Nuclear and supranuclear lesions
- Nuclear lesion (bulbar palsy)
- = bilateral lesion of the motor nucleus of a cranial nerve, its axon, or its NMJ
- Pathophysiology
- Cranial nerves IX, X, XI, and XII are affected
- Equals a “lower motor neuron” lesion, with typical peripheral motor lesion symptoms like atrophy and flaccidity
- Clinical features
- Normal facial expressions (because VII is unaffected)
- Nasal speech
- Dysphagia of fluids
- Atrophic and fasciculating tongue
- Absent gag reflex
- Supranuclear lesion (pseudobulbar palsy)
- = bilateral lesion of the corticobulbar tracts
- Pathophysiology
- Cranial nerves V, VII, IX, X, XI, XII are affected
- Equals an “upper motor neuron” lesion, with typical central motor lesion symptoms like spasticity and hyperreflexia
- Clinical features
- Stiff, spastic facial muscles -> no facial expressions
- Spastic dysarthria (Donald Duck voice)
- Dysphagia
- Spastic tongue
- Pseudobulbar affect/emotional incontinence
- Uncontrollable laughing or crying
- Think Joaquin Phoenix in the Joker
- CN V palsy -> exaggerated jaw jerk reflex
- Brisk gag reflex