The most widely used form of treatment is the periodic (every 3 to 6 months) injection of small amounts of botulinum toxin directly into several sites in the affected muscles. The injections are best guided by palpation of muscles in spasm and by EMG analysis to determine which of the tonically contracted muscles are most responsible for the aberrant posture. All but 10 percent of patients with torticollis have had some degree of relief from symptoms with this treatment. Adverse effects (excessive weakness of injected muscles, local pain, and dysphagia—the latter from a systemic effect of the toxin) are usually mild and transitory. Five to 10 percent of patients eventually become resistant to repeated injections because of the development of neutralizing antibodies to the toxin (Dauer et al).
More recently, the use of deep brain stimulation has found some success in the treatment of cases of idiopathic cervical dystonia that have been refractory to medications and botulinum injection. The internal segments of the globus pallidus and the subthalamic nuclei have been used as targets. This approach is certainly preferable to the former use of ablative lesions in these areas and in the thalami but, as in the randomized trial conducted by Volkmann and colleagues, adverse effects such as dysarthria, dyskinesias and worsening of dystonia occur in a proportion of cases. In the most severe cases of torticollis, a combined sectioning of the spinal accessory nerve and of the first three cervical motor roots bilaterally has been successful in reducing spasm of the muscles without totally paralyzing them. Considerable relief has been achieved for as long as 6 years in one-third to one-half of cases treated in this way (Krauss et al; Ford et al).
Patients in mid and late adult life, predominantly women, may present with the complaint of excessive blinking and involuntary forced closure of the eyes, which is due to spasm of the orbicularis oculi muscles. Any attempt to look at a person or object is associated with a persistent tonic, symmetric spasm of the eyelids (see Fig. 4-8B). During conversation, the patient struggles to overcome the spasms and is distracted by them. Reading and watching television are impossible at some times but surprisingly easy at others. Jankovic and Orman in a survey of 250 such patients found that in the past, before effective treatment, 75 percent progressed in severity over the years to the point, in about 15 percent of cases, of making the patients functionally blind. Some instances of blepharospasm are a component of the Meige syndrome that includes jaw spasms (see next section) or are associated with spasmodic dysphonia, torticollis, and other dystonic fragments. Blepharospasm may also be a result of drug-induced tardive dyskinesia.
One’s first inclination is to attribute this disorder to photophobia or a response to an ocular irritation or corneal dryness, and indeed, the patient may state that bright light is annoying. For example, ocular inflammation, especially of the iris, may produce severe reflex blepharospasm. However, the spasms persist in dim light and even after anesthesia of the corneas. Patients may hold the lid open with a finger and the eyebrow is seen to be displaced downward; in some forms, there is tonic contraction of the frontalis muscles in an apparent attempt to aid lid opening.
In the past, a psychiatric causation was proposed but, with the exception of a depressive reaction in some patients, psychiatric symptoms are lacking, and the use of psychotherapy, biofeedback, acupuncture, behavior modification therapy, and hypnosis has failed to cure the spasms. No neuropathologic lesion or neurochemical profile has been established in any of these disorders (Marsden et al; see also Hallett). A genetic basis is possible although few cases seem to be inherited and there has been no association with the known dystonia genes.