What are the risk factors for intentional tremors of the hands?

Risk Factors for Intentional Tremors of the Hands

The term "intentional tremor" refers to tremor that occurs during voluntary, goal-directed movement toward a target, and the primary risk factor is cerebellar pathway dysfunction, most commonly caused by multiple sclerosis, followed by cerebellar lesions, stroke, or trauma. 1

Understanding Intentional (Kinetic) Tremor

Intentional tremor—also called kinetic or action tremor—manifests specifically during purposeful movement and typically worsens as the limb approaches its target. This distinguishes it from resting tremor (Parkinson's disease) or postural tremor (essential tremor). 2

Primary Risk Factors

Cerebellar Pathway Disease

• Multiple sclerosis is the most common cause of intentional tremor 1
• Cerebellar lesions from any etiology (tumors, infarcts, hemorrhage) 2
• Midbrain lesions affecting cerebellar connections 2

Wilson's Disease

• Copper accumulation in the basal ganglia and cerebellum produces a characteristic "wing-beating" tremor—a coarse, irregular proximal tremor with intentional components 3
• This tremor-rigidity syndrome can present as "pseudosclerosis dominated by tremor" 3
• Risk factors include: family history of Wilson's disease, age <40 years at presentation, concurrent liver disease, and presence of Kayser-Fleischer rings 3

Hepatic Encephalopathy

• Asterixis ("flapping tremor") mimics intentional tremor but is actually a negative myoclonus from loss of postural tone 3
• Risk factors: chronic liver disease, cirrhosis, portosystemic shunting, elevated ammonia levels 3
• Important caveat: asterixis is not pathognomonic—it also occurs in uremia and other metabolic encephalopathies 3

Trauma and Structural Lesions

• Direct cerebellar injury from head trauma 2
• Posterior fossa masses or surgical complications 2

Secondary and Modifiable Risk Factors

Medications and Substances

• Valproate, lithium, amiodarone, SSRIs/SNRIs, and amitriptyline can induce or worsen tremor 4
• Alcohol withdrawal or chronic alcohol use 2
• Cocaine and other stimulants 4
• Risk increases with: polypharmacy, male gender, older age, high doses, and immediate-release preparations 4

Metabolic and Endocrine Factors

• Thyrotoxicosis increases sympathetic activity causing tremor 5
• Hyperparathyroidism, particularly with concurrent uremia 5

Peripheral Neuropathy

• Demyelinating or axonal neuropathies can produce action tremor 2

Functional (Psychogenic) Tremor Considerations

Functional tremor can mimic intentional tremor but has distinct features: 3

• Variable frequency, amplitude, and direction 5
• Worsens with attention, improves with distraction 5
• Sudden onset without progressive course 4
• Distractibility, entrainment, and arrest with contralateral movements 4

Clinical Assessment Priorities

When evaluating intentional tremor, specifically assess for:

• Timing: Does tremor worsen as the hand approaches a target (finger-to-nose test)? 1
• Associated neurological signs: ataxia, dysmetria, nystagmus, dysarthria 3
• Medication history: review all current and recent medications 4
• Liver disease indicators: jaundice, ascites, altered mental status 3
• Age and family history: Wilson's disease typically presents before age 40 3

Important Pitfalls to Avoid

• Do not confuse asterixis with true intentional tremor—asterixis is a negative myoclonus requiring different management 3
• Do not overlook Wilson's disease in younger patients—delayed diagnosis can lead to irreversible neurological damage 3
• Do not assume all action tremors are essential tremor—intentional tremor requires cerebellar pathway evaluation 1
• Do not miss drug-induced tremor—many commonly prescribed medications cause tremor that resolves with discontinuation 4