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PD Prodromal Phase – Braak Staging — SCE Neurology MCQ

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ModerateNeurodegenerative DiseasePD Prodromal Phase – Braak StagingSCE Neurology

A 65-year-old man with recently diagnosed PD asks about non-motor symptoms. His neurologist explains that REM sleep behaviour disorder, constipation, hyposmia, and depression may have preceded his motor diagnosis by years. What is the significance of this prodromal phase?

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Correct answer: A — Non-motor symptoms can precede PD motor diagnosis by 10–20 years — this prodromal phase reflects early alpha-synuclein pathology spreading through the brainstem and peripheral autonomic nervous system before reaching the substantia nigra (consistent with Braak staging)

PD has a well-recognised prodromal phase where non-motor symptoms precede motor diagnosis: RBD (brainstem), hyposmia (olfactory bulb), constipation (enteric nervous system), depression/anxiety, and pain may appear 5–20+ years before tremor/bradykinesia. This is consistent with Braak's staging hypothesis — alpha-synuclein pathology begins in the lower brainstem and olfactory bulb, ascending through the brainstem to reach the substantia nigra (when motor symptoms appear) and eventually the cortex (when cognitive symptoms develop). A: These are integral to PD pathophysiology. C: They precede motor symptoms. D: They are part of PD. E: They occur before any medication.

Reference: NICE NG71; Braak Staging Hypothesis