Neuromuscular Diseases Flashcards
What is Duchenne’s Muscular Dystrophy?
The most common form of MD. Characterized by painless degeneration that progresses for 12-30 yrs, onset at 2-5 yrs of age, can follow the progression with serial CK levels. EKG may lose R wave amplitude. Results in pulmonary restrictive patterns and a poor cough (poor cough is not something you want to see when ur waking up ur pt)
What is Muscular Dystrophy?
MD is a a group of muscle diseases that weaken the musculoskeletal system and prevent locomotion. MD is characterized by progressive skeletal muscle weakness, defects in muscle membranes (lack dystropin, a protein), and the eath of muscle cells and tissue.
MD causes an insidious onset of skeletal muscle weakness, but also effects the myocardium. Cardia muscle is more prominently affected as time goes on -> dysfunction/degernation
What anesthetic considerations need to be made for a pt with Duchenne’s Muscular Dysstrophy?
- Delayed recover from GA and NDMRs.
- AVOID Sux.
- Possible inc. risk of MH
- Inhaled agents may cause rhabdo, but sevo is least damaging.
- Inhalational Anesthetics cause sig weakness of the myocardium, if pt already has baseline weakness, can cause CHF in OR
- prolonged recovery from NDMRs - consider mivaccurium/atracurium
What is the biggest risk in the OR with a pt with Duchenne’s MD?
Myocardial depression/ cardiac arrest associated with inhalational anesthetics
What are the more rare forms of Muscular Dystrophy?
Emery-Dreifuss - x-linked, no emerin
Fascioscapularhumeral - (he saw this on the boards once)
Oculopharyngeal - dysphagia, aspiration
Congenital
What is a myotonia?
A symptom of certain neuromuscular disorders characterized by delayed relaxation/sustained contraction.
Characteristics- defect of Na or Cl channels, minimal or no MR to NDMRs or deep GA, possible relaxation with LAs
What is Myotonic Dystrophy?
Hereditary degenerative disease. Persistent contracture after muscle movement. Peripheral nerves and the NMJ not affected. GI - aspiration risk b/c of discoordination of motor function. Pulm- restrictive pattern (difficult vent), dyspnea. Heart - arrhythmias.
What is Myasthenia Gravis?
Auto-immune disease where antibodies destroy Ach receptors. Onset pharyngeal and ocular weakness. see drooping of upper eyelid, double vision, hoarseness. weakness worsens with exercise. Endrophonium test - increases strength by blocking the breakdown of Ach. Inc [Ach] helps activate muscles.
What are the anesthetic considerations associated with Myasthenia Gravis?
Highly sensitive to NDMRs. Resistant to Sux. Sensitive to CNS depressants. Avoid beta-blockers bc bradycardia is commonly associated with this dz. Does not respond to glyco but atropine might work.
What is a Myasthenic Crisis and what causes it?
weakness due to some exacerbating agent. caused by infections or respiratory failure.
What is a Cholinergic Crisis?
increasing weakness and muscarinic effects caused by too much anti-cholinesterase (usually pyridostigmine). See bradycardia and SLUDGE
How can you differentiate between a cholinergic crisis and myasthenic crisis?
Give 1-10mg of Endrophonium.
Improvement = Myasthenic crisis Worse = cholinergic crisis. consider plasmapheresis.
What is Myasthenic Syndrome? What is another name for it?
Also known as Lambert-Eaton Syndrome. Associated with carcinomas (esp. sm cell lung cancers). IgG antibodies to Ca channels. Decreased Ach in synapse. Onset 5th-7th decade. Proximal muscle weakness. Gait disturbances.
What are the anesthetic considerations associated with Lambert-Eaton Syndrom?
Sensitivity to all MRs.
Prolonged ventilator weaning.
What is Multiple Sclerosis?
an acquired CNS disease that causes demyelination at multiple sites leading to muscle weakness.
Visual defects, nystagmus (voluntary or involunt eye movements)
Limb weakness variable - may be one extremity at first, that will recover, then another limb becomes weka followed by recovery, then you may have fascial droop
