Eduovisual
Nervous System & Special Senses
Myasthenic crisis: recognition and management
— Occurs in ~15–20% of MG patients, usually within the first 2–3 years of diagnosis.
— Bimodal: young women (<40) and older men (>60).
— May be the presenting feature in up to 20% of newly diagnosed MG.
— Infection (~40%, especially respiratory/UTI) — most frequent.
— Medications: aminoglycosides, fluoroquinolones, macrolides, beta-blockers, magnesium, neuromuscular blockers, procainamide, telithromycin (boxed warning), immune checkpoint inhibitors.
— Surgery, anesthesia, pregnancy/postpartum, thyroid dysfunction, tapering of immunosuppression, aspiration.
— Heat, emotional stress, electrolyte disturbance (hypokalemia, hypophosphatemia).
— Known MG patient with new dyspnea, dysphagia, dysarthria, or "I can't lift my head."
— Undiagnosed patient with fluctuating, fatigable ptosis/diplopia + new respiratory complaints.
— Postoperative patient with unexplained failure to wean from ventilator.
Board pearl: A worsening MG patient on pyridostigmine who develops miosis, salivation, diarrhea, and fasciculations has cholinergic crisis, not myasthenic crisis — both cause weakness, but the autonomic signs distinguish them. In practice, cholinergic crisis is rare since pyridostigmine dosing rarely exceeds 480 mg/day; assume myasthenic crisis until proven otherwise.
— Generalized fatigable weakness worse with repetition and at the end of the day.
— Ocular symptoms (ptosis, diplopia) almost always present but rarely the chief complaint in crisis.
— Dysphagia — coughing/choking with liquids, drooling, weight loss.
— Dysarthria — nasal speech, voice fades with prolonged talking ("count to 50" test).
— Jaw weakness — patient props chin with hand.
— Neck flexor weakness — head drop, "can't lift head off pillow."
— Dyspnea on exertion → at rest; orthopnea from diaphragm weakness.
— Tachypnea with shallow breathing; paradoxical abdominal motion when supine.
— Inability to speak in full sentences; staccato speech.
— Anxiety, restlessness, tachycardia = hypercapnia warning signs even before SpO₂ drops.
— Known MG? Antibody status (AChR vs MuSK)? Thymectomy?
— Current meds: pyridostigmine dose/timing, prednisone, mycophenolate, azathioprine, rituximab.
— Recent medication changes, antibiotic exposure (especially fluoroquinolones), iodinated contrast.
— Infectious symptoms (URI, dysuria, diarrhea).
— Pregnancy, recent surgery/anesthesia, missed pyridostigmine doses.
— Vaccinations, immunotherapy starts/tapers.
Key distinction: Pure ocular MG (ptosis/diplopia only for >2 years) almost never progresses to crisis. Generalized MG with bulbar features is the high-risk phenotype — these patients warrant low threshold for ICU admission. Always ask, "When you eat, does food come back through your nose?" — nasal regurgitation is a red flag for palatal weakness and impending aspiration.
— Ptosis — worsens with sustained upgaze >30 seconds (fatigability).
— Ice pack test: ice on closed eyelid for 2 min improves ptosis (>2 mm) — quick bedside diagnostic, sensitivity ~80%.
— Diplopia worsens with sustained lateral gaze; pupils spared (key vs Miller Fisher, botulism).
— Bifacial weakness ("myasthenic snarl" — horizontal smile).
— Weak palate elevation, poor cough, weak gag.
— Proximal > distal weakness; fatigability on repetitive testing (e.g., arms held outstretched, repeated shoulder abduction).
— Neck flexor weakness — sensitive marker; can't lift head off bed against gravity.
— Deep tendon reflexes preserved (vs GBS where they are lost).
— Forced vital capacity (FVC): intubate if <15 mL/kg (or <1 L absolute, or falling rapidly).
— Negative inspiratory force (NIF/MIP): intubate if less negative than −20 cmH₂O.
— Positive expiratory force (PEF/MEP): <40 cmH₂O predicts weak cough/aspiration.
