Seizures Diagnosis and Management

Nisha Kanani, David Cherney

2004

Resources

• Primary Care: Epilepsy. Browne T. R., Holmes G. L. NEJM; 344:1145-1151, Apr 12, 2001.

• Current Concepts: Patients with refractory seizures. Devinsky O. NEJM; 340: 1565-1570, May 20, 1999

• Consensus statements: Medical management of epilepsy. Neurology; 51(5 suppl4): S39-43, Nov 01 1998

• Textbook of clinical neurology. Greenberg• Canadian Driving Guidelines Online

Objectives

1. First seizure evaluation in adults2. Seizure classification 3. Management options

Case

• 32 y/o male taxi-driver is referred for evaluation of a “spell” while walking to the corner store, after which he was found on the ground.

• Brought in by EMS to the ER • Subsequently sent home• What are you going to do and tell

the patient?

Definitions

• Seizure: transient disturbance in cerebral function caused by abnormal neuronal discharge

• Epilepsy: group of disorders represented by recurrent seizures (3% lifetime prevalence)

Evaluating seizures:

1) Is this a seizure?

2) What type of seizure is this? (implications on treatment)

3) Is there an underlying cause?

Is this a Seizure? Seizure Mimics:1) Classic migraines• include transient neurologic symptoms (as in partial seizures).• epilepsy patients twice as likely to have migraines.

2) Syncope• Postural, flaccid paralysis, pre-syncope symptoms, no post-ictal

state• May have fasiculations (convulsive syncope)

3) TIA• Usually no LOC unless basilar stroke, usually negative findings not

positive. Sometimes confusing if post-ictal Todd’s paralysis

4) Pseudo-seizures• 10-45% of patients with refractory epilepsy. Look for history of

abuse. Patients can have both.5) Movement disorders

•

                

Is there an underlying cause?

(rule out secondary causes of seizures)

1o neurologic disorder Systemic disorder

•Head trauma

•Cancer

•Hemorrage

•Stroke

•Vascular malformations

•Meningitis/encephalitis

•Hypoglycemia

•Hyponatremia

•Hypocalcemia

•Uremia

•Hepatic encephalopathy

•Drug OD/withdrawal

•Hyperosmolar states

•Hyperthermia

History

• Witness testimony is key!• Triggers, ictal behaviors, LOC,

behaviour during seizure and the postictal state.

• Seizure precipitants or triggers: – strong emotions, intense exercise, flashing

lights, and loud music (often immediately before the seizure)

– fever, menstruation, lack of sleep, and stress

History

Ask about . . .Drugs, alcohol, constitutional symptoms,

HIV risk factors, fever, head trauma.

Family History (absence and myoclonic seizures may be inherited)

Physical examination• Generally unrevealing • Look for signs of disorders associated with

seizures.• Head trauma, meningismus, sinus infection. • Focal or diffuse neurological abnormalities.• Mental status abnormalities suggest lesions in

the anterior frontal, parietal, or temporal lobes.

• Evaluate for lateralizing abnormalities: weakness, hyperreflexia, positive Babinski sign

Laboratory evaluation

• Glucose, calcium, magnesium, hematology studies, renal function tests, lytes toxicology screens.

• Acute postictal changes: metabolic acidosis and leukocytosis, high CK

• LP if risk factors for infection (fever, HIV positive).

Electroencephalography• Information provided:

• Presence of abnormal electrical activity• Information of type of seizure disorder• Location of seizure focus

• Perform study >48hrs after seizure• Include recordings during sleep, photic

stimulation, hyperventilation.• 50% of patients with epilepsy have

normal single EEG

Electroencephalography

• If normal and high suspicion, repeat study after sleep deprivation

• 10% of persons with true seizure with have normal multiple EEG studies

• +EEG likelihood of second seizure over two years

Neuroimaging in adults with 1st seizure

• Retrospective review of 148 patients studied within 30 days of the seizure

• Structural lesion was identified by CT in 55 (37 percent); 16 (11 percent) had metabolic seizures

• CT findings agreed with the results of neurological examination in 82 percent of cases.

Ramirez-Lassepas, et al. Value of computed tomographic scan in the evaluation of adult patients after their first seizure. Ann Neurol 1984; 15:536.

Neuroimaging

• All patients should receive neuroimaging.

• MRI preferred over CT to identify

small lesions such as cortical dysplasias, infarcts, or tumors.

• CT scan is suitable in emergency situations to exclude a mass lesion, hemorrhage, or large stroke.

When to initiate Antiepileptic drug

therapy

1) Two or more seizures2) Single seizure secondary to identified CNS

lesion with an epileptogenic focus3) Consider if significant occupational risk if

patient suffers a second event.4) Consider if single seizure event with one or

more risk factors for recurrent seizures5) Consider in the elderly patient with increased

risk of seizure related morbidity (age, prolonged post-ictal state)

Risk of seizure recurrence in a patient with an apparently

unprovoked or idiopathic seizure

• 31 to 71% risk in the first 12 months after the initial seizure.

• Risk factors associated with recurrent seizures include the following:

• (1) evidence of a structural lesion • (2) EEG abnormalities • (3) partial type seizure • (4) family history of seizures • (5) focal abnormalities on exam

• Most patients with one or more of these risk factors should be treated

Antiepileptic Drugs of Choice

First-Line

Alternatives

Primary Generalized Tonic-Clonic

Valproic acidCarbamezepinePhenytoin

LamotriginePrimidonePhenobarbital

Partial

CarbamazepinePhenytoin

GabapentinTopiramateTiagabinePrimidonePhenobarbital

Absence

EthosuximideValproate

LamotrigineClonazepam

Atypical Absence, Myoclonic, Atonic

Valproic acid

LamotrigineTopiramateClonazepamFelbamate

Principles of Treatment• Start with an average dose of a first line drug• Poor control? Address compliance, maximize drug

dose, confirm right diagnosis (partial complex v.s generalized)

• Majority of patients are controlled with single antiepileptic drug.

• This drug can be gradually withdrawn if seizure free for two years.

• Seizures recur in 25% of patients without risk factors and 50% of patients without risk factors.

• The drug can be reduced by 25% every two to four weeks.

Principles of Treatment

• 20-35% of patients with epilepsy have persistent seizures despite medical therapy.

• If poor control with maximal dose, monotherapy with second drug.

• Continue to administer first drug until a full dose of second drug reached, then gradually withdraw first drug.

• If monotherapy with two drugs fail, patient may need re-evaluation (repeat MRI/EEG) before polytherapy commenced (1998 guidelines).

Side effects

• Idiosyncratic toxicity: – rash, bone marrow suppression, or

hepatotoxicity.

• Require laboratory tests (e.g., complete blood count and liver function tests)– baseline – during initial dosing and titration

Other management issues:

• Impact on independence, self-esteem, employment.

Driving regulations:• Private drivers cannot drive for 3 months

after a single seizure.• Private drivers can resume driving after being

seizure free for 12 months on medication.

Side effectsCanadian Guidelines

Neurologic Consultation (NEJM 2001)

• Change in the type of seizure

• Uncertain diagnosis (e.g. normal EEG)

• Lack of seizure control in 3 months

• Failure of two monotherapies

• Patient is considering pregnancy

• Prolonged post-ictal state

• History of status epilepticus

Summary

• Management after 1st seizure involves lots of discussion with patient about risks/benefits

• Remember impact on driving: tell the ministry!

• When in doubt about management (especially medications), get a neurologist involved