Botulinum toxin injections for the treatment of oromandibular dystonia

Abstract

Oromandibular dystonia is a neurologic disorder that manifests as involuntary repetitive spasms of the masticatory, lingual, and pharyngeal musculature, resulting in uncontrolled jaw and tongue movements. As with most dystonias, these actions are typically action induced and may cause considerable social distress to affected persons. In some cases, progressive disease may lead to significant dysphagia and/or dysarthria. Before the introduction of botulinum toxin injection, oral pharmacological agents provided limited treatment. This article reviews the assessment of oromandibular dystonia, techniques for intramuscular botulinum toxin injection, and possible posttreatment complications. Dystonia is a neurological phenomenon characterized by repetitive involuntary sustained (tonic) or spasmodic (clonic) muscle contractions that cause abnormal body posturing. 1 The dystonic movements are typically action induced; therefore, the involved body part may appear normal at rest. Dystonia can be categorized as focal, involving one particular small group of muscles; as segmental, involving neighboring groups of muscles; or as generalized, with widespread muscle involvement. However, the craniocervical region is more likely to be affected. 2 The etiologies of dystonia are varied, with the principal cause being idiopathic. Dystonia may also be the result of trauma, tardive syndromes, neurologic insult, neurodegenerative disease, or inherited disorders. Because the etiologies of dystonia may be diverse, consultation with a neurologist is prudent before rendering treatment. Cranial‐ cervical dystonia involves the musculature of the face, periorbita, masticatory complex, tongue, larynx, pharynx, and neck. 3 In this section we will focus on a subset of cranial‐ cervical dystonia known as oromandibular dystonia (OMD). OMD consists of involuntary spasms of masticatory, lingual, perioral, and pharyngeal muscles and may be classified as jaw opening, jaw closing, jaw deviation, and/or tongue protrusion type. When these symptoms are found in conjunction with blepharospasm, the condition is referred to as Meige’s syndrome. These involuntary postures of the tongue and jaw may lead to dysphagia, dysarthria, bruxism, and/or temporomandibular joint subluxation and damage. 4 In addition to physical impairment, the involuntary facial contortions may result in significant social impairment. 5