Anti-Epileptic Drugs Flashcards
True or False, seizure disorders is the most common spontaneous neurological disorder in dogs
True; can occur in any breed (some predisposition) and at any age
What are 4 causes of extracranial (non-CNS) seizure disorders?
- electrolyte imbalance (dec gluc/Ca2+/Mg2+, incr K)
- liver dz
- renal failure?
- drugs/toxins
Two causes of CNS seizure disorders are:
accounts for 90% incidences
- structural brain dz - 45% (tumor, infxn, head trauma)
- idiopathic/genetic epilepsy - 45%
Describe idiopathic epileptic disorder
CNS disorder that manifests as an episode of i_nappropriate intermittent high neuronal activity_
- abnormal discharges originate in > 1 foci and spread into normal tissue
- can manifest as motor, autonomic, sensory, and/or psychic changes
- Normal between episodes
- usually a life-long disorder, may/may not progress
Define seizure
- a clinical manifestation of excessive and/or hypersynchronous neuronal discharges in the brain
- present clinically as episodic impairment or loss of consciousness, that is accompanied by:
- abnormal motor phenomena (convulsive)
- psychic or sensory disturbances (flashes of light)
- ANS signs (SLUD, vomiting)
What 3 things can cause a seizure?
- organic disorders - tumors, intracranial masses, head trauma
- chemicals, drugs, or toxins
- idiopathic
Define convulsion
motor manifestation of seizures that involves involuntary contraction-relaxation of body muscles
Define epilepsy
two or more seizures at least 24 hours apart, resulting from a nontoxic/nonmetabolic cause
Define cluster seizures
a potentially life-threatening condition where there is >1 seizure in a 24 hour period or other regular pattern
Define status epilepticus
a life-threatening condition with continous seizure activity lasting 5 minutes or longer
Describe the 5 phases of the status epilepticus cycle
- Prodromal phase: period preceding onset of seizure often accompanied by characteristic behaviors (hiding, restlessness)
- Aura: sensation of seizure onset + autonomic/other signs (SLUD/vomiting)
- Ictus: the actual seizure event
- Postictal Phase: behavioral pattern that follows the seizure (restlessness, lethargy, polyphagia)
- Inter-Ictal Phase: period b/t seizures, may appear normal
Define anti-epileptic agent
- a group of diverse drugs that reduce symptoms (seizures/convulsions) but DO NOT CORRECT the underlying disorder
- typically life-long tx
- agents can become ineffective
What are the two mechanisms by which anti-epilectics work?
- suppress initiation of neuronal firing in epileptiform foci
- inhibit spread of seizure activity into normal tissues
What are the side effects of anti-epileptics?
- high percentage of animals are refractory to AEDs (25-50%)
- fairly high incidence of side effects
- substantial tolerance to some agents
- loss of clinical efficacy over time
What is the condition that must be met to consider an AED effective?
if > 50% reduction in number of seizures during a given time
