Approximate
risk of seizure
in different situations |
General population
 | Lifetime risk of having a seizure: 10% |
| Epilepsy at some point: 3-4% |
| Epilepsy at any given time: 0.5-1% |
| Acute reactive seizure: 3-4% |
| Single unprovoked seizure: 1% |
| Active epilepsy in age group over 55: 0.9% |
|
Acute Stroke
| Lobar hemorrhage: 23% |
| Subarachnoid hemorrhage: 26% |
| Ischemic stroke: 6%, may be higher in embolic strokes |
|
Prior stroke
| 9% probability over 10 years |
| Early postinfarction seizure(within 2 weeks): risk of recurrent seizure
32% |
|
Brain tumor
| Brain tumor: 30% has seizure as initial symptom |
| Slow growing tumor tends to present with seizures |
| More aggressive tumor usually presents with mass effect |
| Brain mestastasis: 18% presents with seizures |
|
Infection
| Bacterial meningitis: about 25% have seizures, abscess and encephalitis
higher |
| Herpes encephalitis: 50% have seizures |
| Late seizures:
 | Aseptic meningits: risk not increased |
| Bacterial meningitis: risk is 5X of population |
| Viral encephalitis: risk is 10X of population |
|
|
Head injury
| Mild closed head injury: 0.4% |
| Moderate injury (depressed skull fracture or LOC <24 hour: 2.4%, late
seizures 2% |
| Severe head injury (with intracranial mass or LOC > 24 hr: 10.3%, 12%
chance of late seizures. Increase to 36% with presence of early seizure. |
| Penetrating injury: 30-50% risk of late seizures |
|
Metabolic
| Dialysis encephalopathy: 50% have seizures |
|
Alzheimer's disease
| 16% has seizures |
|
Multiple sclerosis
| 4% has seizures |
|
Neuroleptics
| Neuroleptic at therapeutic dose: seizure risk 1.2%
| Higher dose (1g/day of Chlorpromazine): ?9% |
| Thioridazine (Mellaril) ? least epileptogenic |
|
| Clozapine:
| High dose (>600 mg/day): 4.4% |
| Low dose (<300 mg/day): 1.0% |
| rapid upward dosage titration increased the risk of
seizures. |
|
|
Antidepressant
| Tricyclics at therapeutic dose: 0.3-0.6%
| Tricyclics overdose: 8.4% have seizues |
|
| Buproprion at usual dose:
| at higher dose: increased risk, especially if patient has risk factors of
seizure |
|
|
Other medications
| Imipenem may increase chance of seizure
| at high dose, or dose not adjusted according to kidney function |
| or given with theophylline & cyclosporine |
|
| Aminophylline: in chronic treatment, level >30, may cause seizures,
especially in patients with underlying neuro disease. May be refractory to anticonvulsant.
|
| Meperidine: 3% in certain population
| related to the metabolite normeperidine, which has a half-life of 15 to
30 hours and accumulates faster in the setting of
 | renal insufficiency |
| repeated dose |
| hepatic enzyme inducing drugs |
|
|
| Flumazenil
may precipitate seizure especially if
| patient has overdose of tricyclics |
| using benzodiazepine for epilepsy |
| Avoid Flumazenil use in patient who is on tricyclic antidepressants,
cocaine, lithium, methylxanthines, isoniazid, propoxyphene, monoamine oxidase inhibitors,
buproprion HCl or cyclosporine |
|
| Cyclosporine:
| Seizures have been reported in transplant
recipients who were given cyclosporine but whose magnesium concentrations were normal. |
|
|
Alcohol
| Dose dependent |
| 50-100g/day (50g = 3.5 beer or 3 glasses of wine): risk for new seizures
3X of population |
| 300g/day (1.5 pints of 40% ): 20X of population |
|
| Further reading
|
