Tremor

Key Facts

  • Tremor is present in about 80% of PD cases.
  • In PD, tremor is typically asymetric and observed at rest.  It usually improves when performing tasks.
  • Transient upper-limb tremor may initially be subtle.
  • PD tremor is characterized as slow, biplanar, pill-rolling tremor at 4-6 Hz.
  • Higher frequency postural and kinetic tremors also occur.

Clinical Best Practices

  • Treatment for PD tremor is usually levodopa or a dopamine agonist.
  • In rare cases an anticholinergic may be used, but it is usually avoided because of side effects.
  • 20%-40% of patients with PD have refractory tremor, and should be referred to a neurologist or movement disorders specialist.

Tremor is rhythmic movement resulting from involuntary alternating or synchronous contractions of muscle antagonists.  Tremor may be observed in several conditions, and it is important to consider the characteristics of the tremor to narrow in on its cause.

PD tremor and essential tremor (ET) may be confused.  ET is much more prevalent and results in an action tremor, not a rest tremor, and often affects hands, head or voice; the latter two are not seen in PD. PD's resting tremors are observed with the body part completely at rest, and subsides with action or the assumption of a posture.  Onset is typically asymetrically in one hand, although it may be observed elsewhere.  Early in the disease, tremor may be intermittent and may be precipitated by axiety, stress, or clenching of the contralateral hand.