You get a call from ED : "57 year old female with new onset weakness."
[[What are your first thoughts? -> Initial Thoughts - Reporter Questions]]
When approaching any chief complaint, think like a reporter! Ask:
[[Is there a neurologic problem? -> What is "Weakness"?]]
[[WHO? (The patient) -> About the Patient]]
[[WHAT? (The Symptom) -> What is the Problem?]]
[[WHEN? (Time Course/Tempo) -> Time Course and Tempo]]
[[WHERE? (Localization) -> Associated Symptoms]]
Once you've considered these...
[[Get more information from the ED -> Patient History - From ED]]You call the ED and gather more history:
-Weakness started 2-3 days ago. (Relatively acute/subacute)
-Mainly proximal muscles (e.g., difficulty getting out of a chair - initially thought to be fatigue).
-Mild shortness of breath reported.
-Initial labs (CBC, BMP) and vitals were normal. No fever, no recent trauma.
[[Get the history directly from the patient -> Patient History - Talking to the Patient]]This is a 57 year old female.
Knowing basic demographics age, sex, comorbidities- is the first step in understanding the patient.
[[Back to Initial Thoughts -> Initial Thoughts - Reporter Questions]]-Is it true weakness (inability to generate force) or [[fatigue|Fatigue vs. Weakness]] (feeling tired/lacking energy)?
This distinction is crucial early on.
[[Back to Initial Thoughts -> Initial Thoughts - Reporter Questions]]-How quickly did the weakness start (onset) and how fast is it changing (progression/tempo)?
-Acute onset vs. gradual onset?
-Rapid progression vs. slow progression?
-Is it constant or fluctuating (e.g., worse at certain times of day)?
-Tempo helps narrow the differential and guides urgency of workup/management.
[[Back to Initial Thoughts -> Initial Thoughts - Reporter Questions]]What does the patient have difficulty doing? What muscles are involved? Is it symmetric? Are there specific movements like standing up from a chair? Can they walk? Is this worse during the end of the day?
[[Back to Initial Thoughts -> Initial Thoughts - Reporter Questions]]Associated symptoms can point to the location of the problem:
-Blurry vision / diplopia (Cranial Nerves, NMJ)
-Slurred speech / difficulty swallowing (Bulbar involvement - Brainstem, CNs, NMJ, Muscle)
-Shortness of breath (Respiratory involvement - various sites, especially Bulbar/NMJ/Muscle)
-Numbness / tingling / sensory changes (Suggests Nerve involvement, less common in pure Muscle/NMJ)
[[Back to Initial Thoughts -> Initial Thoughts - Reporter Questions]]
-Sometimes patients complain of "weakness" when they are actually experiencing fatigue.
-This can happen in systemic illnesses like sepsis or heart failure.
-They can generate force, but tire quickly.
-True weakness is the inability to generate force despite effort.You talk to the patient yourself:
-Otherwise, no significant past medical history or prior neurological issues.
-Recent treatment for a UTI.
-Patient noticed difficulty getting up from a chair, which they initially attributed to fatigue.
-Now also noticing slurred speech and a little shortness of breath.
-Reports double vision before bed (worse in the evening).
[[What are the most important things to look for on exam? -> Physical Exam - Introduction]]What's your general approach?
-Look at the patient first! Do they appear ill? Are they using accessory muscles to breathe?
-Perform a full neurological exam, focusing on key areas based on the history.
[[What are the key exam components? -> Physical Exam - Components]]Based on the history, focus on:
-Cranial Nerves: Assess for ptosis, eye movements (check for diplopia, especially on [[sustained upgaze|Sustained Upgaze Test]]), facial symmetry, swallowing, speech (dysarthria).
-Motor: Test muscle strength (proximal vs. distal, symmetric vs. asymmetric). Look for atrophy or fasciculations. Assess for [[fatigability|Fatigability Testing]].
-Sensation: Test light touch, pinprick, vibration.
