What is Intention Tremor?
Intention tremor is a type of kinetic tremor that worsens progressively as a voluntary movement approaches its target, characterized by increasing oscillatory amplitude during the deceleration and target phase of goal-directed movements. This tremor is classically associated with cerebellar dysfunction, though it can occur in other conditions including essential tremor.
Alternative Names
Intention tremor is also known by several other terms:
- Action tremor (when referring to tremor during voluntary movement)
- Terminal tremor (emphasizing the worsening at movement endpoint)
- Cerebellar tremor (though this term is often incorrectly used synonymously, as cerebellar pathology can produce multiple tremor types beyond just intention tremor) 1
Key Clinical Characteristics
Defining Features:
- Absent or minimal at rest
- Increases in amplitude as the limb approaches the target during goal-directed movements
- Most evident during tasks requiring precision (e.g., finger-to-nose testing, reaching for objects)
- Typically has a frequency of 3-5 Hz 2
- Shows phase-locked oscillations from trial to trial during movement tasks 2
Important Clinical Distinction: The term "cerebellar tremor" and "intention tremor" are frequently but incorrectly used interchangeably in modern practice. Cerebellar pathology actually produces a heterogeneous spectrum of tremors including postural, kinetic, rest, and orthostatic tremors—not exclusively intention tremor 1, 3.
Prevalence in Essential Tremor
Contrary to traditional teaching that intention tremor is purely cerebellar, 27% of essential tremor (ET) patients demonstrate moderate to severe intention tremor, with an additional 33% showing mild intentional components 4. This challenges the historical notion that intention tremor is pathognomonic for cerebellar disease.
- Intention tremor in ET tends to develop at variable intervals after postural tremor onset
- Older ET patients develop intention tremor more rapidly
- ET patients with intention tremor show objective cerebellar dysfunction on quantitative movement analysis 4
Quantitative Characteristics
Objective accelerometry demonstrates:
- 3-fold increase in tremor amplitude from movement onset to target approach 5
- Slowed movement velocity during deceleration and target phases 4
- Hypermetria (overshooting targets) in affected patients 4
Clinical Pitfalls
Common Misconception: Many clinicians assume intention tremor equals cerebellar stroke or multiple sclerosis. However, intention tremor occurs in approximately one-quarter of ET patients and should not automatically trigger extensive neuroimaging for structural cerebellar lesions in the appropriate clinical context 4.
Diagnostic Specificity: While intention tremor is specific (85%) for distinguishing certain tremor disorders, it has poor sensitivity (45%), meaning its absence does not rule out conditions like ET 6.