Myotonic dystrophy
Case PresentationMarch 2013
Outline
• Case• Background• Signs and symptoms• Treatment• Considerations for anaesthetic• Summary
Case
• 46 year old male• Known myotonic dystrophy• Right open ankle fusion & osteotomy
• WHAT ARE THE ANAESTHETIC CONSIDERATIONS?
Background (1)
• LOTS OF NAMES– Myotonic Dystrophy– Steinert’s Disease– Dystrophica Myotonica– Myotonica Atrophica– Batten-Curschmann’s– Hoffman’s
Background (2)
• Chronic, slowly progressing, highly variable, multisystem disease
• M=F• 1 per 7000/8000 people• Autosomal dominant – DMPK gene, nucleotide
repeat disorder, anticipation• 2 types:– Type 1– Type 2 - Proximal Myotonic Myopathy (PROMM)
Signs and symptoms (1)
• Neuro:– Wasting/weakness of
muscles– Myotonia– Cognitive impairment– Behavioural problems– Excessive sleepiness
• CVS:– Heart conduction
defects; arrhythmias– Cardiomyopathy
• Resp:– Regular chest
infections– Aspiration– Hypoventilation, OSA
Signs and symptoms (2)
• Endocrine:– Insulin resistance,
hypothyroidism– Male infertility– Premature frontal
balding• Opthalmology:– Cataracts– Ptosis
• GI– Swallowing problems– Gallstones– Constipation/
diarrhoea• Skeletal– Scoliosis– Talipes
Useful clinical clue for diagnosis:Failure of spontaneous letting go of the hands following strong handshakes due to myotonia
Definitive diagnosis by:
• DNA analysis• EMG• Slit lamp exam of lens• Serum CK• Serum FSH, testosterone• ECG• Muscle biopsy
Treatment
• No cure or treatment• Manage complications – orthotics,
pacemakers, physio, mobility aids
Myotonic Dystrophy & Anaesthesia
Anaesthetic related problems
• Diagnosis• Getting correct history• Cardio-respiratory complications• Aspiration risk• ? Difficult airway• Analgesic/anaesthetic drugs• Neuromuscular blocking drugs• Myotonia triggers• Pregnancy
Pre-assessment
• Precise diagnosis • Full discussion with patient & family re:
potential risks/benefits• Assessment of function & co-morbidities • Investigations• Anaesthetic plan• Planning post-op care
Cardiac investigations
• Routine ECG– Abnormality may not be apparent on ECG
• If symptomatic– 24 hr ECG tape– Invasive electrophysiological studies– ECHO
• If asymptomatic – annual ECG, 24hr tape every 2 years, TTE every 5 years
Respiratory investigations
• CXR– Subclinical aspiration common
• Pulmonary function tests– Spirometry– ABG
Airway problems
• ? RSI– Aspiration risk– Avoid suxamethonium
• ? Intubation difficulty
Peri-operative management
• Sensitivity to sedative, analgesic, anaesthetic drugs
• Neuromuscular blockade – NDMR in reduced doses (10 - 20%); avoid suxamethonium
• Close temperature control• Use of regional anaesthesia if possible
Peri-operative complications
• OSA, aspiration• Dysrrythmias, cardiac failure• Autonomic dysfunction• Myotonia• Rhabdomyolysis
Myotonia
• Can be precipitated by:– suxamethonium – anticholinesterases – opioids – alterations in temperature/shivering – acidosis
Post-operatively
• Timing of extubation• Avoid hypothermia• Monitor electrolytes• May need higher level of care post op (HDU,
ITU)• High index of suspicion for respiratory
complications• Opioids with caution for post op analgesia
Pregnancy in MD
• Increase in myotonic symptoms• Atonic uterus• PPH common• Mother can pass on congenital form to baby
Case
• Spinal sited with 2.2ml 0.5% heavy marcain and 0.3mg diamorphine
• No sedation required• Oxygen via simple hudson facemask• Uneventful anaesthetic
Summary
• Large spectrum of signs & symptoms• Often misdiagnosed or underdiagnosed
condition• Knowledge & awareness of condition means
the avoidable & expected complications can be minimised
References• http://www.myotonicdystrophysupportgroup.org• FRCA “Neuromuscular disorders and anaesthesia” (2009)
http://www.frca.co.uk/Documents/126%20Neuromuscular%20disorders%20and%20anaesthesia.pdf
• AAGBI Video Platform “Neuromuscular Disease”http://videoplatform.aagbi.org/videoPlayer/?vid=100
• http://mda.org/disease/myotonic-muscular-dystrophy/signs-and-symptoms/adult-onset-MMD
• http://myotonic.org/sites/default/files/pages/files/Anesthesia%20Guidelines.pdf