Bulbar and Pseudobulbar Palsy

Speaking is a voluntary task which is taken for granted but is a highly specialized activity. In order to speak the following parts of the oral cavity need to be used

• Larynx
• Pharynx
• Palate
• Tongue
• Lips

Along with this controlled expiration is required, so that air can be released at the appropriate speed and in appropriate amounts.

The above structures required for speech are controlled by the nervous system. Corticobulbar tracts from both of the motor cortices send signals down to the nuclei of the following nerves

• Vagal nerve
• Facial nerve
• Hypoglossal neve
• Phrenic nerve

The motor aspects of speech, like other movements, are also influenced by the extrapyramidal system via the basal ganglia and the cerebellum.
There is ongoing research in to which areas of the cortex are involved in speech and especially in recovery of speech after a stroke.¹

Speech has two elements - phonation and articulation.

1. Phonation - the production of sounds, a result of the vocal cords in the larynx.
2. Articulation - contractions of the muscles of the various other structures involved in speech i.e. pharynx, palate, tongue and lips. These muscle contractions change the vocal sounds from the larynx thus resulting in noises recognised as words.

This is also called dysarthria or anathria. There are several causes

• Bulbar palsy
• Pseudobulbar palsy
• Cerebellar-ataxic
• Hypokinetic
• Hyperkinetic

Cerebellar-ataxic, hypokinetic and hyperkinetic dysarthria are discussed elsewhere.

Synonyms: lower motor neurone dysarthria, neuromuscular dysarthria, atrophic bulbar paralysis.

Description

Bulbar palsy is the result of diseases affecting the lower cranial nerves (VII - XII). A speech deficit occurs due to paralysis or weakness of the muscles of articulation which are supplied by these cranial nerves. The causes of this are

• Muscle disorders
• Diseases of the motor nuclei in the medulla and lower pons
• Diseases of the intramedullary nerves
• Diseases of the peripheral nerves supplying the muscles

Importantly these lesions do not affect speech in isolation. The bulbar nerves also innervate muscles involved in swallowing and facial muscles.

Presentation

• Lips - tremulous
• Tongue - weak and wasted and sits in the mouth with fasciculations
• Drooling - as saliva collects in the mouth and patient is unable to swallow (dysphagia)
• Palatal movements are absent
• Dysphonia - rasping tone due to vocal cord paralysis; nasal tone if bilateral palatal paralysis
• Articulation - difficulty pronouncing r; unable to pronounce consonants as dysarthria progresses

If the pathology progresses then speech becomes slurred and eventually becomes indistinct.
There may also be neurological deficits in the limbs e.g. flaccid tone, weakness with fasciculations.

Causes^2,3

Synonyms upper motor neurone dysarthria, spastic dysarthria.

Description

Pseudobulbar palsy results from disease of the corticobulbar tracts. Bilateral tract damage must occur for clinically evident disease as the muscles are bilaterally innervated.

Presentation

• Tongue - paralysed, no wasting initially and no fasciculations; "Donald duck" speech; unable to protrude
• Palatal movements absent
• Dribbling persistently
• Facial muscles - may also be paralysed
• Reflexes - exaggerated e.g. jaw jerk
• Nasal regurgitation may be present
• Dysphonic
• Dysphagic
• Emotional lability may also be present

There may also be neurological deficits in the limbs e.g. increased tone, enhanced reflexes and weakness.

Causes^3,2

These will depend on the suspected underlying cause but will involve routine blood tests, imaging of the brain and brain stem (either CT scan or MRI) and electromyography.

All patients should be referred to neurologists. Patients will need admission if dysphagia is present or symptoms are rapidly progressive.
Treatment will be directed to the underlying cause. Postural changes can help with drooling of saliva and may prevent aspiration. Supportive measures may include baclofen for spasticity and anticholinergics for drooling.⁴
Management should involve speech and language therapists and the dietician - although there is no clear evidence on the efficacy of these measures.⁵

• Poor dentition
• Poor nutrition
• Psychological dysfunction
• Progression of underlying disease

This depends on the underlying cause.