Which investigations are recommended to confirm a diagnosis of parkinsonism in a patient presenting with bradykinesia and rigidity?

Recommended investigations to confirm a diagnosis of parkinsonism in a patient presenting with bradykinesia and rigidity:

• Diagnosis of Parkinson's disease is primarily clinical, based on the UK Parkinson's Disease Society Brain Bank Clinical Diagnostic Criteria. No specific blood tests or imaging are routinely required to confirm the diagnosis initially.
• 123I-FP-CIT single photon emission computed tomography (SPECT) may be considered if there is diagnostic uncertainty, particularly to differentiate parkinsonism from essential tremor when clinical features overlap. This imaging should be performed and interpreted by specialists with expertise in its use.
• Structural MRI is not recommended to diagnose Parkinson's disease but may be considered to exclude other parkinsonian syndromes or alternative diagnoses if atypical features are present.
• Positron emission tomography (PET), magnetic resonance volumetry, magnetic resonance spectroscopy, acute levodopa and apomorphine challenge tests, and objective smell testing are not recommended for routine differential diagnosis of parkinsonian syndromes outside clinical trials.

Therefore, the initial approach relies on clinical assessment, with 123I-FP-CIT SPECT reserved for cases where clinical differentiation is difficult, and MRI used selectively to exclude other causes.

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