Differentials
Non-epileptic (dissociative) seizures
SIGNS / SYMPTOMS
Non-epileptic (dissociative) seizures are a common cause of prolonged convulsions and can be confused with status epilepticus.[21]
Key features that may help to distinguish from convulsive status epilepticus include long (>5 minutes) duration of individual seizures, fluctuating course (waxing and waning), asynchronous rhythmic movements, pelvic thrusting, side-to-side head/body movements during a convulsion, closed eyes, ictal crying, and later recall of items during the seizure.[16]
INVESTIGATIONS
The only method to differentiate epileptic from non-epileptic seizures is video-EEG. Video-EEG recording of a non-epileptic event will show no epileptiform activity.
Delirium
SIGNS / SYMPTOMS
This acute state of cognitive and perceptual decline can mimic non-convulsive status epilepticus. In its broader definition, it may include all states of altered awareness or confusion that are commonly referred to as encephalopathy.
Encephalopathy may be secondary to metabolic, toxic, or infectious causes.
INVESTIGATIONS
Distinction between non-convulsive status epilepticus and encephalopathy may be a challenging task, even for a well-trained epileptologist. EEG patterns are often confusing, especially in the case of metabolic encephalopathies such as hepatic or renal.
Laboratory findings such as high liver aminotransferases or ammonia in conjunction with clinical and EEG judgement may help in reaching the correct diagnosis.
Performing EEGs on patients with acute mental changes is strongly recommended.
Coma
SIGNS / SYMPTOMS
Defined as a state of absent cognitive and motor responsiveness.
Non-convulsive status epilepticus can be mistakenly diagnosed as coma.[31] The distinction is crucial, because coma is usually irreversible, whereas non-convulsive status epilepticus is often treatable.
INVESTIGATIONS
EEG may be very helpful in distinguishing coma from non-convulsive status epilepticus. However, certain periodic EEG patterns can be difficult to differentiate from ictal patterns. Such EEG patterns are commonly seen in hepatic or post-anoxic coma.
Performing EEGs on all patients with a presumed diagnosis of coma is highly recommended.
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