening or a perekashivaniye of a mouth, the chewing movements, protrusion of language are observed.
Differential diagnosis is carried out with late dyskinesia — the choreiform hyperkinesia caused by long reception of neuroleptics which often involves mimic and chewing muscles.
Idiopathic cervical dystonia (spastic wryneck) — the most frequent option of focal dystonia which is usually shown on the third — the fourth decade of life violent turn of the head aside, sometimes its inclination forward or back. As well as at other options of dystonia, the hyperkinesia amplifies at nervousness and exhaustion, but decreases after rest and at relaxation. Quite often patients notice that the touch to a chin, a face, a nape facilitates the dystonic tension (corrective gestures). At many patients the hyperkinesia is absent in a prone position, appears at a rising and amplifies when walking. 20% of patients in the first years after an onset of the illness have spontaneous remissions, the proceeding several months, flying is more rare, but then dystonia, as a rule, returns.
In special group allocate focal dystonia which is caused by only the certain specific movement or action, but it does not arise with the participation of the same muscles in other movement. As a rule, these options of dystonia appear against an extremity overload, usually at persons of certain professions if necessary often to repeat the stereotypic movements. The writer's cramp and the pianist's spasm at which painful data of fingers of a brush arise respectively only by the letter or playing a grand piano belong to this group of dystonia, for example.

Treatment.

The dystonia form will best of all respond to treatment DOFA-zavisimaya. As she not always manages to be otdifferentsirovat clinically, it is reasonable to try levodopa drugs in all cases of the dystonia which developed at children's and youthful age. At other forms of dystonia apply in various combinations cholinolytics, benzodiazepines (for example, clonazepam), muscle relaxants (for example, Baclofenum), antiepileptic means (for example, carbamazepine), neuroleptics (for example, Sulpiridum or a haloperidol), the central sympatholytics, the exhausting dopamine reserves in presynaptic depots (Reserpinum), however the positive take manages to achieve not always.
The most effective method of treatment of focal dystonias — botulotoxin injections in the muscles involved in a hyperkinesia. Botulotoxin causes partial paresis of these muscles and by that eliminates dystonia for 3 — 6 months then the injection should be repeated. Sometimes some improvement can achieve by impact on the muscles participating in a hyperkinesia by means of various physiotherapeutic procedures or special gymnastics.
In resistant cases resort to stereotaxic operations on basal gangliya or a thalamus or (for example, at some options of focal dystonia) to peripheral denervation of muscles.

 
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