Myasthenia Gravis EMS Considerations and Triage

Not all Myasthenia Gravis patients will present with obvious symptoms, but may still be struggling with rapidly increasing flaccidity that can lead to critical respiratory distress with partial or total diaphragmatic paralyzation. Anxiety may be present but it is not the cause of Mysasthenic emergency. Do NOT assume the patient is exaggerating symptoms in what may appear to be a benign presentation. Myasthenics can rapidly decline within minutes.

Not addressing a Myasthenic in exacerbation or crisis appropriately can lead to fatality.

Do not rely on single criteria assessment. Evaluation should include: 

1.  Blood pressure and heart rate: In respiratory distress, tacychardia and hypertension can be present. (Please note, Mestinon can cause hypotension and bradycardia.)
2. Respirations: Dypsnea, tachypnea (compensation for weakened inspiratory muscles)  and stridor may be present and exacerbated in the supine position which further weakens the diaphragm.
3. Speech quality: dysphonia, hypophonia, dysarthria, hyponasality and aphonia may be present, are part of bulbar weakness and connected to a flaccid diaphragm. Some patients have a predominance to bulbar weakness but it should always be considered a critical presentation in Myasthenics complaining of difficulty breathing or increasing systemic weakness.
4. Bulbar weakness: Dysphagia, sialorrhea, weak neck flexion and speech quality correlate to a flaccid and partially paralyzed diaphragm.
5. Check co2 with inspiratory flaccidity. Do not rely on osats for stability indicator. 
6. MEP/MIP, NIF, FVC should be part of exhaustive evaluation. Do not use one test in isolation over the other. Difficulty for patient to maintain a good seal on NIF/FVC or inability to repeat attempts due to increasing flaccidity can factor into falsely stable numbers.
7. ABG is not always a reliable indicator as changes in arterial blood gases may not happen until after the patient is critical. Do not use as a single exclusion test.
   
8. Check contraindicated medication list before medicating.
   

Oxygen can be used on route to the closest emergency facility but is a bandaid and will not address Myasthenic respiratory weakness. Myasthenia Gravis respiratory distress is an issue of ventilatory failure and not oxygenation capability. The lung's tissue maintains it's ability to oxygenate during inspiratory paralyzation in the early stages and oxygen levels can remain falsely elevated. Oxygen supplementation can be used for temporary assistance and comfort. NIV support is preferable and can be used to help assist the diaphragm and potentially avoid mechanical ventilation, although ventilation may be required. Avoid muscle relaxers for intubation if possible.

• Patient is not drunk and may be slurring due to bulbar weakness.
  
• Please notify the MG specialist or treating physician on route to the hospital.
  If you suspect exacerbation or crisis please check airway, inspiratory strength, neck flexion, speech quality, ability to clear secretions and swallowing.
  
• Do not lay the patient supine as this increases diaphragm weakness. Lay in an elevated position or elevated to the side.
  
• If the patient appears sleepy and is dyspniec or tacypenic, please check co2 for possible hypercapnia.
  
• Please avoid muscle relaxers.
• Patient may have predominance to respiratory flaccidity while maintaining reasonable levels of extremity and ocular strength. 

A patient may be experiencing varying levels of diaphragmatic paralysis and have stable testing outcomes. These do not rule out advancing exacerbation or crisis. Changes and measurable data may not occur until AFTER the patient has crashed. 

Maintain calm environment and appropriate ventilatory support. Do not wait for the patient to crash to seek NIV solutions. 

Ice packs on the neck, throat and diaphragm can help provide slowed nerve transmission and offer partial, temporary relief. Use as appropriate. Ensure room temperature is also cool and comfortable to allay increased flaccidity.


Cholinergic Crisis Assessment:

SLUDGE syndrome may be helpful in rapid assessment. Both Myasthenic and Cholinergic crisis may see crossover in presentation but these two crisis are very different. 

S : Salivation

L : Lacrimation

U : Urination 

D : Diarrhea 

G : GI Distress 

E : Emesis 

(M) : Miosis 

Cholinergic crisis is an over-stimulation at a neuromuscular junction due  to an excess of acetylcholine (ACh), as a result of the inactivity  (perhaps even inhibition) of the AChE enzyme, which normally breaks down  acetylcholine. Atropine can be used to help reverse Cholinergic crisis. Please assess patient for possible Cholinergic presentation: 

• Diaphoretic
• Sialorrhea
• Emesis
• Diarrhea
• Urination
• Severe GI Distress
• Sudden, pronounced weakness
• Twitching (moderate to severe)