Progressive Bulbar Palsy (PBP) is a rare neurodegenerative disorder that primarily affects the cranial nerves, leading to progressive weakness of the muscles responsible for speech, swallowing, and chewing. It is considered a subtype of motor neuron disease and represents the bulbar onset form of amyotrophic lateral sclerosis (ALS), though it can also occur as an isolated entity.
Overview
Progressive Bulbar Palsy is characterized by progressive dysfunction of the cranial nerve nuclei in the brainstem, affecting the muscles innervated by the vagus (X), glossopharyngeal (IX), and hypoglossal (XII) nerves. The disease leads to progressive bulbar paralysis, which includes dysarthria (slurred speech), dysphagia (difficulty swallowing), and dysphonia (voice changes)[@burrell2016].
Epidemiology
Incidence: Approximately 1-2 per 100,000 individuals annually[@chio2013]
Age of onset: Typically 50-70 years[@logroscino2010]
Gender: Slight male predominance (1.3-1.5:1)[@manera2020]
Accounts for approximately 25-30% of ALS cases, with bulbar-onset ALS being more common in women[@palese2023]
Pathophysiology
Neuropathology
...
Progressive Bulbar Palsy (PBP)
Progressive Bulbar Palsy (PBP) is a rare neurodegenerative disorder that primarily affects the cranial nerves, leading to progressive weakness of the muscles responsible for speech, swallowing, and chewing. It is considered a subtype of motor neuron disease and represents the bulbar onset form of amyotrophic lateral sclerosis (ALS), though it can also occur as an isolated entity.
Overview
Progressive Bulbar Palsy is characterized by progressive dysfunction of the cranial nerve nuclei in the brainstem, affecting the muscles innervated by the vagus (X), glossopharyngeal (IX), and hypoglossal (XII) nerves. The disease leads to progressive bulbar paralysis, which includes dysarthria (slurred speech), dysphagia (difficulty swallowing), and dysphonia (voice changes)[@burrell2016].
Epidemiology
Incidence: Approximately 1-2 per 100,000 individuals annually[@chio2013]
Age of onset: Typically 50-70 years[@logroscino2010]
Gender: Slight male predominance (1.3-1.5:1)[@manera2020]
Accounts for approximately 25-30% of ALS cases, with bulbar-onset ALS being more common in women[@palese2023]
Pathophysiology
Neuropathology
Motor neuron degeneration: Loss of motor [neurons](/entities/neurons) in the brainstem nuclei (hypoglossal nucleus, nucleus ambiguus, facial nucleus)
Bunina bodies: Small intraneuronal inclusions characteristic of ALS
TAR DNA-binding protein 43 (TDP-43) pathology: Ubiquitin-positive inclusions in affected neurons
Corticospinal tract involvement: Often associated with upper motor neuron signs
Genetic Factors
SOD1 mutations: Account for 15-20% of familial ALS cases
[C9orf72](/entities/c9orf72) repeat expansion: Most common genetic cause of ALS/FTD, including bulbar-onset
FUS mutations: Associated with aggressive bulbar-onset disease
[Burrell, J.R., et al. (2016), The origins and emergence of the extracellular aggregation hypothesis (2016)](https://doi.org/10.1136/jnnp-2015-311858)
[Chio, A., et al. (2013), Global epidemiology of amyotrophic lateral sclerosis: A systematic review of the published literature (2013)](https://doi.org/10.1159/000343153)
[Logroscino, G., et al. (2010), Incidence of amyotrophic lateral sclerosis in Europe: Results from a systematic review (2010)](https://doi.org/10.1159/000235992)
[Manera, U., et al. (2020), Sex differences in ALS: A population-based study (2020)](https://doi.org/10.1007/s10072-020-04396-2)
[Palese, F., et al. (2023), Bulbar onset ALS: Clinical features and prognosis (2023)](https://doi.org/10.1007/s00415-023-09657-7)
[Kim, W.K., et al. (2017), ALS with predominant bulbar involvement: A distinct phenotype? (2017)](https://doi.org/10.1007/s00415-017-8545-5)
[Chio, A., et al. (2019), Prognostic factors in ALS: A critical review (2019)](https://doi.org/10.1080/21678421.2019.1582693)