Today we discuss NeuroMuscular Emergencies, such as Guillain-Barre Syndrome, Myasthenia Gravis, Botulism and so much more. NeuroMuscular emergencies seem hard without neurology backing you up, but thanks to the help of NeuroEMCrit editor, Casey Albin, we'll give you the knowledge you need to kick some synaptic ass!

Casey's NeuroMuscular Emergency Paper

Albin Neuro-Muscular

R/O / Consider Before Considering a NeuroMuscular Cause

Metabolic/Endocrine

Get a Metabolic Panel, TSH

• Hypokalemia
• Hyponatremia
• Hyper-or hypothyroid

Screen for Ticks

Exclude a Spinal Level

looking for cord impingement or transverse myelitis

Consider Spinal Epidural Abscess

Casey adds, “The one thing I think may be worth emphasizing (in hindsight) is that we as neurologist think of “neuromuscular weakness” as the term for “peripheral weakness” but I think its so so so crucial that everyone in emergency medicine thinks spinal epidural abscess for any acute weakness presentation.  Usually the patient has severe backpain, but not always. I have been disappointed by inconsistent “upper motor neuron findings” in these patients – they are frequently not hyperreflexic, their toes are often mute – which goes against how textbooks would describe it. (I think this is because often they have co-occuring vertebral body osteomyelitis causing compression of the nerve roots).”

Three Buckets for Emergency NeuroMuscular

Neuropathies

• Guillain Barre

Sensory and motor symptoms. Pain and/or tingling. May see autonomic as well. Often become hypo-reflexic

Neuromuscular Junction Diseases

• Myasthenia Gravis
• Botulism
• Tick Paralysis

Fatigable.

Myopathies

• Rhabdomyolysis
• Immune Checkpoint inhibitor necrotizing myopathy

Send a cpk. Proximal>distal weakness. No sensory involvement. Reflexes are ok (until maybe endstage).

History

Physical Exam

Myasthenia Gravis

Facial weakness, ptosis, extremity weakness. Pupils are spared. Symmetrical, fatigable.

New Presentation

Old man or young woman classically

Need to see a neurologist for full testing and screening

Fatigability Tests

Look up for 30 seconds, ptosis may emerge or get worse

Flap the chicken wing on one side 30 times and then test strength in both arms

Icepack Test

If the eyes have ptosis, place an icepack on one for a couple of minutes, the ptosis should improve on the iced side

Casey has never seen the icepack test work

Here is a youtube video on a bunch of MG Eye Signs from a specialist center in Prague

Myasthenic Crisis

Respiratory failure in a patient with new or established myasthenia

From infection, weaning steroids, medication exposure, or just disease fluctuation

Can temporize respiratory failure with NIPPV (they get better quickly) unless the patient is already hypercapneic. Use true NIPPV, not HFNC.

Intubation Meds

Use the magic rule: neuro=roc

Need ~ 50% the dose of non-depol (rocuronium, etc.) or ~2.5 x the dose of succinylcholine (Mt Sinai J of Med 2002;69(1):31)

so the smart move is just use 50% of your normal rocuronium dose (experts can also avoid paralytics entirely)

Medication Choices in the Mysasthenia Patient

Almost everything is bad.

When it comes to antibiotics, just use what is appropriate as they all can cause issues. Cephalosporins have some of the lowest reported disease interaction.

Plasma Exchange is preferred

Over IVIG

Wait for Neuro to give steroids

Steroids can initially make things worse

Cholinergic Crisis

Really only a board exam ? at this point. Patients are generally not on meds that will cause this and in one series, no cholinergic crisis presented in 11 years. [Roper et al.]

• Myasthenia gravis & myasthenic crisis
• Case Series of Myasthenic Crisis
• Great EM Review Paper on Myasthenia Gravis in the ED

Guillain-Barre Syndrome

Classically, ascending tingling and sensory symptoms possibly accompanied by back pain. Then they may have foot weakness and unsteadiness. Reflexes will be gone in areas in which weakness has progressed. But… there are many variants:

See below for assessment of respiratory status. These patients will have an extended course, so do not use NIPPV–if they need respiratory assistance>>intubate.

