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Bulbar palsy refers to a range of different signs and symptoms linked to impairment of function of the cranial nerves 9, 10, 11, 12, which occurs due to a lower motor neuron lesion in the medulla oblongata or from lesions of the lower cranial nerves outside the brainstem.
Signs and symptoms
- dysphagia (difficulty in swallowing)
- difficulty in chewing
- nasal regurgitation
- slurring of speech
- difficulty in handling secretions
- choking on liquids
- dysphonia (defective use of the voice, inability to produce sound due to laryngeal weakness)
- dysarthria (difficulty in articulating words due to a CNS problem)
- nasal speech lacking in modulation and difficulty with all consonants
- tongue is atrophic and shows fasciculations.
- dribbling of saliva.
- weakness of the soft palate, examined by asking the patient to say aah.
- normal or absent jaw jerk
- absent gag reflex
In addition, there may be lower motor neuron lesions of the limbs.
The ocular muscles are spared and this differentiates it from myasthenia gravis.
- Genetic: Kennedy's disease, acute intermittent porphyria
- Vascular causes: medullary infarction
- Degenerative diseases: amyotrophic lateral sclerosis, syringobulbia
- Inflammatory/infective: Guillain–Barré syndrome, poliomyelitis, Lyme disease
- Malignancy: brain-stem glioma, malignant meningitis
- Toxic: botulism, venom of bark scorpion (species Centruroides), some neurotoxic snake venoms
- Autoimmune: myasthenia gravis
In contrast, pseudobulbar palsy is a clinical syndrome similar to bulbar palsy but in which the damage is located in upper motor neurons of the corticobulbar tracts in the mid-pons (i.e., in the cranial nerves IX-XII), that is the nerve cells coming down from the cerebral cortex innervating the motor nuclei in the medulla. This is usually caused by stroke.