What is the treatment for myoclonic jerks?

Treatment of Myoclonic Jerks

The treatment of myoclonic jerks should be targeted based on the underlying cause, with valproate, levetiracetam, and piracetam being first-line treatments for cortical myoclonus, while clonazepam is the first-line treatment for subcortical/brainstem myoclonus. 1, 2

Diagnostic Approach to Myoclonic Jerks

Before initiating treatment, proper characterization of myoclonus is essential:

• Determine timing of myoclonus: At rest, during posture maintenance, or with action
• Distribution pattern: Focal, multifocal, or generalized
• Stimulus sensitivity: Whether jerks are triggered by specific stimuli
• Associated features: Presence of other neurological symptoms or signs

EEG is crucial for differentiating epileptic from non-epileptic myoclonus and can help classify the type of myoclonus (cortical, subcortical, or spinal) 1.

Treatment Algorithm Based on Myoclonus Type

1. Cortical Myoclonus

• First-line treatments:
  • Valproate (most effective for epileptic myoclonus)
  • Levetiracetam (shown to be effective in 60.4% of patients with juvenile myoclonic epilepsy) 3
  • Piracetam

2. Subcortical/Brainstem Myoclonus

• First-line treatment:
  • Clonazepam 1, 2

3. Focal or Segmental Myoclonus

• Consider:
  • Botulinum toxin injections 1, 2

4. Post-anoxic Myoclonus (Lance-Adams Syndrome)

• First-line treatment:
  • Levetiracetam 1
• Alternative options:
  • Valproate
  • Clonazepam

Special Considerations

1. Combination therapy: Single agents rarely control myoclonus completely; polytherapy with a combination of drugs is often needed 2

2. Medication warnings:

   • Avoid phenytoin and carbamazepine as they can paradoxically worsen cortical myoclonus 1
   • Avoid valproate in women of childbearing age due to risk of fetal malformations 1
   • Opiates can induce or worsen myoclonus 1, 4

3. Refractory cases:

   • Consider deep brain stimulation targeting the globus pallidus pars-interna bilaterally when pharmacological treatments have failed 1

4. Acute management:

   • For status myoclonus (continuous jerking >30 minutes), aggressive treatment is required as it has high specificity (99.8-100%) for poor neurological outcome when occurring within 72 hours post-cardiac arrest 1
   • Propofol can be used for suppression in intensive care settings 1

5. Underlying causes: Always investigate and treat underlying causes, such as:

   • Epilepsy syndromes (especially juvenile myoclonic epilepsy) 3, 5
   • Post-anoxic brain injury 1, 4
   • Metabolic disorders
   • Infectious causes (e.g., neurotoxoplasmosis, even in immunocompetent patients) 6

Monitoring and Follow-up

• Continuous EEG should be considered in patients with diagnosed status epilepticus 1
• Regular follow-up to assess treatment efficacy and side effects
• Adjust medication doses as needed, often requiring higher doses than standard anticonvulsant therapy

The prognosis for myoclonus varies significantly based on the underlying cause. For conditions like Lance-Adams syndrome, 85% of patients show improvement over time, with approximately 77% achieving symptomatic control at a median of 70 days 1.