Screen for and empirically deal with urinary retention

These patients are easy to inadvertently send home. Make a clear plan to warn the patient to come back with ANY worsening

• IBCC on Guillain-Barre
• High risk and low prevalence diseases: Guillain-Barré syndrome. Am J Emerg Med. 2023 Oct 28:75:90-97. doi: 10.1016/j.ajem.2023.10.036.

Botulism

Clostridium botulinum, spore forming anaerobic, gram positive bacilli

Can withstand boiling for hours

Toxin mediated. Blocks ACh release at the NMJ.

Sx 12-36 hrs post-ingestion.  1-3 days after inhalation

Botulinum toxin-can be released as aerosol or spread by contaminated food. The most toxic substance known.

Prevents presynaptic release of ACh, therefore anticholinergic toxidrome, i.e.. dry mouth, ileus, and urinary retention.

1st cranial nerves are effected (pupillary dilation), then descending paralysis/weakness

Dry tongue and sore throat, ileus, urinary retention, double vision, dysarthria, hyporeflexia

Starts c Bulbar palsies then descending flaccid paralysis c intact sensation and decreased reflexes

Four Ds

· Diplopia

· Dysarthria

· Dysphonia

· Dysphagia

Antitoxin and toxoid vaccine available in scant supply.  Two antitoxins bivalent (AB) and trivalent (ABE). Antitoxin available from CDC

Surfaces can be decontaminated c .1% bleach

Not transmissible

May need to demonstrate LP and EMG to exclude other diagnoses. Consider miller fisher variant of guillain barre, get LP if diagnosis is in question in botulism it will be normal

Wound Botulism

Usually in IVDAs (black tar heroin)

PCN 10-20 million units IV/day ± antitoxin, consult toxicologist

Wound debridement

Contact local health department & CDC

• High Risk Low Prevalence: Botulism

When to Intubate or Place on NIPPV Support in NeuroMuscular Emergencies

Can they Lift their Head off the Bed (Neck Flexion)

The myotome that innervates that diaphragm also innervates the neck flexor muscles and the shoulder elevators

Pulmonary Function Testing

20/30/40 Rule

<20 ml/kg vital capacity, -30 or worse on NIF, <40 on maximal expiratory force

Negative Inspiratory Force (NIF)

worse than -20 is bad, better than -30 is good and in-between will require some judgment

Vital Capacity

Normal 4-5 L if a man, 3-4 for a woman

<20 cc/kg IBW (<1-1.5 L) is bad

Single Breath Counting Test

Take a deep breath and then see how high you can count, counting at two numbers per second on that one breath. Normal is 40-50, bad is usually cutoff at <=20

I am more bullish on this than Casey!

Elsheikh et al. showed single breath and neck flexion correlated with PFTs [doi: 10.1002/mus.24929]. There was a false positive, but no false negatives (a pt tested as ok, but actually had low PFTs) in this small study. They considered >25 to be ok respiratory function and also found SBCT# X 116=actual FVC.

Dishnica et al. performed a systematic review which demonstrated test validity [37094510]

It has also been found to correlate in other conditions like asthma, CF, etc.

Trajectory

What is the pace and point of their disease

Tachypnea

Be scared, this is how these patients compensate

Blood Gases

usually are misleading. PaCO2>45 predicts failure of NIPPV in MG.

Intubate GBS, strongly consider NIPPV for MG

More on EMCrit

• Neuromuscular Disorders(Opens in a new browser tab)

Additional New Information on NeuroMuscular Emergencies

• Author
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Scott Weingart, MD FCCM

Editor-in-Chief, at EMCrit.org

An ED Intensivist from NY.
Professor
Nassau University Medical Center
No conflicts of interest (coi).

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