Differentiating Essential Tremor from Parkinsonian Tremor

Clinical Characteristics

Essential tremor is a bilateral action/postural tremor of the upper limbs with a frequency of 4–8 Hz that worsens during voluntary movement and with stress, must be present for ≥ 3 years, and lacks bradykinesia or rigidity. 1
Parkinsonian tremor is an asymmetric resting tremor that diminishes with movement and is accompanied by rigidity (cogwheel or lead‑pipe) and bradykinesia, forming the classic diagnostic triad. 2

Bradykinesia on examination is the key discriminating sign indicating a parkinsonian disorder rather than essential tremor. 2
DaTscan (Ioflupane SPECT/CT) showing normal dopamine‑transporter uptake effectively excludes Parkinsonian syndromes and supports a diagnosis of essential tremor when clinical findings are equivocal. 1
Age of onset > 20 years for a tremor that otherwise resembles essential tremor warrants additional investigation to exclude secondary causes. 1
Abnormal brain CT/MRI in a tremor patient requires further work‑up to rule out structural lesions. 1

First‑line pharmacologic therapy includes propranolol (80–240 mg/day) or primidone; both achieve meaningful tremor reduction in ≈ 70 % of patients. 3
Propranolol contraindications: chronic obstructive pulmonary disease, bradycardia, or congestive heart failure. 3
Refractory essential tremor: unilateral MR‑guided focused ultrasound thalamotomy provides sustained improvement in ≈ 56 % of patients at 4 years with a low complication rate (~4 %). 3
Bilateral deep brain stimulation yields tremor control in ≈ 90 % of refractory cases. 3

Dopaminergic therapy (levodopa and dopamine agonists) is the cornerstone treatment, targeting the underlying nigrostriatal dopamine deficit. 2
Parkinsonian tremor often responds less robustly to dopaminergic agents compared with rigidity and bradykinesia. 2
Beta‑blockers (e.g., propranolol) are not first‑line for Parkinsonian tremor. 3

Progressive supranuclear palsy (PSP) – vertical gaze palsy, early falls, axial dystonia, onset in the sixth–seventh decade. 2
Multiple system atrophy (MSA) – prominent autonomic dysfunction, cerebellar ataxia, or predominant parkinsonism. 2
Corticobasal degeneration (CBD) – asymmetric limb rigidity, dystonia, “alien limb” phenomenon, apraxia. 2