A group of chronic neurologic disorders characterized by recurrent seizures, brought on by excessive excitability of neurons in the brain
Range from brief periods of unconsciousness to violent convulsions; May also experience problems with learning, memory, and mood, which can be just as troubling as their seizures
The incidence of epilepsy is highest in what population?
Very young and elderly
What percentage can be rendered seizure free with drugs?
General term that applies to all types of epileptic events
Limited meaning, applying only to abnormal motor phenomena; For example, the jerking movements that occur during a tonic-clonic (grand mal) attack
Although all convulsions may be called ____, it is not correct to call all seizures ____
Seizures, Convulsions; For example, absence seizures manifest as brief periods of unconsciousness, which may or may not be accompanied by involuntary movements.
Since not all epileptic seizures involve convulsions
Anti-epileptic drugs treat epilepsy rather than anti-convulsants
What are seizures initiated by?
Synchronous, high-frequency discharge from a group of hyper-excitable neurons called a focus
May result from several causes, including congenital defects, hypoxia at birth, head trauma, brain infection, stroke, cancer, and genetic disorders
Seizures are seen when discharge from a focus spreads to other brain areas, thereby
Recruiting normal neurons to discharge abnormally along with the focus
What does the overt manifestations of any particular seizure disorder depend on?
Location of the seizure focus and the neuronal connections to that focus (The connections to the focus determine the brain areas to which seizure activity can spread)
How does a partial or local seizure occur?
When seizure activity invades a very limited part of the brain
What happens if seizure activity spreads to a large portion of the brain?
A generalized seizure develops
An experimental procedure that may explain how a focal discharge is eventually able to generate a seizure
How is experimental kindling performed?
Implanting a small electrode into the brain of an animal
What is the electrode used for in kindling
To deliver localized stimuli for a brief interval once a day; When stimuli are first administered, no seizures result; After repeated once a day delivery, these stimuli eventually elicit a seizure; (Daily stimulations are continued long enough, spontaneous seizures will begin to occur)
An example of what kindling may refer to about seizure development in humans
May account for the delay that can take place between injury to the head and eventual development o seizures; May explain why the seizures associated with some forms of epilepsy become more frequent as time passes; May suggests that early treatment might prevent seizure disorders form becoming more severe over time
Manifest with discrete symptoms that are determined by the brain regions involved
What may the patient experience with simple partial seizures?
Discrete motor symptoms (e.g., twitching thumb), sensory symptoms (e.g., local numbness; auditory, visual, or olfactory hallucinations), autonomic symptoms (e.g., nausea, flushing, salivation, urinary incontinence), or psycho-illusory symptoms (e.g., feelings of unreality, fear, or depression)
Characteristics of simple partial seizures
No loss of consciousness, and persist for 20-60 seconds
Secondarily generalized seizure
Begin as simple or complex partial seizures, and then evolve into generalized tonic-clonic seizures
Characteristics of secondarily generalized seizure
No loss of consciousness, and last 1-2 minutes
At onset, patient becomes motionless and stares with a fixed gaze; Then is followed by a period of automatism (the performance of actions without conscious thought or intention), in which the patient performs repetitive, purposeless movements, such as lip smacking or hand wringing
Characteristics of complex seizure
Impaired consciousness and lack of responsiveness, last 1-2 minutes
Lennox-Gastaut syndrome (LGS)
Severe form of epilepsy that usually develops during the preschool years
Characteristics of Lennox-Gastaut syndrome (LGS)
Developmental delay and a mixture of partial and generalized seizures; Types include partial, atonic, tonic, generalized tonic-clonic, and atypical absence; In children, seizures can be very difficult to treat
Excitatory is greater than inhibitory activity in nerve cells and no matter how many medications cannot restore balance; no medications. Can end up with significant brain injury
Neuronal discharge spreads throughout both hemispheres of the cerebral cortex; Manifest as major convulsions
Tonic-clonic (grand mal) seizures often cause what?
Urination yet not defecation
Characteristics of tonic-clonic (grand mal) seizures
Major convulsions by a period of muscle rigidity (tonic phase) followed by synchronous muscle jerks (clonic phase); Convulsions may be preceded by a loud cry, caused by forceful expiration of air across the vocal cords; Are accompanied by marked impairment of consciousness and are followed by a period of CNS depression, referred to as the postictal state; and last 90 seconds or less
Abnormal condition occurring between the end of an epileptic seizure and return to baseline condition
Absence (petit mal) seizure
Occur primarily in children and usually cease during the early teen years
Characteristics of absence (petit mal) seizure
Loss of consciousness for a brief 10-30 seconds; Usually involve mild, symmetric motor activity (e.g., eye blinking) yet may occur with no motor activity at all; May experience hundreds of these a day
Occur mainly in children
Characteristics of atonic seizure
Sudden loss of muscle tone; If activity is limited to the muscles of the neck, “head drop” occurs; If muscles of the limbs and trunk are involved, a “drop attack” can occur, causing the patient to suddenly collapse
“Head drop” and Drop attack
Muscle “tone” is the muscle’s normal tension; Atonic means “without tone,” so in an atonic seizure, muscles suddenly lose strength; The eyelids may droop, the head may nod, and the person may drop things and often falls to the ground, hence
Occur in a variety of epilepsy syndromes that have different characteristics
Characteristics of myoclonic seizure
Individual usually awake and able to think clearly; Sudden muscle contractions (brief shock-like jerks of a muscle or group of muscles), and last for just 1 second; Activity may be limited to one limb (focal myoclonus) or it may involve the entire body (massive myoclonus)
Status epilepticus (SE)
Occur when seizures last too long or when occur close together, and the individual does not recover between seizures; Just like there are different types of seizures, there are also different types of this; For example, Generalized convulsive SE (life threatening), Absence SE, and Myoclonic SE
2 types of status epilepticus (SE)
Convulsive and Non-convulsive
Convulsive status epilepticus (SE)
Term used to describe the more common form of emergency situation that can occur with prolonged or repeated tonic-clonic (also called convulsive or grand mal) seizures
How does convulsive status epilepticus occur?
