Pseudobulbar Palsy: Key Clinical Features
The most characteristic feature of pseudobulbar palsy is dysarthria (option b), which occurs due to bilateral upper motor neuron lesions affecting the corticobulbar tracts. 1, 2
Distinguishing Features of Pseudobulbar Palsy
Present Features (Upper Motor Neuron Signs)
- Dysarthria is a hallmark manifestation, resulting from spastic weakness of bulbar muscles controlling speech 1, 2
- Dysphonia (option c) occurs with a characteristic nasal quality to the voice 3
- Brisk or exaggerated jaw jerk reflex (NOT normal as in option d) - this is a key distinguishing upper motor neuron sign 1
- Emotional lability (NOT normal emotions as in option f) - patients exhibit pseudobulbar affect with involuntary, inappropriate outbursts of laughter and/or crying 4
- Dysphagia with preserved velopharyngeal closure during swallowing but impaired closure during speech (speech-swallow dissociation) 5
Absent Features (Lower Motor Neuron Signs)
- Gag reflex is typically preserved or hyperactive (NOT lost as in option a) - loss of gag reflex indicates lower motor neuron/bulbar palsy 1
- Tongue shows spastic paralysis with limited movement but NOT flaccid paralysis (option e is incorrect) - flaccid paralysis indicates lower motor neuron involvement 1, 2
Critical Diagnostic Distinctions
The key to differentiating pseudobulbar from bulbar palsy lies in the reflex examination:
- Pseudobulbar palsy: Hyperactive reflexes (brisk jaw jerk, exaggerated gag reflex) due to bilateral upper motor neuron lesions 1
- Bulbar palsy: Absent or diminished reflexes (lost gag reflex, absent jaw jerk) due to lower motor neuron involvement 1
Clinical Presentation Pattern
- Patients present with bilateral corticobulbar tract involvement causing dramatic clinical symptoms despite relatively small CNS lesions 2
- Common causes include bilateral lacunar strokes, multiple sclerosis, motor neuron disease, and bilateral thalamic infarcts 2, 3
- The syndrome includes dysarthria, dysphagia, hypernasal voice, and emotional incontinence 3
Common Pitfalls to Avoid
Do not confuse bulbar symptoms with bulbar localization - patients with pseudobulbar palsy present with severe bulbar symptoms (dysphagia, anarthria, glossplegia) that may be misinterpreted as brainstem lesions, when the actual pathology is supranuclear 2
The speech-swallow dissociation is pathognomonic - velopharyngeal closure remains intact during swallowing but fails during speech and blowing, with quantitative studies showing 80% dissociation in pseudobulbar palsy versus 52% in healthy subjects 5