Approach
• Immediately assess VS: Evaluate for hypoxia, hypo-/hyperglycemia, tachy-/bradycardia, HTN/hypotension, ECG for STEMI & life-threatening arrhythmias, signs of acute CVA
• History: Understand pt’s definition of weakness: Focal vs. generalized
• Ask about: Sensory deficit, CP, SOB, palpitations, recent illnesses (URI, V/D), new meds
• Onset, duration & severity of sxs, exacerbating & alleviating factors, associated sxs
• Consider infection, anemia, acute blood loss, electrolyte abnormalities
• Complete physical exam including thorough neuro exam, rectal for occult blood
• Common labs to consider, esp in elderly & pts w/ comorbidities:
• CBC (w/ differential for MCV), Chem 10, UA, ECG, CXR, ±LFTs
• Consider head CT w/ AMS, trauma, or deficits
GENERALIZED WEAKNESS
Myasthenia Gravis
Definition
• Autoimmune disorder: Antibodies against postsynaptic ACh receptors
History
• Gradual onset symmetric, fluctuating proximal & ocular muscle weakness
• Worsens w/ repetitive activity & throughout day
• Affects women in 20s–30s, men in 60s–70s (peak)
• Exacerbations triggered by stress, infection, pregnancy, surgery, meds (abx, steroids)
Findings
• Proximal weakness & fatigability worse w/ repetitive activity, relieved by rest
• CN affected early (ocular: Ptosis, diplopia; bulbar: Dysarthria, dysphagia)
Evaluation
• Neuro consult if new onset
• Must differentiate MG crisis from cholinergic crisis, as these pts are on cholinergic meds
• Tensilon (edrophonium) test: 2 mg IV over 15 s; binds to AChE, blocking ACh hydrolysis
• May precipitate bradycardia or heart block – have atropine at bedside
• Measuring NIF can identify pts at risk of respiratory failure
Treatment
• Ventilatory support, pyridostigmine, ±plasmapheresis, & IVIG during crisis
• Glucocorticoids can cause initial worsening of sxs
Disposition
• Depends on respiratory fxn; can d/c w/ neuro f/u if no concern for respiratory compromise
Pearls
• Myasthenic crisis: Exacerbation, consider need for respiratory support
• Cholinergic crisis: Weakness from overtreatment w/ meds: ↑ salivation, abd cramping, diarrhea
Lambert–Eaton Myasthenic Syndrome (LEMS)
• Definition: Antibodies against presynaptic ACh-releasing terminal, preventing ACh release
History
• Similar to MG w/ proximal muscle weakness; M > F 40s–80s
• Often paraneoplastic syndrome a/w small cell lung CA
Findings: Proximal muscle weakness, ↓ DTRs, autonomic Dysfxn (postural ↓ BP, ptosis, dry mouth)
Evaluation: Neuro consult, Tensilon test to distinguish from MG; look for underlying cancer
Treatment: Respiratory support, IVIG, plasmapheresis
Disposition: Depends on respiratory status, need for IVIG/plasmapheresis
Guillain–Barré Syndrome (GBS)
Definition: Acute autoimmune demyelinating peripheral neuropathy
History: Progressive ascending weakness over hours–weeks; often recent viral illness (EBV, HSV, HIV), URI (Mycoplasma), gastroenteritis (Campylobacter 10–20% cases), or surgery
Findings: Acute ascending symmetric paralysis & ↓ DTRs ± autonomic Dysfxn, arrhythmias, sensory dysesthesias (back pain). Miller-Fisher variant = ataxia, areflexia, ophthalmoplegia.
Evaluation
• Clinical Dx. W/u is generally to r/o other diagnoses
• LP: ↑ protein, no WBCs or bacteria
Management: Consult neurology. Respiratory support ± IVIG, plasmapheresis.
Disposition: Admit. ICU if respiratory compromise.
Pearls
• Very sens to vasoactive agents; all meds for BP control should be easily titratable
• Avoid succinylcholine (depolarizing neuromuscular blockade), avoid steroids
Amyotrophic Lateral Sclerosis (Lou Gehrig’s Disease)
Definition: Degenerative dz of UMNs & LMNs
History
• Progressive motor weakness & atrophy, fasciculations, spasm. No sensory loss.
• Age >40, M = F
Findings
• Both UMN & LMN findings, initially distal. Fasciculations 2/2 denervation.
• May have dysphagia, dysarthria, spasticity, ↑ DTRs, +Babinski, emotional lability
• Bladder & bowel sphincters & ocular muscles often spared
Evaluation: Neuro consult. Consider MRI brain & spinal cord if new onset.
Treatment: Respiratory support, antispasmodics, treat cx (DVT from immobility)
Disposition: Depends on respiratory status, acuity
FOCAL WEAKNESS
Multiple Sclerosis (MS)
Definition
• Progressive inflammatory demyelinating dz of the CNS
• F > M (2:1), 25–30 yr; 15–20-fold ↑ risk if 1st-degree relative is also affected
• Dx requires 2 distinct episodes w/ differential neurologic sxs correlating to different anatomic lesions
Presentation
• Commonly relapsing-remitting pattern, so may be difficult to obtain full hx
• Typically young adult female w/ 2+ distinct episodes of CNS Dysfxn
• Acute episodes develop over hours–days, stable for days–weeks, resolve gradually
• Ocular sxs common: Internuclear ophthalmoplegia, optic neuritis, variable vision loss
• Optic neuritis (20%): Painful EOM, afferent pupillary defect, ↓ VA, ±papilledema
• Internuclear ophthalmoplegia (INO): Incomplete adduction of eye due to MLF lesion
• Often muscle weakness, spasticity, sensory changes, incontinence, ataxia
• Lhermitte sign: Electric-like shock that travels ↓ spine w/ neck flexion, a/w MS
• Uhthoff phenomenon: Sxs worsen w/ ↑ body temp (exercise, hot bath, fever)
Evaluation
• Neuro consult. MRI is the most useful tool: Discrete demyelinated lesions.
• LP shows pleocytosis (50%), IgG oligoclonal bands (85–95%)
• Look for precipitating factors for exacerbation (eg, infection, hyperthermia)
Treatment
• High-dose corticosteroids are 1st line for exacerbations
• Supportive: Baclofen or BZD (spasticity), carbamazepine/TCA (pain), amantadine (fatigue)
• Per neurology may consider immunomodulating agents
Disposition
• D/c if mild & stable w/ neuro f/u. Admit for severe sxs or w/u.
Transverse Myelitis
Definition
• Inflammation of entire thickness of spinal cord but in limited length
Presentation
• Acute or subacute paraplegia, often asymmetric, often w/ back pain
• Sensory loss below level, sphincter loss below level
• Often h/o recent viral illness
Management
• W/u is generally to r/o other causes; LP (pleocytosis), MRI
• Steroids for postinfectious or demyelinating etiology
Disposition
• Admit, consult neurology