What are the causes and treatments of generalized tremor?

Causes and Treatments of Generalized Tremor

Generalized tremor is caused by various conditions including thyroid disorders, anxiety, essential tremor, Parkinson's disease, and medication side effects, with propranolol being the first-line treatment for many tremor types. 1, 2, 3

Common Causes of Generalized Tremor

Neurological Causes

• Parkinson's disease presents with characteristic resting tremor that improves with voluntary movement 4
• Essential tremor manifests as postural and action tremor, often affecting the hands, head, and voice 2, 5
• Multiple systems atrophy (Shy-Drager syndrome) can cause tremor due to altered basal ganglia function 1
• Cerebellar disorders produce intention tremor that worsens during targeted movements 5, 6

Endocrine and Metabolic Causes

• Thyrotoxicosis and hyperthyroidism cause increased sympathetic activity leading to tremor and nervousness 1
• Hyperparathyroidism, particularly in patients with uremia, can present with tremor 1

Psychological Causes

• Anxiety disorders commonly present with enhanced physiological tremor affecting the upper limbs 7
• Conversion disorder may manifest as functional tremor with variable frequency, amplitude, and direction 8

Medication and Substance-Related Causes

• Medication side effects (particularly stimulants and certain psychiatric medications) 4
• Alcohol withdrawal can cause tremor due to autonomic hyperactivity 5

Clinical Assessment of Tremor

Tremor Classification

• Rest tremor: Present when body part is fully supported against gravity (suggestive of Parkinson's disease) 2, 4
• Postural tremor: Present when maintaining position against gravity (common in essential tremor) 2, 4
• Action/intention tremor: Occurs during voluntary movement (typical of cerebellar disorders) 4, 6

Distinguishing Features

• Tremor frequency helps differentiate causes: Parkinson's (4-6 Hz), essential tremor (8-12 Hz), physiologic tremor (8-12 Hz) 4, 9
• Functional tremors typically worsen with attention and improve with distraction 8
• Flapping tremor (asterixis) suggests hepatic encephalopathy 2

Treatment Approaches

Pharmacological Treatments

First-Line Medications

• Beta-blockers, particularly propranolol (80-240 mg/day), are effective for essential tremor and enhanced physiological tremor 1, 3, 5
• Primidone is another first-line option for essential tremor, effective in up to 70% of patients 3
• For parkinsonian tremor, combination therapy with carbidopa and levodopa remains the first-line approach 5

Second-Line Medications

• Gabapentin has moderate efficacy in tremor management 3
• Clonazepam may be effective for orthostatic tremor 5
• Alprazolam shows similar efficacy to propranolol for anxiety-related tremor 7

Non-Pharmacological Approaches

• Rhythm modification techniques can help control functional tremor by superimposing alternative rhythms 8, 3
• Using gross rather than fine movements can help manage tremor during activities like handwriting 3
• Avoiding muscle tension and co-contraction, as these can worsen tremor 3

Surgical Options for Refractory Tremor

• Deep brain stimulation (DBS) is preferred for bilateral tremor or younger patients needing adjustable treatment 3
• Magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy shows lower complication rates (4.4%) compared to DBS (21.1%) but is not suitable for bilateral treatment 3
• Radiofrequency thalamotomy is available but carries higher complication risks than MRgFUS 3

Treatment Algorithm for Specific Tremor Types

Essential Tremor

1. Start with propranolol (80-240 mg/day) or primidone if tremor affects quality of life 3, 5
2. If first-line agents fail, consider second-line medications like gabapentin 3
3. For medication-refractory cases, consider surgical options based on patient characteristics 3

Parkinsonian Tremor

1. Begin with carbidopa-levodopa combination therapy 5
2. Consider adjunctive therapies if response is inadequate 5
3. Surgical options may be considered for medication-resistant cases 3, 5

Anxiety-Related Tremor

1. Propranolol or alprazolam show similar efficacy 7
2. Address underlying anxiety disorder through appropriate psychiatric treatment 7

Thyrotoxicosis-Related Tremor

1. Propranolol is the most widely studied beta-blocker for treating increased heart rate and tremor in thyrotoxicosis 1
2. Treat the underlying thyroid disorder 1

Important Considerations and Pitfalls

• Beta-blockers should be avoided in patients with chronic obstructive pulmonary disease, bradycardia, or congestive heart failure 3
• Common side effects of beta-blockers include fatigue, depression, dizziness, hypotension, and sleep disturbances 3
• For patients with both essential tremor and hypertension, beta-blockers may provide dual benefits 3
• Avoid prescribing unnecessary aids and equipment for functional tremor as they may reinforce abnormal movement patterns 8, 3
• Regular assessment of tremor severity and medication side effects is essential for optimal management 3