Seizures

Seizures

A seizure occurs due to a focal or generalized abnormal discharge of electrical activity in the brain.

Causes of seizures include:

• Metabolic and electrolyte disturbances

• Mass lesions

• Acute withdrawal from alcohol, benzodiazepines, barbiturates

• Intoxication with illicit drugs, lidocaine, metal poisoning, or carbon monoxide poisoning

• Increased intracranial pressure

• Infections

Seizures can be categorized into focal (with or without impairment in consciousness) or generalized.

Workup

The initial diagnostic evaluation of a first-time seizure in an adult is aimed at excluding metabolic (eg, hypoglycemia, electrolyte disturbances) and toxic (eg, amphetamine use, benzodiazepine/alcohol withdrawal) causes. Basic laboratory tests typically include serum electrolytes, glucose, calcium, magnesium, complete blood count, renal function tests, liver function tests, and a toxicology screen. In addition to laboratory screening, ECG should be obtained in patients with loss of consciousness to evaluate for possible underlying arrhythmia.

Once metabolic and toxic etiologies are excluded as the cause of seizure, most patients require neuroimaging (eg, brain MRI or CT scan) to evaluate for structural brain abnormalities (eg, tumor, stroke, mesial temporal sclerosis) that may serve as a seizure focus. Lumbar puncture can be considered after neuroimaging has ruled out a space-occupying lesion, but it is typically reserved for patients with suspected meningitis (eg, fever, headache, nuchal rigidity).

Generalized

Generalized seizures involve disruptions of electrical activity within the entire brain. Generalized seizures are characterized by a loss of consciousness. Generalized seizures include tonic-clonic (grand mal) seizure and absence seizure.

Absence

An absence seizure is a generalized seizure that typically occurs in school age children and is associated with impairment of consciousness but no loss of postural tone. Typically described as a blank stare and often misinterpreted as daydreaming.

Data suggests involvement of the frontal and somatosensory cortex followed by rapid spread to other regions of the cerebral cortex.

Can be triggered by hyperventilation.,

Children with absence seizures often have psychiatric comorbidities, most often ADHD and anxiety disorders.

Common electroencephalogram (EEG) findings in absence seizures include 3 Hz spike and wave discharges.

Children tend to grow out of their absence seizures as they get older.

Grand Mal

Tonic-clonic (Grand Mal) seizures are characterized by a sudden loss of consciousness and periods of tonic phases and clonic phases. Post-ictal confusion can last for several hours after the event.

In the tonic phase the patient becomes rigid with limb extension. This phase is often associated with apnea. The clonic phase is characterized by muscular jerking.

Tonic-clonic seizures can result in bowel or urinary incontinence and tongue biting.

The postictal period may involve headaches, confusion, sleepiness and Todd’s paralysis.

The electroencephalogram (EEG) finding seen in tonic clonic seizures includes 10-Hz activity during the tonic phase and slow waves during the clonic phase.

Seizure Diagnosis

• Diagnosis of seizures involves patient recollection, talking to witnesses, clinical manifestations and laboratory/ imaging workups.

• A laboratory workup of seizures includes electrolytes, BUN/ creatinine and medication levels.

• MRI/CT of the head is used to rule out any mass lesions or structural abnormalities that could cause a seizure. Do MRI/CT before EEG

• An electroencephalogram (EEG) done during a seizure event can capture the repetitive rhythmic activity. However, partial seizures may not have an abnormal EEG.

• If patient is febrile a lumbar puncture is indicated to rule out infection.

Treatment

Obeservation unless status.

Treatment of seizures typically includes antiepileptic drugs along with treating any underlying causes of the seizure, such as withdrawal, infections, or intoxication.

Antiepileptic drug therapy is reserved for patients with an underlying structural abnormality or an idiopathic seizure that presents with status epilepticus, focal neurologic defects, or abnormal EEG.

Antiepileptic drug choice is dependent on the type of seizure, side effects, mechanism of elimination and teratogenesis.

Valproate is the first line antiepileptic for generalized epilepsy, and lamotrigine is the first line for focal epilepsy.

Benzodiazepines, such as lorazepam, are first line treatments in status epilepticus. If there is no IV access midazolam IM may be used. Once controlled, fosphenytoin is recommended to decrease recurrence.

Ethosuximide is the first line antiepileptic in absence seizures.

Surgical resection may be an option for patients who have medication refractory seizures or anatomic lesion causing the seizures.

In vagus nerve stimulation therapy, a surgically implanted device sends electrical impulses along the vagus nerve to stimulate certain areas of the brain.

Partial Seizure

Focal (formerly partial) seizures begin in one part of the brain and produce symptoms associated with that area of the brain.

Focal seizures account for 70% of patients with epilepsy who are older than 18 years of age.

Symptoms

Focal seizures can be characterized based on the impairment of consciousness. When consciousness is maintained, the seizure is described as a focal seizure without impairment of consciousness. When consciousness is not maintained, the seizure is described as focal seizure with impaired consciousness.

