Oculopharyngeal muscular dystrophy is a genetic disease distinguished by the onset of ptosis, dysphagia, and weakness of voluntary skeletal muscles in elderly individuals. Choking, food regurgitation, and possibly life-threatening aspiration pneumonia are rare but important complications. Due to a lack of clinical suspicion and the rarity of the disease, the diagnosis is often missed. Demographic and clinical findings, as well as genetic studies, are vital in order to make the diagnosis.
With an incidence rate of 0.5-1 per 100,000 individuals in Europe, oculopharyngeal muscular dystrophy (OPMD) is a rare genetic disease in which mutations in genes responsible for the production of polyadenylate binding protein nuclear 1 (PABPN1), an essential molecule for messenger RNA (mRNA) function, leads to a specific type of muscular dystrophy    . However, three specific populations have shown a markedly higher prevalence rate - French Canadians (1 in 1,000 individuals), Israel’s Bukharan Jews that emigrated from Uzbekistan (1 in 600 individuals) and Hispanic Mexicans    . OPMD is transferred through an autosomal dominant pattern of inheritance in the vast majority of cases, although several reports have confirmed autosomal recessive forms as well  . The clinical presentation is distinguished by the appearance of ptosis and dysphagia (as a result of weakness in the levator palpebrae and pharyngeal muscles, respectively) in the fourth to sixth and seventh decades of life, and virtually all individuals who harbor OPMD mutations develop symptoms by the age of 70    . Ptosis is usually bilateral, asymmetric and progressive, as is dysphagia, which may initially be present only with solid foods, but difficulty swallowing liquids, regurgitation and even choking might be seen  . Atrophy of the tongue muscles is also a frequent finding in OPMD, while ophthalmoplegia, dysarthria, and weakness of the pelvic and shoulder girdle muscles are less common findings   . Complications are rare, but aspiration pneumonia, particularly if recurring episodes are seen, can be life-threatening in the absence of an early diagnosis, and the majority of OPMD-related deaths are attributed to aspiration pneumonia . Malnutrition and starvation, due to profound dysphagia, are other documented complications .
The diagnosis of OPMD is often missed, the principal reason being a lack of clinical suspicion, especially in countries with very low prevalence rates  . For this reason, physicians must conduct a comprehensive and detailed clinical workup comprised of a complete patient history and a thorough physical examination in order to identify the underlying cause. Assessing family history is perhaps of vital importance in raising clinical suspicion toward OPMD , particularly if patients are of French Canadian or Bukharan Jewish ancestry. Furthermore, a complete motor evaluation can identify which muscle groups are affected, and if sufficient evidence exists to suspect a myopathy, appropriate laboratory procedures should be implemented. Electromyography (EMG) is useful in excluding other more common conditions responsible for muscle weakness, whereas muscle biopsy is one of the tools to make the diagnosis, although it is not frequently performed  . The presence of filamentous intranuclear inclusions (INIs) on electron microscopy is practically pathognomonic for OPMD and mandates genetic testing for PABPN1 mutations, and is regarded as the definite method   . Because genetic testing is expensive and scarcely available, however, the diagnosis often rests on clinical criteria and the ability of the physician to recognize progressive ptosis and dysphagia in the elderly population, implying that clinical suspicion and awareness of OPMD as a possible diagnosis is the crucial step .