Epilepsy Phys and Pharm Flashcards
What is a seizure?
- occasional, sudden, excessive and rapid discharge of gray matter
- Usually consistent with “postive symptoms” of the gray matter involved
- Ie - visual hallucinations if visual cortex involved
When do negative symptoms from a seizure come into play?
- Following a seizure the patient will experience negative symptoms, or in other words, a loss of function in the areas of brain involved.
- This is the postictal period.
In general, what are the two reasons for the postictal period exhibiting negative symptoms?
The first, neuronal exhaustion; and the second, inhibitory inputs to that area.
What does epilepsy even mean?
The term epilepsy implies chronicity and is generally used to indicate a tendency for recurrent seizures because of an underlying brain abnormality. The incidence of epilepsy is 0.7% which is approximately the same as insulin dependent diabetes.
What are the key elements in the history with a patient’s concern for seizures/epilepsy?
The key elements in the history include: what happened before the seizure (was there any warning)?, what occurred during the spell and what happened afterward? The timeline is also important.
How are seizures classified?
The modern classification of seizures is based upon how seizures begin
*This classification scheme has major implications regarding etiology, treatment and prognosis. The major and most important differentiation is between partial seizures and generalized seizures.
What is a partial seizure? Does that have anything to do with grand mal seizures?
A partial seizure begins in one area of the cortex. It may remain localized or spread to varying degrees including the whole cortex causing a classic grand mal seizure.
- An analogy I often give patients is that a focal seizure is like a fire which begins in one room of a building and can spread to an entire wing or even further to involve the entire building.
- History of the focal onset is not always present for several reasons; it may begin as a “silent area” of the brain, evolution in to a convulsion may occur too rapidly, and the patient may be amnesic for the focal symptom.
What are absence seizures?
In this subgroup are the absence seizures, which involve widespread areas of the cortex but probably not all layers of neurons.
*Many textbooks give the misconception that absence seizures are associated with total unawareness. In reality there are varying degrees of absence seizures, with varying amounts of cognitive impairment during these episodes
Are absence seizures only seen in children?
Another common fallacy is that absences are almost exclusively seen in children. They certainly are more common in the pediatric population, but I would estimate that approximately 10% of the patients that come to the adult Seizure Clinic at University Hospital have primary generalized epilepsy and absences.
Syncope and near syncope are on the differential for epilepsy. What are the 4 major groups of syncope causes?
A. Circulatory
- Inadequate vasoconstrictor mechanisms
- Hypovolemia
- Reduced venous return to heart
- Reduced cardiac output (either mechanical in nature or arrhythmic in nature)
- Altered States of Blood (from hypoxia or anemia or hypoglycemia)
Besides syncope or near syncope, which itself has a pretty broad differential, what else is on your mind during an interview for epilepsy concern?
II. Movement Disorders (Especially myoclonus and paroxysmal dyskinesia III. Fasciculation IV. Stroke/TA V. Migraine VI. Sleep Disorders *Psychogenic/Behavioral factors as well
What are the psychogenic/behavioral factors that may cause epilepsy-type symptoms?
A. Daydreaming B. Hyperventilation syndrome C. Hysterical fainting D. Psychogenic seizures E. Panic attacks
What is the difference between the terms seizure, convulsion and epilepsy?
- Seizure - excessive neuronal discharge characterized as brief, involuntary and episodic
- Convulsion - violent involuntary contraction of voluntary muscles
- Epilepsy - Chronic seizure disorder
What is the consequence of a seizure disorder that goes untreated?
- If severe, the oxygen demand and metabolic demand of the brain drastically increases
- If that area of the brain is worked too hard it will be hypoxic
- The hypoxia will alter the microenvironment of that region of grey matter and pre-dispose for more seizures
- Thus, seizures beget seizures
We were given what 4 general mechanisms for seizure disorder predilections?
• Abnormal voltage gated channel
○ Leads to focal epileptogenesis
• Abnormal ligand gated channels
○ Can decrease inhibition or increase excitation, thus leading to synchronization AND even focal epileptogenesis
• Alterations in extracellular ionic environment
○ These can lead to either propagation or syncrhonization
• Recruitment of normal neurons via anatomical circuits
○ These can lead to either propagation or syncrhonization
What are the steps of seizure progression?
- Focal epileptogenesis
- Synchronization
- propagation
What are the common non-primary causes for epilepsy?
• Mechanical causes (trauma or brain tumor) • Metabolic ○ Hypoxia ○ Hypoglycemia ○ Hypocalcemia ○ alkalosis • Withdrawal symptoms in CNS ○ Depressant drugs ○ toxins
What are the two different kinds of generalized seizure?
• Tonic-clonic and absence (grand mal vs. peri-mal)
• Tonic-clinic
○ 30% and effective drugs are ID’d with the maximal electroshock seizure test (MES)
○ EEG shows high amplitude spikes, 15-40 cycles/sec
○ Loss of postural control, LOC,
○ tonic phase - rigid extension of trunk and limbs)
○ Clonic phase - rhythmic contraction of arms and legs
○ Abnormal behavior, confusion continues even after myoclonus
○ Mechanism - initiation occurs locally with loss og GABA inhibitory tone and propagation is due to degreased GABA tone or increased response to glutamate or just Na channel problems
• Absence - 10%
○ Effective drugs ID’d with pentylenetetrazol (PTZ) test.
○ Usually begins in childhood stops before 20yrs, but not necessarily
○ EEG shows 3 cycles per second
○ Normal muscle tone, impaired consciousness with staring spells
§ With or without eye blinks
○ Function normal after seizure
○ Mechanism - related to oscillatory stimulation of the thalamic-cortical circuitry and inappropriate activation of low-threshold T-type calcium channels
what’s going on in an absence seizure?
• Absence - 10%
○ Effective drugs ID’d with pentylenetetrazol (PTZ) test.
○ Usually begins in childhood stops before 20yrs, but not necessarily
○ EEG shows 3 cycles per second
○ Normal muscle tone, impaired consciousness with staring spells
§ With or without eye blinks
○ Function normal after seizure
○ Mechanism - related to oscillatory stimulation of the thalamic-cortical circuitry and inappropriate activation of low-threshold T-type calcium channels
What’s going on in a tonic-clonic seizure?
• Tonic-clinic
○ 30% and effective drugs are ID’d with the maximal electroshock seizure test (MES)
○ EEG shows high amplitude spikes, 15-40 cycles/sec
○ Loss of postural control, LOC,
○ tonic phase - rigid extension of trunk and limbs)
○ Clonic phase - rhythmic contraction of arms and legs
○ Abnormal behavior, confusion continues even after myoclonus
○ Mechanism - initiation occurs locally with loss og GABA inhibitory tone and propagation is due to degreased GABA tone or increased response to glutamate or just Na channel problems
What are partial seizures?
• Begin focally and don’t spread to the entire cortex
• Simple partial - 10%
○ Key feature is preservation of consciousness
○ Usually of cortical origin in restricted region
○ Jacksonian motor seizures reflect topographic organization of cortex
• Complex partial
○ Loss of or impaired consciousness
○ Psychomotor - involves limbic and temporal/frontal cortex
§ Emotions come into play
• Secondary generalized
• Mechanism - initiation! (rather than propagation) thus more difficult to treat
What are the three first line drugs for primary generalized tonic-clonic seizures?
• Valproate OR • Lamotrigine OR • Levetiracetam OR ○ Alternatives ○ Carbamazepine ○ Topiramate ○ Zonisamide ○ Oxcarbazepine ○ Phenytoin