— Single-breath count test: counting <20 in one breath suggests FVC <1 L.
Step 3 management: Do not rely on pulse oximetry or ABG to decide on intubation in neuromuscular respiratory failure — patients maintain SpO₂ until near-arrest. Trend FVC and NIF every 2–4 hours. Order serial bedside spirometry on admission. CCS-style: place patient in monitored bed, order continuous pulse ox + telemetry, NPO if dysphagia, head of bed 30°, suction setup.
— FVC and NIF — repeat q2–4h; document trend in chart.
— ABG — note: a normal PaCO₂ in a tachypneic MG patient is abnormal and predicts crisis (loss of compensatory hyperventilation). Hypercapnia is a late finding.
— Continuous SpO₂, telemetry, BP.
— CBC with differential (infection), CMP (K⁺, Mg²⁺, PO₄³⁻, Ca²⁺), CRP, procalcitonin.
— TSH (thyroid disease coexists in 10–15% of MG; can precipitate crisis).
— Blood and urine cultures if febrile or any source suspected.
— Influenza/COVID/RSV PCR, sputum gram stain and culture.
— Troponin if elderly or hemodynamic instability (rare MG-associated myocarditis with checkpoint inhibitors).
— β-hCG in reproductive-age women — affects treatment choice.
— Pre-IVIG: IgA level (IgA deficiency → anaphylaxis risk), renal function, hypercoagulable risk assessment.
— Pre-PLEX: coags, fibrinogen, calcium, type & screen.
— CXR: screen for pneumonia, atelectasis, aspiration; assess diaphragm position.
— CT chest (with contrast) when stable: evaluate for thymoma (10–15% of MG patients, more in older men) — surgical implications.
— CT/MRI brain if focal deficits or altered mentation (rules out stroke mimic).
Board pearl: An MG patient presenting with crisis and a mediastinal mass on CXR has thymoma until proven otherwise — thymectomy after stabilization is standard, especially for AChR-positive disease. Avoid iodinated contrast during acute crisis if possible (rare reports of MG worsening); if essential, do not delay life-saving imaging. Key distinction: unlike GBS, CSF in MG is normal — don't routinely LP unless mimic suspected.
— Anti-AChR antibodies: positive in ~85% of generalized MG. Binding > modulating > blocking in sensitivity.
— Anti-MuSK antibodies: in ~40% of AChR-negative patients; predicts bulbar-dominant disease, poor pyridostigmine response, PLEX > IVIG preference.
— Anti-LRP4 and agrin antibodies in seronegative MG.
— Anti-striated muscle antibodies: correlate with thymoma.
— Repetitive nerve stimulation (RNS): decremental response >10% at low frequency (2–3 Hz) in proximal muscle — classic.
— Single-fiber EMG (SFEMG): most sensitive (>95%); shows increased jitter and blocking. Used when RNS is negative and clinical suspicion remains.
— Edrophonium (Tensilon) test — rarely used now due to risk of bradycardia/asystole; have atropine ready. Replaced by ice pack test and serology.
— Review medication list for offenders; check inpatient orders added on this admission.
— Aspiration evaluation: speech pathology swallow eval once stable.
— Consider thymic imaging (CT/MRI chest) in all new MG diagnoses.
— Hepatitis B/C, HIV, TB (QuantiFERON), VZV serology, PPD before chronic steroids/azathioprine.
— TPMT activity before azathioprine (deficiency → severe myelosuppression).
— Vaccinations: pneumococcal, influenza, COVID, shingles (inactivated) before initiating immunosuppression.
Step 3 management: In the crashing patient, do not delay PLEX or IVIG awaiting antibody results. Treatment is clinical. Order serologies and EMG to confirm and to guide chronic therapy choice. CCS pearl: schedule pulmonology and neurology consults on day 1; order swallow eval before advancing diet.
— Intubate for: FVC <15 mL/kg, NIF less negative than −20, PaCO₂ rising, exhaustion, weak cough with secretions, aspiration.
