There are many different types of seizures. Most people recognize a particular type of seizure from what they have experience or observed in mainstream media such as TV and the movies. These are usually Generalized seizures and used to be called Grand mal which means “great sickness”. They are commonly referred to as “fits” or “convulsions”. There are many other types of seizures. The sophistication in seizure distinction is much greater in human medicine but in veterinary medicine we can apply many of the descriptive terms used for humans for our pets. We commonly try to distinguish between Generalized seizures, focal seizures and in those that do not fit a particular category, we call unknown seizures.
Generalized: Formerly Grand mal (video)
- Tonic/Clonic: A sequence consisting of a tonic (muscle contraction or stiffening) followed by a clonic (repeated jerking) phase.
- Tonic: sustained increase in muscle contraction (stiffening), lasting a few seconds to minutes. Extensor or flexor rigidity.
- Clonic: repeated jerking or myoclonus, which is regularly, repetitive involving the same muscle groups usually prolonged at a frequency of 2–3 cycles/second.
- Absence: Recognized as a brief (usually less than 20 sec.) generalized seizure with impaired consciousness and specific EEG changes characterized by spike-and-slow-wave complexes, which are bilaterally represented in the cerebral hemispheres.
- Typical: For a video example, go to: http://www.chihuahuaclubofamerica.com/idiopathic-epilepsy/epileptic-seizures-in-chihuahuas
- Atypical: More pronounced changes in tone. An onset or cessation that is not as abrupt and has EEG changes that dissimilar.
- Absence with special features: Typically has features of rapid, involuntary, disorganized contractions of individual muscle groups (myoclonia) and in humans may involve myoclonia of the eyelids with sensitivity to light.
- Atonic: sudden loss or weakness of muscle tone without an apparent preceding myoclonic or tonic event lasting ≥ 1-2 seconds involving head, trunk or limb musculature.
- Myoclonic: Myoclonus (sudden brief, single or multiple contraction(s) of muscle(s) or muscle groups). Can be of variable areas (i.e. body, or limb).
- Myoclonic (regular and repetitive jerking)
- Myoclonic atonic (regular and repetitive jerking, followed by a sudden loss of muscle strength and a fall - atonic)
- Myoclonic tonic (regular and repetitive jerking, followed by a sudden increase of muscle tone - stiffening)
Focal: Formerly Petit mal (video)
- With cognition: implies an “awareness” of surroundings
- Typically, responsive to verbal cues but may have an “affective” state described as panicked, fearful or anxious.
- With dyscognition: implies an “unawareness” of surroundings
- Typically, “unresponsive” to verbal cues
- There is insufficient evidence to characterize as Generalized, focal, or both.
Not Seizures (video)
- Often a repetitive or involuntary movement may look like a seizure.
- Neck pain
- Cataplexy or Narcolepsy (excessive sleepiness or "sleep attacks")
- Myasthenia gravis (exercise induced weakness)