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Front hemispasm


The front hemispasm is characterized by paroxysms of unilateral involuntary clonic reductions of the mimic muscles innervated by a facial nerve.
Epidemiology of a front hemispasm. The front hemispasm is among frequent motive frustration. Its prevalence reaches 7,4 on 100 000 men and 14,5 on 100 000 women. The disease meets among persons of middle and advanced age more often. Average age of an onset of the illness — about 50 years.

Symptoms of the Front hemispasm:

The hyperkinesia is shown by the clonic twitchings, sudden short-term irregular on duration and frequency, involving separate muscle bundles. They can be single, arise series or merge in longer tonic spasms, the lasting several tens of seconds or minutes. Per day there can be hundreds of attacks.

In the beginning twitchings involve only separate segments of a circular muscle of an eye (most often in a lower eyelid), but gradually extend to all muscle, and then and to adjacent mimic muscles, becoming more frequent and intensive. Muscles of the lower part of the person are usually involved later and to a lesser extent, than muscles of an upper part of the face. In a typical case the spasm is shown by a prishchurivaniye, a zazhmurivaniye, pulling up of a cheek, a corner of a mouth, nose wings, reduction of a muscle of a chin and platizm, sometimes — a nose tip deviation towards defeat.

It is characteristic that all these muscles are involved synchronously, but sometimes twitchings have wavy character, reminding a miokimiya. When involving a stapedial muscle at the time of a spasm in an ear clicks can sound.

In breaks between spasms the person remains symmetric, but at a part of patients on the party of a spasm easy weakness of mimic muscles (less expressed procrastination of a corner of a mouth comes to light at a grin, at a zazhmurivaniye — a leaky smykaniye a century with a symptom of "eyelashes"). And, despite natural progressing of a hyperkinesia, expressiveness of weakness of mimic muscles usually does not increase. Quite often between attacks symptoms of the raised muscle tone in the struck half of the face, for example, more profound, relief nasolabial fold are found.
Owing to the long tonic tension of a circular muscle of an eye narrowing of a palpebral fissure is possible.

At nervousness, the mimic movements, during the conversation and meal the hyperkinesia amplifies. The hyperkinesia can often be provoked a zazhmurivaniye. At rest and the weakened state muscular contractions weaken and urezhatsya. Periodically the hyperkinesia can disappear completely, but usually no more than for several minutes.

Unlike extrapyramidal hyperkinesias, the hemispasm remains in a dream though during its certain phases it can decrease or vanish. At most of patients emotional and personal disturbances, most often uneasiness and a depression which usually have reactive character develop and decrease after elimination of a hyperkinesia.

Having begun in the middle age, the hemispasm usually remains during all subsequent life. Spontaneous remissions are observed exclusively seldom. In the first 1 — 3 years usually there is strengthening of a hyperkinesia, then it is stabilized. But quite often with age nevertheless the tendency to slow progressing is noted.

In 5% of cases the front hemispasm is combined with an epileptiform neuralgia. This combination is usually caused by a compression front and a trifacial a vessel or volume education. At many patients the headache is noted (more often a headache of tension or a tservikogenny headache).

Reasons of the Front hemispasm:

Traditionally allocated primary (essential, or idiopathic) the front hemispasm arising owing to not clear reasons and the secondary (symptomatic) hemispasm caused by a prelum a vascular malformation, a tumor, etc. But in the last decades it was succeeded to find out that the majority of cases of a so-called "idiopathic" hemispasm is caused by a prelum of a facial nerve in the place of its exit from a brainstem a small artery or a vein (most often a branch of a back or front lower cerebellar artery).

The symptomatic hemispasm can be also caused by a prelum of a facial nerve a loop of the basilar artery (at its dolikhoektaziya) expanded with a vertebral artery is much more rare — a tumor of a back cranial pole, aneurism, an arachnoidal cyst, an arteriovenous malformation. Occasionally the hemispasm is caused by defeat of a vnu-tristvolovy part of a nerve (for example, at multiple sclerosis or a heart attack of a trunk). Sometimes it arises in the outcome of an acute neuropathy or an injury of a facial nerve, at a tumor of a parotid gland, Pedzhet's disease. The bilateral hemispasm can be caused by neuroborreliosis, sometimes an idiopathic neuropathy of a facial nerve.
The hemispasm usually results from an easy prelum of a facial nerve, and sometimes and just owing to contact of a nerve and a vessel. Its development requires only partial injury of a nerve usually insufficient for emergence of symptoms of paralysis of mimic muscles. It should be noted that the neurovascular conflict quite often comes to light at patients with a hemispasm and on not struck party, and also at healthy faces therefore a neurothlipsia — a necessary, but not sufficient condition for development of a hemispasm. At a vascular compression of a nerve the hemispasm most often develops in that case when the vessel contacts to a root of a facial nerve in the field of its exit from a brainstem.

This short site of a nerve (length of only 5 mm) is most sensitive to a prelum owing to the fact that it represents the place of contact of the central myelin formed by oligodendrocytes and the peripheral myelin created by schwannian cells. In this transitional zone a myelin layer thinner, than in other sites of a nerve. Besides, the hemispasm develops more often at a prelum of a front surface of a nerveroot whereas the prelum of a back surface of a root quite often is asimptomny.

In a zone of contact of a vessel and a nerve conditions for ectopic generation of impulses which can extend orto-and antidromno are created. Continuously following antidromic impulses gradually change a functional condition of neurons of a motive kernel of a facial nerve, causing their hyper excitability and spontaneous categories (kindling-effect).

