Pathophysiology of seizures and epilepsy

Postictal phase (2)

Confusion, fatigue, headache, muscle aches, excessive salivation Patients gradually regain consciousness

Convulsive Status epilepticus (2)

Constitutes the majority of cases of status epilepticus Characterized by prolonged convulsions without regaining consciousness

Epilepsy Complications Long Term (2)

Difficulty learning Permanent brain damage

EEG of absence seizure

Generalized, symmetric, 3-Hz spike-and-wave discharge (SWD) that begins and ends suddenly; normal background activity

Manifestations of seizures (5)

Manifestations: depend on the location of the seizure activity Motor cortex → Motor convulsions Sensory cortex → Abnormal sensations Temporal cortex → Emotional disturbances It can also involve alteration in the level of arousal

Nonconvulsive Status epilepticus (3)

Marked by nonconvulsive seizure Characterized by coma, confusion, somnolence.. Largely underdiagnosed

Classification of epileptic seizures Simple Psychological

Memory or emotional disturbances

Unclassified seizures Neonatal seizures (4)

Most common: hypoxia-ischemia during delivery Infections (meningitis) Intracranial hemorrhage (premature infants) Hypoglycemia (Diabetic mother)

Classification of epileptic seizures Tonic

Muscle stiffness, rigidity

Simple partial Seizure (4)

No impairment of consciousness Symptoms depending on the site of seizure activity - Motor: repetitive flexion/exetension of upper limp, smacking lips - Sensory: flashing lights, localized numbness or tingling of the skin - Autonomic: flushing, sweating, piloerection

Epilepsy vs. Seizure (2)

Not everything that looks like a seizure is a seizure and not every seizure is related to epilepsy A person with epilepsy is prone to having repeated seizures, but someone who has just one seizure may not have epilepsy.

Epileptogenic focus (2)

is an aggregate of neurons within the brain that are hyperexcitable and remain in a state of partial depolarization This means that the membrane potential can reach the threshold easily and fire an action potential by stimuli

Status epilepticus (5)

seizure lasting longer than 15 minutes or recurrent seizures without period of consciousness in between Involves serious systemic effects: cardiorespiratory dysfunction, hyperthermia , metabolic dysfunction. Can lead to irreversible neuronal injury Mortality rate is very high (~20%), especially if treatment is not initiated quickly Status epilepticus is always a medical emergency and must be treated immediately (based on the evidence that 5 minutes is sufficient to damage neurons and that seizures are unlikely to self-terminate by that time)

Epilepsy Occurrence (3)

Around 50 million people worldwide have epilepsy In the USA: - Prevalence: ~1% (2.5 million) - Incidence: 125,000-180,000 new cases per year - Total annual epilepsy-associated costs: $12.5 billion Epilepsy is more commonly seen in children and older adults but can occur at any age

Classification of epileptic seizures Complex

Automatisms such as lip smacking, chewing, fidgeting, walking and other repetitive, involuntary but coordinated movements

Unclassified seizures Infantile spasms (3-12 months) (3)

Caused by organic brain dysfunction Associated with mental retardation Difficult to treat

Evaluation of seizure (3)

Electroencephalography (EEG) refers to the recording of the brain's spontaneous electrical activity over a short period of time, usually 20-40 minutes, as recorded from multiple electrodes placed on the scalp EEG taken during a seizure-free interval is normal in almost half of the cases Activating procedures are usually performed to provoke abnormalities (hyperventilation, sleep, sleep deprivation)

Epilepsy Causes

Idiopathic : No known cause (70% of the cases) Symptomatic : Identifiable cause (30% of the cases) Cerebral edema CNS infections Brain injury Intracranial hemorrhage Brain tumor Stroke Metabolic disturbances Drug abuse

Absence seizure (petit mal) (5)

Impairment of consciousnes Symptoms (very brief 10-30 sec) - Staring, upward rotation of the eye, lip smacking (confused with daydreaming) Occur predominantly in children Can be precipitated by hyperventilation Anterograde anmesia (but no confusion after episode)

Complex partial seizure (4)

Impairment of consciousness Symptoms - Involuntary repetitive movements (automatisms) such as chewing, lip smacking, swallowing, "picking" movements of the hand - In some cases more complex behaviors such as a display of emotion , shouting Confusion and anterograde amnesia following the seizure

Myoclonic seizure (3)

Impairment of consciousness Symptoms - Sudden jerking in the muscles, often those in the extremities Usually coexist with other forms of generalized seizure disorder

Epilepsy Complications Short Term (3)

Injury from falls, bumps, or self-inflicted bites during a seizure Injury from having a seizure while driving or operating machinery Inhaling fluid into the lungs, which can cause aspiration pneumonia

Clonic phase

Jerking motions of the limbs and the face (clonic muscle contractions ), increase in salivation.

