17.4 Headache & Neuromuscular Emergencies: Migraine, Cluster, Myasthenic Crisis, Guillain-Barré & Bell's Palsy
Key Takeaways
For acute migraine in the ED, the American Headache Society says clinicians should offer IV metoclopramide, IV prochlorperazine or SC sumatriptan, plus dexamethasone to reduce recurrence.
Hydromorphone was far less effective than IV prochlorperazine for ED migraine in the HIT trial (2017), so opioids are not a first-line migraine treatment.
Cluster headache attacks are aborted with 100% oxygen at 12 to 15 L/min by non-rebreather mask for 15 minutes or with sumatriptan 6 mg SC.
Myasthenic crisis is treated with IVIG 2 g/kg or plasma exchange; fluoroquinolones, aminoglycosides, macrolides and IV magnesium can worsen weakness.
Corticosteroids do not help Guillain-Barré syndrome, but within 72 hours of onset they improve recovery in Bell's palsy.
17.4 Headache & Neuromuscular Emergencies: Migraine, Cluster, Myasthenic Crisis, Guillain-Barré & Bell's Palsy
Note
Exam scope: 2025 outline subtopic 2B7 (Pharmacotherapy for Neurology). Stroke, intracranial and subarachnoid hemorrhage, status epilepticus and traumatic brain injury are covered in Chapter 5; botulism antitoxin logistics in Section 14.3.
Dangerous Headaches First
Before treating a headache as migraine, look for red flags of a secondary cause:
- Sudden "thunderclap" onset or the worst headache of the patient's life: subarachnoid hemorrhage (Section 5.2)
- Fever with a stiff neck: meningitis (Section 12.1)
- New headache after age 50, jaw claudication or visual symptoms: giant cell arteritis
- Pregnancy or postpartum status: preeclampsia (Section 13.3) or cerebral venous thrombosis
- Anticoagulant use, cancer, immunosuppression or papilledema
- Several people in a household with headache: carbon monoxide (Section 9.2)
Giant cell arteritis threatens vision. The 2021 ACR/Vasculitis Foundation guideline supports starting high-dose glucocorticoids, such as prednisone 1 mg/kg/day (commonly 40 to 60 mg), without waiting for the temporal artery biopsy. Patients with visual loss usually receive IV methylprednisolone 500 to 1,000 mg daily for 3 days first.
Acute Migraine in the ED
American Headache Society Evidence Assessment (2016)
| Recommendation | Agents |
|---|---|
| Should offer | IV metoclopramide 10 mg; IV prochlorperazine 10 mg; SC sumatriptan 6 mg |
| Should offer to prevent recurrence | IV dexamethasone (commonly 10 mg) |
| May offer | IV ketorolac, IV valproate, IV acetaminophen, IV dihydroergotamine (DHE) with an antiemetic, droperidol, chlorpromazine, and others |
| May avoid | IV hydromorphone, IV morphine; IV diphenhydramine on its own (it does not add pain relief) |
Key Drug Details
- Dopamine antagonists (metoclopramide, prochlorperazine, droperidol) are the workhorses of ED migraine care. Higher metoclopramide doses (20 or 40 mg) were no better than 10 mg. Akathisia is the main adverse effect; infusing over about 15 minutes reduces it, and diphenhydramine is often given with the dose to prevent it.
- Sumatriptan 6 mg SC is most useful early in an attack. Contraindications include coronary, cerebrovascular or peripheral vascular disease, uncontrolled hypertension, hemiplegic or brainstem aura, and a triptan or ergot in the past 24 hours.
- Dihydroergotamine 0.5 to 1 mg IV (after an antiemetic) is effective for prolonged migraine. It must not be given within 24 hours of a triptan, in pregnancy, in vascular disease, or with strong CYP3A4 inhibitors (boxed warning for ergotism and ischemia).
- Dexamethasone given once reduces moderate to severe headache recurrence over the next 72 hours (number needed to treat about 9). It does not speed initial relief.
- Opioids: in the HIT trial (2017), IV hydromorphone was much less likely than IV prochlorperazine to give sustained relief, and the trial stopped early. Opioids also promote return visits and medication-overuse headache.
- Greater occipital nerve block with a local anesthetic is a reasonable option for patients who cannot take, or do not respond to, the drugs above.
Pregnancy and Discharge
In pregnancy, acetaminophen and metoclopramide are preferred. Avoid valproate and DHE, and avoid NSAIDs after about 20 weeks. At discharge, warn patients about medication-overuse headache (simple analgesics on 15 or more days a month, or triptans on 10 or more days a month) and refer for preventive therapy when attacks are frequent.
Cluster Headache
Cluster attacks are severe, one-sided headaches around the eye with tearing, nasal congestion and restlessness, lasting 15 to 180 minutes.
- 100% oxygen at 12 to 15 L/min by non-rebreather mask for 15 minutes
- Sumatriptan 6 mg SC, or zolmitriptan nasal spray
- Short courses of oral steroids or an occipital nerve block can bridge the patient until preventive treatment (commonly verapamil, with ECG monitoring for heart block) takes effect.
Myasthenia Gravis and Myasthenic Crisis
Myasthenic crisis is respiratory failure from weakness of the breathing and swallowing muscles. Infection, surgery, pregnancy and medications commonly trigger it.
