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The two most common conditions that are characterized by involuntary movements of the face are blepharospasm and facial spasm (hemifacial spasm).
Essential blepharospasm is a chronic disorder characterized by an involuntary clonic (repetitive) or tonic (sustained) bilateral closure of the eyelids. Long believed to be of functional origin, blepharospasm is now considered to be a cranial dystonia. When the involuntary contractions also affect other cranial and cervical muscles, as is the case in the majority of patients, the disorder is known as the Meige syndrome, or craniocervical dystonia. The muscles that may be involved in Meige syndrome include those of the face, mandibular region, pharynx, and larynx. In a case, all or only some of these muscles may be involved. The different muscle groups can also be involved in isolation, as in oromandibular dystonia, spasmodic dysphonia, and cervical dystonia.1,2 The prevalence of the syndrome is five to 10 cases per 100,000 people.3 It affects primarily middle and older age adults and is more frequent in women.
Clinical Features
Ocular discomfort, a feeling of grittiness, and excessive blinking are frequently the first manifestations of blepharospasm. In many cases, as the illness progresses, forceful eyelid spasms may appear.
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The involuntary eyelid closure worsens as the day progresses. Bright light, talking, reading, and exposure to wind enhance the symptoms, whereas darkness, singing, yawning, and being attentive to a task may attenuate them. After an initial period of progression of variable duration (months to years), the course of this condition generally stabilizes. Whereas in mild cases, the repeated eye closure is primarily a source of annoyance, in the more severe cases, it may lead to functional blindness. For many patients, ordinary activities such as reading, watching television, driving, and crossing the street become problematic, if not impossible.1,2
Apraxia of Lid Opening
Some patients with blepharospasm experience difficulty opening the eyes in the absence of visible squeezing of the eyelids. These patients are believed to have apraxia of lid opening, which is an intermittent inability to open the eyes voluntarily, not due to blepharospasm, ptosis, oculomotor abnormalities, sympathetic dysfunction, or myopathy. Apraxia of lid opening may represent a variant of blepharospasm in which the involuntary contractions of the lid are not visible because they are confined to the pretarsal and septal portions of the orbicularis oculi. Alternately, apraxia of lid opening may be due to involuntary levator palpebrae muscle inhibition.4-6
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Treatment
The most effective treatment of essential blepharospasm consists of the chemical denervation of the orbicularis oculi muscle by means of botulinum toxin injections.7,8 The injections must be repeated at 3- to 4-month intervals. Oral medications are of limited usefulness. Medications most commonly used are anticholinergics such as trihexyphenidyl, GABAergics such as baclofen and clonazepam, and tetrabenazine.9-11 Lid myectomy is the surgical treatment of choice and is generally reserved for patients with an unsatisfactory response to oral medication or botulinum toxin injections.12
Treatment of apraxia of lid opening with oral medications is unrewarding. Botulinum toxin injections may be of benefit but to a lesser degree than in blepharospasm.13 Some of the treatment failures of botulinum toxin in blepharospasm are likely to be due to the concomitant presence of apraxia of lid opening. Treatment options for patients with apraxia of lid opening that did not improve with botulinum toxin include lid crutches and surgical suspension of the eyelids to the frontalis muscle. Following the latter procedure, the eyelids may be raised by contraction of the forehead muscles.6
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Facial spasm is a syndrome characterized by involuntary intermittent contractions of some or all the muscles of one side of the face. The disorder affects adults of all ages. The estimated prevalence is 7.4 cases per 100,000 men and 14.5 per 100,000 women.14
Clinical Features
Facial spasm can occur at any age, but it is extremely rare in childhood. It most commonly affects middle-aged adults. Facial spasm occurs in both sexes but is more frequent in women. Although bilateral cases have been described, facial spasm is primarily a unilateral condition. It begins most frequently with unilateral, painless, twitching of the orbicularis oculi muscle. With time, the twitching becomes more severe with stronger and more frequent contractions and spreads to involve the paranasal, perioral, and platysma muscles. Clonic (repeated) contractions may become more tonic (sustained), thereby producing persistent closure of the eye and distortion of the face. The spasms may be exacerbated by stress and fatigue, and typically persist during sleep. Clicking noises in the ipsilateral ear that may accompany the spasms are attributable to contractions of the tensor tympani muscle. Neurological examination is otherwise normal. In patients with poor vision in the contralateral eye, repeated closure of the eye on the side of the spasm may cause intermittent functional blindness. Periods of remission may occur but are unusual. Although not a disabling condition, hemifacial spasm is annoying and embarassing.15,16
Diagnosis
Facial spasm can be readily diagnosed in the typical case. The most common error is to confuse it with blepharospasm. This confusion can be avoided if one remembers that, unlike blepharospasm, facial spasm is a unilateral condition. Other common conditions from which facial spasm must be distinguished include myokymia, post-paralytic facial spasm, and facial tics. Myokymia, which may be limited to the lids or may involve the whole face, is usually unilateral; the contraction of the involved muscles is asynchronous. In post-paralytic facial spasm, there is a history of a preceding facial palsy, signs of a persisting facial paralysis, and evidence of aberrant regeneration of the facial muscles. Facial tics may be difficult to distinguish from both facial spasm and blepharospasm. The onset of the contractions during childhood, the suppressibility of the contractions, and the presence of tics in other body parts may indicate facial tics.16
Etiology
It is thought that the facial spasms are caused by pulsatile compression of the root entry zone (the transition area between central and peripheral nervous system myelin) of the facial nerve by elongated vessels or by abnormally located normal vessels.17
The vessels most commonly implicated are the anterior inferior and the posterior inferior cerebellar arteries. The compression may cause abnormal neuronal discharges by either ephaptic transmission (crosstalk) between the branches of the facial nerve or by retrograde changes in the facial nucleus. Although the likelihood that facial spasm is caused by a tumor in the cerebello-pontine is small, especially in a patient without other neurologic signs, it is advisable to exclude such a diagnosis by performing appropriate imaging studies.
Treatment
Carbamazepine18 is the most frequently prescribed oral medication to treat facial spasms. However, little evidence exists demonstrating that carbamazepine or other drugs are effective. A significant measure of relief is obtained by the injection of botulinum toxin A into the abnormally contracting muscles.7,8,19
Not infrequently, a suboptimal dose (i.e., a dose less than that required to completely arrest the spasm) must be used to avoid an undesirable upper lip droop. Microvascular decompression of the facial nerve is a more definitive treatment.17,20,21 Results of this treatment have been reported to be excellent in 84% of patients, partially successful in 7%, and failures in 9%. Following surgery, the spasm generally disappears in 3 to 10 days, but occasionally it persists for several weeks. Reoperation may provide relief for patients in whom the spasm persists following a first operation. The most common complication of surgery is deafness, which occurs in 3% of cases. Residual facial weakness has been reported in 1% of patients.
