Myotonia less important to patients with myotonic dystrophy than other symptoms

University of Rochester Medical CenterJul 26 2012

Complex, multi-system diseases like myotonic dystrophy - the most common adult form of muscular dystrophy - require physicians and patients to identify which symptoms impact quality of life and, consequently, what treatments should take priority. However, a new study out this month in the journal Neurology reveals that there is often a disconnect between the two groups over which symptoms are more important, a phenomenon that not only impacts care but also the direction of research into new therapies.

"In order to design better therapies we must first develop a clear understanding of what patients think are the key mental and physical burdens of this disease," said University of Rochester Medical Center (URMC) neurologist Chad Heatwole, M.D., lead author of the study. "It is clear from this study that, in the case of myotonic dystrophy, researchers have not always been concentrating on the symptoms that are most important to the patient."

Myotonic dystrophy has been characterized as one of the most diverse and complex genetic diseases with a wide range of symptoms ranging from fatigue, muscle weakness, cognitive impairment, depression, difficulty sleeping, impaired vision, pain, difficulty swallowing, gastrointestinal problems, and myotonia, the inability to relax muscles after contraction - such as when clenching a fist - that is the hallmark of the disease. The severity and onset of these symptoms can vary from patient to patient.

As a result, physicians and patients are often confronted with a bewildering array of treatment options and researchers have previously had no comprehensive method to measure the meaningful impact of experimental therapies. Further impetus for a patient-centered approach has come from a recent push by the federal Food and Drug Administration to require that new drugs take into account what outcomes patients feel are important.

Using a national database of muscular dystrophy patients developed by URMC, Heatwole and his colleagues surveyed 278 people with myotonic dystrophy type-1. They asked them not only which symptoms they were experiencing, but which ones have the most impact on their lives. Answers were cross referenced with the respondent's age and a genetic measure - called CTG repeat length - that roughly correlates with the severity of the disease.

The study revealed that certain symptoms like myotonia which are experienced by more than 90 percent of individuals with the disease are less important to patients than symptoms such as such as fatigue, limited mobility, and sleep problems. Respondents also identified specific symptoms that have the greatest impact on their lives. These included difficulty having children, not being able to stay in the standing position, and difficulty holding down a job.

"One of the more surprising results is that myotonia - the condition that gives the disease its name - is down the list of things that patients feel most affect their daily lives," said Heatwole. "These insights will not only have important implications for how patients are treated, but also how new therapies for the disease are evaluated by building better outcome measures."

Using this data, Heatwole and his colleagues have developed a questionnaire for myotonic dystrophy patients that weights patient responses based on their study findings. The questionnaire, called a disease-specific patient reported outcome measure is one of many which is being developed for neuromuscular diseases at the URMC by Heatwole and his team and will enable researchers to more precisely measure whether the impact of experimental therapies is meaningful to patients. The myotonic dystrophy outcome measure is already being used in two clinical trials at the University of Rochester.