Parkinson's disease - clinical fact sheet and MCQ

Overview

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterised by both motor and non-motor symptoms. Its prevalence increases with age, making it a common condition encountered in Australian general practice.¹ 

Diagnosis 

Early recognition of PD facilitates optimal management. Patients may present with classic motor symptoms such as unilateral rest tremor, bradykinesia, rigidity, and postural instability.^1,2 However, non-motor symptoms—including constipation, anosmia, rapid eye movement sleep behaviour disorder, and urinary urgency—often precede motor manifestations and should raise clinical suspicion.¹

Parkinson’s disease may be diagnosed by the presence of bradykinesia, plus one of:²

• muscular rigidity

• slow rest tremor

• postural instability not attributable to another dysfunction

It's important to differentiate PD from other conditions. Red flags suggesting alternative diagnoses include:¹

• tremor that is absent at rest but present with posture or use of the hands (consider essential or dystonic tremor)

• early recurrent falls (consider progressive supranuclear palsy)

• severe orthostatic hypotension (>30mmHg decrease in blood pressure) (consider multiple system atrophy)

• early cognitive impairment (consider normal pressure hydrocephalus or progressive supranuclear palsy)

• lack of response to levodopa (consider progressive supranuclear palsy or multiple system atrophy)

• bilateral and symmetrical Parkinsonism (consider medication-induced Parkinsonism, especially if dopamine-blocking drugs such as prochlorperazine, metoclopramide, antipsychotic medications, have been introduced recently or patient has been exposed for extended periods)

Note that this is not an extensive list of PD mimics or red flags. A thorough history and neurological examination are essential, as PD remains a clinical diagnosis. 

Management

1. Pharmacological treatment 

• Levodopa, which is converted into dopamine by the enzyme dopa-decarboxylase (DDC), remains the most effective treatment for motor symptoms¹ and is associated with the fewest adverse effects, particularly in patients >70 years² 

• Levodopa may be combined with dopa-decarboxylase inhibitors (carbidopa or benserazide) to enhance central nervous system bioavailability by reducing conversion in the periphery.¹Dopamine agonists (contraindicated in those with a history of impulse control disorder), which act directly on dopamine receptors to mimic dopamine’s effects,  and monoamine oxidase B inhibitors, can be considered, particularly in mild cases; these are effective and well-tolerated alternatives¹

• Amantadine or anticholinergics may be useful alternatives or adjuncts if levodopa is inadequate at controlling tremor; initiation by a specialist is recommended²

Regular assessment and monitoring of non-motor symptoms enable the clinician to support the implementation of effective interventions. 

2. Non-pharmacological interventions

Multidisciplinary care is vital. Consider initiating non-pharmacological intervention during early-stage disease where practical.¹

• Physiotherapy can be tailored to the patient’s specific motor challenges^2,3

• Occupational therapy assists with daily living activities, such as handwriting³

• Speech therapy addresses speech disorders and dysphagia³

Regular assessment and monitoring of non-motor symptoms enable the clinician to support the implementation of effective interventions. 

General practitioners are often at the forefront of management for PD, both for undiagnosed patients with early symptoms and those with a known diagnosis seeking ongoing care. Though support from a neurologist is recommended where appropriate, GPs are well-positioned to improve quality of life for patients living with PD by adopting a holistic and proactive approach.

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Quiz

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References

1. Waller S, Williams L, Morales-Briceño H, Fung VSC. The initial diagnosis and management of Parkinson’s disease. AJGP 2021; 50(11):793-800.

2. Therapeutic Guidelines. Parkinson disease. 2018. https://app.tg.org.au/viewTopic?topicfile=parkinson-disease. (last viewed Dec 2024).

3. Höglinger, G, German Parkinson’s Guidelines Committee & Trenkwalder, C. Diagnosis and treatment of Parkinson´s disease (guideline of the German Society for Neurology). Neurol Res Pract 2024; 6, 30. https://doi.org/10.1186/s42466-024-00325-4

4. Zuzuárregui JRP, During EH. Sleep Issues in Parkinson's Disease and Their Management. Neurotherapeutics 2020; 17(4):1480-1494. https://doi.org/10.1007/s13311-020-00938-y.