-Reflexes: Test deep tendon reflexes. Look for hyperreflexia or [[hyporeflexia/areflexia|Hyporeflexia/Areflexia]].
-Respiratory: Perform bedside tests like [[breath count|Bedside Respiratory Assessment]] and neck flexion/extension.
[[Summarize This Patient's Exam Findings -> Patient's Exam Findings Summary]]Putting it all together for our 57F:
-Relatively acute onset (2-3 days), progressive weakness.
-Weakness is predominantly proximal.
-Fatigability is present (worse with activity/evening double vision, difficulty standing from chair).
-Mild bulbar symptoms (slurred speech, double vision, mild SOB).
-Sensation is normal.
-Reflexes are normal.
-No atrophy or fasciculations.
-Breath count is 25
[[Based on these findings, what is your differential diagnosis? -> Differential Diagnosis Buckets]]1-Ask the patient to look straight up and hold it as long as they can.
2-Observe their eyelids and eyes for drooping or drift downwards.
This is a bedside test for fatigability of the ocular muscles, common in myasthenia gravis.
[[Back to Physical Exam Components -> Physical Exam - Components]]True weakness that gets worse with repetitive activity is a hallmark of neuromuscular junction (NMJ) disorders.
1-Ask the patient to repeat a movement (e.g., finger tapping, repeatedly lifting arms). Does the strength decline?
2-Sustained Upgaze Test (see [[previous|Sustained Upgaze Test]])
3-Ice Pack Test: For suspected ptosis, placing an ice pack over the eyelid for 2-5 minutes can temporarily improve ptosis in myasthenia gravis.
Clinical Tip: No ice pack? A glove filled with ice water from the nurse's station can work as an improvised ice pack!
[[Back to Physical Exam Components -> Physical Exam - Components]]-Absent or significantly reduced deep tendon reflexes can point towards certain diagnoses, particularly peripheral nerve problems like GBS or demyelinating polyneuropathies.
-Muscle and NMJ disorders typically have preserved reflexes early on.
[[Back to Physical Exam Components -> Physical Exam - Components]]-Critically important in new weakness, especially if there's bulbar involvement or shortness of breath!
-Breath Count: Have the patient take a deep breath and count aloud on that single breath. -A count less than 25 is concerning for impaired respiratory muscle strength.
-Neck Flexion/Extension: Test strength against resistance. These muscles are often affected early in myasthenia and reflect diaphragmatic strength. If you can easily overcome resistance, it suggests significant weakness needing urgent attention.
-These bedside tests help quickly assess for respiratory compromise, even before formal PFTs or blood gas results are back.
[[More on Respiratory Assessment -> Formal Respiratory Assessment (ED/Labs)]]
[[Back to Physical Exam Components -> Physical Exam - Components]]In the ED or initially, order:
NIF/MIP (Negative Inspiratory Force / Maximum Inspiratory Pressure) & FVC (Forced Vital Capacity): Objective measures of respiratory muscle strength and lung capacity.
NIF/MIP < -30 cmH2O or FVC < 20 ml/kg are concerning and suggest need for close monitoring or potential intubation
VBG (Venous Blood Gas): Check for hypercapnia (elevated CO2). This is a late sign of respiratory failure in neuromuscular weakness. Hypoxia is even later!
[[Where do this patient's findings point? -> Patient's Exam Findings Summary]]Which is highest on the differential for THIS patient?
[[Brain Problem? -> Brain Problem]]
[[Spinal Cord Problem? -> Spinal Cord Problem]]
[[Motor Neuron Problem (e.g., ALS)? -> Motor Neuron Disease]]
[[Peripheral Nerve Problem (Neuropathy)? -> Peripheral Nerve Problem]]
[[Muscle Problem (Myopathy/Myositis)? -> Muscle Problem]]
[[Neuromuscular Junction Problem? -> Neuromuscular Junction Problem]]
-Typically presents with focal deficits (one side of the body), potentially altered mental status, visual field cuts, etc.