In focal seizures with impaired consciousness (previously called complex partial seizures), the seizure remains localized to one area (often in the temporal lobe) of the brain and consciousness is altered.

Seizure activity may consist of repetitive movements like lip-smacking or chewing, known as automatisms, in addition to other jerking or nonsensical actions. Auditory, visual, or olfactory hallucinationsmay also be present.

Postictal confusion or disorientation may be present after the event.

Focal seizure without impairment of consciousness (previously called simple partial seizure) remain localized to one area of the cerebral cortex and there is no loss of consciousness.

Symptoms often include localized twitching or jerking in the body as well as sensory or autonomic disturbances.

Simple partial seizures may evolve into focal seizure with impaired consciousness.

Todd's

Todd’s paralysis is a focal weakness in a part of the body after a seizure, a phenomenon that may be seen after a focal seizure without impairment of consciousness or other types of seizures.

Status Epilepticus

Status epilepticus is a sustained unconsciousness with persistent convulsive activity in a seizing patient.

Status epilepticus is classified as a seizure lasting longer than 5 minutes or at least 2 seizures in which function is not regained between ictal events.

Most common causes of status epilepticus include:

• Withdrawal of anticonvulsants

• Alcohol withdrawal

• Trauma

• Seizure disorder

• Metabolic abnormalities

Patients with convulsive status epilepticus present with characteristic motor manifestations that vary according to the seizure type. Generalized convulsive status epilepticus always has impaired consciousness and bilateral tonic muscle stiffening, followed by rhythmic jerking of the limbs (clonus) that is usually symmetric.

Focal status epilepticus presentation depends on the location of the epileptogenic brain area. Focal motor status epilepticus may have progression of focal jerking activity of a limb usually without impaired consciousness.

Status epilepticus is a clinical diagnosis made based on the presentation of the patient and history of the current seizure. A detailed history and neurologic examination is important to determine the underlying cause of status epilepticus.

More subtle forms of status epilepticus may need an EEG to make the diagnosis.

Treatment of status epilepticus first revolves around maintaining airway, breathing and circulation (ABCs). Intravenous benzodiazepines are used to end current seizure activity while fosphenytoin is preferred prevent future seizures.

Seizure Syndromes

Status Epilepticus is a continuous unremitting seizure lasting longer than 5-10 minutes OR recurrent seizures without a return to normal baseline lasting for 30 minutes or more.

Treatment consists of airway stabilization (possibly requiring intubation), administration of IV benzodiazepine (lorazepam or diazepam) and loading dose of fosphenytoin, and phenobarbital (if seizures not controlled by prior measures).

Status epilepticus is a medical emergency.

EPC

A rare disorder in which continuous focal motor seizure activity is present (can be thought of as a FOCAL status epilepticus).,

Patients experiencing epilepsia partialis continua (EPC) may have focal myoclonus or Jacksonian march (spread of seizure on same side- from distal part of the limb to the face, a reflection of the spread of the electrical activity in the brain).

Symptoms may occur every few seconds or minutes and can last for an extensive duration (days to months, or even years in some cases).

EPC most commonly affects the hands, feet, or head.

Treatment of EPC may involve anti-seizure medications after first ruling out more serious underlying pathology such as a tumor or brain abscess.

Febrile

Febrile convulsions is a seizure associated with an increase in body temperature (fever), often associated with a viral illness (like an upper respiratory infection).

Febrile convulsions normally occur in children ages 6 months to 6 years.

Febrile convulsions are often a diagnosis of exclusion as serious conditions such as meningitis or encephalitis must be ruled out first.

Most patients with febrile convulsions do not require treatment (in some cases anti-seizure medications may be used) and will eventually grow out of the condition as they age.

Children experiencing a febrile seizure may exhibit twitching in their extremities, a loss of consciousness, and irregular breathing.

West syndrome

infantile spasms is a type of generalized seizure disorder that occurs in infants (usually within 6 months of age).,

Can be idiopathic or sequelae of other conditions.

Symptoms of West syndrome include recurrent jerks or spasms of body including head and extremities, mental retardation, delays in motor development.

EEG finding show hypsarrhythmia (abnormal interictal pattern showing chaotic and disorganized electrical activity in the brain).

Treatment consists of administration of ACTH (hormone), prednisone, anti-seizure medications.

This condition is difficult to treat; prognosis is highly variable and dependent on response to therapy as well as treatment of underlying conditions (if one is present).

Lennox-Gastaut

A type of epilepsy manifesting in childhood (usually around ages 2-6).,

Children with Lennox-Gastaut syndrome (LGS) experience frequent severe seizures of different seizure types.

Seizures often occur multiple times throughout the day lasting from seconds to minutes.

Children with LGS often have some degree of mental retardation, behavioral problems, as well as a loss in developmental milestones after the onset of seizure activity.

EEG finding is a slow spike and wave pattern.

LGS is difficult to treat and full seizure control is rarely achieved in patients with this condition. Treatment for LGS includes:

• Anti-seizure medications

• Vagus nerve stimulation therapy

• Ketogenic diet

• Rarely surgery