Bulbar palsy is weakness of bulbar musculature of lower motor neurone origin. This may be differentiated clinically from bulbar weakness of upper motor neurone origin (pseudobulbar palsy).
Clinical features of bulbar palsy include:
- Dysarthria of flaccid/nasal type;
Dysphagia, often with nasal regurgitation;
- Weak ("bovine") cough; risk of aspiration;
- +/− Wasted, fasciculating tongue;
- +/− absent jaw jerk;
- +/− absent gag reflex.
Bulbar palsy is usually neurogenic. Recognized causes include:
- Brainstem disorders affecting cranial nerve motor nuclei (intrinsic):
- motor neurone disease (which may also cause a pseudobulbar palsy)
- Cranial nerve lesions outside the brainstem (there may be associated sensory signs):
- Infiltration by carcinoma, granuloma
- Neuromuscular junction transmission defect:
- myasthenia gravis.
A myogenic bulbar palsy may be seen in oculopharyngeal muscular dystrophy, inclusion body myositis, or polymyositis.