What are the diagnosis criteria for essential tremors?

Essential Tremor Diagnostic Criteria

Essential tremor is diagnosed primarily by the presence of bilateral action tremor of the arms and hands that persists for at least 3 years, with absence of isolated head and voice tremor and absence of task- and position-dependent tremor. 1

Core Diagnostic Features

• Essential tremor presents primarily as bilateral action tremor (postural or kinetic) involving the hands and forearms that is visible and persistent 2
• The tremor must be present for at least 3 years for definitive diagnosis 1
• Tremor frequency typically ranges between 4-8 Hz 3
• Consciousness remains intact during tremor episodes 4

Supporting Diagnostic Features

• Tremor may also affect the head, voice, legs, feet, trunk, jaw, chin, and tongue 2
• Positive family history is common but not required for diagnosis 1
• Good response to low-dose voltage-gated sodium channel blockers, especially carbamazepine/oxcarbazepine 4
• Tremor typically worsens with emotional stress, caffeine consumption, and physical exertion 5
• Tremor improves with small amounts of alcohol in many patients 6

Differential Diagnosis

Essential tremor must be differentiated from:

• Parkinson's disease tremor (primarily resting tremor) 6
• Enhanced physiologic tremor (triggered by anxiety, exercise, caffeine) 5
• Dystonic tremor (associated with abnormal posturing) 6
• Drug-induced tremor (medication history important) 6
• Cerebellar tremor (primarily intention tremor with ataxia) 7
• Intentional tremor (coarse, irregular, "wing-beating" appearance with cerebellar pathology) 7

Red Flags That Suggest Alternative Diagnosis

• Duration of attacks greater than 1 minute 4
• Age of onset over 20 years 4
• Abnormalities in brain CT/MRI scanning 4
• Presence of other neurologic or systemic problems 4
• No response to anticonvulsants 4
• Abnormal results of interictal examinations 4

Exclusionary Criteria

The following conditions must be excluded:

• Cerebrovascular disease 4
• Demyelinating disease, especially multiple sclerosis 4
• Metabolic disorders:
  • Hyperthyroidism 4
  • Calcium-phosphate metabolism disorders 4
  • Glucose metabolism disorders 4
  • Kernicterus 4
• Brain trauma 4
• Psychological disorders 4

Classification of Essential Tremor

• Essential tremor is now recognized as a syndrome with both motor and non-motor features 2
• Motor features include:
  • Postural tremor (when maintaining a position against gravity) 6
  • Kinetic tremor (during voluntary movement) 6
  • Intentional tremor (as approaching a target) 2
  • Rest tremor (in some cases) 2
• Non-motor features may include:
  • Cognitive issues (memory and executive problems) 2
  • Psychiatric symptoms (anxiety, depression, social phobia) 2
  • Sensory abnormalities (olfactory deficits, hearing loss) 2

Clinical Assessment

• Detailed history should include:
  • Age of onset 1
  • Progression pattern 1
  • Triggering factors 5
  • Family history 1
  • Medication history 6
  • Impact on daily activities and quality of life 1
• Physical examination should focus on:
  • Tremor characteristics (frequency, amplitude, distribution) 6
  • Presence during different positions and activities 6
  • Associated neurological signs 1

Severity Classification

• Severity is typically classified based on functional impact:
  • Mild: Minimal interference with daily activities 8
  • Moderate: Some interference with daily activities 8
  • Severe: Significant interference with daily activities 8

Common Pitfalls in Diagnosis

• Misdiagnosing Parkinson's disease as essential tremor (look for bradykinesia, rigidity, and postural instability in Parkinson's) 6
• Failing to recognize enhanced physiologic tremor (which is usually temporary and related to specific triggers) 5
• Overlooking drug-induced tremor (careful medication history needed) 6
• Missing dystonic tremor (look for abnormal posturing) 6
• Confusing flapping tremor (asterixis) seen in hepatic encephalopathy with essential tremor 4

By systematically evaluating patients using these criteria and carefully excluding other causes of tremor, clinicians can accurately diagnose essential tremor and initiate appropriate treatment when symptoms interfere with function or quality of life 8.