The Best Seizure Diagnostic Tool Is Not a Medical Device

Abstract

The diagnosis of seizures and epilepsy is primarily based on the history, but history-taking is fraught with difficulties and has serious limitations, which is one reason for the common misdiagnosis of seizures. EEG is a very useful tool, but routine EEG has poor sensitivity, and prolonged EEG-video monitoring, the gold-standard for diagnosis, is only useful for patients with frequent events. Smartphones are ubiquitous, and their videos are increasingly used as an extension of the history and a diagnostic tool. Stand-alone videos should be considered a diagnostic tool and treated as such, including with a Current Procedural Terminology (CPT) code, the American uniform nomenclature for medical procedures, which is used for billing and reimbursement.

• Anecdote 1: I was asked to review an ambulatory EEG for a second opinion. The patient had a seizure episode during the study, and the EEG showed dramatic waveforms typical for chaotic movement artifacts (Figure), highly suspicious for a nonepileptic event. I expressed my suspicion and asked if video was available. It was, and upon review, it showed a definite psychogenic event (Video 1). The interesting part is that both the neurologist and the EEG company, who wanted the second opinion, sent the EEG but not the video, assuming that the EEG was the most important. The key was the video, not the EEG.

• Anecdote 2: Patient in hospital with new episodes of left facial jerking. Neurology service orders stat EEG. Tech prepares to come from home, which will take 2 hours until the patient is connected. A 7-second cellphone video (Video 2) from the resident shows a clear focal motor (clonic) seizure of the left face. EEG eventually performed 2 hours later showed no EEG changes and added nothing. The key was the video, not the EEG.

Figure. Sample of the EEG for the Patient of Anecdote 1, During the "Seizure" in Question.

EEG shows dramatic waveforms typical for chaotic movement artifacts, highly suspicious for a psychogenic nonepileptic event.

Video 1

Definite psychogenic event.Download Supplementary Video 1 ^{(27.6MB, mov)} via http://dx.doi.org/10.1212/200117_Video_1

Video 2

Clear focal motor (clonic) seizure of the left face.Download Supplementary Video 2 ^{(4MB, mp4)} via http://dx.doi.org/10.1212/200117_Video_2

Those 2 situations illustrate old habits (a knee-jerk EEG order) and misconceptions (EEG is the way to diagnose seizures). Video is often a better diagnostic tool than EEG.

EEG-Video Monitoring Is the Gold-Standard for the Evaluation of Seizures and Seizure-Like Events

For epileptologists, an EEG-video recording is similar to a “seizure biopsy.” It is to the epileptologist what the skin biopsy is to the dermatologist. By recording the episode in question, it achieves the following:^1-3

• 1. Confirms the diagnosis of epileptic seizures vs other episodes that can mimic seizures;

• 2. If the events are not epileptic, the video (semiology) will usually allow to diagnose the events as psychogenic (the most common at epilepsy centers) or other possible differential diagnoses⁴;

• 3. If epilepsy is confirmed, it usually allows to specifically categorize the type (idiopathic generalized epilepsy, generalized epilepsy of the Lennox-Gastaut type, and focal epilepsy);

• 4. If focal epilepsy, together with semiology, EEG may help identify lobar or multilobar localization (which has major implications for nonpharmacologic treatment options).

In addition to monitoring for interictal epileptiform discharges, similar to any EEG, the principle of EEG-video is to record the events in question with both EEG and video. Beyond the diagnosis of epilepsy, EEG is of course critical for the precise diagnosis of epilepsy type and localization of focal epilepsy (for surgical treatment). For this purpose, both EEG and video (semiology) are critical.

In most situations, both components (EEG and video) are important, including interpreting each one in the context of each other.^1-5

EEG Can at Times Be More Important Than Video (and in Fact Video May Add Nothing)

This would include the following: (1) Patients with infrequent events where the goal is to capture interictal epileptiform discharges, not to record events. (2) Purely subjective symptoms, i.e., suspected auras or focal aware seizures, where the video will provide no additional information. (3) Possible “nonconvulsive” or “subclinical” seizures or status, where by definition, there is nothing visible on video. In fact, for this very purpose, the use of rapid EEG devices is growing.⁶

There Are Many Situations Where Video Is More Important Than EEG

Focal seizures with no visible EEG changes (focal motor seizures, frontal lobe seizures) either because the focus is too small or the EEG is obscured by artifact. For nonepileptic episodes, the video is often more useful than the EEG and may allow for a more specific diagnosis, such as psychogenic vs other possibilities in the differential diagnosis.⁴

Limitations of EEG-Video

EEG-video monitoring has obvious limitations in time: it is limited to a few days. EEG has an equivalent of Holter monitor that can be used for several days (ambulatory EEG-video)² but not an equivalent of cardiac event loop monitors, which can monitor for months. For that reason, there is an increasing number of monitoring devices,^7,8 but they are limited to major motor (convulsive) events and more for detection than diagnosis. Limitations in space: very focal seizures (“focal aware” seizures) may have no surface EEG changes, and EEG may be obscured by artifact in events with vigorous motor activity. EEG-video is not available everywhere. Epilepsy monitoring unit are scarce in developing countries and in rural areas of developed countries. Furthermore, even in the United States where most medium-sized cities have an epilepsy centers and large cities have several, the wait time is often unrealistically long (months) for inpatient EEG-video monitoring. EEG-video monitoring is also expensive and cumbersome.

