Superior oblique myokymia

The superior oblique myokymia (of myos, μῦς Greek: " muscle " and kyma, κύμα Greek for "wave" ) is a very rare form of eye tremor. It is an episodic, single-sided micro- tremor of the superior oblique eye muscle (musculus obliquus superior). This is caused by uncontrolled activities of individual fibers of supplying it fourth cranial nerves, the trochlear nerve. A superior oblique myokymia is not to be confused with other pathological form of nystagmus, the nystagmus.

Symptoms

The affected eye a very fine, vertical, depending on the viewing direction or rotating tremor occurs. These attacks, hold for a few seconds, can occur several times a day and are usually felt themselves clearly from the patient. At the same time they take illusory movements ( oscillopsia ) and tilted diplopia true ( diplopia). The complaints are therefore sometimes perceived very intense. However Between attacks the finding is usually completely normal.

Sometimes you can provoke the tremor by looking down and inhibited by looking up. Although it is difficult to see during the Abblicks for the examiner, as he goes in the activities of normal innervated muscle fibers; see the patient again but straight, the affected nerve fibers are still excited by the previous infraduction and increase your chances to perceive the tremor. Nevertheless, the movements due to their low amplitude and high frequency are often identify only with the help of a special ophthalmologic apparatus ( slit lamp ).

Although the affected muscle may show, in rare cases, paralysis, usually occur on no other neurological disorders.

Patients usually describe very typical and characteristic for the disease symptoms. Nevertheless, they are often mistaken for hysterics. A correct diagnosis could easily be found if you would think of them.

Causes

The superior oblique myokymia is a benign disease whose cause has not been clarified yet secure. Probably it is triggered on the trochlear nerve by pressing the back of the brain artery ( posterior cerebral artery ).

In addition, a simultaneous case of lead poisoning and adrenoleukodystrophy have been described ever. However, the coincidence of these diseases could also have been inferred. Furthermore, a simultaneous case of epilepsy was documented.

The result of a specific neurological examination series using magnetic resonance imaging (MRI ) corroborated the assumption that the disorder could be caused by pressure on the nerve. Since then discussed to classify the superior oblique myokymia as a so -called neurovascular compression syndrome.

Treatment and prognosis

Although the superior oblique myokymia may disappear by themselves, in many cases, the spontaneous healing rate is known to be low. In severe subjective complaints may come into question a drug treatment with the membrane-stabilizing carbamazepine ( Tegretol ) or with beta -blockers ( propranolol, betaxolol ). However, the relationship between efficacy and adverse effects of these drugs is rather unfavorable in this case. If even after months of treatment there is no improvement, helps possibly a surgical transection and excision of the tendon of the superior oblique muscle. The resulting paralysis can then be mostly compensated satisfactorily more is done to the other eye muscles. However, the result remains a defect healing. Therefore, this relatively radical treatment seems necessary because a half-hearted weakness of the affected muscle from experience, easy to recurrence (relapse ) leads to the disease.

The neurosurgical decompression ( microvascular decompression) of the trochlear nerve can be an alternative in some cases. This corresponding successes have already been achieved, so that the hypothesis is supported also, after a superior oblique myokymia caused by pressure on the nerve.