— Avoid succinylcholine (unpredictable response) and prolonged nondepolarizers — use reduced-dose rocuronium (~50%) and have sugammadex available, or perform awake fiberoptic intubation.
— NIV (BiPAP) trial reasonable in alert, cooperative patient without severe bulbar weakness or copious secretions — can avert intubation in ~50%. Contraindicated with significant dysphagia (aspiration risk).
— Both PLEX and IVIG are first-line; choose based on patient factors (see chunk 7).
— Start within 24 hours of crisis recognition.
— Many centers hold pyridostigmine in intubated patients to reduce secretions and avoid confounding cholinergic toxicity; resume at lower dose when extubating.
— Start/continue prednisone, but be aware of transient worsening within 5–10 days of high-dose steroid initiation (~50% of patients) — this is why steroids should ideally begin after PLEX/IVIG response in crisis.
— Stop offending drugs; treat infection with MG-safe antibiotics (e.g., ceftriaxone, vancomycin, TMP-SMX); avoid fluoroquinolones, aminoglycosides, macrolides.
CCS pearl: Admit to ICU for any crisis or impending crisis. Order: continuous monitoring, q2h FVC/NIF, NPO until swallow cleared, DVT prophylaxis, stress ulcer prophylaxis, head of bed 30°, neurology consult, pulmonology consult, plasmapheresis or IVIG order, hold offending meds. Board pearl: Steroid-induced worsening is a classic test answer — patients get worse before they get better.
— Removes circulating pathogenic antibodies.
— Typical course: 5 exchanges (1–1.5 plasma volumes) over 7–10 days, every other day.
— Onset: rapid — improvement often within 1–3 sessions, peak ~1 week.
— Preferred for: MuSK-positive MG, severe/rapid crisis, IgA deficiency, fluid overload risk, thromboembolism risk.
— Requires central venous access (large-bore); risks: hypotension, hypocalcemia (citrate), coagulopathy, line infection, bleeding.
— Dose: 2 g/kg total over 2–5 days (typically 0.4 g/kg/day × 5).
— Onset similar to PLEX; durability ~3–6 weeks.
— Preferred for: poor venous access, hemodynamic instability, sepsis (PLEX removes antibiotics), pediatric patients.
— Contraindications/cautions: IgA deficiency (anaphylaxis — check level first), renal failure (use sucrose-free preparation), thrombosis risk (hyperviscosity), CHF (volume load), hemolysis.
— Pre-medicate with acetaminophen ± diphenhydramine; ensure adequate hydration.
— Prednisone 1 mg/kg/day (or methylprednisolone IV equivalent) once airway secured and PLEX/IVIG initiated.
— Warning: steroid-induced exacerbation in ~50% within 5–10 days — start after initiating PLEX/IVIG, or start low and titrate up.
— Long-term taper over months.
— Symptomatic only; does not modify disease.
— Typical: 30–60 mg PO q4–6h; max ~120 mg q3h.
— Hold during mechanical ventilation to reduce secretions; restart when weaning.
— MuSK-positive patients tolerate it poorly — often worsens.
Step 3 management: PLEX and IVIG are equally effective in AChR-MG crisis. Pick based on patient factors — both are correct in board stems; the wrong answer is to delay them.
— Preoxygenate with NIV if tolerated.
— Suction secretions; upright positioning.
— Resuscitate volume status (PLEX/IVIG tolerance).
— Etomidate or propofol — preferred for hemodynamic stability and lack of neuromuscular interaction.
— Ketamine acceptable.
— Avoid succinylcholine when possible — resistance at the depolarizing receptor (need higher dose) but prolonged effect unpredictable; also risk in chronic immobilized patient (hyperkalemia).
— Rocuronium at ~50% dose — MG patients are markedly sensitive to nondepolarizing agents; duration prolonged.
— Sugammadex reverses rocuronium/vecuronium rapidly — should be available at bedside.
— Awake fiberoptic intubation an option in cooperative patients with anticipated difficulty.
— Lung-protective settings (Vt 6–8 mL/kg IBW).
— Adequate PEEP to prevent atelectasis given weak inspiratory effort.
