From the Guidelines
Treatment of post anoxic myoclonus and seizures should begin with antiepileptic medications, with levetiracetam (Keppra) at 500-1000 mg twice daily being the first-line option due to its efficacy and favorable side effect profile, as supported by the most recent guidelines 1.
Key Considerations
- Post anoxic myoclonus and seizures occur after brain injury due to oxygen deprivation, typically following cardiac arrest.
- Myoclonus is a particularly common clinical manifestation of hypoxic-ischemic brain injury, identified in approximately 20% of cardiac arrest survivors.
- EEG monitoring is crucial during the acute phase to detect subclinical seizures and distinguish among different types of myoclonus.
Treatment Options
- For myoclonus specifically, clonazepam (0.5-2 mg three times daily) or valproate (starting at 500 mg twice daily, titrating up to 1500-2000 mg/day) are effective options.
- In refractory cases, a combination therapy may be necessary, potentially adding zonisamide (100-400 mg daily) or piracetam (8-24 g daily in divided doses).
- Sedation with propofol or midazolam may be necessary for status epilepticus.
Prognosis and Management
- Prognosis varies significantly, with early myoclonic status epilepticus generally indicating poor neurological outcomes, while Lance-Adams syndrome (action myoclonus) has a better prognosis.
- Treatment should be initiated promptly while addressing the underlying cause and maintaining adequate cerebral perfusion, oxygenation, and normothermia.
- Regular reassessment of medication efficacy and side effects is essential for optimal management, as supported by recent studies 1.
From the Research
Post-Anoxic Myoclonus and Seizures
- Post-anoxic myoclonus, also known as Lance-Adams syndrome, is a condition that may develop following hypoxic brain injury and is resistant to pharmacological therapy 2.
- The condition is characterized by severe, completely incapacitating myoclonic jerks that do not respond to treatment with commonly used agents such as valproate and clonazepam alone or in combination 2.
- Levetiracetam has been shown to be a promising agent in improving functional level and overall quality of life of patients with post-anoxic myoclonus, with studies demonstrating a clear abatement of myoclonus without unwanted side-effects 2, 3.
Treatment and Prognosis
- Levetiracetam has been found to have antimyoclonic properties, with studies suggesting that it may be effective in treating post-anoxic myoclonus at lower doses than other agents such as piracetam 3.
- The prognosis for patients with postanoxic myoclonus status epilepticus is generally poor, with most patients dying or remaining in a persistent vegetative state 4, 5.
- Early onset of myoclonic seizures after anoxia has been identified as a poor prognostic factor, with delay in recovery of neurological function also associated with a worse prognosis 5.
Levetiracetam Efficacy
- Levetiracetam has been shown to be effective in treating epileptic negative myoclonus, with a dramatic effect observed in a patient with severe epileptic negative myoclonus 6.
- The antimyoclonic effect of levetiracetam has been found to be maintained over a period of years, with long-term follow-up necessary to confirm efficacy 6.