The UK Parkinson’s Disease Society Brain Bank criteria (often called the Queen Square Brain Bank criteria) are classic clinical criteria used to diagnose idiopathic Parkinson’s disease (PD). They were developed to improve diagnostic accuracy in life, and they remain widely referenced even though newer criteria (such as the MDS-PD criteria) are now also in use.

These criteria organize diagnosis into three steps:

1. Step 1 – Diagnosis of a parkinsonian syndrome
2. Step 2 – Exclusion criteria for idiopathic PD
3. Step 3 – Supportive positive criteria for idiopathic PD

Step 1 – Diagnosis of a parkinsonian syndrome

To be considered as having a parkinsonian syndrome, the patient must have:

• Bradykinesia (slowness of initiation and progressive reduction in speed/amplitude of repetitive movements)
  PLUS at least one of:
• Muscular rigidity
• 4–6 Hz resting tremor
• Postural instability not primarily due to visual, vestibular, cerebellar, or proprioceptive dysfunction

If Step 1 is not fulfilled, the Brain Bank criteria cannot be applied to diagnose idiopathic PD.

Step 2 – Exclusion criteria for Parkinson’s disease

A range of historical and clinical features rule out idiopathic PD under these criteria, for example:

• History of repeated strokes with stepwise progression
• Repeated head injury
• Definite encephalitis
• Oculogyric crises
• Neuroleptic treatment at onset of symptoms
• More than one affected relative
• Sustained remission
• Strictly unilateral signs after 3 years
• Supranuclear gaze palsy
• Cerebellar signs
• Early, severe autonomic failure
• Early, severe dementia (memory, language, praxis)
• Babinski sign
• Structural lesions (tumour, normal-pressure hydrocephalus) on imaging
• Clearly negative response to high-dose levodopa (without malabsorption)
• MPTP exposure

If any exclusion criterion is present, the diagnosis of idiopathic PD is not supported by the Brain Bank criteria.

Step 3 – Supportive positive criteria

To diagnose “definite” idiopathic PD using these criteria, the patient must:

• Fulfil Step 1,
• Have no Step 2 exclusions,
• Have three or more of the following supportive features:

1. Unilateral onset
2. Rest tremor present
3. Progressive disorder
4. Persistent asymmetry (side of onset more affected)
5. Excellent response (≈70–100%) to levodopa
6. Severe levodopa-induced chorea
7. Levodopa response for ≥5 years