What is the most likely diagnosis and recommended work‑up and treatment for a patient presenting with extremely slow blink, eyelid ptosis, hypomimic (expressionless) face, flat voice, stooped posture, bradykinesia, reduced arm swing, gait freezing, rhythmic foot movement (possible tremor), and decreased lip pursing/tongue clicking?

Parkinson's Disease: Most Likely Diagnosis

This patient has classic Parkinson's disease and requires immediate initiation of levodopa/carbidopa therapy after completing a focused diagnostic workup to exclude secondary causes. 1, 2

Clinical Diagnosis

The constellation of symptoms meets diagnostic criteria for Parkinson's disease, which requires bradykinesia plus at least one of the following: resting tremor or rigidity. 1 This patient demonstrates:

• Bradykinesia (extremely slow blink, slow task initiation, reduced arm swing, frozen stance) 1, 3
• Resting tremor (rhythmic foot movement) 1, 4
• Rigidity (implied by stooped posture and neck positioning) 1, 3
• Hypomimia (expressionless face, flat voice) 3
• Postural abnormalities (stooped posture when standing and seated) 3
• Gait freezing (stands frozen, no arm swing when walking) 2, 3

The decreased lip pursing and tongue clicking over recent months may represent evolution of parkinsonian features rather than stereotypies. 3

Essential Diagnostic Workup

Obtain the following tests to exclude treatable secondary causes before confirming idiopathic Parkinson's disease: 5, 1

• MRI brain without contrast to rule out structural lesions, strategic subcortical infarcts, or white matter disease 1
• Thyroid function tests (TSH, free T4) to exclude hyperthyroidism 5
• Serum ceruloplasmin if patient is under age 50 to screen for Wilson's disease 5
• Calcium and phosphorus levels to exclude hypoparathyroidism or basal ganglia calcification 5
• Comprehensive medication review to identify drug-induced parkinsonism (antipsychotics, metoclopramide, valproate) 5

If the clinical presentation remains atypical or uncertain after initial workup, obtain I-123 ioflupane SPECT/CT (DaTscan) to differentiate Parkinson's disease from essential tremor or drug-induced tremor; reduced dopamine transporter binding confirms parkinsonian syndrome. 1

Critical Caveat: CAR T-Cell Therapy History

If this patient has received anti-BCMA CAR T-cell therapy (ciltacabtagene autoleucel or idecabtagene vicleucel), consider Movement and Neurocognitive Treatment-Emergent Adverse Events (MNTs) instead of Parkinson's disease. 6, 1 MNTs present identically to Parkinson's disease with bradykinesia, tremor, hypomimia, flat affect, and postural instability but are levodopa unresponsive. 6 Onset typically occurs 11-108 days post-infusion. 6 For mild MNTs, consider dexamethasone 10 mg daily; for severe or refractory cases with high circulating CAR T-cell levels, consider cyclophosphamide to ablate CAR T cells. 6

Treatment Algorithm

First-Line Pharmacologic Therapy

Initiate levodopa/carbidopa immediately as first-line treatment for motor symptoms (tremor, rigidity, bradykinesia). 5, 2 Levodopa provides the most robust symptomatic benefit and should not be delayed once disability develops. 2, 7 Dopamine agonists can be used as alternative or adjunct therapy. 5

Do not withhold levodopa due to concerns about future complications—there is no reason to postpone symptomatic treatment in patients developing disability. 7

Baseline Assessment

Administer the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) to establish baseline motor function, activities of daily living, and non-motor symptoms for tracking disease progression. 1

Non-Motor Symptom Management

Address the following non-motor features with targeted therapies: 2

• Psychiatric symptoms (apathy, flat affect): Consider selective serotonin reuptake inhibitors 2
• Cognitive decline (if present): Consider cholinesterase inhibitors 2
• Constipation (common prodromal feature): Increase fiber, fluids, and consider polyethylene glycol 7

Multidisciplinary Interventions

Refer immediately to physical, occupational, and speech therapy to address gait freezing, postural instability, hypophonia, and functional limitations. 2, 7 Exercise programs complement pharmacologic treatment and should be initiated at diagnosis. 2, 7

Conduct nutritional risk assessment, as 15% of community-dwelling Parkinson's disease patients are malnourished. 1

Prognostic Considerations

This patient's presentation suggests mild-to-intermediate motor-predominant Parkinson's disease (49-53% of cases), which typically shows good response to dopaminergic medications and slower disease progression. 2 The absence of early prominent cognitive decline, hallucinations, or severe dysautonomia argues against diffuse malignant subtype (9-16% of cases with poor medication response and faster progression). 2

Common Diagnostic Pitfalls to Avoid

• Do not diagnose Parkinson's disease without confirming bradykinesia—tremor alone is insufficient. 5
• Do not assume all elderly patients with tremor have Parkinson's disease—essential tremor is more prevalent and presents with postural/kinetic tremor without bradykinesia. 5
• Always review medication history first—drug-induced parkinsonism is reversible and must be excluded. 5
• Do not miss Wilson's disease in younger patients—measure ceruloplasmin in anyone under 50. 5
• Beware of psychogenic parkinsonism (rare but documented): tremor that entrains to other movements, varies in frequency, subsides with distraction, and lacks typical decrementing amplitude of bradykinesia suggests functional overlay. 8

Red Flags for Alternative Diagnoses

Refer to subspecialty movement disorders if any of the following are present: 2, 3

• Early falls or postural instability (suggests progressive supranuclear palsy)
• Early dementia or hallucinations (suggests Lewy body dementia)
• Prominent dysautonomia (suggests multiple system atrophy)
• Ophthalmoparesis or ataxia (suggests atypical parkinsonism)
• Poor or absent response to adequate levodopa trial (600-1000 mg/day for 2-3 months)