When the active part of a tonic-clonic seizure lasts 5 minutes or longer; When an individual goes into a second seizure without revovering consciousness from the first one, and if an individual is having repeated seizures for 30 minutes or longer; Requires emergency treatment
Treatment for convulsive status epilepticus
Urgent medical treatment; Oxygen and other support for breathing, intravenous fluids, and emergency medications; Continuous EEG monitoring may be needed to monitor seizures and response; Tests may be needed to find cause of seizure; Individuals with a known cause, such as a brain infection, brain tumor or stroke, may have a worse outlook than those with no other medical problems or known cause; At times, medicines called anesthetics are used in the hospital to put a person into a coma to stop seizures
Non-convulsive status epilepticus (SE)
Term used to describe long or repeated absence or complex partial seizures
Characteristics of non-convulsive status epilepticus (SE)
Individual may be confused or not fully aware of what is going on, yet they are not unconscious like in a tonic-clonic seizure; Symptoms are more subtle and hard to tell seizure symptoms from recovery period; No consistent time frame on when these seizures are called an emergency, as it depends in part on how long an individual’s typical seizures are and how often they occur
Treatment for non-convulsive status epilepticus (SE)
Emergency medical treatment in a hospital setting; EEG testing may be needed to confirm the diagnosis first; Individuals with this type of stuatus are also at risk for convulsive status epilepticus, thus quick treatment is required
Characteristics of status epilepticus (SE)
Defined as a seizure that persists for 30 minutes or longer
Generalized convulsive status epilepticus (SE)
Most common emergencies encountered in clinical practice; Range of seizure continuum extends from isolated seizure to repetitive seizures to status epilepticus; Life threatening; Occurs not only in individuals with epilepsy, yet also in the context of other neurological disorders and systemic illness; Prompt recognition and treatment are required to prevent associated complications
Neuronal damage in generalized convulsive status epilepticus (SE)
Is heavily dependent on the duration with the duration having a bearing on therapeutic interventions; The longer a seizure continues, the more refractory (resistant to a process or stimulus) to simple therapy it becomes, and refractory seizures carry a high risk of therapeutic complications
Medicine is not bringing seizures under control; Also known as uncontrolled, intractable, or drug-resistant epilepsy; Refers to both children and adults
Absence status epilepticus (SE)
Prolonged, generalized absence seizure that usually lasts for hours and can even last for days; The cardinal symptom is the altered state of consciousness, while the patient is usually fully alert and partially responsive
Typically manifest as generalized tonic-clonic convulsions of short duration; Children, who experience these seizures, are not at high risk of developing epilepsy later in life
Characteristics of febrile seizure
Fever-associated seizures common among children ages 6 months to 5 years
End diastolic volume that stretches the right or left ventricle of the heart to its greatest dimensions under variable physiologic demand
Represents the intrinsic ability of the heart muscle (cardiac muscle or myocardium) to contract. Changes in the ability to produce force during contraction result from incremental degrees of binding between myosin (thick) and actin (thin) filaments
Described as the pressure that the chambers of the heart must generate in order to eject blood out of the heart and thus is a consequence of the aortic pressure (for the left ventricle) and pulmonic pressure or pulmonary artery pressure (for the right ventricle). The pressure in the ventricles must be greater than the systemic and pulmonary pressure to open the aortic and pulmonic valves, respectively
As afterload increases
Cardiac output decreases
Systemic hypertension increases the left ventricular (LV) afterload due to
The LV must work harder to eject blood into the aorta. This is because the aortic valve will not open until the pressure generated in the left ventricle is higher than the elevated blood pressure in the aorta
Pulmonary hypertension is increased blood pressure within the right heart leading to the lungs, and it indicates
A regionally applied increase in afterload dedicated to the right side of the heart, divided and isolated from the left heart by the intraventricular cardiac septum
Due to the increased afterload, the ventricle has to work harder to accomplish its goal of
Ejecting blood into the aorta. Thus in the long-term, the increased afterload (due to the stenosis) will result in hypertrophy of the left ventricle to account for the increased work required
Aortic insufficiency (Aortic Regurgitation) increases afterload due to
A percentage of the blood that is ejected forward regurgitates back through the diseased aortic valve
Mitral insufficiency (Mitral Regurgitation) decreases afterload due to
In ventricular systole under MR, regurgitant blood flows backwards/retrograde back and forth through a diseased and leaking mitral valve. The remaining blood loaded into the LV is then optimally ejected out through the aortic valve. With an extra pathway for blood flow through the mitral valve, the left ventricle does not have to work as hard to eject its blood (i.e., there is a decreased afterload). Afterload is largely dependent upon aortic pressure
The basic equation for cardiac output is heart rate X stroke volume?
What do capillaries do in the body?
The sites for exchange of fluid, oxygen, carbon dioxide, nutrients, hormones and wastes
What are the functions of the circulatory system?
Remove carbon dioxide and metabolic waste, help fight infection, and delivery of O2, nutrients, hormones, electrolytes
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