In honor of Valentine's day this past weekend, I thought we might discuss when the heart tries to act like the brain...known as syncope vs. seizures.
Seizures and syncope are both described as a temporary loss of consciousness. Clinical signs of seizures often include collapse, some form of somatic movement, and a display of autonomic activation (e.g. urination, defecation, salivation, pupillary dilation) but these signs can be subtle in some patients. Clinical signs of syncope may also include collapse with occasional loss of bladder or bowel function. However, the pathophysiology, differential diagnoses, diagnostic testing and treatment plans are markedly different therefore differentiation between seizures and syncope is critical! What are my top 5 ways to differentiate between seizures and syncope?
Autonomic signs: Loss of bladder control has been reported with syncope and is a common finding with seizures. Other autonomic changes such as loss of bowel function, salivation, lacrimation and dilation of pupils have not been reported with syncope and are regularly reported with seizure disorders.
Post ictal phase: blindness, disorientation and at times, aggression can be seen for minutes to hours following a seizure. Animals with syncope may appear momentarily disoriented but typically they are back to normal within seconds of a return to consciousness.
Timing of the event – It is more common for seizures to occur when the pet is at rest, and syncope to occur when the pet is in motion or accelerating. We know this doesn't apply 100% of the time but can be a very helpful to ask what the pet was doing immediately before it collapsed.
Evidence of metabolic disease: Evidence of metabolic diseases known to cause seizures such as hypoglycemia, hypocalcemia or hepatic failure concurrently identified in a patient with a history of acute collapsing episodes should lead the clinician to consider a seizure disorder. Without a doubt, patients with metabolic diseases can also have concurrent metabolic derangement however I will use this as a tool when trying to sort between seizures and syncope.
Neurologic examination abnormalities. This one is obvious. If the pet has neurologic abnormalities that localize to the prosencephalon (forebrain) it is reasonable to consider this lesion localization over syncope. You could turn this upside down and say that if the pet has evidence of a cardiac arrhythmia or cardiac disease, syncope may be considered more likely. I have seen several patients that have been unfortunate enough to have BOTH syncope and seizures but, thankfully, that is rare.
I hope this helps you differentiate between seizures and syncope. Let me know if you have any other ways to differentiate between seizures and syncope in your practice.
Thanks for reading and stay warm, my friends! Remember, if you're working with a dog or cat with neurologic disease, I'm an email or telephone call away! Better yet, schedule a consult and we can work through the case side-by-side.