Neurology
Summary
The diagnostic testing for seizure involves a range of tests which aim to gather objective data related to a patient's seizure activity. An initial fingerstick to assess blood glucose levels is essential to rule out hypoglycemia while an EKG can help rule out long QT syndrome and arrhythmia. In addition, WBC, lactic acid, and CPK levels might be elevated following a seizure, though these levels can also indicate an infection and are thus non-specific. In terms of blood work, a complete blood count, complete metabolic panel, urinalysis, alcohol, toxicology screen, and relevant anti-epileptic drug levels should all be ordered and considered.
Medical imaging becomes critical for patients with first-time seizures or with recurrent seizures that present concerning symptoms such as a change in seizure pattern. A CT scan is the initial imaging test to identify any potential structural causes. However, an MRI is often ordered following the CT scan as it is more sensitive in detecting subtle pathology, and particular attention must be paid to the hippocampus to rule out signs of hippocampal sclerosis, a common cause of mesial temporal lobe epilepsy. If an underlying infection is suspected, a lumbar puncture is indicated. Before a lumbar puncture, however, a CT scan must be done to rule out conditions causing elevated intracranial pressure. Lastly, an EEG (electroencephalography) should be completed for first-time seizure generally within 48 hrs and more emergently if the post-ictal state seems prolonged or if a seizing patient is given paralytics.
Lesson Outline
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FAQs
A fingerstick blood glucose test is essential to rapidly ensure the patient is not hypoglycemic. Hypoglycemia, or low blood sugar, can cause symptoms similar to a seizure. Therefore, it's important to rule this out as the cause before considering other differential diagnoses.
An EKG, or electrocardiogram, is used to rule out arrhythmia or long QT syndrome, which can mimic or trigger seizures. This test measures the electrical activity of the heart and helps identify any heart rhythm issues.
Elevated levels of white blood cells (WBC), lactic acid, and creatine phosphokinase (CPK) may be seen after a convulsive episode. However, these are non-specific changes and do not confirm a seizure. They may suggest that a seizure has occurred, or they could be due to other underlying issues like an infection.
A CT scan of the head is the initial imaging performed for a first seizure or a recurrent seizure with concerning symptoms. It can help rule out other causes like a brain tumor or stroke. An MRI follows a CT as itÕs a more sensitive test, and special attention is paid to the hippocampus because damage or abnormalities in this area are often associated with seizures.
A lumbar puncture is indicated if the presentation is consistent with an underlying infection, and a CT head should be done prior to this procedure. An electroencephalogram (EEG) should be completed for a first-time seizure, and more emergently if the post-ictal state seems prolonged or if a seizing patient has been given paralytics. The EEG measures electrical activity in the brain and can help pinpoint the area where seizures are originating and indicate whether treatment is effective.
