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1280 Seizures: Characteristics and Differentiation Seizures, Refractory or Poorly Controlled

Seizures: Characteristics and Differentiation
VetBooks.ir Seizures, Differentiation From Other Events

Narcolepsy/
Seizure (Grand Mal) Seizure (Partial) Syncope Episodic Weakness Cataplexy
Precipitating Usually none; can occur during rest Usually none Exertion, pain, micturition, Exertion or none Excitement, feeding
event defecation, cough, stressful
event
Prodrome Minutes to days; atypical behavior Seconds; acute weakness, None (disorder is None
(e.g., anxious, more withdrawn, staggering, vocalization, neuromuscular)
attention-seeking) ± vomiting autonomic stimulation
Aura None Marks onset of None None None
partial seizure
Event features Chomping, hypersalivation, tonic- Localized signs Motionlessness; flaccid or Gradual or sudden loss Instantaneous loss of
clonic limb motion; duration often rigid extension of limbs; of muscle tone, causing muscle tone; animal is
1-2 minutes but duration >5 minutes opisthotonos possible; recumbency; mentation immobile (sleeping) but
is consistent with seizure and highly no tonic-clonic activity; and consciousness remain appears to be aware of
inconsistent with syncope duration generally transient normal; no tonic-clonic its surroundings.
(<1 minute) activity
Recovery Slowness returning to consciousness; Varies Rapid recovery of normal Highly variable; generally Fairly rapid (several
disorientation (commonly 10 minutes mentation; often able to reflective of course of onset seconds to 1 minute),
or longer); blindness, circling, and walk (and considered back (gradual onset associated with appearance of
other signs of central nervous system to normal by owner) within with slow recovery); in some waking from sleep
dysfunction common minutes cases, rapid-onset disorders
may have a protracted course

Convulsive syncope (anoxic or anoxic-epileptic seizures) are syncopal events generally caused by cardiac arrhythmias that produce profound syncope, temporary cerebral hypoxia, and seizures. Therefore,
clarification of the type of event observed by the owner (syncope versus seizure) may be difficult and generally rests on the observation of an episode, the presence of heart disease, and the documentation
of a severe bradycardia or tachycardia during the event. Videotaping of an episode by the owner and cardiac event monitoring (pager-size portable electrocardiographic [ECG] unit that is triggered by the
owner when an event occurs) can be invaluable in clarifying whether an animal is experiencing seizures versus syncope.
Modified from Ettinger SJ, Feldman EC: Textbook of veterinary internal medicine, ed 6, St. Louis, 2005, Saunders, p 27.

Seizures, Refractory or Poorly Controlled

Factors Responsible for Inadequate Control of Seizures
Medication and Dosage Other Precipitating Factors
Improper choice of drug Additional medications
Insufficient drug dosage Additional diseases
Delayed increase in dosage Physical or psychological stress
Inadequate increase in dosage Diagnostic Failures
Too rapid change of medication Extracerebral causes of seizures
Too rapid reduction of dosage Progressive brain lesions
Excessive fluctuations in serum concentrations Misidentification of episodes
Inappropriately combined drugs Syncope
Failure to monitor serum levels Myasthenia gravis
Noncompliance Narcolepsy/cataplexy
Drug-drug interactions
Modified with permission from Kirk RW, Bonagura JD, editors: Kirk’s Current veterinary therapy XI: small animal practice, St. Louis, 1993, Saunders, p 986.

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