Impact of video-ambulatory electroencephalography on the medical management of epilepsy

Diagnostic utility of prolonged ambulatory video-electroencephalography monitoring

OBJECTIVES

Ambulatory video-electroencephalography (video-EEG) represents a low-cost, convenient and accessible alternative to inpatient video-EEG monitoring, however few studies have examined their diagnostic yield. In this large-scale retrospective study conducted in Australia, we evaluated the efficacy of prolonged ambulatory video-EEG recordings in capturing diagnostic events and resolving the referring question.

METHODS

Sequential adult and paediatric ambulatory video-EEG reports from April 2020 to June 2021 were reviewed retrospectively. Data collection included patient demographics, clinical information, and details of events and EEG abnormalities. Clinical utility was assessed by examining i) time to first diagnostic event, and ii) ability to resolve the referring questions - seizure localisation, quantification, classification, and differentiation (differentiating seizures from non-epileptic events).

RESULTS

Of the 600 reports analysed, 49 % captured at least one event, and 45 % captured interictal abnormalities (epileptiform or non-epileptiform). Seizures, probable psychogenic events (mostly non-convulsive), and other non-epileptic events occurred in 13 %, 23 % and 21 % of recordings respectively, with overlap. Unreported events were captured in 53 (9 %) recordings, and unreported seizures represented more than half of all seizures captured (51 %, 392/773). Nine percent of events were missing clinical, video or electrographic data. A diagnostic event occurred in 244 (41 %) recordings, of which 14 % were captured between the fifth and eighth day of recording. Reported event frequency ≥ 1/week was the only significant predictor of diagnostic event capture. In recordings with both seizures and psychogenic events, unrecognized seizures were frequent, and seizures may be missed if recording is terminated early. The referring question was resolved in 85 % of reports with at least one event, and 53 % of all reports. Specifically, this represented 46 % of reports (235/512) for differentiation of events, and 75 % of reports (27/36) for classification of seizures.

CONCLUSION

Ambulatory video-EEG recordings are of high diagnostic value in capturing clinically relevant events and resolving the referring clinical questions.

The Yield of Ambulatory Video-EEG: Predictors of Successful Event Capture

Background and Objectives

The purpose of this study was to assess the likelihood of capturing a patient's typical event in question on ambulatory video-EEG monitoring (AVEM) based on certain baseline patient or event characteristics.

Methods

We retrospectively reviewed 300 studies that resulted between June 2021 and August 2022 ordered by adult epileptologists. Patients were included in event analysis if the study was ordered for the purpose of capturing an event (and excluded for all other purposes).

Results

A total of 149 studies were included in event analysis. Sixty-eight patients (46%) had their typical events captured on AVEM. Diagnosis was an epileptic seizure in 17 patients (25%), psychogenic nonepileptic seizure in 7 (10%), and other nonepileptic events in 44 (65%). Regarding event frequency, for patients who on average had daily events, 84% had events captured, which corresponds to a significantly increased odds ratio (OR 17.90, 95% CI 7.55-42.44, p < 0.001). For those who had events <1 per week to ≥1 per month, only 9% had events captured (OR 0.06, 95% CI 0.02-0.19, p < 0.001). No patients who had events less frequently than once per month had a diagnostic AVEM. Regarding the number of antiseizure medications (ASMs), the odds ratio was increased for those not on ASMs (OR 2.65, 95% CI 1.17 -6.03, p = 0.02) and decreased for those on 1 ASM (OR 0.28, 95% CI 0.13 -0.60, p = 0.001). There was no statistical significance based on event type (motor vs nonmotor), prior seizure diagnosis, history of psychiatric comorbidity, or presence of a focal brain lesion.

Discussion

Certain baseline characteristics can increase or decrease the pretest probability of capturing a typical event on AVEM, particularly the frequency of events and number of ASMs. This can be useful information for clinicians before ordering a study so that resources can be properly allocated.

The Yield of Ambulatory EEG-Video Monitoring

INTRODUCTION

The availability of ambulatory EEG-video monitoring gives an alternative to traditional inpatient EEG-video, but its yield and diagnostic value are not well known. This study evaluates the yield of ambulatory EEG-video for the diagnosis of epilepsy.

METHODS

We retrospectively reviewed the ambulatory EEG-video monitoring data from 200 consecutive and unselected patients aged 12 years and older performed by a single company (RSC Diagnostic Services) between January 2018 and May 2018. Studies were processed by two senior certified long-term monitoring EEG technologists and interpreted by neurologists.

RESULTS

Of the 200 patients, 130 (65%) were women, mean age was 45 years. Mean duration of studies were 76.6 hours (range 23-175 hours). There were 110 studies (55%) with events recorded and 101 (92%) were captured on video. Epileptic events accounted for 17.8% (18/101) of the events captured and 9% (18/200) of our total cohort. Nonepileptic diagnosis accounted for 38% of the total number of patients in study (76/200).

CONCLUSION

Ambulatory EEG-video monitoring may be a useful alternative to inpatient epilepsy monitoring unit, particularly with high clinical suspicion for nonepileptic events.

