Table 2 Features differentiating Parkinson’s disease from essential tremor
FeatureParkinson’s diseaseEssential tremor
Age at onset (y)55–7510–80
Family history+/–++
Tremor frequency (Hz)4–65–10
Tremor characteristicsSupination–pronationFlexion–extension
Influencing factors
    RestIncreasesDecreases
    ActionDecreasesIncreases
    Mental concentrationDecreasesIncreases
    WritingDecreases (micrographia)Increases (tremulous)
    WalkingIncreasesDecreases
    AlcoholDecreases
Postural tremorRe-emergentWithout latency
Kinetic tremor+/–Yes
Limb tremorAsymmetricSymmetric
Distribution other than limbsFace, jaw, lips, chinHead, voice
Neuroimaging—dopaminergic systemMarked dopaminergic deficitMild dopaminergic deficit
Mid-brain sonographyMarked hyper-echogenicityMild hyper-echogenicity
NeuropathologyNigrostriatal degeneration, Lewy bodiesMild cerebellar degeneration, Lewy bodies in the substantia nigra, brainstem and cerebellum some cases
TreatmentAnticholinergics, amantadine, dopaminergic drugs, deep brain stimulationAlcohol, beta-blockers, primidone, topiramate, gabapentin, botulinum toxin, deep brain stimulation