Definition of Intention Tremor
Intention tremor is a tremor that occurs during goal-directed voluntary movements, characterized by oscillations that increase in amplitude as the limb approaches its target. 1, 2
Key Defining Characteristics
Intention tremor specifically manifests during target-directed movements, distinguishing it from rest tremor (present at rest), postural tremor (present when maintaining a position against gravity), or simple kinetic tremor (present during any voluntary movement). 2
Clinical Features
The tremor amplitude progressively increases during the deceleration and target phase of movement as the limb approaches its intended destination 3
Intention tremor is most evident during tasks requiring precision, such as the finger-to-nose test or reaching for an object 1, 3
The oscillations are perpendicular to the direction of movement and become more pronounced as the target is approached 3
Anatomical Basis
Intention tremor is classically associated with lesions in the cerebellum or its connected pathways, including the superior cerebellar peduncle and dentato-rubro-thalamic tract 1, 4
- Common causes include multiple sclerosis, cerebellar stroke, spinocerebellar ataxias, and cerebellar tumors 4, 5
Important Clinical Distinctions
Not to Be Confused With:
Asterixis ("flapping tremor") - which is actually a negative myoclonus consisting of loss of postural tone, not a true tremor, commonly seen in hepatic encephalopathy 6
Functional tremor - which shows variable frequency, amplitude, and direction, is entrainable, worsens with attention, and improves with distraction 7, 8
Essential tremor with kinetic component - though 25% of essential tremor patients may develop features of intention tremor, particularly in advanced disease 3
Clinical Assessment
Intention tremor can be objectively quantified as increased amplitude of curvature during the deceleration and target phase of movement, with associated slowing of the grasping movement and potential hypermetria 3