Medical management and pharmacology update
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Dentistry and the myasthenia gravis patient: a review of the current state of the art

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Myasthenia gravis (MG) is a chronic neuromuscular disease characterized by muscular weakness and fatigability. Dental management of patients diagnosed with MG presents a challenge to the oral health care provider. The purpose of this article was to review the etiology, pathogenesis, diagnosis, and clinical signs and symptoms associated with MG, highlighting the role of the oral health care provider in the process of diagnosis and management of the oral and dental complications that might be associated with the disease, while avoiding myasthenic crisis. A discussion of the recent approaches to treatment of the disease and current research on MG is presented.

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Epidemiology

Myasthenia gravis is uncommon. Estimated annual incidence is 3-30 per 1,000,000.3 Women are affected more often than men, with a ratio of ∼3:2. Although any age group can be affected, it is most frequently observed in women in their second and third decades and men in their fifth and sixth decades of life.

Etiopathogenesis

Myasthenia gravis is an autoimmune disease with antibodies directed toward the acetylcholine receptors at the neuromuscular junctions.3 Autoantibodies are thought to reduce the availability of the target antigens, the nicotinic acetylcholine receptors, by 3 possible mechanisms: accelerated endocytosis and degradation of the receptors, functional blockade of the acetylcholine-binding sites, and complement-mediated damage to the acetylcholine receptors (AChRs).4, 5 Decreased numbers of functional

Clinical Features

The initial phase of MG presents as ptosis and diplopia due to the weakness of the extraocular muscles. The disease remains restricted to the extraocular muscles in ∼15% of patients, with widespread muscle weakness usually developing in the remaining 85%.2, 18 Scherer et al.19 described the “peek sign” in ocular MG patients, where after complete initial apposition of the lid margins, they quickly (within 30 s) start to separate and the sclera starts to show. Facial and masticatory muscle

Diagnosis

The initial clues to the diagnosis of MG are usually the history and physical findings. However, the diagnosis must be confirmed by laboratory tests. The serum level of AChR antibodies is considered to be a diagnostic “gold standard.” These antibodies are found in 80%-85% of patients with generalized MG but in only 50%-60% of the cases of ocular MG.29 A proportion of patients without antibodies against the AChR have antibodies against the MuSK protein.10 The diagnosis of MG can be confirmed

Oral Manifestations of MG

Functional limitations result from weakness of facial and masticatory muscles.20, 22 Patients with bulbar MG (weakness of muscles innervated by the lower brainstem) have poor masticatory performance.36, 37 This condition can also be found in patients with progressive muscular dystrophy38 and cerebral palsy.39 The clinical deficiency in muscular strength could sometimes be so severe that patients may have to support the lower jaw during meals to perform mastication and between meals to prevent a

Medical Management

Ideally, treatment of MG should eliminate the specific pathogenic autoimmune response to AChR, without otherwise suppressing the immune system or producing other adverse side effects. Medical management of MG includes anticholinesterase (AChE) agents, surgical thymectomy, immunosuppressive therapy, elimination of autoantibodies by plasma exchange, and modulation of the autoimmune response by intravenous Ig.

Anticholinesterase agents are considered to be the preferred choice. They improve muscle

Dental Management

Dentistry can be a part of normal health care for the myasthenic patient and should not be feared or avoided. Communication between the patient, neurologist, and oral health care provider is of paramount importance to avoid medical and functional complications. Multiple short early-morning appointments should be scheduled. This allows the dental or oral surgical care to be undertaken with the advantage of greater muscular strength typically noted during the morning hours.2 Oral AChE agents

Prognosis

Myasthenia gravis is no longer considered to be a terminal disease. When associated with a thymoma, particularly in older patients, MG has a poor prognosis.29 Quality of life can vary depending on the severity and the cause. The drugs used to control MG either diminish in effectiveness over time (cholinesterase inhibitors) or cause severe side effects of their own (immunosuppressants). A small percentage (∼10%) of MG patients are found to have tumors in their thymus glands, in which case a

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