Intention tremor is an involuntary movement characterized by rhythmic, uncontrolled shaking that appears during purposeful actions, such as reaching for an object. This article provides an overview of intention tremor, detailing its characteristics, common underlying causes, diagnostic methods, and available management strategies.
Defining Intention Tremor
Intention tremor is characterized by rhythmic, involuntary muscle contractions that manifest during voluntary, goal-directed movements. This shaking typically worsens as the affected limb approaches its intended target, such as an arm shaking increasingly as it nears a cup. It is a subtype of kinetic tremor, meaning it occurs during motion rather than at rest.
The tremor’s amplitude tends to be high, causing the limb to “zigzag” significantly. It is often described as broad and coarse, with a low frequency, typically below 5 Hertz. This contrasts with resting tremors, which occur when the body part is relaxed and supported against gravity and often subside with movement. Intention tremor can affect muscles in the arms, legs, and speech, potentially leading to a shaky voice.
Common Underlying Causes
Intention tremor primarily results from damage or dysfunction within the cerebellum, the part of the brain responsible for coordinating voluntary movements, balance, and posture. This strong association leads to intention tremors often being referred to as cerebellar tremors.
Multiple sclerosis (MS) is a common cause, as it can lead to lesions in the cerebellum and its connecting pathways. Other neurological conditions and events that can cause this tremor include stroke, traumatic brain injury, and brain tumors. Certain genetic conditions, such as Wilson’s disease, and neurodegenerative diseases like spinocerebellar ataxia, can also lead to cerebellar damage. Additionally, alcohol use disorder and certain medications, including some anti-seizure drugs, have been linked to intention tremors.
Diagnostic Approaches
Healthcare professionals diagnose intention tremor through a thorough evaluation, including reviewing medical history and conducting a detailed neurological examination. The medical history helps identify potential underlying conditions. During the neurological exam, the clinician assesses coordination, gait, reflexes, and observes the tremor’s characteristics.
A common test is the finger-to-nose test, where the patient touches their nose then the examiner’s finger; an individual with intention tremor will exhibit coarse, side-to-side movements that intensify as the finger approaches the target. The heel-to-shin test similarly evaluates lower extremity tremors. Imaging tests, such as magnetic resonance imaging (MRI), may also be performed to identify damage in the cerebellum or its associated pathways.
Management Strategies
Managing intention tremor involves a multidisciplinary approach focused on addressing the underlying cause and alleviating symptoms. While no established pharmacological cure exists, certain medications may help reduce its severity. Some drugs used for essential tremors, such as propranolol and primidone, have shown some benefit. Other medications like clonazepam and topiramate have also been explored.
Non-pharmacological therapies play a significant role in improving function and quality of life. Physical therapy helps individuals improve coordination, balance, and gait. Occupational therapy assists with adapting daily tasks and provides strategies to cope with the tremor, such as using adaptive equipment. In severe cases where other treatments are insufficient, surgical options like deep brain stimulation (DBS) may be considered. DBS involves implanting electrodes in specific brain regions to deliver electrical impulses that regulate abnormal brain activity and reduce tremor.