Question

A 65-year-old man presents with a 1-year history of slowness of movement and mild resting tremor in his right hand. Over the past few months, he has also developed rigidity on the same side, but the left side remains normal. There is no history of antipsychotic use or cerebrovascular disease. Which of the following features most strongly supports the diagnosis of idiopathic Parkinson’s disease?

• A. Bilateral symmetrical rigidity at onset
• B. Asymmetrical motor symptoms early in the disease course
• C. Absence of disease progression over time
• D. Early appearance of levodopa-induced dyskinesias

Hint:

Other key features supporting idiopathic PD include an excellent, sustained response to Levodopa therapy and the presence of a classic "pill-rolling" rest tremor (4-6 Hz).
Red flags suggesting a different diagnosis include early falls, early autonomic failure, rapid progression, or lack of response to levodopa.

Answer 1

The Correct Option is B

Concept:
Idiopathic Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by the loss of dopaminergic neurons in the substantia nigra pars compacta.
The core clinical features form the acronym TRAP: Tremor (resting), Rigidity (cogwheel), Akinesia/bradykinesia, and Postural instability.
Distinguishing idiopathic PD from atypical parkinsonian syndromes (like Multiple System Atrophy or Progressive Supranuclear Palsy) and secondary parkinsonism relies heavily on specific clinical patterns.
Explanation:
• A cardinal clinical hallmark of idiopathic Parkinson's disease is the profound asymmetry of symptoms at the onset of the disease.

• Patients almost universally present with symptoms (tremor, rigidity, or bradykinesia) starting in one limb or on one side of the body. Even as the disease eventually progresses to involve both sides, the initially affected side usually remains more severely impaired.

• Option (A), Bilateral symmetrical rigidity at onset, is a "red flag" that strongly argues against idiopathic PD. Symmetrical onset is characteristic of drug-induced parkinsonism (e.g., from typical antipsychotics or metoclopramide) or atypical parkinsonism syndromes (Parkinson-plus syndromes).

• Option (C), Absence of disease progression, contradicts the neurodegenerative nature of Parkinson's disease, which is inherently progressive over time.

• Option (D), Early appearance of levodopa-induced dyskinesias, is another red flag. While dyskinesias are a common late complication of long-term levodopa therapy in PD, their appearance very early in treatment suggests an alternative diagnosis, such as Multiple System Atrophy (MSA).

• The patient in the scenario exhibits classic right-sided resting tremor, bradykinesia, and rigidity with a normal left side, flawlessly representing the asymmetric onset pattern.
Final answer:
The presence of asymmetrical motor symptoms early in the disease course is one of the strongest clinical indicators of idiopathic Parkinson's disease.