4 Botulinum Neurotoxin for Meige Syndrome



10.1055/b-0040-175227

4 Botulinum Neurotoxin for Meige Syndrome

Niv Mor and Andrew Blitzer


Summary


Meige syndrome is a focal dystonia characterized by oromandibular dystonia with blepharospasm. Spasms are usually bilateral, symmetric, and nonrhythmic. Meige syndrome is a neurologic disorder of the basal ganglia. Although electromyography can be helpful, diagnosis is mostly based on history and physical examination. The singular use of systemic medications has often been insufficient in treating Meige syndrome. Targeted botulinum neurotoxin (BoNT) injection to the affected muscles has been most effective. The positive effects of BoNT occur over a 12-week period, and most potential side effects are mild and self-limiting. Deep brain stimulation has shown promise in suppressing dystonic brain signals and is usually reserved for cases where BoNT injections have been ineffective.




4.1 Introduction


Meige syndrome is a rare focal dystonia characterized by oromandibular dystonia (OMD) and blepharospasm. The disorder was first described in 1910 by the French neurologist Henry Meige. Most cases occur in the sixth decade of life and are twice as common in women than in men. Although symptoms are typically first seen between 30 and 70 years of age, cases have been reported in younger individuals. Muscle spasms usually progress gradually and increase in intensity to incorporate more muscle groups over a period of 1 to 4 years. 1



4.2 Symptoms


The orofacial spasms associated with Meige syndrome are usually bilateral, symmetric, and nonrhythmic lasting from seconds to minutes. Blepharospasm results in involuntary blinking sometimes causing eye irritation or dry eyes. 2 Symptoms often occur in response to bright lights, emotional stress, wind, air pollution, or other stimuli. Blepharospasm can start unilaterally but often progresses to include both eyes. Severe cases may result in involuntary eye closure. OMD is often seen as involuntary contractions of the jaw. Patients often have difficulty either opening or closing their mouth and can present with jaw clenching, teeth grinding, or repeated lip pursing. In some cases, the tongue and throat is affected resulting in tongue protrusion, dysphagia, or dyspnea. 3



4.3 Pathophysiology


The exact symptomatology and severity of Meige syndrome varies for each individual. Historically, the disorder was considered psychogenic in origin. While symptoms are susceptible to psychosocial stressors, the condition is generally understood as neurologic in origin and resulting from a combination of genetic and environmental factors. Secondary Meige syndrome can occur in the context of neurodegenerative disorders, after the chronic administration of neuroleptics or in patients with focal brain lesions. Cases of secondary Meige syndrome have helped localize the disorder to the basal ganglia or the mesencephalic/diencephalic region of the central nervous system. 4 A study using functional magnetic resonance imaging (fMRI) showed reduced activation of the primary motor and ventral precortex during involuntary oromandibular movements in addition to increased activation of the somatosensory cortex. These findings likely reflect reduced cortical inhibition in motor and premotor cortex in combination with altered somatosensory activity. 5



4.4 Workup


The diagnosis of Meige syndrome is based on a comprehensive history and physical examination focusing on the ophthalmologic, otolaryngologic, and neurologic systems. A patient’s medication history may reveal the presence of other neurological disorders or highlight any risk factors for secondary Meige syndrome. A thorough family history focusing on the presence of other neurologic disorders is also important.


Next, it is essential to adequately identify the specific affected muscles. Attention should be given to orbicularis oris, depressor anguli oris, orbicularis oculi, temporalis, masseter, platysma, and pterygoid muscles (Fig. 4‑1).

Fig. 4.1 (a) Front view of muscle anatomy with attention to orbicularis oculi, orbicularis oris, depressor anguli oris, temporalis, masseter, and platysma muscles. (From Gilroy AM et al. Atlas of Anatomy. 1st Ed. New York: Thieme Medical Publishers; 2008. Based on: Schuenke M, Schulte E, Schumacher U. THIEME Atlas of Anatomy: Head and Neuroanatomy. Illustrations by Voll M and Wesker K. 1st Ed. New York: Thieme Medical Publishers; 2008.)
Fig. 4.1 (b) Side view of muscle anatomy with attention to orbicularis oculi, orbicularis oris, depressor anguli oris, temporalis, masseter, and platysma muscles. (From Gilroy AM et al. Atlas of Anatomy. 1st Ed. New York: Thieme Medical Publishers; 2008. Based on: Schuenke M, Schulte E, Schumacher U. THIEME Atlas of Anatomy: Head and Neuroanatomy. Illustrations by Voll M and Wesker K. 1st Ed. New York: Thieme Medical Publishers; 2008.)

Once the affected muscles are identified, objective confirmation using electromyography (EMG) can also be performed. Consultation with a neurologist who specializes in the treatment of movement disorders will be helpful in starting the patient on any appropriate oral medications and in identifying any additional neurologic symptoms. Consultation with an ophthalmologist will be helpful in establishing the patient’s baseline vision and assessing if any ophthalmologic treatment will be required. Lastly, one may consider consultation with a dentist specializing in oral physiology to see if there has been any adverse effect on the patient’s dentition or dental health. 6



4.5 Treatment


Treatments with systemic medications have often been unsatisfactory and temporary. Nonetheless, approximately one-third of patients are treated with systemic neurologic agents. Some systemic medications include dopaminergic/anticholinergics, tetrabenazine, benzodiazepines, and baclofen. Ablative surgery has proven to be ineffective and is no longer utilized as acceptable treatment. Historically, ablative surgery was limited to controlling blepharospasm and included eyelid myectomy, blepharoplasty, and lid lifts. Patients with refractory primary generalized dystonia have shown remarkable symptom improvement with globus pallidus deep brain stimulation (DBS). 7 ,​ 8 Botulinum neurotoxin (BoNT) injections directed at the affected muscles have shown great success in controlling patients’ associated muscle spasms.



4.6 Deep Brain Stimulation


Although the exact mechanism of action for DBS is not fully understood, DBS has been shown to decrease patients’ symptoms by suppressing the excessive brain signals seen in dystonia. 9 DBS is not appropriate for all patients and not all patients will have the same results. Generally, patients experience 50 to 60% reduction of symptoms following DBS. Some patients have reported 80 to 90% reduction of symptoms. Results have been sustained with some experiencing improvement up to 20 years following surgery. 9 Younger patients who are positive for the DYT1 gene mutation who are treated earlier for the progression of the disorder have had better results than those with nongenetic acquired dystonia. 9 ,​ 10 ,​ 11 Results with DBS to treat focal cranial nerve dystonia, including blepharospasm and OMD, have also been promising. 9 DBS is usually reserved for cases of severe dystonia when other treatments, such as BoNT injections, have been ineffective.

Only gold members can continue reading. Log In or Register to continue

May 4, 2020 | Posted by in ANESTHESIA | Comments Off on 4 Botulinum Neurotoxin for Meige Syndrome
Premium Wordpress Themes by UFO Themes