Orphenadrine

Involuntary movements of the face, tongue, palate, pharynx, vocal cords and neck are grouped into the broad classification of cranial-cervical dyskinesias (Table 1).(1) In many dyskinesias, there is evidence of pathology in the basal ganglia or the midbrain. Areas of the basal ganglia involved in orofacial control may be particularly susceptible to the aging process and to the effects of neuroleptic drugs, since the development of many cranial-cervical dyskinesias appears to relate to advancing age or drug or other toxin exposure.

Dystonic movement disorders are characterized by muscle tone abnormalities, often manifested as increased muscle tone or muscle spasms. Meige syndrome is characterized by buccolingual, lower facial and eyelid spasms. The eyelid spasm alone is referred to as essential blepharospasm. Hemifacial spasm is pathophysiologically unrelated to the dystonias and is best classified under the broad heading of myoclonus.

This article reviews the diagnosis and management of Meige syndrome, essential blepharospasm and hemifacial spasm. All three conditions manifest with facial squeezing, and all share common treatment modalities.

Cranial-Cervical Dystonia

Dystonia is probably the most common form of spontaneous cranial-cervical dyskinesia, and Meige syndrome is a frequent pattern of dystonia in the cranial-facial region.

In dystonic movement disorders, involuntary contractions begin in one muscle group and spread over time to involve adjacent muscle groups. Contractions of the eyelids, lower facial muscles or orobuccolingual region may be termed Meige syndrome Figure 1). Contractions around the mouth, including the j aw, tongue and pharynx, may be classified as oromandibular dystonia (Brueghel's syndrome). Contractions of the neck muscles are classified as nuchal dystonia (i.e., torticollis, retrocollis, anterocollis), while contractions of the vocal cords are termed spastic dysphonia.

With cranial-cervical dystonia, areas of involvement are overlapping and may represent the same disease process with different innervational levels and severity of involvement. It is common for a patient who presents with dystonia in one area to develop dystonia in other cranial-cervical areas over time.(2)

Lesions in the basal ganglia and the brainstem sometimes cause secondary facial dystonia. Gliosis and abnormal neurotransmitter levels have also been demonstrated in the midbrain and brainstem nuclei of patients with Meige syndrome.(3) Abnormalities of brainstem auditory-evoked potentials at the pontine level have been found in one-third of patients with Meige syndrome or essential blepharospasm,(4) providing further evidence of brainstem pathology in these disorders.

WORK-UP

Despite the brain abnormalities that may be present, Meige syndrome, as well as other cranial-cervical dystonias, remains a clinical diagnosis. No specific laboratory test or imaging study is necessary to diagnose cases with a characteristic onset and typical clinical features. Neurologic evaluation, laboratory tests and imaging studies may be indicated in atypical cases.

MANAGEMENT

Therapy of idiopathic Meige syndrome is difficult. Some patients may respond to one or more of the therapies used to treat essential blepharospasm or hemifacial spasm, such as botulinum A toxin (Oculinum). Small doses of botulinum A toxin may be injected into facial muscles to dampen the spasms associated with Meige syndrome, although these injections must be administered carefully to avoid facial paralysis. The oral medications used to treat benign essential blepharospasm also may be useful in controlling facial spasms.

Essential Blepharospasm

Essential blepharospasm, also termed benign essential blepharospasm, is a progressively debilitating form of cranialcervical dystonia characterized by chronic, forceful spasm of the eyelid protractor muscles, principally the orbicularis oculi. This dystonia is three times more common in women than in men and occurs after age 50 in 72 percent of cases.

The onset of essential blepharospasm is usually heralded by an increased frequency of blinking. The dystonia progresses to sustained and then forceful lid closure, culminating in uncontrollable eyelid spasm.(3) The course of the disorder fluctuates and is marked by spontaneous remissions and exacerbations. Symptoms generally progress for several years, reaching a plateau five to seven years after the onset.

Patients with benign essential blepharospasm may initially complain of photophobia, ocular pain, dry eyes or other seemingly unrelated causes of uncontrollable eyelid closure. In many cases, the correct diagnosis is made only after multiple physicians have been consulted and the disease has progressed.

Fatigue, bright lights and social interactions may exacerbate essential blepharospasm. Sensory and proprioceptive tricks," such as whistling, humming, singing or massaging a pressure point, may temporarily relieve the spasm in some patients. Because of these factors, as well as the fluctuating course and limited organic signs, misdiagnosis is common, and the condition is frequently thought to be psychogenic in origin.

WORK-UP

An ophthalmic examination is important to ensure that the eyelid spasm is not secondary to an ocular condition such as corneal disease, uveitis, macular disease or cataracts. Ophthalmologic causes of reflex blepharospasm are listed in Table 2.5 Ocular conditions, especially dry eyes, frequently exacerbate essential blepharospasm, and treatment of concurrent ocular conditions may reduce the eyelid spasm to a level that the patient finds tolerable.

