Does myotonic dystrophy typically progress to respiratory failure?

From the Guidelines

Myotonic dystrophy often progresses to respiratory failure, particularly in advanced stages of the disease, with respiratory complications being one of the most frequent primary causes of death in patients with myotonic dystrophy type 1 (DM1) 1. The progression to respiratory failure is attributed to the weakening of respiratory muscles, including the diaphragm and intercostal muscles, leading to breathing difficulties. Patients with myotonic dystrophy commonly develop sleep-disordered breathing, alveolar hypoventilation, and reduced vital capacity. Some key points to consider in the management of myotonic dystrophy include:

• The severity and progression rate of respiratory involvement vary between the two main types: type 1 (DM1) typically has more severe respiratory involvement than type 2 (DM2) 1.
• Regular pulmonary function testing is essential for patients with myotonic dystrophy, with vital capacity measurements being particularly important.
• When respiratory symptoms develop, non-invasive ventilation such as BiPAP is often initiated, typically starting with nighttime use 1. The respiratory failure in myotonic dystrophy results from both the direct weakening of respiratory muscles and central nervous system dysfunction affecting respiratory drive, particularly during sleep. In patients with DM1, cardiac manifestations are also present in approximately 80% of cases, and the risk of developing cardiac disease is higher in younger patients, with respiratory complications and cardiac arrhythmias being the most frequent primary causes of death 1.

From the Research

Respiratory Failure in Myotonic Dystrophy

• Myotonic dystrophy type 1 (DM1) is a genetic disorder that can lead to respiratory complications, including respiratory failure 2, 3, 4, 5.
• Respiratory failure is a common cause of death among patients with DM1, with studies suggesting that it is often related to the progression of respiratory muscle dysfunction 2, 5.
• Factors that influence the severity and progression of respiratory muscle dysfunction in DM1 include CTG repeat size, disease duration, and the presence of symptoms such as restrictive respiratory impairment 2.
• Non-invasive home mechanical ventilation (HMV) has been shown to improve gas exchange, quality of life, and survival in DM1 patients with chronic hypercapnic respiratory failure 4.
• However, compliance with HMV can be poor, especially in patients without subjective symptoms of respiratory failure, and is influenced by factors such as education, follow-up, and the presence of excessive leaks or ventilator dysfunction 3.

Progression to Respiratory Failure

• The natural history of respiratory decline in DM1 patients is not fully understood, and few predictors of the progression of respiratory dysfunction have been identified 2.
• Studies have reported a wide variability in the clinical phenotype of DM1, making it challenging to determine disease measures directly related to respiratory functional decline 2.
• Annual changes in forced vital capacity (FVC) have been reported to be around -1.42% in DM1 patients, indicating a gradual decline in respiratory function over time 2.
• The presence of respiratory symptoms, such as nocturnal arterial oxygen desaturation, can be a predictor of long-term compliance with HMV and may indicate a higher risk of respiratory failure 3.