see also:

• Cranial nerve examination
• Neuropathies
• motor neurone disease (MND)

• bulbar palsy is lower motor neuron weakness of the muscles innervated by the cranial nerves IX, X and XII, while pseudobulbar palsy is an upper motor neuronal weakness of these muscles
• cranial nerve IX (glossopharyngeal nerve):
  • mixed nerve, including the afferent fibres for the gag reflex, and somatic sensory and bitter/sour taste sensation from the posterior one-third of the tongue, parasympathetic inputs to parotid gland, etc.
  • the only motor component is to stylopharyngeus muscle
  • damage can thus cause loss of taste to post. third tongue and impaired swallowing
• cranial nerve X (vagus nerve):
  • efferent fibres for the gag reflex
    • Levator veli palatini muscle, pharynhgeal constrictors, etc
  • recurrent laryngeal nerve
• cranial nerve XII (hypoglossal nerve):
  • motor nerve only;
  • innervates all the extrinsic and intrinsic muscles of the tongue, except for the palatoglossus which is innervated by the vagus nerve
  • isolated damage to the nerve is rare but may be caused by:
    • tumours, wounds, sarcoid, multiple sclerosis (MS), presence of an ectatic vessel in the hypoglossal canal
  • vertebrobasilar stroke may affect both hypoglossal nerves and facial and trigeminal nerves resulting in tight oral musculature, dysarthria, difficulty eating and chewing
  • the most common disease affecting it is motor neurone disease (MND)
  • if the damage is to the nerve itself (a lower motor neuron lesion), the half wasted, fasculating tongue will curve toward the damaged side, owing to weakness of the genioglossus muscle of affected side
  • if the damage is to the nerve pathway (an upper motor neuron lesion) the tongue will curve away from the side of damage, due to action of the affected genioglossus muscle, and will occur without fasciculations or wasting
• these conditions result in difficulty with chewing, talking, and swallowing and may also cause drooling

• decreased reflexes - gag reflex and jaw jerk
• dysphagia
• atonic muscle wasting with fasciculations and wrinkling of the tongue and reduced palatal movement
• nasal speech
• emotions are not affected

• normal or increased reflexes - gag reflex and jaw jerk
• spastic weakness - small, tight tongue that cannot be protruded
• dysphagia
• “Donald Duck” speech
• labile emotions
• bilateral upper motor limb signs

• myasthenia gravis
• lyme disease
• botulism
  • afebrile patient with signs and symptoms of acute progressive bulbar palsies and descending neuromuscular paralysis should be highly suspected of having botulism
• Brown–Vialetto–Van Laere syndrome
  • rare, bulbopontine paralysis, usually preceded by progressive bilateral nerve deafness;
  • weakness is in the distribution of motor cranial nerves III, and VII to XII
• Worster-Drought syndrome or congenital suprabulbar paresis
  • selective weakness of the orbicularis oris muscle, tongue and soft palate leading to dysarthria and drooling
• X-linked bulbospinal muscular atrophy (Kennedy's disease)
  • rare, starts in 3rd-5th decades of men
  • some complain of exercise-induced muscle cramps and hand tremors several years before weakness develops
  • proximal muscles are affected first, followed by bulbar involvement, which may become marked and facial fasciculations with moderately raised CK levels

• motor neurone disease (MND)
  • ALS
  • progressive bulbar palsy
    • if involves corticobulbar tracts may also cause a pseudobulbar-like emotional lability
    • initial features are usually slurred speech, hoarseness and low volume of speech with choking or aspiration of meals
    • https://en.wikipedia.org/wiki/Progressive_bulbar_palsy
  • Progressive muscular atrophy (PMA) or Duchenne-Aran muscular atrophy
    • extremely rare; childhood (Fazio-Londe disease presents between 2-12yrs, and those aged 1-5yrs may present with stridor) and adult forms;
    • 4% of MND; similar features to ALS but lacks UMN features and has a somewhat better prognosis
    • https://en.wikipedia.org/wiki/Progressive_muscular_atrophy
• syringobulbia
• Miller-Fisher variant of Guillain-Barre syndrome (GBS)
• polio
• subacute meningitis eg. lymphoma
• neurosyphilis
• brainstem CVA

• bilateral internal capsule stroke (CVA)'s
  • are the most common cause
  • may cause acute mutism with with paralysis of the bulbar and facial muscles
  • if it is also associated with severe limb weakness then this results in a “locked-in” syndrome
• multiple sclerosis (MS)
• motor neurone disease (MND)
  • ALS
  • progressive bulbar palsy
• high brainstem tumours
• head injury