Understanding Parkinson’s Disease Coding & Clinical Features
A recent question to the AHA Coding Clinic asked whether Parkinson’s Disease (PD) with tremor could be coded as Parkinson’s Disease with dyskinesia. The official guidance was clear:
“Codes in subcategory G20.B-, Parkinson’s disease with dyskinesia, should only be assigned when dyskinesia associated with Parkinson’s disease is specifically documented by the provider.”
New ICD-10-CM Codes Effective October 1, 2023:
- G20.A1 – Parkinson’s disease without dyskinesia, without mention of fluctuations
- G20.A2 – Parkinson’s disease without dyskinesia, with fluctuations
- G20.B1 – Parkinson’s disease with dyskinesia, without mention of fluctuations
- G20.B2 – Parkinson’s disease with dyskinesia, with fluctuations
- G20.C – Parkinsonism, unspecified
Tremor vs. Dyskinesia in Parkinson’s Disease
Both tremor and dyskinesia are movement disorders associated with PD, but they differ significantly in cause, presentation, and treatment. Here's a breakdown:
1. Tremor in Parkinson’s Disease
- Definition: Involuntary, rhythmic, oscillatory movement of a body part
- Typical Type in PD: Resting tremor — appears when the body part is at rest and improves with movement
- Characteristics:
- Frequency: 4–6 Hz
- Location: Commonly begins in one hand (e.g., “pill-rolling” tremor between thumb and fingers)
- Asymmetry: Often starts on one side of the body
- Triggers: Worse at rest, improves with movement or posture
- Cause: Dopamine depletion in the basal ganglia
- Treatment:
- Dopaminergic medications (e.g., Levodopa)
- Deep Brain Stimulation (DBS) in advanced cases
2. Dyskinesia in Parkinson’s Disease
- Definition: Abnormal, involuntary movements that are fluid, dance-like, or jerky
- Type in PD: Levodopa-induced dyskinesia (LID) — occurs as a side effect of long-term levodopa therapy
- Characteristics:
- Timing: Occurs at peak dopamine levels or during medication transitions
- Appearance: Chorea (random jerky movements), dystonia (sustained contractions), or both
- Location: May involve limbs, trunk, or face
- Triggers: High-dose or long-term levodopa use
- Cause: Pulsatile dopamine stimulation causes maladaptive changes in the basal ganglia
- Treatment:
- Adjusting levodopa (e.g., smaller, more frequent doses)
- Adding adjunct therapies (amantadine, dopamine agonists)
- Advanced options: DBS or continuous infusion (e.g., Duodopa)
Key Differences Between Tremor and Dyskinesia
- Nature:
- Tremor: Rhythmic and oscillatory
- Dyskinesia: Irregular, flowing, or jerky
- Timing:
- Tremor: Worse at rest, better with movement
- Dyskinesia: Tied to medication timing (often peak-dose)
- Cause:
- Tremor: Dopamine deficiency
- Dyskinesia: Long-term use of levodopa
- Treatment Focus:
- Tremor: Dopamine replacement
- Dyskinesia: Medication adjustment or adjuncts
Clinical Pearls
- Tremor is a core symptom of Parkinson’s and may be present at diagnosis.
- Dyskinesia is typically a treatment-related complication, appearing after years of therapy.
- Proper distinction between tremor and dyskinesia is essential for correct coding and treatment planning.
Additional Clarification from Coding Clinic (Q4 2023)
“Parkinson’s disease is a progressive neurodegenerative condition presenting with motor symptoms (e.g., tremors of hands, arms, legs, or head) and non-motor symptoms (e.g., depression, anxiety, pain).
Dyskinesia is defined as involuntary movements of the face, arms, legs, or trunk.
Fluctuations refer to alternating ON episodes (positive response to levodopa) and OFF episodes (return of symptoms as medication wears off).”














