Understanding the Brain

Braak staging

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A. Schematic initial progression of Lewy body deposits in the first stages of Parkinson's Disease, as proposed by Braak and colleagues. B. Localization of the area of significant brain volume reduction in initial PD compared with a group of participants without the disease in a neuroimaging study which concluded that brain stem damage may be the first identifiable stage of PD neuropathology.[1]
Positive Alpha-Synuclein staining of a Lewy body in a patient with Parkinson's disease.


The Braak staging is a classification of Parkinson's disease (PD) based on pathological findings.

The main pathological characteristic of PD is cell death in the substantia nigra and more specifically the ventral part of the pars compacta, affecting up to 70% of the cells by the time the patient dies.[2] The mechanisms by which the brain cells are lost are varied.[3] One mechanism consists of an abnormal accumulation of the protein alpha-synuclein bound to ubiquitin in the damaged cells. This protein accumulation forms inclusions called Lewy bodies.[2]

According to the Braak staging Lewy bodies first appear in the olfactory bulb, medulla oblongata and pontine tegmentum, individuals at this stage being asymptomatic. As the disease evolves, Lewy bodies later attain the substantia nigra, areas of the midbrain and basal forebrain, and finally reach areas of the neocortex.[2]

References

  1. Jubault T, Brambati SM, Degroot C, et al. (2009). "Regional brain stem atrophy in idiopathic Parkinson's disease detected by anatomical MRI". PLoS ONE 4 (12): e8247. doi:10.1371/journal.pone.0008247. PMC 2784293. PMID 20011063. 
  2. 2.0 2.1 2.2 Davie CA (2008). "A review of Parkinson's disease". Br. Med. Bull. 86: 109–27. doi:10.1093/bmb/ldn013. PMID 18398010. 
  3. Obeso JA, Rodriguez-Oroz MC, Goetz CG, et al. (June 2010). "Missing pieces in the Parkinson's disease puzzle". Nat. Med. 16 (6): 653–61. doi:10.1038/nm.2165. PMID 20495568.