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Scott M. Rickert and Andrew Blitzer

Benign essential blepharospasm is a focal dystonia that results in an involuntary closure of the musculature around the eye. This involuntary movement is typically chronic and persistent in nature, resulting in a functional blindness in which there is an intact visual pathway. Although rare (1 in 20,000), it tends to occur in the fifth and sixth decades of life. Botulinum neurotoxin (BoNT) injection to the local musculature has proven effective in many reported trials.1–3

Hemifacial spasm, first described by Gowers in 1884, is not a dystonia but a segmental myoclonus resulting in a recurrent, involuntary, synkinetic dystonic muscular contractions of the face. The muscles in contracture are those innervated by the facial nerve and are typically unilateral. There are rare cases of bilateral involvement. It typically occurs in the fourth and fifth decade of life with a prevalence of 1 in 10,000 and typically first presents in the orbicularis oculi. The most common cause of facial nerve interruption is believed to be an aberrant vascular loop (from the posterior inferior cerebellar artery) causing local compression.⁴ Other causes of compression may include local tumor, vascular malformation, and infectious processes. Hemi facial spasm can be misdiagnosed as isolated blepharospasm, orbicularis oculi myokymia, or synkinetic movements post–Bell’s palsy. Therefore, it is important to thoroughly evaluate and correctly diagnose all dystonias. Anticonvulsive medication, such as oral doses of carbamazepine or valproic acid, helps to control central myoclonus. Intramuscular injection of BoNT reliably reduces synchronous spasms in a safe, repeatable way.5–7 Defazio et al⁸ reported a 95% response rate and with others, corraborated the effectiveness of BoNT/A in relieving the symptoms of primary hemifacial spasm.⁹

Oromandibular dystonia (OMD) is char acterized by dystonic muscular contractions affecting the jaw, mouth, and lower face. In more severe cases, the tongue musculature may be involved. In patients with OMD, involuntary contractions may involve the muscles that open the jaw and close the jaw, and muscles of mastication. This leads to a significant variety of presentations in OMD. Associated findings may include spasms of jaw closure with difficulty opening the mouth, jaw clenching or bruxism, spasms of jaw opening, and sideways deviation or protrusion of the jaw. Additional symptoms may also be present, such as lip tightening/pursing, retraction of the corners of the mouth, and deviation or protrusion of the tongue. Because these findings vary in presentation but are localized, many patients with OMD may present with jaw pain, eating difficulties, or dysarthria.

Dystonic spasms can sometimes be provoked by certain activities, such as talking, chewing, or biting. There have been reported incidences of medications causing orofacial dystonia or tardive dystonia, such as weak serotonin reuptake inhibitor, but no exact mechanism has been found.¹⁰ Particular sensory tricks may help to temporarily alleviate a patient’s OMD symptoms. Reports of successful sensory tricks include chewing gum, talking, placing a toothpick in the mouth, lightly touching the lips or chin, or applying steady pressure in the submental region. Dystonic spasms may extend to involve nearby areas including the muscles of the eyelids, nose, neck, or vocal cords. Although some medications have been used, their efficacy is low in OMD. BoNT is the preferred treatment for all types of OMD but is most effective in the jaw-closure subtype.^2,9,11,12 Tongue injections are contraindicated due to the risk of aspiration.

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