Blepharospasm may arise secondarily from chronic administration of neuroleptic agents (e.g., tardive dystonia), or it may coexist with Parkinson's disease. Other secondary causes of blepharospasm or facial dystonia include strokes in the upper brainstem and multiple sclerosis involving the brainstem.

No diagnostic work-up is indicated in cases with characteristic features and presentation. Laboratory tests and imaging studies such as computed tomographic (CT) scanning or magnetic resonance imaging (MRI) are generally unrevealing and are not considered necessary for the work-up of patients who present with typical essential blepharospasm or Meige syndrome and an otherwise unremarkable history and neurologic examination. Atypical features (e.g., acute onset) or the presence of other neurologic signs suggests the need for imaging studies and neurologic evaluation.

MANAGEMENT

Unconventional Therapy. Benign essential blepharospasm has been treated with a variety of unconventional therapies, including psychotherapy, biofeedback, acupuncture, and herbal and folk remedies. Such approaches generally are of little value, although they may provide a brief period of perceived relief. Some benefit may be derived from the use of dark eyeglasses or ptosis crutches attached to eyeglasses or from the administration of artificial tears.

Pharmacotherapy. Numerous drugs have been reported to be effective in relieving benign essential blepharospasm and the cranial-cervical dystonias. In most cases, however, relief is only partial and short-lived. Some patients experience significant long-term relief with oral medications alone. For most patients, the benzodiazepines, such as lorazepam (Ativan), 0.5 to 2.0 mg two to three times daily, clonazepam (Klonopin), 0.5 to 5.0 mg three times daily, or oxazepam (Serax), 10 to 30 mg three to four times daily, are effective medications. Mild anticholinergics, including orphenadrine citrate (Norflex), one 100-mg tablet twice daily, and trihexyphenidyl (Artane), 1 to 3 mg three times daily, may be effective. Recently, cyproheptadine (Periactin), an antihistamine with antiserotonergic and anticholinergic properties, has been promoted as a pharmacologic treatment for essential blepharospasm.(6)

Oral medications are most useful in controlling very mild blepharospasm or in suppressing lower facial spasms in patients with Meige syndrome previously treated with botulinum A toxin injection or surgical myectomy. Drug therapy should be instituted at a low dose; to obtain the desired effect, the dose is then increased as tolerated. A different medication should be tried if objectionable side effects occur, the selected drug is ineffective after a trial of two to six weeks or the effect is lost over weeks or months. Forty to 60 percent of patients note some relief of facial spasm with drug therapy.

Botulinum A Toxin. The A toxin serotype produced by Clostridium botulinum is a potent paralytic drug. Since the initial report in 1984, (7)botulinum A toxin has been used extensively in the treatment of the cranial-cervical dystonias, especially essential blepharospasm and the blepharospasm component of Meige syndrome. In early 1990, botulinum A toxin was approved by the U. S. Food and Drug Administration for use in the treatment of strabismus, essential blepharospasm and other disorders of facial nerve function in patients over 12 years of age.

Subcutaneous injection of botulinum A toxin into the eyelids and eyebrows relieves spasm for an average of three months in 85 to 90 percent of patients. The efficacy of botulinum injection and the low risk of side effects have made botulinum A toxin the preferred therapy for disabling benign essential blepharospasm. Spasmodic torticollis has also been treated effectively with injections into the involved neck muscles.(8)

The side effects of botulinum toxin type A are generally well tolerated. Exposure keratitis, a frequent side effect, is managed with an ocular lubricant (e.g., artificial tears), applied four times daily, and with a nonmedicated ophthalmic ointment (e.g., Refresh PM), applied to the eyes at night for several weeks after the injections.

Diffusion of the toxin into the deeper tissues occasionally results in ptosis (paralysis of the levator palpebrae superioris) or diplopia (inferior oblique muscle weakness). These side effects generally resolve within several weeks. Injections of the toxin into the lower face to control the oromandibular manifestations of Meige syndrome must be done cautiously, because facial drooping and drooling can occur following the injection.

SURGICAL TREATMENT

Radical myectomy currently is the preferred surgical treatment for blepharospasm.(9) This procedure, which involves extirpating the squeezing muscles around the eyelids, is indicated for functionally disabling essential blepharospasm resistant to other forms of therapy. During surgery, it is also possible to repair coexisting defects, including brow ptosis, blepharoptosis and lateral canthal laxity.

Good functional results may be obtained in about 80 percent of patients who undergo radical myectomy.(10) However, because of the excellent results achieved with injections of botulinum A toxin, myectomy now plays a lesser role in the management of benign essential blepharospasm. Hemifacial Spasm

Hemifacial spasm is characterized by involuntary paroxysmal bursts of tonic or clonic contraction of muscles innervated by the facial nerve. The disorder is etiologically distinct from benign essential blepharospasm and the other facial dystonias. The average age of onset (45 years) is less than that in the facial dystonias, and the female-to-male preponderance is also less (3:2).

