Paper II — Parkinsonism and movement disorders

Rapid Revision Grid — Q53 to Q60

Numbers to memorise

Parkinson's disease: prevalence ~1% over 65; levodopa 300–600 mg/day, 3–4 doses, 30 min pre-meal; challenge dose 150–250 mg; rest tremor 4–6 Hz; depression ~50%; constipation ~50%; delayed gastric emptying ≥70%; orthostatic hypotension in 30–40% of PD patients.

Orthostatic hypotension: ≥20 mmHg systolic or ≥10 mmHg diastolic within 3 minutes; delayed form after 6 minutes; pooled prevalence 22% in community-dwelling older adults, 23.9% in long-term care. Drug-induced parkinsonism: recovery over weeks to months; ~20% have persisting signs; DaTSCAN normal. Multiple system atrophy: prevalence 3.4–4.9/100,000; autonomic features before or within 2 years of motor onset; median survival 6–10 years; hot cross bun sign in ~75% of MSA-C.

Essential tremor: 3% general population, 5% over 60, 21.7% over 95; propranolol and primidone reduce amplitude by 30–70%; MRgFUS second side at ≥9 months.

Restless legs syndrome: augmentation 7–10% per year on dopamine agonists; ferritin target >75–100 µg/L, transferrin saturation >20%.

Ageing brain: atrophy 0.2%/year at 30–50 → 0.3–0.5%/year at 70–80; impaired distal vibration sense in one-third over 60; ankle jerks lost in one-third by 80; Alzheimer's 6–8% over 65, ~30% over 85, prevalence doubling every 5 years. Clozapine: discontinue permanently if neutrophils <1500/mm3.

Guidelines, trials and approvals to cite (2023–2026)

Source One-line message

AGS Beers Criteria 2023 Antipsychotics and metoclopramide are potentially inappropriate in older adults — the formal basis for preventing drug-induced parkinsonism NSD-ISS and SynNeurGe, Lancet Neurol Parkinson's disease and DLB redefined biologically as neuronal α-synuclein disease using 2024 CSF α-synuclein seed amplification assay Revised Alzheimer's Association criteria, Alzheimer's disease defined by core biomarkers including blood p-tau217, not by clinical 2024 syndrome Lancet Commission on dementia, 2024 14 modifiable risk factors account for about 45% of dementia; vision loss and high LDL cholesterol newly added Crexont (Aug 2024), Vyalev (Oct 2024), Extended-release oral levodopa, 24-hour subcutaneous levodopa prodrug infusion, and Onapgo (Feb 2025) subcutaneous apomorphine infusion for motor fluctuations Kaplitt et al., JAMA Neurol 2024 Staged bilateral focused ultrasound thalamotomy is effective in essential tremor, second side at ≥9 months ADAPT-PD → FDA approval Feb 2025 Adaptive closed-loop DBS driven by beta-band local field potentials for PD with motor fluctuations Exenatide-PD3, Lancet 2025 Weekly exenatide did not slow Parkinson's disease progression — no disease-modifying therapy exists (Expression of Concern issued June 2026)

AASM RLS guideline, J Clin Sleep Med Jan Gabapentinoids and IV ferric carboxymaltose are first line; dopamine agonists are 2025 recommended against because of augmentation MDS MSA criteria 2022, validated 2023– Four certainty levels including possible prodromal MSA; 94% specificity for clinically 2026 established MSA FDA labelling change, March 2026 Vitamin B6 deficiency and seizure warning added to all carbidopa/levodopa products Drugs of choice Situation Drug of choice Parkinson's disease in the elderly Levodopa with a peripheral decarboxylase inhibitor Early-morning akinesia Dispersible levodopa (dispersible Madopar)

Peak-dose dyskinesia Amantadine 200–400 mg/day (renal dose adjustment)

Wearing-off / end-of-dose fluctuation COMT inhibitor (entacapone) or Stalevo Levodopa-induced nausea Domperidone — never metoclopramide Psychosis in Parkinson's disease Clozapine or pimavanserin Depression in Parkinson's disease Venlafaxine Dementia or apathy in Parkinson's disease Rivastigmine Neurogenic orthostatic hypotension (PD, MSA) Droxidopa; alternatives midodrine, fludrocortisone, compression Essential tremor Propranolol or primidone Refractory essential tremor Vim DBS or focused ultrasound thalamotomy Restless legs syndrome Gabapentin / pregabalin plus iron repletion (2025 AASM)

Tardive dyskinesia Valbenazine or deutetrabenazine Cortical myoclonus Levetiracetam, valproate or piracetam Focal dystonia Botulinum toxin injection