This hyperexcitability of neurons of a kernel of a facial nerve decreases after a decompression of a facial nerve. In Ya. B. Yudelson (1980) opinion, the paroksizmalnost of manifestations and change of EEG at patients with a hemispasm, can demonstrate secondary involvement of supranuklearny structures — increase in activity of the reticular activating system, dysfunction of limbic structures. According to Vl.Golubev (1986), and lead injury of a nerve which can have the form of focal demyelination to formation of the centers of ectopic activity and efapatichesky transmission of impulses, plays a role of a starting factor whereas in implementation of a hyperkinesia and its "maturing" neurodynamic processes in which both peripheral, and central levels of an innervation of the person are involved have major importance.

More than at 60% of patients with a front hemispasm arterial hypertension which, on the one hand, can be the cause of expansion, lengthening and crimpiness of a vessel, and, on the other hand, the investigation of a prelum an abnormal vessel of side department of a myelencephalon which supports the centers controlling function of cardiovascular system comes to light.

Treatment of the Front hemispasm:

Medicamentous therapy includes use of antikonvulsant (carbamazepine, Phenytoinum, clonazepam, valproic acid, a gabapentin) and Baclofenum. However they have positive effect, more often moderate, only at a third of patients, and over time efficiency of drugs can decrease.

At identification of the reason of a compression of a facial nerve at patients of young and middle age an operative measure is shown (for example, a microvascular decompression of a facial nerve). Especially it is reasonable at gradually increasing weakness of muscles of a corner of a mouth. The essence of a microvascular decompression consists in separation of an artery from a facial nerve — the squeezing artery will be mobilized and separated from a nerve by means of a sponge, a piece of the pressed cotton wool, a muscle fragment, or teflon.

The positive effect is reached approximately in 85% of cases. Complications are noted infrequently (5 — 10%) and include paresis of mimic muscles, deafness, numbness of the person, dizziness, a liquorrhea, but they in most cases have passing character, only certain patients have resistant complications (most often paresis of mimic muscles and relative deafness).

However in recent years resort to an operative measure more and more seldom, and local administration of botulotoxin of type A in the muscles involved in a hyperkinesia becomes treatment of the choice at a front hemispasm. Botulotoxin contacts a presynaptic membrane of a neuromuscular synapse and slows down release of acetylcholine that leads to partial chemical denervation of muscles in which the injection is carried out. In most cases improvement is shown within 48 — 72 hours after an injection and 2 — 3 more weeks continue to accrue.
Full remission after administration of botulotoxin is observed seldom — patients report to a thicket about reduction of expressiveness of symptoms by 75 — 90%. Some patients feel twitchings though externally reductions of muscles do not come to light neither visually, nor palpatorno. As especially often disturbs patients zazhmurivany eyes, injections originally make only in a circular muscle of an eye (as well as at a nictitating spasm). At the same time often patients are helped by lower doses, than at a nictitating spasm of 15-50 PIECES of Botox or 40 — 125 PIECES of disport (perhaps, because of involvement of a nerve and partial denervation of muscles).

However administration of botulotoxin in a circular muscle of an eye can lead to easing not only it reductions, but also reductions of other mimic muscles. In this regard assume that the circular muscle of an eye works as a peculiar trigger for muscles of the lower half of the face.

Complications at administration of botulotoxin are usually connected with excess weakness of the injected muscles or distribution of botulotoxin on the next muscles. They include a ptosis, weakness of closing of eyes, a lagophthalmia that can lead to a keratitis, dryness of an eye, a sight illegibility, dacryagogue. Occasionally doubling meets. Unlike a nictitating spasm, at patients with a hemispasm even the minimum ptosis is swept up (against the background of the healthy party). As a rule, complications spontaneously regress within several days or weeks.

If reduction of a spasm of a circular muscle of an eye is not enough for simplification of spasms of a muscle of a forehead and the lower half of the face, botulotoxin can be injected in a muscle of arrogant men, a cross part of a nasal muscle, a mental muscle, the muscle lowering an under lip, a laughter muscle, to a platizm. It is necessary to consider that narrower therapeutic window is characteristic of muscles of the lower half of the face (a difference between the dose of botulotoxin eliminating a hyperkinesia and the dose causing paresis) therefore at administration of drug in them the risk of side effect significantly increases.

It is necessary to avoid injections in the muscles lifting a mouth corner, malar muscles, a circular muscle of a mouth (in an upper lip). The main side effect connected with injections in the lower half of the face — weakness of mimic muscles with asymmetry of the person, omission of a corner of a mouth, hypersalivation, biting of a gingiva. Injections in muscles of a forehead can lead to temporary omission or impossibility of a raising of eyebrows.

The effect of an injection of botulotoxin keeps on average about 4 — 5 months, then gradually weakens that demands repeated injections. Unlike a nictitating spasm, improvement remains is longer, but at repeated introductions its duration and expressiveness usually do not tend to increase. On condition of regular administration of botulotoxin 2 — 3 times a year efficiency of drug remains during the long time. The tachyphylaxis and tolerance develop extremely seldom.

Most of patients had effective also an introduction to muscles of hemoterapevtichesky means of doxorubicine (hemomiektomiya), but long-term efficiency and safety of this method of treatment is so far not investigated.

In treatment of patients physiotherapeutic methods and acupuncture can be useful, however they seldom render a little lasting effect. In the presence of a depression and a chronic headache of tension antidepressants, first of all tricyclic are shown (amitriptyline, доксепин).

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