epilepsy

Introduction

A tendency towards recurrent seizures.

Defined as >= 2 unprovoked seizures > 24 hours apart or

1 unprovoked seizure with a risk of further seizures of >= 60%

Classification

Epilepsy syndromes:

• benign childhood epilepsy
• juvenile myoclonic epilepsy
• idiopathic generalized epilepsy
• focal epilepsy, epilepsia partialis continuans
• temporal lobe epilepsy (most common syndrome in adults)
• post-traumatic epilepsy
• febrile seizures

* International League Against Epilepsy has updated its system for classifying epilepsies

• focal is now used instead of partial
• focal seizures are now classified by awareness
• the terms dyscognitive, simple partial, complex partial, psychic, & secondarily generalized are no longer used

Etiology

• inherited syndromes
• congenital brain malformations
  • focal cortical dysplasia
• infection
• head trauma (most common cause in children)*
• brain tumors
• stroke (most common in elderly)
• neurodegenerative disease, dementia
• risk factors for late-life epilepsy
  • hypertension
  • diabetes mellitus
    • highest risk: black patients with diabetes
  • smoking
  • apoE4 allele
• reduced risk associated with
  • physical activity is a negative risk factor
  • moderate alcohol consumption is a negative risk factor

* no mention of febrile seizures

Epidemiology

• cumulative lifetime incidence in U.S. is 3%
• 44% of patients with epilepsy report seizures under control

Clinical manifestations

• risk of recurrent seizures is > 60%

Diagnostic criteria

• diagnosis of epilepsy requires 2 or more unprovoked seizures 24 hours apart, or
• one unprovoked seizure plus >= 60% likelihood of additional seizure(s) within 10 years (a single seizure 1 month after a stroke), or
• presence of an epilepsy syndrome

* resolution of epilepsy may be considered if

• a patient has outgrown an age-dependent epilepsy syndrome
• 10 years without a seizure & off anticonvulsants for 5 years

Laboratory

• avoid routine drug levels in patients with epilepsy
• see ARUP consult

Diagnostic procedures

• electroencephalogram (EEG)
  • do not routinely order EEG as initial part of syncope workup
  • negative results do not exclude epilepsy
    • electroencephalography is 40-50% sensitive in diagnosing epilepsy
• video EEG monitoring should be considered
  • patients not responding to 2 or more anticonvulsants
  • seizures requiring further characterization
    • gold standard for classifying type of epilepsy

Radiology

• magnetic resonance imaging
  • negative results do not exclude epilepsy
• do not routinely obtain neuroimaging after an acute seizure in a patient with established epilepsy

Complications

• major depression
• bipolar disorder
• cognitive impairment
• increased risk of bone fractures
• increased risk of sudden, unexplained death
  • 11 year mortality ~ 0.9%
    • up to 1% with intractable seizures, multiple anticonvulsants
  • 3-fold risk of unnatural mortality
  • 5-fold risk of unintentional medication overdose
    • opioid & psychotropic major implicated drugs
    • anticonvulsants not implicated in overdoses
• increased risk of major cardiovascular events (RR=1.6)

• disease interaction(s) of ADHD with epilepsy & febrile seizures
• disease interaction(s) of epilepsy with cardiovascular events

Management

• see specific form of seizure
• anticonvulsant therapy
  • avoid valproic acid in women of child-bearing age
  • levetiracetam or lamotrigine*
    • anticonvulsants of choice in women of child-bearing age
    • discovery of pregnancy is not reason enough to stop anticonvulsant
      • uncontrolled seizure can result in fetal anoxia & death
    • no significant interactions with hormonal contraceptives
    • dosage reduction in patients with renal failure
  • levetiracetam, lamotrigine & gabapentin are anticonvulsants of choice in older patients
  • do not prescribe long-term anticonvulsant therapy to patients with withdrawal seizures
• patients who do not respond to combination of 2 anticonvulsants are considered refractory
• patients with refractory epilepsy should be referred to an epilepsy center for evaluation
• avoid drugs the lower seizure threshold
  • among antibiotics Zosyn with lower risk of triggering seizures than levofloxacin, cefepime, imipenem
• medical marijuana may improve seizure control & quality of life in refractory epilepsy
  • high out-of-pocket costs & inconvenient access cited as reasons for discontinuation
• behavioral interventions can reduce seizures in patients with refractory epilepsy
  • muscle relaxation with diaphragmatic breathing (29%)
  • control focused-attention activity with extremity movements (25%)
• neurosurgery to remove epileptic focus for patients with refractory focal seizures
  • laser ablation when location of seizure activity can be pinpointed is FDA-approved but not approved by Aetna

* avoid valproic acid, phenobarbital, phenytoin, topiramate, carbamazepine in pregnant women & women of child-bearing age

More general terms

• seizure; epileptic seizure
• chronic neurologic disease

More specific terms

• Amish infantile epilepsy syndrome
• benign familial infantile convulsions
• benign familial neonatal epilepsy
• childhood absence epilepsy
• epilepsy during pregnancy
• epilepsy female-restricted with mental retardation (convulsive disorder & mental retardation)
• epilepsy X-linked with variable learning disabilities & behavior disorders (XELBD)
• epileptic encephalopathy early infantile type 2; atypical CDKL5-related Rett syndrome
• focal epilepsy
• generalized epilepsy & paroxysmal dyskinesia
• generalized epilepsy with febrile seizures (GEFS)
• idiopathic generalized epilepsy
• infantile epileptic encephalopathy
• intractable childhood epilepsy with generalized tonic-clonic seizures (ICEGTC)
• myoclonic epilepsy
• myoclonic epilepsy with ragged-red fibers (MERRF) syndrome
• nocturnal epilepsy
• pyridoxine-dependent epilepsy; neonatal epileptic encephalopathy; pyridoxine-5'-phosphate oxidase deficiency; PNPO deficiency
• status epilepticus

Additional terms

• hormonal effects on epilepsy

Patient information

epilepsy patient information