Classification of epileptic seizures Simple Motor

Jerking, muscle rigidity, spasms, head-turning

Classification of epileptic seizures Atonic

Loss of muscle tone

Non-epileptic seizures can be caused by a number of conditions (6)

Low blood sugar Fainting Heart disease Stress or anxiety Stroke Drug and alcohol withdrawal

MRI and CT (2)

Magnetic resonance imaging (MRI) and computed tomography (CT) are medical imaging techniques used in radiology to determine the existence of structural or functional abnormalities MRI provides much greater contrast between the different soft tissues of the body than computed tomography (CT) does

Status epilepticus Causes (8)

Only 25% of people who experience status epilepticus have epilepsy Stroke Hemorrhage Intoxicants, adverse reactions to drugs, consumption of alcohol Drug overdose or abrupt withdrawal Brain infection (meningitis) Brain tumors Traumatic brain injury

Classification of epileptic seizures (2)

Partial (focused) - Specific region of the brain Generalized - Diffuse regions of the brain

Partial seizure with secondary generalization (2)

Partial seizures can spread to involve both cerebral hemispheres, and produce a generalized seizure, usually of clonic-tonic type Often difficult to distinguish these from a primarily generalized clonic-tonic seizure

Epilepsy Diagnosis (8)

Patient history (head trauma, infection, drugs or substance abuse) Physical examination (injury, tongue bite) An eyewitness account Blood tests (Plasma glucose, serum prolactin, electrolytes) lumbar puncture (meningitis, encephalitis) Toxicology screening in blood and urine (Drug abuse, overdose) Electroencephalography (EEG) : brain electrical activity Brain imaging with MRI or CT scan

Cellular mechanisms of seizure generation (3)

Seizure is generated due to imbalance between the excitatory and inhibitory neurotransmission Too much excitation - Ionic-inward Na+, Ca++ currents - Neurotransmitter: glutamate, aspartate Too little inhibition - Ionic-inward CI-, outward K+ currents - Neurotransmitter: GABA

Pathophysiology of seizure

Seizure results from a paroxysmal high-voltage electrical discharge of susceptible neurons within an epileptogenic focus.

Refractory Status Epilepticus

Seizures lasting longer than 2 hours (or 2 or more seizures/hour) despite treatment

Partial (focused) (2)

Simple partial - No impairment of consciousness Complex partial - Impairment of consciousness

Partial Seizures (3)

Simple partial seizures Complex partial seizures Partial seizures with secondary generalization

Treatment of epilepsy (5)

Single seizure: May or may not treat depending on likelihood of recurrence Epilepsy: - Antiepileptic drugs - Surgery - Vagus nerve stimulation - Ketogenic diet

Classification of epileptic seizures Myoclonic

Sporadic (isolated), jerking movements

Classification of epileptic seizures Absence

Staring, upward rotation of the eye, lip smacking

Atonic seizures (drop seizures) (5)

Sudden loss of postural muscle tone and impaired consciousness (1 to 15 sec) Can occur while standing, walking or sitting, and are often noticeable by a head drop Risk of serious injury (hitting the face or head) No postictal confusion Usually seen in children

Tonic phase (4)

Sudden stiffness of the body (tonic muscle contraction) ; contraction of the jaw muscles (biting of the tongue can occur) Epileptic cry Respiration impaired (cyanosis) Increased sympathetic tone (HR↑, BP ↑, pupils dilate, incontinence)

Classification of epileptic seizures Partial seizure with secondary generalization

Symptoms that are initially associated with a preservation of consciousness that then evolves into a loss of consciousness and convulsions

Tonic-clonic seizures (grand mal)

The most common type of generalized epilepsy Often begins without warning (no aura) Three phases - Tonic phase (10-20 sec) - Clonic phase (~2 min) - Postictal phase (minutes to hours)

Generalized seizures (5)

Tonic-clonic (grand mal) Absence (petit mal) Myoclonic Atonic Tonic

Classification of epileptic seizures Tonic-Clonic

Unconsciousness, convulsions, muscle rigidity Repetitive, jerking movements

Classification of epileptic seizures Simple Sensory

Unusual sensations affecting either the vision, hearing, smell taste or touch

Aura (3)

Vague prodromal symptoms experienced in the hours leading up to the seizure It often manifests as the perception of a strange light, an unpleasant smell or confusing thoughts or experiences. Some people experience aura without a subsequent seizure Epileptic seizure can occur with or without aura

Epilepsy

a condition in which a person has recurrent seizures due to a chronic, underlying process

Seizure

an abnormal, excessive , disorderly discharge from neuronal aggregate in the CNS resulting in a brief disruption of brain electrical function

Convulsion

is a medical condition where body muscles contract and relax rapidly and repeatedly

Generalized (5)

subdivided according to the effect on the body (consciousness always lost or impaired) Absence Myoclonic Tonic Tonic-clonic Atonic