— Daily SBT once mechanics improve; assess FVC, NIF, secretion burden, mental status, cuff leak.
— FVC >15–20 mL/kg, NIF more negative than −25 to −30, manageable secretions, awake and cooperative, resolution of underlying trigger.
— Consider extubation directly to NIV to bridge respiratory muscle recovery.
— Reintubation rate ~25% — set expectations.
— Consider if intubated >2 weeks or repeated failed extubations.
— Central line for PLEX if peripheral access inadequate.
— NG tube for medications (crushed pyridostigmine) and feeding.
— Thymectomy — not performed during crisis; deferred until clinical stability (weeks), then via VATS or transsternal approach. Indicated in thymoma (all) and AChR-positive nonthymomatous MG aged 18–65 (MGTX trial).
Board pearl: MGTX trial showed thymectomy + prednisone superior to prednisone alone for AChR-positive generalized MG aged 18–65 — fewer hospitalizations, lower steroid burden over 3 years.
— Rising incidence — late-onset MG often AChR-positive, male predominant, thymoma more common (CT chest mandatory).
— Higher mortality in crisis (10–15% vs 4–8% overall).
— More comorbidities: CAD, CHF, CKD, dementia — complicate IVIG (thrombosis, fluid overload) and PLEX (hemodynamic shifts).
— Polypharmacy review is essential — beta-blockers, statins (rare worsening), CCBs, fluoroquinolones often present.
— Steroid risks amplified: osteoporosis, hyperglycemia, delirium, infection — bone protection (calcium, vitamin D, bisphosphonate), PJP prophylaxis with TMP-SMX if prednisone ≥20 mg/day for ≥4 weeks.
— Delirium screening (CAM-ICU) daily.
— Higher rate of prolonged ventilation and tracheostomy.
— IVIG: avoid sucrose-containing preparations (acute kidney injury); use sucrose-free products; ensure adequate hydration; reduce infusion rate.
— Pyridostigmine: renally cleared — reduce dose in CKD/dialysis.
— Steroids: dose adjust based on comorbid hypertension, diabetes.
— Mycophenolate/azathioprine: monitor cytopenias closely.
— Azathioprine hepatotoxicity — check LFTs at baseline and periodically.
— Mycophenolate generally safe; monitor.
— Avoid hepatically cleared drugs that worsen MG (e.g., chlorpromazine).
— IVIG → thrombosis and CHF exacerbation risk.
— PLEX → fluid shifts, hypocalcemia → arrhythmia risk.
— Continuous telemetry during therapy.
Step 3 management: In an elderly MG patient in crisis with CKD and CHF, PLEX is generally preferred over IVIG to avoid volume load and thrombotic/renal risks — assuming the patient can tolerate central access and hemodynamic shifts. Board pearl: Always rule out thymoma in late-onset MG — CT chest is part of the workup.
— MG course unpredictable: ~1/3 improve, 1/3 stable, 1/3 worsen — crisis risk highest in first trimester and postpartum.
— Safe medications: pyridostigmine (preferred), prednisone (preferred immunosuppressant), azathioprine (continue if already on), IVIG, PLEX.
— Avoid: mycophenolate (teratogenic — D-class; switch preconception), methotrexate, cyclophosphamide.
— Magnesium sulfate is contraindicated for preeclampsia/eclampsia in MG — precipitates severe crisis. Use levetiracetam or phenytoin for seizure prophylaxis instead.
— Labor: vaginal delivery preferred; second stage may require assistance (forceps/vacuum) due to fatigue. Cesarean only for obstetric indications.
— Anesthesia: regional preferred over general; avoid neuromuscular blockers if possible.
— High relapse risk in first weeks.
— Pyridostigmine, prednisone, IVIG, azathioprine compatible with breastfeeding.
— Occurs in ~10–20% of infants born to AChR-positive mothers from transplacental antibody transfer.
— Symptoms: hypotonia, poor feeding, weak cry, respiratory distress within hours to days of life.
— Self-limited (resolves in 2–4 weeks); supportive care; pyridostigmine or IVIG if severe.