-Pure symmetric weakness is less common unless it's a bilateral process or diffuse encephalopathy
Our patient has proximal, symmetric weakness and is alert.
[[Back to Differential Diagnosis Buckets -> Differential Diagnosis Buckets]]-Lesions below the brainstem typically cause Upper Motor Neuron (UMN) signs below the level of the lesion (spasticity, hyperreflexia, Babinski sign).
-Might have a clear sensory level.
-Our patient has normal tone/reflexes and no sensory level.
[[Back to Differential Diagnosis Buckets -> Differential Diagnosis Buckets]]-Can cause progressive weakness (UMN and/or LMN signs). LMN signs include atrophy and fasciculations. Bulbar symptoms can occur.
-Our patient has no atrophy or fasciculations noted, and normal reflexes.
[[Back to Differential Diagnosis Buckets -> Differential Diagnosis Buckets]]-Can cause weakness, often more distal initially, but can be proximal. Key features are often sensory loss (numbness, tingling) and hyporeflexia or areflexia. Acute, rapidly progressive neuropathy (like GBS) is a major concern.
-Our patient has preserved sensation and normal reflexes.
[[Back to Differential Diagnosis Buckets -> Differential Diagnosis Buckets]]-Typically causes proximal, symmetric weakness, similar to our patient. Can sometimes cause bulbar symptoms. Sensation and reflexes are typically preserved. Labs like CK would often be elevated in inflammatory myopathies (myositis).
-Our patient has proximal weakness, preserved sensation/reflexes. CK is not mentioned in initial labs but would be a good test here.
[[Back to Differential Diagnosis Buckets -> Differential Diagnosis Buckets]]-Key features include weakness (often proximal or bulbar) that is fatigable, preserved sensation, and preserved or reduced (but not absent) reflexes early on.
This fits our patient's presentation of proximal, fatigable weakness, bulbar symptoms, and normal sensation/reflexes very well!
Specifically, [[Myasthenia Gravis (MG) -> Myasthenia Gravis (MG)]] is the leading suspect.
[[What are the next steps? -> Next Steps - Initial Actions]]
[[Back to Differential Diagnosis Buckets -> Differential Diagnosis Buckets]]Where should the patient go? Is this someone who needs the ICU for close monitoring of respiratory status, or can they be managed on the floor?
-Use your bedside and formal respiratory assessments (Breath Count, NIF/FVC) to guide this decision.
-Initiate Monitoring: Frequent neurological checks (e.g., Q2-4 hour neuro checks, repeat respiratory assessments).
-Order Key Labs/Studies:
[[What labs and studies should be ordered? -> Labs and Studies - New Weakness]]MG is an autoimmune disorder affecting the neuromuscular junction. Antibodies block or destroy acetylcholine receptors (AChR) or other related proteins (like MuSK) on the muscle side of the NMJ. This prevents the nerve signal from effectively activating the muscle, causing weakness and fatigability.
[[What about Myasthenia Gravis Antibodies? -> MG Antibodies]]
[[Continue to Next Steps -> Next Steps - Initial Actions]]Key antibodies to check for suspected MG:
Acetylcholine Receptor (AChR) Antibodies: Most common (Binding, Blocking, Modulating).
Muscle-Specific Kinase (MuSK) Antibodies: Less common, but important to check especially if AChR antibodies are negative OR if the patient has prominent bulbar symptoms or respiratory issues at onset.
[[Back to Myasthenia Gravis -> Myasthenia Gravis (MG)]]
[[Continue to Next Steps -> Next Steps - Initial Actions]]
[[Back to Labs and Studies -> Labs and Studies - New Weakness]] Based on the differential, consider:
-Baseline Labs: CBC, BMP (already done), LFTs, CK.
-Infection/Inflammation: UA, ESR, CRP (UTI can trigger MG flare!).
-Toxic/Metabolic: Heavy metals (less likely here, but consider in neuropathy workup).
-Specific to NMJ/Muscle:
[[AChR and MuSK Antibodies| MG Antibodies]]
-Consider CSF: If neuropathy is still a significant concern.
