Transcript
Page 1: Myotonic Dystrophy - Anaesthetic Considerations

Myotonic dystrophy

Case PresentationMarch 2013

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Outline

• Case• Background• Signs and symptoms• Treatment• Considerations for anaesthetic• Summary

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Case

• 46 year old male• Known myotonic dystrophy• Right open ankle fusion & osteotomy

• WHAT ARE THE ANAESTHETIC CONSIDERATIONS?

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Background (1)

• LOTS OF NAMES– Myotonic Dystrophy– Steinert’s Disease– Dystrophica Myotonica– Myotonica Atrophica– Batten-Curschmann’s– Hoffman’s

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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)

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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

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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

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Useful clinical clue for diagnosis:Failure of spontaneous letting go of the hands following strong handshakes due to myotonia

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Definitive diagnosis by:

• DNA analysis• EMG• Slit lamp exam of lens• Serum CK• Serum FSH, testosterone• ECG• Muscle biopsy

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Treatment

• No cure or treatment• Manage complications – orthotics,

pacemakers, physio, mobility aids

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Myotonic Dystrophy & Anaesthesia

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Anaesthetic related problems

• Diagnosis• Getting correct history• Cardio-respiratory complications• Aspiration risk• ? Difficult airway• Analgesic/anaesthetic drugs• Neuromuscular blocking drugs• Myotonia triggers• Pregnancy

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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

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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

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Respiratory investigations

• CXR– Subclinical aspiration common

• Pulmonary function tests– Spirometry– ABG

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Airway problems

• ? RSI– Aspiration risk– Avoid suxamethonium

• ? Intubation difficulty

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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

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Peri-operative complications

• OSA, aspiration• Dysrrythmias, cardiac failure• Autonomic dysfunction• Myotonia• Rhabdomyolysis

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Myotonia

• Can be precipitated by:– suxamethonium – anticholinesterases – opioids – alterations in temperature/shivering – acidosis

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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

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Pregnancy in MD

• Increase in myotonic symptoms• Atonic uterus• PPH common• Mother can pass on congenital form to baby

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Case

• Spinal sited with 2.2ml 0.5% heavy marcain and 0.3mg diamorphine

• No sedation required• Oxygen via simple hudson facemask• Uneventful anaesthetic

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Summary

• Large spectrum of signs & symptoms• Often misdiagnosed or underdiagnosed

condition• Knowledge & awareness of condition means

the avoidable & expected complications can be minimised

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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


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