- common chronic neurological disorder that is characterized by recurrent (two or more) seizures unprovoked by any immediately identifiable cause. - these seizures are transient signs and/or symptoms due to abnormal, excessive or synchronous neuronal activity in the brain.
Classified in 5 ways:
By their first cause (or etiology).
By the observable manifestations of the seizures, known as semiology.
By the location in the brain where the seizures originate.
As a part of discrete, identifiable medical syndromes.
By the event that triggers the seizures, as in primary reading epilepsy.
In 60-70% of patients, no specific cause for their seizures can be identified. Epilepsy in these patients is referred to as being idiopathic (i.e., no definite cause).
B. Infants/children: congenital malformations, perinatal injuries or hypoxia, developmental neurologic disorders, metabolic defects, injury, and infection are common causes of seizures.
C. Young Adults: head trauma, brain tumors, infection, and arteriovenous malformations are common causes of seizures.
D. Elderly: cerebrovascular disease, CNS degenerative diseases, and brain tumors are common causes.
E. Genetic - risk increased 2-3 times in individuals with first degree relative with epilepsy.
DIAGNOSIS A. Steps in Diagnosis of Epilepsy 1. Confirm Patient Has Epilepsy
Other conditions to consider in differential: pseudoseizures, syncope, breath holding spells, narcolepsy, hemiplegic migraines, drug toxicity, transient ischemia attack.
b. Following factors delineate epilepsy from above: abrupt onset, genuine loss of consciousness (if not simple partial), brief duration, rapid recovery, stereotypic episodes.
c. Pseudoseizures (seizures occurring on a psychogenic basis, "hysterical seizures") present a common and difficult diagnostic problem, especially since many patients may have both pseudoseizures and epilepsy. Factors differentiating pseudoseizures from epilepsy include:
Precipitating factors with a strong emotional or psychological component
"Non-physiological" seizure patterns - violent thrashing or flailing of all 4 limbs, particularly when movements asynchronous; preservation of consciousness despite motor activity of arms and legs; rage and directed violence as ictal events; gradual build up and prolonged resolution of seizure; lack of tongue biting, incontinence and postictal confusion.
Events preceding seizure: What was happening before the seizure ? What time was it ? Does patient recognize onset of seizure by a smell, visual disturbance, sound or odd feeling ?
Events during the seizure: What are the initial events ? Is consciousness lost or altered ? What kind of body movements occurred ? How long did the seizure last ? Did the person urinate or bite his/her tongue ?
Events after the seizure (i.e., postictal period): Is the patient alert, drowsy, or confused ? Was there any numbness or weakness ?
An effort should also be made to identify any precipitating factors. Factors known to precipitate epilepsy in susceptible patients include: sleep deprivation, fever, emotional stress, lack of food, alcohol/drug withdrawal, pregnancy, menses, and various sensory stimuli (i.e., photosensitivity, television, reading, eating, music). Identification and avoidance, where possible, of these factors may assist in reducing the frequency of seizures.
2. Physical And Neurological Examination 3. Clinical Laboratory Data
a. Measurement of fluctuations in electrical activity within brain recorded from electrodes on scalp. Role: confirm presence of epilepsy, diagnosis of seizure type, long term prognosis.
b. EEG findings alone do not confirm or deny diagnosis of epilepsy. Important to correlate EEG findings to clinical events. c. Detection of abnormal EEG enhanced by use of multiple recordings and specific activating techniques. d. EEG patterns having clinical correlations
5. Neuroimaging Studies:
Magnetic resonance imaging (MRI) or computed tomography are useful in identifying structural lesions in brain. MRI appears more sensitive in detecting lesions in patients with epilepsy. Consider in patients > age 18, in children with partial seizures, and in presence of abnormal neurologic findings, or focal slow-wave abnormalities on EEG.
CLASSIFICATION OF EPILEPTIC SEIZURES Seizures are classified according to their clinical features and patterns seen on the EEG.
Epileptic seizures are divided into two broad categories:
a. GENERALIZED - initial onset indicates involvement of both sides of the brain
b. PARTIAL - initial onset indicates involvement of only a localized area of the brain
A. Partial Seizures - those seizures where initial onset arises from a localized area of brain. - caused by localized injury to brain and diagnostic evaluation for the presence of a focal lesion (i.e., tumor, vascular malformation, stroke, trauma, neurodegenerative disease) is required. - further subdivided based on whether consciousness is maintained (i.e., simple partial) or impaired (i.e., complex partial) - most common type experienced by adults
1. Simple Partial Seizures a. No loss of consciousness patient is alert and able to respond to questions or commands and afterwards remembers what happened during the seizure may precede complex partial or secondarily generalized seizures (referred to asAURA) b. Clinical manifestations of simple partial seizure usually relate to the particular area of brain involved, and thus a wide variety of symptoms are possible, including motor, sensory, autonomic, and psychic manifestations. For any given patient, symptoms will be same with each seizure. c. Motor seizures reflect involvement of the motor or supplementary motor cortex and cause a change in muscle activity may be restricted to one body part or spread to other muscles on same side or both sides (secondary generalization) of the body Most Common : Tonic Movements (neck stiffening, sustained deviation of eyes to one side) Clonic (Jerking) Movements
may experience a temporary numbness or weakness in the affected body part (Todd's paralysis)
h. Prognosis: good seizure control obtained in 30-50%
2. Complex Partial Seizures (Temporal Lobe, Psychomotor Epilepsy) a. Impairment of consciousness observed b. Associated with initial aura aura is a simple partial seizure which may then progress to a complex partial (and/or generalized tonic-clonic) seizure c. Simple to complex automatisms (repetitive motor activity that is purposeless, undirected, and inappropriate)
d. Average duration 1 to 3 minutes e. Postictal phase - confusion, lethargy, altered behavior, amnesic for event f. Prognosis: good seizure control in 40-60% g. Most common seizure type seen in adult, account for up to 60% of adult epilepsies
3. Partial Seizures Secondarily Generalized - partial seizure may progress through several stages reflecting spread of discharge to different brain areas - seizure may begin as simple partial (i.e., aura), progress to complex partial and subsequently become secondarily generalized (tonic-clonic)
B. Generalized Seizures
-those seizures where first clinical changes indicate initial involvement of both hemispheres. The initial clinical event is a loss of consciousness. Various types of generalized seizures differentiated by absence or presence of specific motor activity.