— Pediatrics/NICU consult on delivery.
— Onset <18 years; prepubertal cases often seronegative, post-pubertal more like adult MG.
— Crisis less common; treatment principles similar; avoid chronic steroids when possible due to growth effects — favor IVIG, mycophenolate, rituximab.
— Thymectomy considered in AChR-positive generalized juvenile MG.
Board pearl: A pregnant MG patient with preeclampsia getting IV magnesium → sudden respiratory failure is a classic Step 3 stem. The answer: stop magnesium, secure airway, give calcium gluconate, and use alternative seizure prophylaxis.
— Ventilator-associated pneumonia (VAP) — incidence ~25% in MC; use VAP bundle (HOB elevation, chlorhexidine oral care, subglottic suction, daily sedation interruption).
— Atelectasis from weak cough — chest physiotherapy, incentive spirometry.
— Aspiration pneumonia from bulbar dysfunction — NPO + swallow eval before diet.
— Mucus plugging — aggressive suctioning, humidification.
— Stress cardiomyopathy (Takotsubo) — particularly with prolonged crisis.
— Arrhythmias from electrolyte shifts during PLEX (hypocalcemia, hypokalemia).
— DVT/PE — immobility plus IVIG procoagulant effect; mechanical + chemical prophylaxis.
— IVIG: headache (most common), aseptic meningitis, AKI, thrombosis, hemolysis, anaphylaxis (IgA deficient).
— PLEX: hypotension, hypocalcemia (citrate), bleeding, line infection, pneumothorax.
— Steroids: transient worsening, hyperglycemia, psychosis, infection, osteoporosis, adrenal suppression.
— Pyridostigmine excess: cholinergic symptoms, increased secretions, bradycardia.
— Hospital-acquired pneumonia, line sepsis, C. difficile, UTI (catheter).
— Opportunistic infections on chronic immunosuppression: PJP, CMV, HSV/VZV reactivation, hepatitis B reactivation (screen and prophylax with rituximab).
— ICU-acquired weakness (critical illness myopathy/neuropathy) — confounds extubation.
— Steroid myopathy with prolonged high-dose steroids.
— ICU delirium, post-ICU PTSD, depression.
— Steroid-induced mood changes.
Key distinction: Persistent weakness after PLEX/IVIG response may represent critical illness myopathy, not refractory MG — EMG can differentiate and avoids unnecessary escalation of immunotherapy.
— Mechanical ventilation or NIV.
— FVC <20 mL/kg or NIF less negative than −25.
— Severe bulbar dysfunction with aspiration risk.
— Need for PLEX with central line and hemodynamic monitoring.
— Rapidly worsening trajectory regardless of absolute numbers.
— Stabilized after PLEX/IVIG, off ventilator, FVC trending up, manageable secretions.
— Neurology — diagnostic confirmation, immunotherapy plan.
— Pulmonology/critical care — ventilation strategy, extubation readiness.
— Anesthesiology — if intubation anticipated or perioperative MG.
— Speech-language pathology — swallow evaluation before any PO intake.
— Nutrition — enteral feeding plan during NPO.
— Physical/occupational therapy — early mobilization to prevent ICU weakness.
— Pharmacy — medication review for MG-exacerbating drugs.
— Cardiothoracic surgery — for thymectomy planning (post-stabilization).
— Social work/case management — disposition, durable medical equipment, home health.
— Psychiatry — for steroid-induced mood disturbance, ICU delirium, adjustment.
— Community hospitals without PLEX capability or neuro-ICU should transfer early to tertiary center — do not delay for "stabilization."
— Ensure airway secured before transfer if any borderline mechanics.
— Most MG patients have good prognosis even after crisis — emphasize that mechanical ventilation is usually time-limited and reversible. This nuance affects goals-of-care conversations.
CCS pearl: On the CCS screen, a deteriorating MG patient should trigger: move to ICU, consult neurology, consult pulmonology/CC, order FVC/NIF q2h, start PLEX or IVIG, hold offending drugs, NPO, cultures, broad-spectrum antibiotics if infection suspected. Step 3 management: Don't wait for ABG hypercapnia to intubate — by then, decompensation is imminent.
