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Parkinson’s Disease By Nik Sanyal This = movement disorder caused by degeneration of dopamine pathways in substantia nigra Characterised by: TREMOR RIGIDITY BRADYKINESIA +/- postural instability Epidemiology + Risk Factors Peak age of onset = 55-65 Men > Women 2nd most common neurodegenerative disease after Alzheimer’s Risk factors: Age Gender Spring birth Exposure to pesticides e.g. paraquat or Agent Orange Pathogenesis Most cases = idiopathic PD. Leading to a progressive degeneration + development of Lewy bodies in substantia nigra. Other pathways – mesocortical, mesolimbic + tubero-hypophyseal Genetics (lead to early onset): mutations in c’some 6 = AR PD Alpha synuclein mutation Parkin gene Dopamine has a role in disinhibition of motor activity hence why reduced levels leads to dyskinesia. Pathophysiology Cell death in substantia nigra (particularly pars compacta) leads to reduced dopamine secreting cells. Dopamine acts to facilitate release of inhibition and as such in PD there is greater exertion required to initiate a movement as there is less release of inhibition. Clinical features 1) Resting tremor = usually unilateral before it becomes generalised. It is 4-6 Hz pill-rolling. Typically absent during activity. 2) Rigidity = lead pipe. Cog-wheeling occurs when lead pipe rigidity is broken up by tremor. 3) Bradykinesia = festinant gait (slow to start + small shuffling steps + difficult turns) Has diminished arm swing = leads to recurrent falls. You also get reduction in amplitude of repetitive movements. Other features Progressive decline over years Mask-like face Impaired swallowing – drooling, choking on food Cognitive decline = depression + dementia Quiet voice progressing to dysarthria Micrographia (small + spidery writing) DDx Wilson’s Lewy Body dementia: get visual hallucinations CJD: Dementia + myoclonic jerking Parkinson’s plus Huntington’s disease Drug-induced PD Antipsychotics (APAT side effects: acute dystonia, parkinsonism, akathisia, tardive dyskinesia) Lithium Benign essential tremor Rarely at rest, worse on movement Family hx NICE criteria for Dx Exclude other causes Bradykinesia + at least 1 of: Rigidity 4-6Hz resting tremor Postural instability Supportive criteria: Unilateral Progressive nature Asymmetry before bilateral Response to L-Dopa Investigations Typically a clinical diagnosis Use: Bedside: BP lying + standing, urine dip Bloods: Genetic testing for Huntington’s or caeruloplasmin for Wilson’s Imaging: CT/MRI Fail to respond to L-Dopa Can visualise structural defects Special tests: DAT scan can differentiate between drug-induced + PD. Conservative management Advice + explanation, consider nonphysical problems (depression, poor sleep, dementia). Limited time frame for meds so start when really needed + started by neurologist! MDT: specialist nurses, OT, SALT, psychiatrist, GP, neurologist, dietician Inform DVLA REHAB Medical management Drugs alter the natural progression – they just improve symptoms. Levodopa Is the most effective drug. It crosses the BBB and enters the nigrostriatal neurones and is converted to dopamine. Give with dopa-decarboxylase inhibitor e.g. carbidopa to inhibit peripheral metabolism. S/E = N+V, confusion, on-off phenomena, wearing off + dyskinesia, hallucination Dopamine agonists e.g. Pramipexole = good for motor sx 1st line in younger patients MAO-B inhibitors = selegiline = block dopamine breakdown. Good for motor sx. COMT inhibitors = entacapone = inhibits peripheral break down. S/E = hepatotoxic, N+V, confusion. Amantadine: can be used as monotherapy in early PD but has poor evidence base. Enhances dopamine release. Apomorphine can reduce off periods given as s/c injection. S/E confusion + hallucinations Surgical Deep brain stimulation Pallidotomy involves surgical destruction of the globus pallidus to control dyskinesia. Complications Infection Aspiration Bed pneumonia sores Poor nutrition Falls PD dementia Prognosis Slowly progressive Mean duration 15 years Variable severity Earlier age of onset = poorer prognosis Death usually from complications e.g. pneumonia. Parkinson’s plus syndromes Disorders with parkinsonism + additional features + specific pathology. Vascular dementia Orthotic hypotension = multi-system atrophy gives insomnia, somnolence, restless legs, hallucinations. Use fludrocortisone for BP Dementia + vertical gaze palsy= progressive supra-nuclear palsy Kayser-Fleischer rings = Wilson’s Apraxic gait – communicating hydrocephalus Good luck! Parkinson’s notes http://www.patient.co.uk/doctor/parkinson ism-and-parkinsons-disease Extrapyramidal exam http://youtu.be/6PDxANv_ME8 Gait http://youtu.be/7SyTpEdhBLw
