Pseudobulbar palsy vs Bulbar palsy
How to tell Pseudobulbar palsy and Bulbar palsy apart when a board question makes them look alike.
Pseudobulbar is UMN bulbar with brisk jaw/emotional lability; bulbar is LMN bulbar with atrophy/fasciculations.
Side by side
Bilateral upper motor neuron corticobulbar lesions causing dysarthria, dysphagia, brisk jaw jerk, spastic tongue, emotional lability, and no tongue atrophy or fasciculations.
Lower motor neuron lesions of cranial nerve nuclei or nerves causing dysarthria, dysphagia, nasal speech, weak gag, tongue atrophy, fasciculations, and flaccid weakness.
Bilateral supranuclear corticobulbar tract damage removes cortical control over bulbar motor nuclei.
Damage to lower motor neurons in the medulla or exiting cranial nerves weakens bulbar muscles directly.
Spastic dysarthria, brisk jaw jerk, exaggerated gag reflex, pseudobulbar affect (uncontrolled laughing or crying without matching emotion), and absent tongue atrophy support pseudobulbar palsy from bilateral corticobulbar UMN lesions, classically multiple strokes, MS, or progressive supranuclear palsy.
Flaccid nasal dysarthria, tongue atrophy with fasciculations, absent or reduced gag, and absent jaw jerk support bulbar palsy from LMN cranial nerve nucleus involvement, classically progressive bulbar palsy of ALS, myasthenia gravis (fatigable, improves with rest), or Guillain-Barré bulbar variants.
The trap
Both cause dysarthria and dysphagia from cranial nerves IX, X, and XII territory failure, so the cardinal symptoms are identical. UMN versus LMN signs decide: pseudobulbar (bilateral UMN corticobulbar lesions, classically multiple strokes or MS) gives spastic tongue without atrophy, brisk jaw jerk, exaggerated gag, and pseudobulbar affect (uncontrolled laughing or crying without matching emotion); bulbar (LMN nuclei in the medulla) gives flaccid wasted tongue with fasciculations, absent jaw jerk, and nasal speech. ALS classically shows both because UMN and LMN are simultaneously affected.
The repair move
For bulbar symptoms, inspect jaw jerk, tongue tone, atrophy, fasciculations, and emotional lability.
Try a free question
CoreA patient with bilateral internal capsule strokes has dysarthria, dysphagia, emotional lability, brisk jaw jerk, and spastic tongue without atrophy or fasciculations. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Pseudobulbar palsy. Bilateral UMN corticobulbar signs with brisk jaw and emotional lability support pseudobulbar palsy.
Why the other choices are tempting
- B. Bulbar palsy has LMN signs such as tongue atrophy and fasciculations.
- C. Bell palsy is peripheral CN VII facial weakness.
- D. Myasthenia gravis causes fatigable weakness.
- E. Trigeminal neuralgia causes electric facial pain.
Flashcards
Tap a card to flip it.
What lesion type causes pseudobulbar palsy?
Bilateral upper motor neuron corticobulbar lesions cause pseudobulbar palsy.
What reflex supports pseudobulbar palsy?
A brisk jaw jerk supports pseudobulbar palsy.
Quick answers
What is the fastest way to tell Pseudobulbar palsy from Bulbar palsy?
Pseudobulbar is UMN bulbar with brisk jaw/emotional lability; bulbar is LMN bulbar with atrophy/fasciculations.
What is the key clue for Pseudobulbar palsy?
Bilateral upper motor neuron corticobulbar lesions causing dysarthria, dysphagia, brisk jaw jerk, spastic tongue, emotional lability, and no tongue atrophy or fasciculations.
What is the key clue for Bulbar palsy?
Lower motor neuron lesions of cranial nerve nuclei or nerves causing dysarthria, dysphagia, nasal speech, weak gag, tongue atrophy, fasciculations, and flaccid weakness.
What is the common trap with Pseudobulbar palsy vs Bulbar palsy?
Both cause dysarthria and dysphagia from cranial nerves IX, X, and XII territory failure, so the cardinal symptoms are identical. UMN versus LMN signs decide: pseudobulbar (bilateral UMN corticobulbar lesions, classically multiple strokes or MS) gives spastic tongue without atrophy, brisk jaw jerk, exaggerated gag, and pseudobulbar affect (uncontrolled laughing or crying without matching emotion); bulbar (LMN nuclei in the medulla) gives flaccid wasted tongue with fasciculations, absent jaw jerk, and nasal speech. ALS classically shows both because UMN and LMN are simultaneously affected.