Myotonic Type 1 & 2

Myotonic dystrophy type 1 (DM1)

 

Name: ___________________________________________________________

Date of birth: ______________________________________________________

Emergency contact: ________________________________________________

GP name: ________________________________________________________

GP contact: ______________________________________________________

If presenting at an emergency department, contact the neurology/neuromuscular team and respiratory team at: _________________________________________

as soon as possible on: _____________________________________________

Respiratory

  • Chronic respiratory failure is common in myotonic dystrophy type 1 (DM1). It may present with early morning headaches, fatigue and excessive daytime sleepiness, but is often first identified following an episode of pneumonia or a difficult or prolonged extubation following general anaesthetic.
  • Pneumonia is very common and requires prompt management.
  • If supplemental oxygen is required during a respiratory crisis it must be carefully controlled and carbon dioxide levels monitored, especially in the context of chronic respiratory failure. Non-invasive ventilation (NIV) may be required but is often poorly tolerated.
  • Assisted coughing with chest physiotherapy and breath-stacking techniques with an AMBU bag helps to clear lower airways secretions. This can also be facilitated by a cough assist device.
  • Immunisations should be kept up to date, including the flu and pneumococcal vaccines

 Cardiac

  • Bradyarrhythmias and tachyarrhythmias are very common in DM1 and must be considered in patients with palpitations, fainting, dizziness and shortness of breath but may be symptomless. ECG is mandatory and will often demonstrate prolonged PR and QRS interval.
  • Clinically significant cardiomyopathy is uncommon in DM1, and if present other causes should be considered.

Anaesthetics/sedation

  • There is an increased sensitivity to sedatives, inhaled anaesthetics and neuromuscular blockade, especially in more severe forms of DM1. It is essential that the anaesthetist is aware of the diagnosis of DM1 so that appropriate plans can be made for post-operative monitoring.
  • Local anaesthetics and nitrous oxide are safe, e.g. for minor dental procedures. Ideally the surgery should occur in a specialist centre with staff experienced in managing these individuals.
  • Detailed anaesthetic guidelines are available at: smn.scot.nhs.uk/myotonicdystrophy.html.

 

GI/Liver/Cognitive (EDS)

Gastrointestinal (GI)

  • Constipation, diarrhoea and abdominal pain are very common in DM1 but may need assessment to exclude other causes.
  • Aspiration pneumonia, secondary to dysphagia, is common.
  • Patients should be assessed by a SALT (speech and language therapist) if they have swallowing problems.

Liver

Liver enzymes (AST/ALT/alkaline phosphatase) may be mildly raised on blood tests in up to 50 percent of patients. The clinical setting dictates whether further investigation is indicated.

Cognitive

  • Excessive daytime sleepiness (EDS) is common and is most often owing to CNS involvement. Sleep apnoea and chronic respiratory failure also need to be considered.
  • Dysexecutive problems and apathy are common. Patients may miss appointments. Telephone reminders, longer appointment times and a more lenient approach to discharge following DNAs may help.

Precautions/recommendations

Patients often have facial myopathy, slurred speech and EDS, which may make it difficult for patients to express their feelings. It may also make patients look worse than they feel.

 Fractures and falls

  • Owing to weakness and poor balance, patients with DM1 are at high risk of frequent falls.
  • If ambulant before fracture, internal fixation is preferable to casting as it helps to preserve muscle and speeds a return to walking.
  • Orthotics input is often important, especially for ankle weakness.
  • Consider checking vitamin D levels and bone mineral density, especially following a fall or fracture.

 

Myotonic dystrophy type 2 (DM2)

 

Name: ___________________________________________________________

Date of birth: ______________________________________________________

Emergency contact: ________________________________________________

GP name: ________________________________________________________

GP contact: ______________________________________________________

If presenting at an emergency department, contact the neurology/neuromuscular team and respiratory team at: _________________________________________

as soon as possible on: _____________________________________________

 

Respiratory

  • Chronic respiratory failure is relatively uncommon in myotonic dystrophy type 2 (DM2) in comparison to myotonic dystrophy type 1 (DM1). It may present with early morning headaches, fatigue and excessive daytime sleepiness, but is often first identified following an episode of pneumonia or a difficult or prolonged extubation following general anaesthetic.
  • If supplemental oxygen is required during a respiratory crisis it must be carefully controlled and carbon dioxide levels monitored, especially in the context of chronic respiratory failure. Non-invasive ventilation (NIV) may be required but is often poorly tolerated.
  • Assisted coughing with chest physiotherapy and breath-stacking techniques with an AMBU bag help to clear lower airways secretions. This can also be facilitated by a cough assist device.
  • Immunisations should be kept up to date, including the flu and pneumococcal vaccines.

 Cardiac

  • Bradyarrhythmias and tachyarrhythmias are less common in DM2 in than in DM1. They should still be considered in patients with palpitations, fainting, dizziness and shortness of breath but may be symptomless. ECG is mandatory and will often demonstrate prolonged PR and QRS interval.
  • Clinically significant cardiomyopathy is uncommon in DM2, and if present, other causes should be considered.

Anaesthetics/sedation

  • Unlike in DM1, studies have suggested that there does not appear to be an increased sensitivity to sedatives, inhaled anaesthetics and neuromuscular blockade in DM2. However, it is essential that the anaesthetist is aware of the diagnosis of DM2 and any background respiratory problems, so that appropriate plans can be made for potential prolonged post-operative monitoring
  • Local anaesthetics and nitrous oxide are safe, e.g. for minor dental procedures.
  • Detailed anaesthetic guidelines are available for DM1 and may also be applicable in patients with severe DM2. You can find them at: www.smn.scot.nhs.uk/myotonicdystrophy.html.

Endocrine/GI/Liver/Cognitive (EDS)

 

Endocrine

Increased incidence of type 2 diabetes mellitus in DM2.

 Liver

Liver enzymes (AST/ALT) may be mildly raised on blood tests in up to 50 percent of patients. The clinical setting dictates whether further investigation is indicated.

Gastrointestinal

  • Constipation, diarrhoea and abdominal pain are common in DM2 but may need assessment to exclude other causes.
  • Aspiration pneumonia, secondary to dysphagia, is not common in DM2.
  • Patients should be assessed by a SALT if they have swallowing problems.

Cognition

  • Excessive daytime sleepiness (EDS) is common. Sleep apnoea and chronic respiratory failure need to be considered as contributing to the cause of EDS.
  • Dysexecutive problems and apathy are not common in DM2, in comparison with DM1. Intellectual disability has not been found in DM2, although changes in cognition, behaviour and personality have been described.

 Fractures and falls

  • Owing to weakness and poor balance, patients with myotonic dystrophy are at high risk of frequent falls when their muscles are significantly involved.
  • Weakness affects the proximal muscles often more than the distal muscles in DM2 which may cause problems with climbing stairs, getting out of a chair, and off the floor.
  • If ambulant before fracture, internal fixation is preferable to casting as it helps to preserve muscle and speeds a return to walking.
  • Cataracts are common in DM2 and should be considered in all patients with falls.
  • Orthotics input is often important, especially for ankle weakness.
  • Consider checking vitamin D levels and bone mineral density, especially following a fall or fracture.