myoclonic seizure

Introduction

See also myoclonus.

Classification

• considered generalized seizure involving the entire body

Etiology

• hypoxia
• lipid storage disease
• encephalitis
• Creutzfeldt-Jakob disease
• metabolic encephalopathy due to:
  • respiratory failure
  • chronic renal failure
  • hepatic failure
  • electrolyte imbalance
• occasionally normal action
• associated with sleep deprivation, alcohol use, visual stimuli & stress

Epidemiology

• most common adult generalized epilepsy
• onset in teenagers & young adults

Clinical manifestations

• sudden, brief, irregular involuntary contractions of the limbs, trunk or facial muscles
  • duration may be very short (1 second)
  • described as twitches, spasms, jerks or shakes
  • suddenly dropping an item is a common symptom
• may occur more often upon awakening
• generally no loss of consciousness

Diagnostic procedures

• electroencephalography (EEG) after a period of sleep

Differential diagnosis

• myoclonus is a twitch of a single muscle group that may or may not be due to seizure activity
  • myoclonus of sleep is normal as is the EEG

Management

• agents of choice
  • valproate (Depakote)
  • baclofen
  • clonazepam
• Alternative agents
  • phenobarbital
• patients with juvenile myoclonic epilepsy require lifelong anticonvulsant therapy

* lamotrigine may worsen myoclonic seizures

More general terms

• primary generalized seizure
• myoclonus