Seizures: Forming the differential diagnoses list (Proceedings)

Diagnosis of seizures

Clients frequently use the term "seizure" to describe many different episodic events. The most common episodic events to rule out are listed in Table 1.

Table 1. Types of episodes

A good history includes analysis of the events leading up to the "episode", what occurred, and the nature and duration of the post-ictal abnormalities. Often it is easier to understand what a client is describing by having them mimic the behavior. "Shaking" can sometimes denote shivering, tremors, or normal REM sleep behavior. The duration of the ictal component of the seizure is frequently greatly overestimated by the client, who may include prodromal and post-ictal signs in the duration. To help determine the nature of the event the following list of questions will help.

Making a list of differential diagnoses of seizures is most aided by the age at time of onset, signalment, history, physical exam, and neurologic exam. Animals with idiopathic epilepsy will not have interictal deficits. However, some dogs with intracranial disease may have seizures as the initial clinical sign. Presence of neurological deficits indicates an underlying cause for the seizure other than primary generalized epilepsy. Using age ranges, the most common causes of seizures can be determined. Not all causes within an age range will be applicable to every case. Thus, using signalment, history, physical exam and neurologic exam will help narrow down the list of possibilities. Within age groups, the diseases can be divided into categories by the DAMNIT-V system. Examples are not complete, but give a guideline of more common diseases.

0-1 years

1-4 years

>5 years