How do I diagnose and treat Parkinson disease?

Diagnosis and Treatment of Parkinson's Disease

Diagnosis

Parkinson's disease diagnosis requires bradykinesia (slowness of movement with progressive reduction in speed and amplitude during repetitive actions) PLUS at least one of the following: resting tremor, rigidity, or postural instability. 1, 2 The diagnosis is primarily clinical and must be confirmed by a movement disorder specialist or general neurologist, as correctly diagnosing parkinsonian syndromes on clinical features alone is challenging. 1

Essential Diagnostic Features

• Bradykinesia is mandatory - look for slowness affecting fine motor tasks (buttoning clothes, writing), gross motor activities (walking, turning), facial expressions, and speech. 1
• Resting tremor - typically 4-6 Hz, present at rest and diminishing with action. 3, 4
• Rigidity - assess by passively moving the patient's limbs while they relax; note constant resistance throughout range of motion (lead-pipe rigidity) or ratchet-like resistance when combined with tremor (cogwheel phenomenon). 1
• Use activation maneuvers (having the patient open/close the opposite hand) to enhance detection of subtle rigidity. 1

Imaging Algorithm

First-line imaging: MRI brain without contrast to rule out structural causes, focal lesions, vascular disease, or alternative diagnoses - often normal in early PD but essential before proceeding. 1, 2

Second-line imaging when diagnosis remains uncertain: I-123 ioflupane SPECT/CT (DaTscan) differentiates true parkinsonian syndromes from essential tremor and drug-induced parkinsonism. 1, 2

• Shows decreased radiotracer uptake in striatum, progressing from posterior putamen to anterior caudate. 1
• A normal DaTscan essentially excludes parkinsonian syndromes. 1
• Cannot differentiate among specific parkinsonian syndromes (PD vs. MSA vs. PSP vs. CBD). 1

Exclude Secondary Causes (Especially Age <50)

• Wilson's disease - measure serum ceruloplasmin, 24-hour urinary copper, slit-lamp exam for Kayser-Fleischer rings. 1
• Drug-induced parkinsonism - review medication history (antipsychotics, antiemetics). 1, 3
• Thyroid dysfunction - obtain TSH, free T4. 1
• Metabolic disorders - assess calcium-phosphorus metabolism, blood glucose, serum bilirubin. 1

Red Flags Suggesting Atypical Parkinsonism (Not Idiopathic PD)

• Early severe autonomic dysfunction, cerebellar signs, or pyramidal signs → Multiple System Atrophy. 1
• Vertical gaze palsy (especially downward) → Progressive Supranuclear Palsy. 1
• Asymmetric rigidity with alien hand phenomenon → Corticobasal Syndrome. 1
• Ataxia → consider alternative diagnosis. 1

Common Diagnostic Pitfalls

• Confusing drug-induced parkinsonism with idiopathic PD - DaTscan is normal in drug-induced cases. 1
• Missing atypical parkinsonian syndromes that have different prognoses and treatment responses. 1
• Skipping structural MRI before ordering functional imaging. 1
• Not using activation maneuvers during rigidity assessment, missing subtle findings. 1

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Treatment

Levodopa-based therapy (carbidopa-levodopa) is the gold standard first-line treatment for Parkinson's disease. 2 This remains the mainstay of PD treatment with the best symptomatic control for motor symptoms. 3, 4

Pharmacologic Management

Initial therapy:

• Carbidopa-levodopa - most effective for motor symptoms (tremor, rigidity, bradykinesia). 2, 3
• Dopamine agonists (e.g., ropinirole) - alternative for early PD, may delay levodopa-related motor complications. 2

Advanced therapies for complications:

• Levodopa-carbidopa enteral suspension - for patients with "off periods" (worsening symptoms when medication wears off), medication-resistant tremor, or dyskinesias. 3
• Deep brain stimulation - for medication-resistant tremor, off periods, and dyskinesias. 3

Non-Motor Symptom Management (Nondopaminergic Approaches)

• Psychiatric symptoms (depression, anxiety) - selective serotonin reuptake inhibitors. 3
• Cognitive impairment - cholinesterase inhibitors. 3
• Constipation - requires specific management as part of autonomic dysfunction. 5, 3
• Sleep disorders (REM sleep behavior disorder) - may require specific interventions. 3, 6

Nutritional Monitoring

Regular monitoring of nutritional status is essential throughout disease course - 15% of community-dwelling PD patients are malnourished and 24% are at medium-high risk. 5, 2

• Monitor body weight changes regularly. 5
• Supplement vitamin D, folic acid, and vitamin B12 as needed. 5
• Screen for dysphagia, which occurs in 60-80% of patients (often asymptomatic initially). 5

Rehabilitative and Supportive Care

• Physical activity and exercise - endurance and resistance exercises slow disease progression and may improve quality of life. 5
• Physical, occupational, and speech therapies - complement pharmacologic treatments. 3
• Palliative care - integral part of PD management throughout disease course. 3

Disease Monitoring

• Use Unified Parkinson's Disease Rating Scale (UPDRS) or Movement Disorder Society-UPDRS (MDS-UPDRS) to assess disease severity and progression. 2
• Monitor for motor fluctuations, dyskinesias, and cognitive decline as long-term complications. 2

Critical Treatment Pitfalls

• Delaying levodopa therapy unnecessarily - it remains the most effective symptomatic treatment. 3, 4
• Focusing only on motor symptoms while neglecting non-motor symptoms that significantly impact quality of life. 3, 6
• Not recognizing when patients need advanced therapies (deep brain stimulation, enteral levodopa) for medication-resistant symptoms. 3
• Inadequate nutritional monitoring leading to preventable malnutrition. 5