Epilepsy Diagnosis – Seizures vs seizure mimics?

Your Doctor arrives at epilepsy diagnosis (see here to know what is epilepsy?) by carefully analyzing your symptoms (seizure episodes). This is to decide if these episodes are indeed epileptic seizures. Most important thing here is not all episodes of loss of consciousness, unresponsiveness and shaking are seizures. Many other episodes can look similar to seizures (seizure mimics). Differentiating between seizures and mimics is the critical first step in the diagnosis of epilepsy.

Epilepsy Diagnosis – detailed history analysis:

You can help your doctor arriving at the correct diagnosis. Please describe the episode in great detail and answer the doctor’s questions correctly and accurately. The context in which the seizures occur, how the episodes start, how they progress and how do they end are crucial bits of the information needed. Detailed analysis of the history is of paramount importance in arriving at the correct diagnosis. Thus diagnosing epilepsy is purely clinical and no single test will confirm the diagnosis.

Epilepsy Diagnosis – role of home video recordings

Video recordings of the episodes in your smart phone help doctors distinguish between seizures and mimics. Try to record the episode with full child in view rather than focusing on only the face or limbs. What a 1000 words does not convey, a video of 10 seconds can easily clinch the diagnosis. Rarely, video-EEG recording of seizures is required to make this distinction.

What tests are used in epilepsy diagnosis?

Epilepsy is not a single disease (ref what is epilepsy?) and rather there are many different types of epilepsy. This is especially true in children and teenagers who have variety of different epilepsy types. Knowing the correct epilepsy type and epilepsy syndrome is of critical importance to proceed with successful treatment. Treatment differs considerably depending on the epilepsy type. Tests are usually performed to support the clinical diagnosis of epilepsy (EEG), to know which type of epilepsy one is dealing with (EEG/video-EEG) and to detect the underlying cause of epilepsy (MRI of the brain, genetic tests, etc). EEG is not a confirmatory test; thus normal EEG does not rule out epilepsy.

Normal test reports rule out epilepsy diagnosis, don’t they?

Normal EEG and normal brain scan (MRI) does not rule out epilepsy diagnosis! In fact most patients with epilepsy have normal brain MRI. MRI of the brain is similar to the hardware of the computer. Despite the computer hardware being perfectly normal, software problem(s) might exist. Likewise, epilepsy patients with electrical disturbances can have perfectly normal brain structure in the MRI scan. Thus many children with epilepsy have normal MRI and normal EEG reports.

The abnormal brain signals in epilepsy are episodic and intermittent, ie not occurring constantly all the time. So the routine EEG (brain wave test) recorded for 20-30 minutes could miss the abnormality completely. When the seizure focus is very deep down in the brain, EEG may not detect any abnormalities. It is essential to record longer duration of EEG for 40-60 minutes including sleep all children with epilepsy, as abnormalities might be noted only during sleep and awake EEG could be normal.

The interesting point to note here is that all these tests can be normal in patients with epilepsy, thus ruling out some of the more sinister causes. Even after all the test results come back as normal, still the diagnosis remains epilepsy. In most cases, exact cause of epilepsy is not identifiable. In most patients, epilepsy can be treated with anti seizure medications even if we do not know the exact underlying root cause for the epilepsy. This is because, the medications we use to control seizures remain the same and are mostly not chosen based on the underlying cause of epilepsy.

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