Imaging:
-[[Chest CT -> Chest CT for thymoma]] for Thymoma is essential in new MG diagnosis!
-Neuroimaging (Brain/Spine) if CNS process is still in the differential based on features.
[[Back to Next Steps - Initial Actions -> Next Steps - Initial Actions]]
[[Continue to Acute Management -> Acute Management - Overview]]For acute, severe or rapidly worsening weakness, especially with respiratory compromise (Myasthenia Crisis):
Prioritize Airway & Breathing (monitoring, potential intubation)!
Consider [[Acute Treatment|Acute Treatment Options]].
Be aware of medications that can [[worsen MG|Medications to Avoid in MG]].
[[Move to Long-Term Management -> Long-Term Management (Brief)]]-About 15% of MG patients have a thymoma (tumor of the thymus), and about half of patients with thymoma develop MG.
-Thymectomy (surgical removal of the thymus/thymoma) can improve MG symptoms, especially in younger patients with thymoma. It's a crucial part of the workup for new MG.
[[Back to Labs and Studies -> Labs and Studies - New Weakness]]
[[Back to Long-Term Management -> Long-Term Management (Brief)]] Once stabilized from an acute episode, management transitions to chronic control of MG. This often involves:
-Steroids (usually at lower doses than initial acute flares, or started carefully)
-Immunosuppressants (e.g., azathioprine, mycophenolate mofetil, rituximab)
-Pyridostigmine (symptomatic treatment)
-[[Thymectomy -> Chest CT for thymoma]] if indicated (especially with thymoma).
-This aims to prevent future flares and improve baseline strength.
[[Key Takeaways from this case -> Key Takeaways]]The primary acute treatments for Myasthenia Crisis or severe flares are aimed at rapidly removing or neutralizing antibodies:
-IVIG (Intravenous Immunoglobulin): Pooled human antibodies. Mechanism complex, includes blocking autoantibodies. Generally well-tolerated.
-Plasmapheresis (PLEX): Blood is filtered to remove antibodies. Can work slightly faster than IVIG, but requires a large line and may be logistically more complex.
-The choice between IVIG and PLEX depends on patient factors, institutional capabilities, and provider preference.
[[Back to Acute Management - Overview -> Acute Management - Overview]]
[[Continue to Long-Term Management -> Long-Term Management (Brief)]]A long list exists, but common culprits that can precipitate or worsen MG flares include:
-Certain Antibiotics (especially fluoroquinolones, aminoglycosides)
-Beta Blockers
-Calcium Channel Blockers
-Neuromuscular Blocking Agents (can cause prolonged paralysis if needed for intubation/surgery)
-Magnesium
-High-dose Steroids (can initially worsen symptoms before getting better - "steroid-induced worsening" - in acute flares)
-Pyridostigmine (excessive doses can cause cholinergic crisis, looks like weakness + secretions)
-Always check for drug interactions when managing an MG patient!
[[Back to Acute Management - Overview -> Acute Management - Overview]]
[[Continue to Long-Term Management -> Long-Term Management (Brief)]]Let's summarize the main points from this case:
-Not all weakness is neurologic; consider mimics like fatigue from systemic illness.
-Tempo (onset & progression) and Localization ("reporter" questions: Who, What, When, Where) are fundamental to evaluating new weakness.
-Sensory exam and reflexes help differentiate Nerve problems (sensory loss, hyporeflexia) from Muscle/NMJ problems (preserved sensation/reflexes).
-Always assess respiratory function OBJECTIVELY early on using bedside tests (Breath Count, Neck Flexion/Extension) and formal tests (NIF/MIP, FVC, VBG). This guides triage to ICU vs. floor.
-For suspected Myasthenia Gravis, look for fatigability, bulbar symptoms, proximal weakness, and preserved sensation/reflexes. Order AChR/MuSK antibodies and a Chest CT for thymoma.
-Be mindful of medications that can worsen MG.
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