Monitoring Respiratory Function
Pulse oximetry and blood gases change late. Use bedside respiratory mechanics, often remembered as the "20/30/40 rule":
- Vital capacity below 20 mL/kg
- Maximal inspiratory pressure weaker than −30 cm H2O
- Maximal expiratory pressure below 40 cm H2O
Any of these, or a declining trend, should prompt ICU care and planning for elective intubation.
Treatment
| Therapy | Notes |
|---|---|
| IVIG 2 g/kg divided over 2 to 5 days | Similar efficacy to plasma exchange; check IgA status, watch for volume overload, kidney injury and thrombosis |
| Plasma exchange (about 5 exchanges) | Works faster in some patients; needs central access |
| High-dose corticosteroids | Can cause temporary worsening in the first 1 to 2 weeks, so they are usually started alongside IVIG or plasma exchange in a monitored setting |
| Pyridostigmine | Often held while the patient is intubated because it increases secretions |
Newer maintenance drugs include FcRn blockers and complement C5 inhibitors (eculizumab, ravulizumab, zilucoplan). C5 inhibitors carry boxed warnings and REMS programs for life-threatening meningococcal infection. Treat fever in these patients as possible meningococcemia.
Drugs That Can Worsen Myasthenia
- Fluoroquinolones (boxed warning), aminoglycosides, macrolides and telithromycin
- IV magnesium
- Beta-blockers, procainamide and quinidine
- Hydroxychloroquine, chloroquine and quinine
- Botulinum toxin
- Immune checkpoint inhibitors, which can also cause new myasthenia
Intubating a patient with myasthenia: patients are relatively resistant to succinylcholine, so higher doses (such as 1.5 to 2 mg/kg) are often used. They are very sensitive to non-depolarizing agents, so expect prolonged paralysis from rocuronium and keep sugammadex available.
Guillain-Barré Syndrome (GBS)
GBS causes ascending, symmetric weakness with loss of reflexes, often after a respiratory or GI infection.
- IVIG 0.4 g/kg/day for 5 days (2 g/kg total) or plasma exchange started within 2 to 4 weeks of onset speeds recovery. Combining them adds no benefit.
- Corticosteroids are not effective and are not used.
- Respiratory failure: use the 20/30/40 thresholds. Rapid progression, inability to cough or lift the head, and bulbar weakness predict the need for ventilation.
- Dysautonomia: blood pressure and heart rate can swing widely. Treat with short-acting, titratable drugs, and use caution with drugs that cause hypotension or bradycardia.
- Avoid succinylcholine because denervated muscle releases dangerous amounts of potassium (Section 4.3).
- Neuropathic pain responds to gabapentinoids. Give VTE prophylaxis to patients who cannot walk.
Botulism
Botulism causes descending, symmetric paralysis that starts with the cranial nerves (double vision, drooping eyelids, slurred speech, difficulty swallowing) in an alert patient. Contact the state health department immediately: CDC releases heptavalent botulinum antitoxin for children and adults, and botulism immune globulin (BabyBIG) for infant botulism. Avoid aminoglycosides, which worsen neuromuscular blockade. Wound botulism in people who inject drugs also needs debridement.
Bell's Palsy
Bell's palsy is an acute peripheral facial nerve palsy affecting the whole half of the face, including the forehead. Rule out stroke (which spares the forehead), Lyme disease, zoster and otitis.
- Oral corticosteroids started within 72 hours of onset (AAO-HNS 2013), for example prednisolone 50 mg daily for 10 days or prednisone 60 mg daily for 5 days followed by a taper.
- Antivirals alone are not recommended; adding valacyclovir to steroids is optional.
- Eye protection is essential: lubricating drops by day, ointment and taping at night, to prevent corneal injury.
A 32-year-old woman with known migraine has a typical 14-hour headache with nausea and no red flags. She took sumatriptan 100 mg orally 3 hours ago without relief. Which ED regimen is most consistent with American Headache Society recommendations?
Prochlorperazine 10 mg IV, plus dexamethasone 10 mg IV
Sumatriptan 6 mg SC, plus diphenhydramine 50 mg IV
Dihydroergotamine 1 mg IV with metoclopramide 10 mg IV
Hydromorphone 1 mg IV, repeated every 30 minutes as needed
A 45-year-old with generalized myasthenia gravis has worsening shortness of breath, a weak cough and difficulty swallowing. Her vital capacity is 1.1 L (her ideal body weight is 60 kg). The team is choosing antibiotics for a possible aspiration pneumonia. Which antibiotic should be avoided if possible?
Levofloxacin
Ceftriaxone
Piperacillin-tazobactam
Ampicillin-sulbactam
A 38-year-old man has had ascending leg weakness and areflexia for 5 days after a diarrheal illness. Nerve studies support Guillain-Barré syndrome. He can still walk with help, but his vital capacity is falling. Which treatment plan is most appropriate?
IVIG 0.4 g/kg/day for 5 days with close respiratory monitoring
Methylprednisolone combined with IVIG for a synergistic effect
Pyridostigmine 60 mg orally every 4 hours
Methylprednisolone 1 g IV daily for 5 days
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