Neurosurgery notes/Functional/Movement disorders/Tremor/Essential tremor

Essential tremor

View Details
logo
Parent item
Tremor

How do you examine an essential tremor patient

  • History
      1. Is the movement disorder actually tremor?
      1. Is the tremor isolated, or are there accompanying neurologic abnormalities?
      1. What are the phenomenologic features of the tremor?
  • Examination
    • Some forms of tremor take >30s to emerge
    • Examine all patients in the true rest position, with hands pronated and resting on their lap.
      • Ask the patient to reposition her or his hands with pinkies down and thumbs up, as both parkinsonian and Holmes tremors are often triggered by this posture.
    • Posture (Without holding of these 2 postures, any postural-reemergent tremor will be missed, as will the rare postural crescendo tremor of Wilson’s disease)
      • Ask patients to raise their arms forward in an outstretched position, holding it for at least 10 seconds.
      • Follow this with a request for the patient to hold his or her arms outstretched to the sides—in the wing-beating position—for at least 10 seconds as well.
    • Next, assess the patient’s ability to repeatedly bring the finger of an outstretched arm and hand to her or his own nose repeatedly and bilaterally, understanding that patients with action (kinetic) tremor will hurry through this maneuver in order to improve accuracy.
    • Ask the patient to write in both script and print and to draw the Archimedes spiral with each hand while ensuring that the patient keeps his or her writing arm off the table and extends the spiral to the edge of the page
        • notion image
  • Observe the patient walking to see if gait triggers his or her tremor.
  • In patients with specific tremor disorders, observing maneuvers that trigger tremor can be particularly useful.
    • Essential tremor (ET) to
      • Draw a straight line connecting 2 dots,
      • Pour water between cups with each hand,
      • Drink from a cup,
      • Use soup spoon to drink liquid.
    • Task-specific or position-specific tremors
      • Writing,
      • Playing a musical instrument
      • Holding an object such as a racquet or golf club.
    • Orthostatic tremor
      • Standing,
      • Tremor typically resolves when the patient touches a wall or walks.

Essential tremor

Definition

  • Isolated tremor syndrome of bilateral upper limb action tremor
  • At least 3 years’ duration
  • With or without tremor in other locations (e.g., head, voice, or lower limbs)
  • Absence of other neurological signs, such as dystonia, ataxia, or parkinsonism.

Numbers

  • Prevalence 0.5%
  • M>F

Clinical features

  • Bilateral postural
  • Intentional tremor
  • Kinetic tremor upper limbs
    • Can affect head/ voice

Pathology

  • Aberrant activity in Dentato-rubro-thalamic tract (DRT).
  • Targets with proven results are
    • VIM;
    • Zona incerta;
    • Posterior subthalamic area (PSA)

Treatment

  • Non medical
    • Weighed utensils,
    • Ingesting a bit of alcohol at the beginning of dinner,
  • Medical
      • Drug
      Initial Dose
      Typical Dose
      Side Effects
      Primidone
      12.5-25 mg/day at bedtime
      150-750 mg/day at bedtime or in 2 divided doses
      Ataxia, confusion, dizziness, fatigue, flu-like symptoms, nausea, sedation
      Propranolol
      20-80 mg/day in 2 divided doses
      120-320 mg/day in 1-2 doses
      Bradycardia, erectile dysfunction, drowsiness, fatigue, hypotension, shortness of breath with exercise
      Gabapentin
      300-900 mg/day in 3 divided doses
      1200-3600 mg/day in 3 divided doses
      Ataxia, dizziness, nausea, sedation, weight gain
      Levetiracetam
      500 mg/day
      2000 mg/day
      Dizziness, drowsiness, fatigue, weakness
      Topiramate
      25-50 mg/day at bedtime or in 2 divided doses
      150-300 mg/day in 2 divided doses
      Acute angle closure glaucoma, confusion, difficulty concentrating, drowsiness, fatigue, nausea, paraesthesia, weight loss
      Zonisamide
      25 mg/day at bedtime
      200 mg/day
      Headache, drowsiness, fatigue, paraesthesia
    • Most effective is primidone and propranolol
    • Botulinum toxin injections
  • Surgery
    • 25-55% of essential tremor patients are refractory to medications
    • Options
      • VlM DBS
        • Used over last 30 years superseding classic thalamotomy
        • Indications for VIM DBS for Essential Tremor (also same criteria for dystonic tremor)
          • Medical treatment resistant tremor
          • Needs to be impacting quality of life severely
          • Tremor amplitude of around 2-3 cm
          • Lack of significant cognitive or neuropsychiatric vulnerabilities
          • Good speech and gait (both can be worsen post-op with DBS due to stimulation side effects although are reversible)
      • VIM Lesioning
        • Thalamotomy
          • MR guided Focussed Ultrasound is the newer "non-invasive"

Essential tremor plus

  • Definition
    • ET Tremor + additional neurological signs of uncertain significance such as impaired tandem gait, questionable dystonic posturing, memory impairment, or other mild neurologic signs of unknown significance that do not suffice to make an additional syndrome classification or diagnosis.
  • ET with tremor at rest should be classified here.

Exclusion criteria for ET and ET plus

  • Isolated focal tremors (voice, head)
  • Orthostatic tremor with a frequency >12 Hz
  • Task- and position-specific tremors
  • Sudden onset and step-wise deterioration