Blepharospasme

Blepharospasme/ Benign Essential Blepharospasm adalah suatu distonia fokal bilateral yang ditandai dengan spasme umum yang bermula sebagai kedutan ringan (mild twitches) atau pun mengedip yang sering dan terjadi secara involunter. Hal ini terjadi karena kontraksi m.orbicularis oculi. Kondisi ini lama kelamaan akan berlanjut menjadi kebutaan akibat ketidakmampuan eposidik membuka kelopak mata.

Etiologi blepharospasme bersifat muti faktor, terdiri dari gangguan ekstra pyramidal dan batang otak maupun faktor psikologis. Penelitian menggunakan MRI menunjukan adanya lesi fokal pada batang otak bagian rostral, diencephalon dan ganglia bsalis. Pada kasus blepharospasme essensial menunjukan adanya suatu hiperaktivitas sirkuit lortikal. Selain itu juga blepharospasme dapat disebabkan oleh obat-obatan untuk mengobati parkinson, trauma pada mata, blepharitis, mata kering, Tourette syndrome

Gejala klinis blepharospasme diawali dengan mengedip yang berlebihan saat terpapar dengan cahaya, angin maupun stres, dengan progresivitas sesuai berjalannya waktu dapat terjadi spasme involunter M.Orbicularis oculi secara bilateral, spasme dapat terjadi secara hebat dan menetap. Terdapat juga droopy eyelids, fotofobia, pengelihatan kabur, kedutan pada kelopak mata yang tidak terkendali.

Penatalaksanaan kasus ini adalah penggunaan kacamata hitam untuk menghindari pemicu nya terhadap cahaya, menjaga kebersihan kelopak mata untuk mencegah iritasi, dan penggunaan artificial tears untuk mengurangi gejala. Selain itu ada pula injeksi berulang secara periodik Botulinum toxin type A dapat menghasilkan paralisis otot terlokalisir. Injeksi daro Botox ini bersifat temporer. Onset of action rata-rata adalah 2-3 hari, dan efek puncak terjadi sekitar 7-10 hari setelah injeksi. Efeknya pun bervariasi sekitar 3-4 bulan. Untuk tindakan operatif dapat dilakukan myectomy

Blepharospasm is a neurological condition characterized by forcible closure of the eyelids. The purpose of the Benign Essential Blepharospasm Research Foundation (BEBRF) is to undertake, promote, develop and carry on the search for the cause and a cure for benign essential blepharospasm and other related disorders and infirmities of the facial musculature.

Blepharo means "eyelid". Spasm means "uncontrolled muscle contraction". The term blepharospasm ['blef-a-ro-spaz-m] can be applied to any abnormal blinking or eyelid tic or twitch resulting from any cause, ranging from dry eyes to Tourette's syndrome to tardive dyskinesia. The blepharospasm referred to here is officially called benign essential blepharospasm (BEB) to distinguish it from the less serious secondary blinking disorders. "Benign" indicates the condition is not life threatening and "essential" is a medical term meaning "of unknown cause". Patients with blepharospasm have normal eyes. The visual disturbance is due solely to the forced closure of the eyelids.

Blepharospasm should not be confused with:

Ptosis - drooping of the eyelids caused by weakness or paralysis of a levator muscle of the upper eyelid

Blepharitis - an inflammatory condition of the lids due to infection or allergies Hemifacial spasm - a non-dystonic condition involving various muscles on one

side of the face, often including the eyelid, and caused by irritation of the facial nerve. The muscle contractions are more rapid and transient than those of blepharospasm, and the condition is always confined to one side

Sumber : http://www.blepharospasm.org/

Since the central control center for blepharospasm is unknown, drug therapy directed against this as of yet unidentified center tends to follow a "shotgun approach." Historically, an extensive list of drugs has been used to treat blepharospasm, in part because blepharospasm initially was considered a manifestation of psychiatric illness, and because no one drug was demonstrably more efficacious than another. Recently, these psychoactive medicines have been used not for their psychotropic action but for their motor system action.