— Ascending weakness, areflexia, often post-infectious (Campylobacter, CMV).
— Sensory symptoms (paresthesias) common; autonomic dysfunction.
— CSF: albuminocytologic dissociation (elevated protein, normal cell count).
— NCS: demyelinating pattern.
— Treatment: IVIG or PLEX (steroids not helpful, unlike MG).
— Antibodies to presynaptic voltage-gated calcium channels.
— Associated with small cell lung cancer (~50%).
— Proximal weakness that improves with repeated use (post-exercise facilitation) — opposite of MG.
— Hyporeflexia with autonomic features (dry mouth, orthostasis, impotence).
— RNS: incremental response at high frequency (>20 Hz).
— Treatment: 3,4-diaminopyridine (amifampridine), treat underlying malignancy.
— Descending flaccid paralysis, dilated/fixed pupils, prominent autonomic features (dry mouth, ileus, urinary retention).
— Sources: home canning (foodborne), wound (IV drug use, especially black tar heroin), infant (honey).
— Treatment: equine antitoxin ASAP (do not wait for confirmation); supportive ventilation.
— Immune checkpoint inhibitor-induced MG (pembrolizumab, nivolumab) is increasingly recognized and may overlap with myocarditis and myositis — high mortality; treat with steroids + IVIG/PLEX and stop the checkpoint inhibitor.
Key distinction: Pupils — spared in MG, dilated/fixed in botulism, normal in GBS (or sluggish in Miller Fisher), miotic in organophosphates. This single exam finding rapidly narrows the differential in a paralyzed patient.
— Sudden onset, cranial nerve deficits, often crossed signs, altered consciousness, may have "locked-in" pattern.
— Pupillary abnormalities, hemiparesis, dysarthria.
— MRI brain with diffusion is diagnostic; time-sensitive for thrombolysis/thrombectomy.
— Generalized weakness with mental status change in elderly often mimics neuromuscular decline.
Board pearl: Always consider basilar stroke in a patient with sudden bulbar symptoms and quadriparesis without fatigability — it is a "can't miss" diagnosis with a treatment window. Key distinction: MG weakness fluctuates over the day and is fatigable; stroke weakness is sudden and static; GBS weakness is progressive over days and symmetric ascending. Time course is your best diagnostic tool when the exam is ambiguous.
— Prednisone: start once airway secured and PLEX/IVIG response seen; typical 60 mg/day, then alternate-day dosing, taper over months to lowest effective dose.
— Steroid-sparing agents (added early to reduce steroid burden):
— Azathioprine 2–3 mg/kg/day — check TPMT first; monitor CBC, LFTs.
— Mycophenolate mofetil 1–1.5 g BID — common first choice; monitor CBC.
— Rituximab — particularly effective in MuSK-positive MG; also refractory AChR.
— Eculizumab/ravulizumab (C5 complement inhibitors) — refractory AChR-positive generalized MG; meningococcal vaccination required before initiation.
— Efgartigimod, rozanolixizumab (FcRn inhibitors) — newer options that reduce IgG.
— Maintenance IVIG or PLEX every 3–6 weeks for refractory cases.
— All patients with thymoma.
— AChR-positive generalized MG aged 18–65 within 3–5 years of diagnosis (MGTX trial).
— Not for MuSK-positive disease.
— Avoid: aminoglycosides, fluoroquinolones, macrolides (esp. telithromycin), beta-blockers (use cautiously), magnesium, procainamide, quinine/quinidine, IV contrast (caution), botulinum toxin, neuromuscular blockers without anesthesia awareness.
— Provide a MG medication alert card and MedicAlert bracelet.
— Annual influenza vaccine (inactivated), pneumococcal series, COVID-19 vaccination, RSV vaccine (≥60), shingles (Shingrix, inactivated — safe on immunosuppression).
— Pre-immunosuppression: hep B, TB, VZV screening.