The Diagnosis of Seizures and Seizure-Like Events Has Always Been and Continues to Be Primarily Based on History

because most patients with seizures or seizure-like events do not have frequent enough events to be captured in a few days of EEG-video. History alone has serious limitations,^9-11 which explain the frequent misdiagnosis of seizures as well documented at epilepsy centers. Infrequent events are often undiagnosable and can be a major source of frustration for neurologists. Uncertain diagnoses of seizures often result in precautionary (and understandable) prescriptions of antiseizure medications, which are ineffective if events are not epileptic and are also not devoid of side effects.

Videos Are a Powerful Extension of the History

This includes mainly cellphone videos but also home videos (no longer expensive to place in the home) and security cameras. The diagnostic value of videos has been shown to be high. One study¹² found that the odds of receiving a correct diagnosis increased from 79 to 95%.¹² Another study¹³ reported that cellphone video diagnosis agreed with eventual final EMU diagnosis in 94% of patients. Because virtually everyone has a smartphone, it can be said that “everyone owns half an Epilepsy Monitoring Unit.¹³ Unlike EEG, a cellphone camera can be used quickly and “as needed” when an episode occurs, especially infrequent ones.

Like Every Diagnostic Tool, Videos Have Limitations

They cannot be obtained if the patient is alone and incapacitated, if the events are too short, or if the witnesses are panicking and unable to use the smartphone. The quality is obviously variable, although recent studies suggest that it is often enough to make a diagnosis.^12-14 Similar to any other test, including EEG, videos are only as good as who interprets them. As expected, reliability is lower when videos were interpreted by nonexperts compared to experienced epileptologists.¹²

Conclusions

Consistent with the age-old adage that epilepsy is a clinical diagnosis, video, which is an extension of the history, is often more helpful than EEG for the diagnosis of seizures, at least for the diagnosis of seizures vs not. The field of neurology needs to evolve with the time and with technology. The assumption that “EEG” is the key for diagnosing seizures, and the old-fashion knee-jerk reaction to order “an EEG” (often without video), should be revisited. Oftentimes, including in the hospital, a “quick and dirty” cellphone video is more useful (and faster and cheaper) than a fancy EEG. Stand-alone video, however, by no means competes with the gold standard of EEG-video. It complements it. The EEG component remains essential, especially for localization and surgical treatment.

Because the use of video recordings for diagnosis is a new phenomenon, there are many unanswered questions and potential unintended consequences of their ubiquitous use. There are important issues of storing, transmission, sharing, and HIPAA, which have yet to be ironed out since the technology is relatively recent. This is evolving, and already several EMR accept media, including video clips, as part of the patient charts, although for now only brief and limited. Special secure email accounts dedicated to video clips can also be created. There are also HIPAA-compliant smartphone Apps.¹²

Another important question is who should be interpreting videos. Any clinician should be able to because they are an extension of the history, but when and if there is a billable CPT code, it should likely require the same credentials as the interpretation of EEG-video. This may have to be expanded to (and adjusted for) different paroxysmal symptoms because the value of videos likely extends beyond seizures and applies to other paroxysmal symptoms in the differential diagnosis of seizures (e.g., TIAs, syncope, movement disorders, and migraines). Similarly, education and board certification examinations may have to adjust and have more emphasis on video clips rather than just EEG.

There are many CPT codes for various types of EEGs, including for EEG-video and EEG with no video, but to date, there is no code for stand-alone video (without EEG). For the reasons discussed here, stand-alone videos have truly become a diagnostic tool, and they deserve their own CPT codes. Questions remain about what a billable unit would be, based on duration, complexity, or other factors. More data and research are needed before making video review an official diagnostic tool with a CPT code, but it is likely time to begin that discussion.

For now, and from a practical point of view, clinicians should make use of cellphone videos to help with diagnosis while remaining cautious based on the limitations discussed here.

Appendix. Author

Study Funding

The author reports no targeted funding.

Disclosure

S.R. Benbadis consults/advises for Bioserenity, Ceribell, Eisai, Greenwich (Jazz), LivaNova, Neurelis, NeuroPace, SK Life Science, Sunovion, and Zogenix (UCB); is part of the speakers bureau for Aquestive, Bioserenity, Eisai, Greenwich (Jazz), LivaNova, Neurelis, SK Life Science, Stratus, Sunovion, and Zogenix (UCB); is the Florida Medical Director for Stratus (EEG) and Nexus Neuro (EEG); is a member of Epilepsy Study Consortium; and received grant support from Cerevel Therapeutics, Ovid Therapeutics, Neuropace, Greenwich (Jazz Pharmaceurical), SK Life Science, Xenon Pharmaceuticals, UCB, Marinus, Neuroelectrics Corporation, Longboard, and Janssen. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/cp.