Disease/Condition Differentiating Signs/Symptoms Differentiating Tests
Resting Tremor
Parkinson disease Resting and action tremor, with rigidity, bradykinesia, and postural instability.
Also, masked facies, cogwheeling, gait abnormalities, and early morning dystonia.
A dopaminergic agent (e.g., levodopa) trial can clarify the diagnosis.
Lewy body dementia Dementia, hallucinations, fluctuating mental status.
History is often sufficient for diagnosis
Neuropsychometric testing may distinguish domains of cognitive deficits
Multiple system atrophy
Progressive supranuclear palsy Gaze palsies and early falls within 1 year of diagnosis.
Neurologic examination: vertical gaze palsy and significant postural instability
Evidence of midbrain atrophy on MRI brain can be supportive of PSP diagnosis, but is not definitive
Cortical basal degeneration Apraxia, alien limb phenomenon, cortical sensory loss on neurologic exam None
Toxin-induced tremor History of carbon monoxide, manganese, or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) exposure.
Acute onset
MRI brain: abnormalities (T2 changes) in basal ganglia noted
Postencephalitic parkinsonism    
Action Tremor
Essential tremor Characterized by a progressive tremor of the upper extremities, present in posture and action, without other neurologic signs or symptoms.
Problems with fine motor tasks
Clinical Dx
Propranolol, Primidone
Enhanced physiologic tremor
All normal, healthy individuals exhibit physiologic tremor.
It can be enhanced by intake of stimulants and other drugs, by withdrawal from drugs or alcohol, during certain medical conditions (elevated thyroid hormone levels or low glucose level), and by stress and fatigue.
Enhanced physiologic tremor occurs in the absence of a neurologic disease and is high-frequency postural and kinetic tremor that occurs in the arms, legs, and voice but not the head.
A medication history looking for agents that cause enhanced physiologic tremor, and TFTs screening for hyperthyroidism.
In some patients, quantitative computerized tremor analysis with accelerometers attached to the arms can help in diagnosing enhanced physiologic tremor.
It is usually reversible once the cause is corrected.
Hypoglycemia Symptoms include sweating, anxiety, tachycardia, and tremor. Patients may also experience fatigue, dizziness, visual disturbances, and confusion. Symptoms are generally seen as the plasma glucose level falls to <55 mg/dL (3 mmol/L).
All patients may require supportive care with glucose and/or glucagon while awaiting definitive therapy for the underlying condition
Thyrotoxicosiss Symptoms include palpitations, heat intolerance, diaphoresis, weight loss, and anxiety.  Thyroid function testing should be considered in every patient who presents with an action tremor.
Treatment options are radioactive iodine therapy, antithyroid drugs, and surgery.
Pheochromocytomaa Symptoms include headache, sweating, and tachycardia. Patients often have hypertension. The tremor occurs due to excess catecholamines. This is typically evaluated by measuring urinary and plasma fractionated metanephrines and catecholamines.
Treatment includes medical options (phenoxybenzamine, phentolamine) and surgical options (open or laparoscopic adrenalectomy).
Alcohol withdrawall Mild tremors may occur within hours after cessation of drinking.
Continued alcohol withdrawal can lead to seizures, fever, and delirium with hallucinations, dehydration, and dangerous autonomic instability (delirium tremens).
These usually occur 2 to 4 days after alcohol cessation but can happen as long as 10 days later.
Alcohol withdrawal requires close monitoring and treatment. Benzodiazepines remain the cornerstone of treatment.
Cerebellar tremor
(multiple sclerosis, trauma, or stroke))
Fragile X tremor ataxia syndrome (FXTAS)    
Orthostatic tremor    
Primary writing tremor    
Neuropathic tremor    
Mixed (rest & action) Tremor
Rubral tremor    
Dystonia Dystonic movements or postures, pain, a geste antagoniste, or muscular hypertrophy. If the clinical diagnosis is in doubt, genetic testing can help diagnose dystonia.
Wilson disease Occurs in patients <40 years of age.
Characterized by resting and action tremor.
Other neurologic abnormalities present (e.g., dystonia, dysarthria, depression, cognitive impairment).
A low serum ceruloplasmin (<20 mg/dL) would indicate the patient had Wilson disease.
Ophthalmologic examination with a slit lamp reveals Kayser-Fleischer rings in most patients who have neurologic signs.
Drug-induced tremor
(Caffeine, Alcohol withdrawal, antipsychotics, reglan, lithium, levothyroxine, TCA, Valproic Acid, Reserpine)
Occurs following ingestion of certain drugs (e.g., lithium carbonate, theophylline valproic acid, cyclosporine, caffeine).
The tremor may affect the hands, arms, head, eyelids, or other muscles, but rarely affect the legs or feet.
The shaking usually involves small, rapid movements, >5 times a second.
The tremor will occur in a reasonable time frame following drug ingestion.
Flapping tremor  
Psychogenic tremorr