b. Although onset may occur at any age, most commonly occurs during second decade of life. c. Average duration 2 to 5 minutes. d. Postictally, patients lethargic/sleepy lasting several minutes to hours. e. Incontinence seen in early postictal phase in approx. 35% of patients. f. In patients with primary generalized tonic-clonic seizures, seizures seen most commonly on awakening and to a lesser extent in evening when relaxing. g. Prognosis: good seizure control in 70-85%.
2. Absence (Petit Mal)
a. Onset between 4 and 14 years and often resolve by age 18.
b. Clinical description - Brief episodes of staring with impairment of awareness and responsive that begin without warning and end suddenly, leaving patient alert and attentive. In simple absence seizures, patient only stares. In the more common complex absence seizures, staring is accompanied by simple automatic movements such as blinking of eyes, drooping of head, or chewing.
c. Duration - short (10-45 secs), patients usually unaware of occurrence.
e. Characteristic EEG pattern of 3 per second spike and waves; may be precipitated in large percent of patients by hyperventilation.
f. 25 to 50% of patients go on to develop generalized tonic-clonic (GTC) seizures.
g. Development and intelligence are usually normal and long term prognosis is good, particularly in patients who do not develop GTC.
h. Important in children to differentiate from complex partial seizures, since treatment and prognosis vary. In contrast to absence, complex partial seizures usually have a longer duration (minutes vs. seconds), are often preceded by aura, and typically have a brief period of postictal confusion. Also, the EEG pattern is markedly different between the two seizure types.
b. Clinical description - similar to typical absence except that loss of responsiveness during seizure is often less complete and more gradual in onset and cessation; Also clonic, tonic and atonic components (i.e., increase or decreases in muscle tone) are more pronounced than in typical absence. Commonly seen in patients with Lennox-Gaustaut syndrome in conjunction with myoclonic, atonic and tonic seizures.
c. EEG findings: slow spike and wave (< 2.5 Hz) discharge and/or incompletely generalized spike-waves
d. Not precipitated by hyperventilation
e. Often associated with mental retardation or structural CNS damage f. Prognosis: response to therapy and long term prognosis dependent on presence of underlying neurologic deficit and/or mental retardation. Good response seen only 20-30% of patients.
b. Clinical description- sudden and total loss of muscle tone and posture control that causes eyelids to drop, head to nod and patient to fall to ground - "drop attack"; not necessarily associated with loss of consciousness. Must wear helmet to protect from head injury. May or may not have postictal symptoms.
c. Average duration 10 to 60 seconds; brief, if any, postictal symptoms
d. Other seizure types common in patients with atonic seizures. May be observed in conjunction with myoclonic seizures and atypical absence (Lennox-Gaustaut Syndrome)
e. Prognosis to therapy dependent on presence of underlying neurological deficit and/or mental retardation
a. Sudden, brief shock-like jerk of a muscle or group of muscles, often occurs in healthy people as they fall asleep. Epileptic myoclonus usually causes synchronous and bilateral jerks of the neck, shoulders, upper arms, body, and upper legs.
b. Myoclonic seizures occur in a variety of epilepsy syndromes.
6. Tonic seizures
a. Characterized by sudden bilateral stiffening of the body, arms, or legs. Tonic seizures usually last less than 20 seconds and are more common during sleep.
b. Primarily seen in younger children; commonly associated with metabolic disorder or underlying neurological deficit
c. Frequently occur with other seizure types and in various epilepsy syndromes
d. Duration 10-60 seconds; brief, if any, postictal symptoms
A. Primary goal of drug therapy is the complete suppression of seizures in the absence of disabling side-effects. Prognosis of epilepsy has improved in last decade, and at present about 60-70% of newly diagnosed patients can be expected to achieve complete seizure control following institution of effective monotherapy (one drug).
B. When epilepsy cannot be controlled completely, the aim of treatment is to attain the best compromise between the desire to maximize seizure control and the need to keep side-effects within acceptable limits for the individual patient.
C. Therapy should maintain or restore the patient’s lifestyle and ability to lead an active life.
Drug therapy not indicated for seizures due to acute reversible medical problem
Therapy not necessary for certain benign epilepsies (febrile seizures, rolandic epilepsy)
Following first unprovoked seizure- while some benefit may occur by initiating therapy in high risk patients, present consensus is to delay therapy until patient experiences a second unprovoked seizure.