Most patients respond incompletely or not at all to pharmacotherapy. At best, pharmacotherapy provides only partial, transient relief. Patients react differently to the various pharmacologic agents, and there is no way to predict which patient may respond to any particular agent. Tricyclic antidepressants do not directly help blepharospasm but are useful if there is depression exacerbating the symptoms. Drugs with the highest percentages of favorable patient responses include lorazepam (67% of patients), clonazepam (42%), and Artane (41%). The relief provided by these agents is variable.

Although drugs from a variety of different classes have demonstrated some effectiveness in blepharospasm, drug therapy for blepharospasm and facial dystonias usually are based upon the following 3 unproven pharmacologic hypotheses: (1) cholinergic excess, (2) GABA hypofunction, and (3) dopamine excess. Pharmacotherapy is generally less effective than BOTOX® injections and, thus, is reserved as second-line treatment for spasms that poorly respond to BOTOX®, such as in mid-face and lower-face spasm.

Botulinum toxin

Botulinum A toxin, or BOTOX®, is regarded as the most effective treatment of choice for the rapid but temporary treatment of orbicularis spasm. More than 95% of patients with blepharospasm report significant improvement with use of the toxin. The toxin interferes with acetylcholine (ACh) release from nerve terminals, causing temporary paralysis of the associated muscles. Botulinum A toxin is the

product of the bacteria, Clostridium botulinum(a large anaerobic, gram-positive, rod-shaped organism).

Once injected, the toxin rapidly and firmly binds at receptor sites on cholinergic nerve terminals in a saturable fashion. The toxin is internalized through the synaptic recycling process. Paralysis of muscle is a result of the inhibition of the release of vesicular ACh from the nerve terminal. It is assumed that the toxin attaches to the ACh-containing vesicles in the nerve terminal and prevents calcium-dependent exocytosis.

The paralytic effect is dose related, with a peak of effect at 5-7 days after injection. Patients typically note the onset of relief 2.5 days after injection, with a mean duration of relief from symptoms of 3 months. More than 5% of treated patients have sustained relief for more than 6 months, although some patients require injections as often as monthly. It takes as much as 6-9 months for the injected muscles to recover from the effects of the toxin, and, occasionally, muscles do not fully return to their preinjection level of function. Some have suggested that the development of antitoxin antibodies or the progressive atrophy of muscle may account for variations in the dose response curve, but no studies have supported these findings.

Complications of botulinum toxin injections include ptosis (7-11%), corneal exposure/lagophthalmos (5-12%), symptomatic dry eye (7.5%), entropion, ectropion, epiphora, photophobia (2.5%), diplopia (< 1%), ecchymosis, and lower facial weakness. One of the more common adverse effects, ptosis, is due to diffusion of toxin from the upper eyelid injection sites to the exquisitely sensitive levator muscle. The incidence of ptosis has been reported as high as 50% of patients treated more than 4 times. In the hands of experienced injectors, the rate of complications such as ptosis is presumably less. Injection of botulinum toxin into the medial and lateral pretarsal orbicularis is usually sufficient to stop spasms for the duration of effect; avoiding central injections to the preseptal and preorbital orbicularis should help reduce the risk of ptosis.

Meticulous technique in the administration of BOTOX® helps ensure reliable and consistent results. BOTOX® should be hydrated with 0.9% nonpreserved saline, which should be introduced slowly into the vacuum-sealed vial to prevent frothing. Once reconstituted, the solution should be used within a few hours or refrigerated.

At the first treatment, use of a total dose of no more than 25 units per eye, divided among 4-6 periocular injection sites is recommended to avoid adverse effects. Subsequent treatments should be adjusted depending on patient response to the initial doses. At each site, inject 2.5-10 units of BOTOX®. Use of lower volumes (higher concentrations) is suggested to avoid the risk of spread to adjacent areas. The solution should be injected subcutaneously over the orbicularis oculi and intramuscularly over the thicker corrugator and procerus muscles. Patients may return home without restrictions of activity. Most patients require repeated treatment every 3 months, but this ranges from 1-5 months.

Sumber : http://emedicine.medscape.com/article/1212176-treatment