• Clinical science

Bulbar palsy

Abstract

Bulbar palsy and pseudobulbar palsy are rare types of motor neuron disease that affect the cranial motor nerves. Bulbar palsy is a lower motor neuron palsy that affects the nuclei of the IXth, Xth, XIth, and XIIth cranial nerves. Pseudobulbar palsy is an upper motor neuron palsy that affects the corticobulbar tracts of the Vth, VIIth, IXth, Xth, XIth, and XIIth cranial nerves. Any condition which disrupts or damages the cranial nerve nuclei or corticobulbar tracts can cause bulbar or pseudobulbar palsy (e.g., stroke, multiple sclerosis, infections, brain stem tumors). Both bulbar and pseudobulbar palsy are seen mainly in men over 75 years old and present with progressive dysarthria and dysphagia. In addition, patients with pseudobulbar palsy present with a lack of facial expression, difficulty chewing, and emotional lability. Lower motor neuron signs (atrophy and fasciculations of the tongue, absent gag reflex) differentiate bulbar palsy from pseudobulbar palsy, which presents with upper motor neuron signs (spastic tongue, exaggerated gag, and jaw jerk reflexes). Diagnosis is mainly clinical. CSF analysis and MRI of the brain help identify the etiology. Treatment is mainly supportive. Prognosis is poor, with a life expectancy of 1–3 years after diagnosis.

Epidemiology

  • Incidence:Unknown; accounts for ∼ 0.2% of all motor neuron diseases
  • Age: 75–80 years
  • Sex: >

References:[1]

Epidemiological data refers to the US, unless otherwise specified.

Subtypes and variants

Bulbar palsy and pseudobulbar palsy are motor neuron diseases characterized by the progressive degeneration of cranial motor neurons. Other motor neuron disorders include amyotrophic lateral sclerosis, primary lateral sclerosis, and spinal muscular atrophy.

Bulbar palsy Pseudobulbar palsy
Etiology
Pathophysiology
  • Bilateral degeneration of the nerve nuclei of cranial nerves IX, X, XI, and XII
  • Lower motor neuron palsy of the respective muscles
  • Bilateral degeneration of corticobulbar tracts to nerve nuclei of cranial nerves V, VII, X, XI, and XII
  • Upper motor neuron palsy of the respective muscles
Clinical features
  • Facial expression: normal
  • Speech: nasal speech
  • Dysphagia, drooling, nasal regurgitation
  • Tongue
  • Palatal movement: absent
  • Gag reflex: absent
  • Jaw jerk: normal
  • Emotions not affected
  • Facial expressions: absent (expressionless face)
  • Speech: spastic dysarthria (husky, nasal voice)
  • Difficulty in chewing
  • Dysphagia, drooling, and nasal regurgitation
  • Tongue
  • Palatal movement: absent
  • Gag reflex: brisk (exaggerated)
  • Jaw jerk: exaggerated; clonic
  • Emotional incontinence (pseudobulbar affect)

References:[2][3][4][4][5][6][7][8][9]

Diagnostics

Bulbar palsy and pseudobulbar palsy are clinical diagnoses based on clinical features. Tests are performed to diagnose the underlying condition.

Treatment

References:[10]

Prognosis

  • Poor prognosis
  • Most common cause of death is respiratory complications secondary to recurrent aspiration (e.g., pneumonia).

References:[11]