Step 3 management: Before discharge, ensure: pneumococcal + influenza vaccine, MG drug-avoidance handout, neurology follow-up in 1–2 weeks, PCP follow-up in 1 week, written taper schedule.
— PCP within 1 week — medication reconciliation, vital signs, blood glucose on steroids, mood, infection screening.
— Neurology within 1–2 weeks, then every 1–3 months until stable, then every 3–6 months.
— Pulmonology if persistent respiratory symptoms or NIV at home.
— Speech therapy for residual dysphagia; outpatient swallow eval if any concern.
— PT/OT for deconditioning, ICU-acquired weakness.
— Symptom diary: ptosis, diplopia, swallowing, breathing, fatigue patterns.
— MG-ADL and MG-QOL15 scales at each visit for objective tracking.
— FVC/spirometry at outpatient visits in higher-risk patients.
— Steroid monitoring: weight, BP, glucose (HbA1c q3 months), bone density yearly, cataract screening, mood.
— Azathioprine: CBC weekly × 1 month, then monthly; LFTs monthly initially.
— Mycophenolate: CBC monthly; pregnancy prevention (REMS).
— Rituximab: hep B reactivation surveillance, infusion reactions, hypogammaglobulinemia (IgG levels).
— Avoid driving during active diplopia or limb weakness; clear with neurology before resuming.
— Heat avoidance (saunas, hot tubs) — heat worsens MG.
— Pace activity; rest periods; energy conservation strategies.
— Job accommodations for fatigue.
— Avoid strenuous repetitive tasks during exacerbation.
— Pregnancy planning with maternal-fetal medicine.
— Myasthenia Gravis Foundation of America (MGFA) — patient resources, support groups.
— Crisis warning signs: increasing dyspnea, dysphagia, head drop — call neurology or go to ED.
— Medication list and emergency card to share with all providers.
— Screen for depression and anxiety at each visit (PHQ-9, GAD-7); common after ICU stay.
— Refer for therapy and pharmacotherapy as needed; SSRIs generally safe.
Board pearl: Patients who develop crisis once have ~30% risk of recurrence — long-term immunotherapy optimization is the cornerstone of prevention.
— Patient may be unable to speak due to bulbar weakness — assess capacity carefully; written communication, blinking, or surrogate decision-maker may be needed.
— For PLEX, IVIG, central line, intubation: obtain consent before respiratory failure when possible; document discussions with surrogate when patient cannot consent.
— Advance directives and code status — discuss early, while patient can communicate; reaffirm with family.
— Frame mechanical ventilation as typically reversible and time-limited — most MG patients recover and return to baseline. This nuance matters for elderly patients or those with multiple comorbidities considering DNR/DNI.
— Avoid premature withdrawal in MG crisis — prognosis is better than most ICU paralytic conditions.
— Medication reconciliation at every transition — a fluoroquinolone or beta-blocker added on admission or by another team is a classic preventable trigger. Place "MG medication allergy/alert" in EHR.
— Anesthesia hand-off: flag MG diagnosis pre-op; communicate with anesthesia about NMBA sensitivity.
— Mandatory reporting: report adverse drug reactions (FAERS) for new MG-triggering medications, especially with immune checkpoint inhibitors — emerging signal.
— Discharge transition: highest readmission/relapse risk in first 2 weeks — confirm follow-up appointments before discharge, provide direct neurology contact, written warning signs, and pharmacist medication review.
— Vaccination timing: live vaccines contraindicated on immunosuppression — document and educate.
— Counsel on driving restrictions during diplopia/weakness — varies by state law; some states require physician reporting of conditions affecting safe driving.
— Refractory MG patients should be informed of available trials (FcRn inhibitors, complement inhibitors, CAR-T) — equitable access is an emerging ethical concern given high cost.
— Eculizumab, efgartigimod, rituximab have high cost — engage social work and specialty pharmacy early for prior authorization and copay assistance.
Step 3 management: Document a clear medication alert in the EHR before discharge — this single intervention prevents the next iatrogenic crisis.
