NEUROLOGY
A
mentor who kindled my interest in epilepsy had some favorite sayings that I still hear echoing in the recesses of my subconscious from time to time. “Seizures are not like fractures,” she would say, “and they are not like appendicitis. When you treat seizures you are not treating something you can see or feel, you are treating a story.” Then again: “Epilepsy is not a seizure or even a collection of seizures. Epilepsy is a process that has potential to change a person over time and you have to deal with this if you want to really help a person.” I remember reacting the way most eager trainees react: nodding my head, trying to appear interested, but thinking to myself, “What is she talking about? And why won’t she talk about something that can be defined, quantified, and examined in a proper scientific study?” More than 20 years later, I am beginning to understand. And hard scientific data of the sort I craved as a beginner are beginning to demonstrate three
New approaches, rooted in experience Science begins to catch up with what we’ve long known about epilepsy By Thaddeus Walczak, MD
basic ideas that experienced practitioners treating epilepsy had always known: • Precise diagnosis is critical in epilepsy, but it is not always easy to achieve. • Persistent epilepsy is associated with significant comorbidities that often affect quality of life more than the seizures. Diagnosing and treating these is just as important as treating the seizures. • Aggressive treatment reduces seizures and may also reverse or prevent the development of comorbidities. Each of these keys to diagnosing and treating epilepsy is discussed below.
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MINNESOTA PHYSICIAN FEBRUARY 2012
Diagnosing epilepsy
Precise diagnosis is critical in epilepsy but it is not always easy to achieve. A person presenting with a potential seizure presents with a story rather than with a physical sign or a test result. More so than with most other disease entities, diagnosis of seizure depends on the description of what happened to the patient. It is even more challenging than usual because much of the time the patient is impaired during the event. The clinician is left with the patient’s recollections of what happened before and after the seizure. An observer history is probably the most useful piece of historical information but requires some detective work by a person experienced in the many clinical manifestations that epileptic seizures can take. Neuroimaging is critical to exclude intracranial lesions that may be causing the epilepsy, but we must remember that not all imaging is created equal. Magnetic resonance imaging (MRI) detects potentially epileptogenic lesions far more often than CT scanning. Epilepsydirected magnetic resonance imaging with sequences sensitive for mesial temporal sclerosis, cavernomas, and cortical dysplasia is more useful still and should be pursued if initial imaging is unremarkable and seizures are not controlled. Electroencephalography (EEG) is even more critical but some experience is necessary to interpret results correctly. First, specific findings such as epileptiform spikes and sharp waves are highly associated with epilepsy but many other abnormalities are nonspecific. Determining whether any given waveform is epileptiform is a subjective call and depends on the
experience of the interpreter. Unfortunately, “overreading” of EEGs and subsequent incorrect diagnoses of epilepsy are still common and often cause unnecessary distress. Second, diagnostic utility of EEG is dependent on the sampling time (duration of recording). The epileptiform spikes and sharp waves highly associated with epilepsy are not always present and may not appear during a routine hourlong study. This is not uncommon; almost half of people with seizures recorded in our unit will not have epileptiform sharp waves or spikes after multiple EEGs. Therefore, a normal EEG cannot rule out epilepsy. Finally, continuous videoEEG recording can overcome these limitations. Longer recording times increase opportunities to record diagnostic findings. More importantly, the events of interest can actually be recorded with EEG and video. This allows an unambiguous determination of whether or not the events are epileptic. Recording characteristic events with video-EEG monitoring is the only way to be sure that the events in question are epileptic. This may not always be necessary, but it is essential if seizures do not respond to treatment. Why is accurate diagnosis so important? Because accurate diagnosis determines treatment and allows realistic assessment of prognosis. If diagnosis is uncertain, treatment becomes a series of shots in the dark. Many physicians do not realize that up to one-quarter of people with seizures not responding to medications do not have seizures at all but, rather, other types of attacks that superficially mimic seizures and are often psychiatrically based. Obviously, treating with antiseizure medications in this situation is a recipe for frustration. Even if the diagnosis of epilepsy is certain, the type of epilepsy syndrome will determine the best treatment. This has been illustrated in several class I studies reported in the last several years. The SANAD trial demonstrated convincingly that valproate was more effective for primary generalized tonic-clonic seizures than lamot-