Epilepsy

Seizures A seizure is as a sudden, disorderly discharge of cerebral neurons. Seizures involve a transient alteration in brain function (motor, sensory, autonomic, or psychic clinical manifestations)

Definition A chronic neurologic disorder manifesting by repeated epileptic seizures (attacks or fits) which result from uncontrolled discharges of neurons within the central nervous system The clinical manifestations range from a major motor convulsion to a brief period of lack of awareness. The uncontrollable nature of the attacks is characteristic of epilepsy.

Epidemiology and course 5% of the population suffer a single sz at some time 0.5-1% of the population have recurrent sz = EPILEPSY 70% = well controlled with drugs (prolonged remissions) 30% epilepsy at least partially resistant to drug treatments

Types of Seizures Seizures can be classified as either partial or generalized The type of seizure as well as the signs and symptoms that accompany the seizure depend on the part of the brain in which the seizures occur

Types of Seizures - Partial Partial Seizures are seizures that begin locally (in one part of the brain) Simple Partial seizure (consciousness not impaired) Complex partial seizure (consciousness impaired) Secondary generalized seizure (begins as partial and transitions into a generalized seizure)

Types of Seizures - Generalized Generalized seizures are bilaterally symmetric; there is no local onset and although they involve the entire brain, physical control is rarely lost. Types of GS include: Absence seizures (petit mal)- staring, slight body movement and short periods of unawareness Myoclonic seizures- sudden jerks of arms and legs Atonic seizures (drop attacks)- suddenly collapse or fall down Tonic-clonic seizures (grand mal)- most severe type of seizure; characterized by loss of consciousness, body stiffening, shaking and sometimes tongue biting

Partial and Generalized Primary Generalized Seizure Partial Seizure Partial Seizure with Secondary Generalization

Etiology - Epilepsy Metabolic defects Congenital malformation Genetic predisposition Perinatal injury Postnatal trauma Myoclonic syndromes Infection Brain tumor Vascular disease Fever Drug and/or alcohol abuse

Pathogenesis A seizure occurs when a burst of electrical impulses in the brain escape their normal limits (past threshold). They spread to neighboring areas and create an uncontrolled storm of cortical nerve cell electrical activity. The electrical impulses can be transmitted to the muscles, causing twitches or convulsions.

Pathogenesis The 19th century neurologist Hughlings Jackson suggested “a sudden excessive disorderly discharge of cerebral neurons“ as the causation of epileptic seizures. Recent studies in animal models suggest a central role for the excitatory neurotransmiter glutamate and inhibitory gamma amino butyric acid (GABA) (decreased)

Normal CNS Function Excitation Inhibition glutamate, aspartate GABA

Hyperexcitability reflects both increased excitation and decreased inhibition glutamate, aspartate Inhibition GABA Excitation Modified from White, IGES, 2001

Diagnosis Diagnostic tests include: EEGs can be used to confirm diagnosis and determine type of seizure An MRI may be ordered if the initial medications pt. is on fail to control seizures or a CT scan if pt. is an older adult Plasma levels of electrolytes, glucose and calcium levels, renal function tests, liver function tests and even drug screening may be performed

Diagnosis If the pt. has already been diagnosed with epilepsy: anti-epileptic drug (AED) levels may be tested to ensure that the dosage levels are accurate An ECG can exclude cardiac cause of symptoms or seizure CSF may be tested for infection

Treatment Current treatment methods can control seizures for approximately 66% of people with epilepsy. Treatments include: Anti-epileptic drugs are the most common form of treatment Brain surgery is performed if seizures originate in a small, defined area in the temporal or frontal lobes, but is not common otherwise due to added risk of damaging vital brain functions

Diagnosis & Treatment cont. Vagus nerve stimulation- a vagus nerve stimulator is implanted into the chest beneath the collarbone, wraps around the vagus nerve and stimulates the brain to inhibit seizures Children (and some adults) who don’t respond to medicinal treatment have been prescribed a high-fat, high-protein and low carbohydrate diet to produce ketones, which allow the body to use fat instead of glucose for energy. The exact mechanism for why this works is unknown.

Epilepsy - Treatment The majority of pts respond to drug therapy (anticonvulsants). In intractable cases surgery may be necessary. The treatment target is seizure-freedom and improvement in quality of life! The commonest drugs used in clinical practice are: Carbamazepine, Sodium valproate, Lamotrigine (first line drugs) Levetiracetam, Topiramate, Pregabaline (second line drugs) Zonisamide, Eslicarbazepine, Retigabine (new AEDs) Basic rules for drug treatment: Drug treatment should be simple, preferably using one anticonvulsant (monotherapy). “Start low, increase slow“. Add-on therapy is necessary in some patients…

Witness Response When you see someone having a seizure you should: Loosen their clothing Move surrounded objects that the seizing individual could hurt him/herself on Stay until seizure ends to make sure the person is okay and can get up