Orthognathic Surgery and Partial Glossectomy in a Patient With Merosin-Deficient Congenital Muscular Dystrophy

Abstract

Muscular dystrophy (MD) describes a group of hereditary muscular diseases. The molecular mechanisms that cause the different forms of MD vary, as do the incidence and impact on a patient’s quality of life. The most common form, Duchenne MD, follows an Xlinked inheritance pattern and occurs with an incidence of approximately 1 in 3,500 live-born male infants. However, rarer forms such as congenital MD (CMD) also exist. CMD has an autosomal recessive inheritance pattern that, according to 1 Italian sample, has an incidence of only 0.7 per 100,000 live births. 1 CMD is characterized by severe muscle hypotonia (first noticeable at birth or within the first months of life), generalized muscle weakness, and muscle contractures of varying severity that result in delayed or missed developmental motor milestones. Each type of CMD is subclassified based on the specific molecular defect or deficiency. One of the more common types of CMD is merosindeficient CMD (MDCMD), which accounts for up to 30% of CMD cases in European countries. CMD results from a deficiency of laminin 2 chains (merosin) because of mutations in the LAMA2 gene located on chromosome 6q22. MDCMD is a severe form of MD that is manifested by an inability to ambulate independently secondary to muscle weakness/contractures and a respiratory insufficiency that may require tracheostomy. 2 Although MDCMD is rare, it and other forms of MD are important to the oral and maxillofacial surgeon because of the impact of the disease on oral and facial anatomy and function. Of particular concern to the oral and maxillofacial surgeon is the phenotype often associated with MDs, which includes bimaxillary discrepancies often presenting with apertognathia. 3 The significance of the malocclusion can be heightened by the compromised masticatory forces resulting from MD. 4,5 Patients with MD may also exhibit limited maximal incisal opening (MIO) because of contracture of the muscles of mastication. In addition, the presence of macroglossia can add to the overall stomatognathic dysfunction and increase the potential for relapse in the postoperative period. 6 Through the surgical treatment of these conditions, the oral and maxillofacial surgeon can address the functional and facial cosmetic concerns the patient may have.