What causes hand tremors?

What Causes Hand Tremors

Hand tremors result from multiple distinct etiologies that require systematic categorization based on tremor characteristics (rest vs. postural vs. kinetic), associated symptoms, and underlying pathophysiology—ranging from benign physiologic tremor to serious neurodegenerative and metabolic disorders.

Primary Tremor Categories and Their Causes

Essential Tremor (Most Common Pathologic Tremor)

• Essential tremor is the most common tremor disorder, presenting as postural and kinetic tremor with frequency between 4-8 Hz, primarily affecting upper extremities and head 1, 2
• Approximately 50% of cases are hereditary, indicating a genetic component 2
• Involves dysfunction of the central motor network including cerebellum, thalamus, and cortical networks 3
• Can cause significant disability interfering with activities of daily living, mood, and socialization 4

Parkinsonian Tremor

• Parkinson's disease causes a characteristic 4-6 Hz resting tremor in arms and legs that may also have postural components 5, 1, 2
• Results from depletion of dopamine in the corpus striatum after approximately 40-50% of dopaminergic neurons in the substantia nigra have been lost 5, 6
• Classic presentation includes resting tremor, bradykinesia, and rigidity 5
• The tremor can affect various body parts including mouth/face 5

Cerebellar/Intentional Tremor

• Intentional tremor is characterized by coarse, irregular tremor that becomes more pronounced during goal-directed movements, often with "wing-beating" appearance during finger-to-nose testing 7
• Caused by lesions of the cerebellum and midbrain, multiple sclerosis affecting cerebellar pathways, or traumatic brain injury 7, 1
• Associated with dysarthria (slurred speech) and ataxic gait 7
• May cause shakiness of the trunk in addition to extremity tremor 2

Physiologic Tremor (Enhanced)

• Present in all individuals but can become symptomatic when enhanced by drugs, caffeine, stress, fatigue, or other circumstances 1, 2
• Physical exercise significantly increases tremor amplitude, with effects persisting up to 24 hours depending on exercise type 4
• Upper-body exercises produce more variance in tremor than lower-body exercises 4

Metabolic and Toxic Causes

Wilson's Disease

• Presents with characteristic tremor classified as "pseudosclerosis dominated by tremor" 7
• Can manifest with tremor, dystonia, and parkinsonian features along with drooling and oropharyngeal dystonia 5
• Requires checking serum ceruloplasmin, 24-hour urinary copper, and slit-lamp examination for Kayser-Fleischer rings 5

Hepatic Encephalopathy

• Causes asterixis or "flapping tremor" (technically a negative myoclonus) 4, 7
• Hand tremor results from incongruity in tension of various muscles with hyperextension of wrist as fingers spread apart 4
• Common symptom in early and middle phases of overt hepatic encephalopathy 4

Drug-Induced and Toxic Tremor

• Certain medications can cause or exacerbate tremor 7, 1
• Alcohol can cause tremor both acutely and during withdrawal 1
• Toxic exposures affecting cerebellar function contribute to intentional tremor 7

Functional Neurological Disorder

Functional Tremor

• Characterized by variability in frequency and amplitude, and most importantly, distractibility (stopping when attention is redirected) 8
• Represents a real neurological condition caused by potentially reversible miscommunication between brain and body 8
• Lacks the consistent patterns seen in organic tremor syndromes 8
• Can occur on a psychogenic basis as a conversion disorder 1, 2

Other Important Causes

Peripheral Neuropathy

• Can manifest with tremor as part of the neuropathic syndrome 1

Trauma

• Direct injury can result in tremor, particularly when affecting cerebellar structures or connections 7, 1

Atypical Parkinsonian Syndromes

• Progressive supranuclear palsy (PSP) presents with parkinsonian features including tremor, with early prominent gait dysfunction and postural instability 5
• Multiple system atrophy (MSA) can present with tremor in the MSA-P subtype with predominant extrapyramidal features 5

Critical Diagnostic Approach

To determine the specific cause, characterize the tremor precisely:

• Rest tremor (occurs when body part completely supported against gravity) suggests Parkinson's disease 1, 9
• Postural tremor (occurs with maintained posture) suggests essential tremor or enhanced physiologic tremor 1, 9
• Kinetic tremor (occurs with movement) suggests essential tremor or cerebellar pathology 1, 9
• Intentional tremor (worsens during goal-directed movements) indicates cerebellar dysfunction 7, 9

Assess frequency: 4-6 Hz suggests Parkinson's, 4-8 Hz suggests essential tremor, higher frequencies suggest physiologic tremor 1, 10

Look for associated features: bradykinesia and rigidity (Parkinson's), ataxia and dysarthria (cerebellar), distractibility (functional), systemic signs (metabolic/toxic) 7, 8, 5

Common pitfall: Assuming all hand tremors are benign essential tremor without considering serious underlying causes like Wilson's disease in younger patients, Parkinson's disease, or cerebellar pathology requiring specific treatment 5, 1