Seizure definition
- Abnormal electrical activity in the brain
- Too much excitation vs too little inhibition
- Paroxysmal event
Where are seizures generated?
- From the cortex
- Specifically from layers 3 and 5 of the pyramidal cells
What questions do you need to get with regards to history of seizures?
- Description of episode (don’t assume it’s a seizure until you get a description)
- Time of occurrence (most common when the patient is sleeping)
- Description of patient before and after the episode
What are the four components of a seizure?
- Prodrome
- Aura
- Ictus
- Post ictus
What is the prodrome?
- Period of time before a seizure
How long can prodrome last?
- A few days
Signs of prodrome
- Changes in behavior
- Attention seeking
- Hiding
- Fearful
What is an aura?
- Period of time immediately preceding a seizure
What is ictus?
- The seizure itself
What can happen during ictus?
- Loss of consciousness and recumbency
- Tonic
- Clonic
- Autonomic discharges –> urination and defecation
What is tonic?
- Extensor rigidity
What is clonic?
- Flexion
How long can the post-ictal period last?
- Minutes to days
Characteristics of post-ictal period?
- Blindness
- Pacing
- Hunger/thirst
- Sleepy
- Ataxic
What are the types of seizures?
- Generalized
- Partial (simple vs complex)
- Behavioral/psychomotor
- Atypical
Generalized seizures
- Loss of consciousness
- Recumbent
- Tonic (muscle rigidity)
- Clonic (contraction and relaxation of muscles)
- Autonomic discharges (urination, salivation, defecation)
- Must cross the corpus callosum
How long do generalized seizures last?
- 1-1.5 minutes
- Feels like it lasts forever, but it doesn’t
Behavioral/psychomotor seizures
- They would spaz out on their limbs depending on the surface
Simple partial seizure
- Clinical manifestation is localized to one body region
- Mentally appropriate
Partial complex seizure
- Altered mental status
- Clinical manifestation localized to one body region
- In general, no loss of consciousness
Psychomotor seizure signs
- Fly biting, tail biting
- Difficult to discern from behavior issue
Paroxysmal episodes (NOT SEIZURES!)
- vestibular disease
- Narcolepsy/cataplexy
- Syncope
- REM disorders
- Pain (cervical)
- Movement disorders
Epilepsy definition
- 2 or more unprovoked epileptic seizures separated by 24 hours or more
- CHRONIC condition
Causes of epilepsy in veterinary patients
- many different causes
- Structural
- Genetic/idiopathic (are they teh same?)
- Reactive seizures (not epilepsy)
Questions to ask to determine which epilepsy does the patient have?
- Is the episode a seizure?
- What is the patient signalment?
- Age of onset?
- Is the patient normal between episodes?
- Are there inter-ictal deficits
Structural epilepsy
- Physical abnormality in the brain
- e.g. hydrocephalus
Causes of structural epilepsy
- Tumors
- Inflammatory conditions (immune mediated vs infectious)
- Anomalous –> hydrocephalus
- Trauma
- CVA (strokes)
Intracranial structural diseases (as well as what age they tend to occur)
- Neoplasia (>7 years of age)
- CVA (older patients)
- Anomalous (younglings)
- Inflammatory - MUO (Young to middle aged toy breeds)
- Trauma (based on hx)
What is one of the hallmark features of structural epilepsy?
- INTERICTAL DEFICITS
- e.g. 3 seizures once a month but pacing and change in bheavior
- e.g. neuro deficits post-seizures lasting more than 7 days
- Typically lateralizing*
What are the causes of reactive seizures?
- Extra-cranial
Examples of causes of reactive seizures
- Portosystemic shunts or liver dysfunction**
- Hypoglycemia**
- Toxins - ethylene glycol, metaldehyde, etc.
- Typically symmetrical deficits if present
What age do genetic seizures tend to occur?
- Ages 1-5 years
Inter-ictal period in genetic seizures?
- Normal inter-ictal period
How to diagnose genetic seizures (i.e. idiopathic epilepsy)?
- Need MRI/CSF for diagnosis
- Diagnosis of exclusion ultimately
Which breeds are predisposed to genetic epilepsy?
- Golden Retrievers
- Labradors
- Belgian Shepherds
- Legato Romagnolo
- Border Collies
- Australian Shepherds
- Boerboels
Diagnostic workup for the patient with seizures
- Thorough physical/neurological examination
- CBC/Chem/UA
- Bile acids test (pre + post) +/- NH4
- +/- 3 view thoracic radiographs
- Brain MRI +/- CSF analysis
- +/- EEG (Gold standard in people)
What’s the difference between a seizure and epilepsy?
- Seizure = abnormal electrical activity in the brain
- Epilepsy = at least 2 unprovoked epileptic seizures separated by 24 hours
Cluster seizure definition
- 2 or more seizures in a 24 hour period
Status epilepticus
- Seizure lasting >5 minutes
- Incomplete recovery between seizures
When to institute therapy for seizures?
- > 1 seizure per 6 months
- Structural disease present (e.g. brain tumor)
- Cluster seizures
- Status epilepticus
Goals of epilepsy therapy
- Decrease severity of seizures
- Decrease number of seizures
- Ideally 1 seizure every 2-6 months
RARELY DO WE COMPLETELY ELIMINATE!