— Autoimmune thyroid disease (~10–15%), type 1 diabetes, RA, SLE, pernicious anemia, vitiligo.
— Thymic hyperplasia in ~65% of AChR-positive MG (young women).
— Thymoma in 10–15% — older patients; CT chest mandatory at diagnosis.
— Antibiotics: aminoglycosides, fluoroquinolones, macrolides, telithromycin, clindamycin (high dose).
— Cardiac: beta-blockers, procainamide, quinidine, quinine.
— Neuro: phenytoin, gabapentin (occasionally), lithium.
— Anesthetic: neuromuscular blockers, IV magnesium, lidocaine (high dose).
— Other: D-penicillamine (induces MG), interferon-α, immune checkpoint inhibitors.
— Statins rare but reported worsening — usually safe.
— Pupils spared in MG (always).
— Reflexes preserved (vs GBS, LEMS).
— Weakness fatigable (sustained upgaze, single-breath count, repetitive arm abduction).
— Ice pack test improves ptosis in MG (cold inhibits acetylcholinesterase).
— AChR: 85%, all phenotypes, thymus pathology, responds to pyridostigmine, thymectomy useful.
— MuSK: bulbar/respiratory predominant, women>men, no thymic pathology, poor pyridostigmine response, PLEX > IVIG, rituximab very effective.
Board pearl: "Fluctuating weakness + spared pupils + preserved reflexes + worsening with repeated effort" = MG until proven otherwise. Key distinction: "Spared pupils" alone separates MG from botulism on a stem.
— Known MG patient on pyridostigmine + prednisone, recent URI, presents with worsening dyspnea, nasal speech, head drop. FVC 12 mL/kg. → Answer: intubate, start PLEX or IVIG, treat infection with MG-safe antibiotic, hold offending drugs.
— Patient hospitalized for pneumonia given levofloxacin or azithromycin, develops progressive weakness and respiratory failure. → Answer: stop the antibiotic, switch to ceftriaxone, begin PLEX/IVIG.
— Weakness with miosis, salivation, diarrhea, fasciculations, bradycardia = cholinergic. → Answer: hold pyridostigmine, atropine, supportive care.
— Newly diagnosed MG started on high-dose prednisone, worsens at day 7. → Answer: expected effect; continue steroids, support with PLEX or IVIG.
— Pregnant MG patient with preeclampsia given IV magnesium → respiratory failure. → Answer: stop magnesium, intubate, give calcium gluconate, use phenytoin/levetiracetam for seizure prophylaxis.
— Ascending weakness, areflexia, post-Campylobacter = GBS (not MG).
— Descending weakness with dilated pupils = botulism.
— Proximal weakness improving with effort, hyporeflexia, smoker = LEMS → look for SCLC.
— Suspected MG with positive ice pack test → AChR antibodies first, then SFEMG if negative.
— New MG diagnosis → CT chest to evaluate for thymoma.
— MG patient before elective surgery → optimize with PLEX/IVIG pre-op, avoid long-acting NMBAs, regional anesthesia preferred.
— Bulbar predominant, poor pyridostigmine response → rituximab.
— Patient on pembrolizumab develops ptosis, dyspnea, troponin elevation. → Answer: stop ICI, high-dose steroids + IVIG/PLEX, evaluate for myocarditis and myositis overlap.
Step 3 management: When in doubt on a stem, treat the airway first, then PLEX or IVIG, then steroids, then identify trigger — this sequence is the most common correct answer order.
Myasthenic crisis is the life-threatening neuromuscular respiratory failure of MG that demands immediate FVC/NIF-driven airway assessment, urgent PLEX or IVIG, trigger identification (infection or offending drug), and ICU-level multidisciplinary care.
Board pearl: Pupils spared + reflexes preserved + fatigable weakness = MG. Key distinction from cholinergic crisis: look for SLUDGE/miosis/fasciculations. CCS pearl: ICU bed, q2h FVC/NIF, PLEX or IVIG, hold offending drugs, NPO with swallow eval, neurology and pulmonology consults on day 1 — that is the winning move set.