Consensus-Based Care Recommendations for Pulmonologists Treating Adults with Myotonic Dystrophy Type 1

Abstract

<b><i>Purpose of Review:</i></b> Myotonic dystrophy type 1 (DM1) is a severe, progressive genetic disease that affects approximately 1 in 2,500 individuals globally [Ashizawa et al.: Neurol Clin Pract 2018;8(6):507–20]. In patients with DM1, respiratory muscle weakness frequently evolves, leading to respiratory failure as the main cause of death in this patient population, followed by cardiac complications [de Die-Smulders et al.: Brain 1998;121(Pt 8):1557–63], [Mathieu et al.: Neurology 1999;52(8):1658–62], [Groh et al.: Muscle Nerve 2011;43(5):648–51]. This paper provides a more detailed outline on the diagnostic and management protocols, which can guide pulmonologists who may not have experience with DM1 or who are not part of a neuromuscular multidisciplinary clinic. A group of neuromuscular experts in DM1 including pulmonologists, respiratory physiotherapists and sleep specialists discussed respiratory testing and management at baseline and during follow-up visits, based on their clinical experience with patients with DM1. The details are presented in this report. <b><i>Recent Findings:</i></b> Myotonic recruited 66 international clinicians experienced in the treatment of people living with DM1 to develop and publish consensus-based care recommendations targeting all body systems affected by this disease [Ashizawa et al.: Neurol Clin Pract. 2018;8(6):507–20]. Myotonic then worked with 12 international respiratory therapists, pulmonologists and neurologists with long-standing experience in DM respiratory care to develop consensus-based care recommendations for pulmonologists using a methodology called the Single Text Procedure. This process generated a 7-page document that provides detailed respiratory care recommendations for the management of patients living with DM1. This consensus is completely based on expert opinion and not backed up by empirical evidence due to limited clinical care data available for respiratory care management in DM patients. Nevertheless, we believe it is of relevance for professionals treating adults with myotonic dystrophy because it addresses practical issues related to respiratory management and care, which have been adapted to meet the specific issues in patients with DM1. <b><i>Summary:</i></b> The resulting recommendations are intended to improve respiratory care for the most vulnerable of DM1 patients and lower the risk of untoward respiratory complications and mortality by providing pulmonologist who are less experienced with DM1 with practical indications on which tests and when to perform them, adapting the general respiratory knowledge to specific issues related to this multiorgan disease.

Noninvasive Home Mechanical Ventilation in Adult Myotonic Dystrophy Type 1: A Systematic Review

“…With regard to indication for HMV initiation in DM1 patients, consensus meetings are mainly based on expert opinion in combination with low evidence studies and have suggested to start HMV when there are symptoms suggestive of chronic respiratory insufficiency in combination with daytime or nocturnal hypercapnia or FVC <50% of predicted [28, 29]. However, certain symptoms, like excessive daytime sleepiness and fatigue may be classified as signs of hypoventilation, but in DM1 patients, they are likely of multifactorial origin and, therefore, the result of HMV on such symptoms may be disappointing and discouraging for patients and caregivers [30, 31].…”

Assessment of Respiratory Function and Need for Noninvasive Ventilation in a Cohort of Patients with Myotonic Dystrophy Type 1 Followed at One Single Expert Center

“… Peak cough expiratory flow (PCEF) expressed in L/min, and the maneuver was performed with a mask of fitting size, having the patient seated, and asking him/her to inhale as much air as possible and then to cough it out heavily. As per general and disease-specific guidelines, PCEF < 270 L/min was considered suggestive of a potentially ineffective cough, while a PCEF < 160 L/min signaled a high risk of pneumonia and respiratory failure [ 18 ]. Maximal inspiratory pressure and expiratory pressure (MIP and MEP, respectively) expressed in cmH2O were performed using a mouth pressure meter MicroRPM (Micro Medical, Kent, UK) as a series of 3 to 5 maximal isometric respiratory maneuvers.…”

“…Secondly, the clinical presentation of respiratory involvement varies between patients: in some patients, the muscle weakness may predominate, while in the majority, it is the CNS component, which may present as sleep-related breathing disorders including central apneas [ 17 ] and excessive daytime sleepiness that are independent of breathing issues and may not be alleviated by respiratory interventions such as CPAP, BPAP, or respiratory muscle training. Lastly, although there are several protocols recommending to use noninvasive ventilation (NIV) to correct for chronic respiratory insufficiency in DM1 [ 4 , 18 ], the criteria to launch NIV in DM1 are variably applied, the effects of NIV on clinical symptoms vary [ 19 – 21 ], and overall patients' adherence is limited [ 4 , 11 , 19 ].…”

Myotonic Dystrophies: A Genetic Overview

“…Myotonia can also involve cranial muscles, such as the tongue and chewing muscles, and impair their function and cause discomfort. Neuromuscular respiratory insufficiency combined with aspiration pneumonia can at times be a presenting feature in DM1 and lead to prolonged intensive care unit stays or the need for invasive ventilation [ 20 ].…”