The condition typically begins with intermittent twitching of one eyelid. Over months to years, the twitching progresses to involve other ipsilateral areas of facial nerve innervation Figure 2). In many patients, tension and fatigue are aggravating factors. Associated findings include mild facial weakness, ipsilateral hearing loss and, occasionally, vertigo."

Clinical examination alone usually separates hemifacial spasm from other unilateral facial spasms. In some patients, electromyography of the facial muscles and blink reflex testing help distinguish hemifacial spasm from other conditions with a similar appearance.

Diagnostic features of some of the conditions that cause facial spasm are summarized in Table 3.(11) The differential diagnosis of hemifacial spasm includes facial synkinesis, hemifacial contracture and transient myokymia. In facial synkinesis and hemifacial contracture, mass movement of the facial muscles results from aberrant nerve regeneration following a facial palsy. Transient myokymic twitching is rapid undulation or flickering contraction of individual fascicles of a facial muscle, usually following stress, sleep deprivation or excessive alcohol or caffeine ingestion. Persistent or progressive facial myokymia may be associated with multiple sclerosis or brainstem glioma; a work-up is indicated in patients with this condition.

Hemifacial spasm is thought to result from cross-compression of the facial nerve by an anomalous vessel at the root entry zone of the facial nerve into the brainstem in the cerebellopontine angle. This pulsating compression damages the seventh cranial nerve and stimulates its aberrant depolarization. Because of the frequent association of hemifacial spasm with dolichoectasia (an elongated vascular dilatation) of the vertebrobasilar system and the occasional association of hemifacial spasm with brain tumors, a contrast CT scan or MRI is recommended in the evaluation of these patients.

MANAGEMENT

Pharmacotherapy. Since it has been theorized that hemifacial spasm is caused by a damaged facial nerve or a hyperactive facial nucleus, anticonvulsant drugs with membrane-stabilizing activity have been tried in its treatment. Anticonvulsants such as phenytoin (Dilantin) and carbamazepine (Tegretol) may occasionally control hemifacial spasm; however, less than 25 percent of patients benefit from such therapy. The short-acting benzodiazepines and the weak anticholinergics recommended in the treatment of essential blepharospasm are sometimes effective in suppressing mild hemifacial spasm.

Botulinum A Toxin. Injections of botulinum A toxin have been effective in treating the periorbital manifestations of hemifacial spasm, with few complications. As in the treatment of essential blepharospasm, injection must be performed carefully since even temporary facial drooping is very disconcerting to the patient.

Many experts feel that the response to injections of botulinum A toxin is even better in hemifacial spasm than in essential blepharospasm, with a longer-lasting effect achieved at a lower dosage. The high efficacy of botulinum A toxin in hemifacial spasm almost obligates the physician to try this therapy before proceeding to surgery.

SURGICAL TREATMENT

As in the treatment of essential blepharospasm, destructive procedures such as selective facial nerve avulsion have nearly been abandoned as a treatment of hemifacial spasm. The myectomy procedure as described for essential blepharospasm has been modified and successfully used in patients with hemifacial spasm. In one study,(12) myectomy produced good results in 20 of 21 patients.

Microvascular decompression of the facial nerve through submastoid craniectomy and microscopic manipulation of the vessels surrounding the facial nerve at its root entry zone in the cerebellopontine angle is effective in the treatment of hemifacial spasm. In a review of 433 patients, (13) 364 patients (84 percent) with hemifacial spasm were reported to be "cured" with one operation; permanent complications were encountered in 70 patients (16 percent). Microvascular decompression provides a chance for permanent cure in patients with severe hemifacial spasm who have not responded to other modes of therapy and who are willing to risk neurosurgical complications.

Final Comment

In both benign essential blepharospasm and hemifacial spasm, signs and symptoms become more severe when patients are under stress. Consequently, these conditions frequently are misdiagnosed as psychogenic disorders. Social embarrassment and functional deficits may lead to depression and reclusiveness. Consequently, it is essential that facial dyskinesias be recognized by primary care physicians. Fortunately, most patients can be functionally and socially rehabilitated. Generally, the sooner a correct diagnosis is made, the better the disease and its treatments are accepted by the patient. Preparation of this manuscript was supported in part by an unrestricted grant from Research to Prevent Blindness, New York City, to the Department of Ophthalmology at the University of Utah School of Medicine, Salt Lake City, and the Bethesda Eye Institute, St. Louis.

COPYRIGHT 1991 American Academy of Family Physicians
COPYRIGHT 2004 Gale Group