Long-term Home Video EEG for Recording Clinical Events

SUMMARY

Around 50 years after the first EEG acquisition by Hans Berger, its use in ambulatory setting was demonstrated. Ever since, ambulatory EEG has been widely available and routinely used in the United States (and to a lesser extent in Europe) for diagnosis and management of patients with epilepsy. This technology alone cannot help with semiological characterization, and absence of video is one of its main drawbacks. Addition of video to ambulatory EEG potentially improves diagnostic yield and opens new aspects of utility for better characterization of patient's events, including differential diagnosis, classification, and quantification of seizure burden. Studies evaluating quality of ambulatory video EEG (aVEEG) suggest good quality recordings are feasible. In the utilization of aVEEG, to maximize yield, it is important to consider pretest probability. Having clear pretest questions and a strong index of suspicion for focal, generalized convulsive or non-epileptic seizures further increases the usefulness of aVEEG. In this article, which is part of the topical issue "Ambulatory EEG," the authors compare long-term home aVEEG to inpatient video EEG monitoring, discuss aVEEG's use in diagnosis and follow-up of patients, and present the authors' own experience of the utility of aVEEG in a teaching hospital setting.

The clinical value of long - term electroencephalogram (EEG) in seizure - free populations: implications from a cross-sectional study

Backgroud

This study aimed to explore the clinical value of long - term electroencephalogram (LTM EEG) in seizure-free individuals taking antiepileptic drugs (AEDs) for more than 2 years. We try to look for clinical factors associated with epileptiform activity on LTM EEG in seizure free patients. We hope that the detection of epileptiform activity by the LTM EEG recording can develop the better treatment strategy.

Methods

The LTM EEG recordings of 770 individuals with a definite diagnosis of epilepsy were assessed. Two hundred sixty-two individuals accorded with the inclusion criteria and exclusion criteria. We collect the demographic and clinical information and LTM EEG data of these 262 individuals. We analysed the data by one-way analysis of variance and Cox proportional hazards models.

Results

We found that more epileptiform activity were found with LTM EEG recording than regular EEG recording in seizure-free individuals. We found several clinical factors could be associated with epileptiform activity on LTM EEG in seizure free patients by a one-way analysis: symptomatic or cryptogenic epilepsy [hazard ratio (HR) = 2.6], history of cerebral trauma (HR = 7.5), and abnormal imaging findings (HR = 3.1). The following factors suggested a correlation between history of cerebral trauma (HR = 2.4) and history of cerebral surgery (HR = 3.4) with epileptiform activity on LTM EEG presentation by multivariate logistic regression analysis.

Conclusions

The study indicated a correlation of a number of factors with abnormal LTM EEG presentation: symptomatic or cryptogenic epilepsy, history of cerebral trauma, history of cerebral surgery, and abnormal imaging findings. The LTM EEG recording may help find epileptiform activity in high risk seizure-free individuals. The individuals need be reevaluated the therapeutic strateagies, and increase the hope to reach real seizure-free.

Prevalence and clinical correlates of non-convulsive status epilepticus in elderly patients with acute confusional state: A systematic literature review

Non-convulsive status epilepticus (NCSE) is a potentially treatable condition that poses considerable diagnostic challenges. NCSE is thought to be more common in the elderly than in the general population, however additional diagnostic challenges complicate its recognition in older patients, because of the wide differential diagnosis with common underlying causes of acute confusional state in this age group. We set out to review the existing evidence on the clinical correlates of NCSE in the elderly population. A systematic literature review was conducted according to the methodological standards outlined in the PRISMA statement to assess the clinical correlates of NCSE in patients aged 60 or older. Our literature search identified 11 relevant studies, which confirmed that the incidence of NCSE increases with age, in particular with regard to focal forms with impairment of consciousness. Female gender, history of epilepsy (or a recently witnessed seizure with motor features), and abnormal ocular movements appeared to correlate with the diagnosis of NCSE in the elderly, prompting prioritization of electroencephalography tests for diagnostic confirmation. Epidemiological data in the elderly vary widely because of the heterogeneity of definitions and diagnostic criteria applied across different studies. Based on our findings, it is recommended to keep a low threshold for requesting electroencephalography tests to confirm the diagnosis of NCSE in elderly patients with acute confusional state, even in the presence of a presumed symptomatic cause.

Exploding Head Syndrome in the Epilepsy Monitoring Unit: Case Report and Literature Review

Diagnosis of paroxysmal events in epilepsy patients is often made through video-telemetry electroencephalography in the epilepsy monitoring unit. This case report describes the first-ever diagnosis of exploding head syndrome in a patient with longstanding epilepsy and novel nocturnal events. In this report, we describe the presentation of exploding head syndrome and its prevalence and risk factors. In addition, the prevalence of newly diagnosed sleep disorders through video-telemetry electroencephalography in the epilepsy monitoring unit is briefly reviewed. This report also illustrates the novel use of clobazam for the treatment of exploding head syndrome.

Diagnostic accuracy of paroxysmal spells: Clinical history versus observation

Our goal was to evaluate how accurate neurologists are at differentiating between different paroxysmal events based on clinical history versus observation of the spell in question. Forty-seven neurologists reviewed 12 clinical histories and videos of recorded events of patients admitted in the Epilepsy Monitoring Unit (EMU). They were asked to diagnose events as epileptic seizures, non-epileptic behavioral spells (NEBS), or other physiologic events as well as rate their confidence in their diagnosis. The median diagnostic accuracy for all paroxysmal events was 67% for clinical history and 75% for observation (p=.001). This was largely due to the difference in accuracy within the subgroup of patients with NEBS (67% history vs. 83% observation, p<.001). There were trends for higher diagnostic accuracy and increased inter-rater agreement with higher levels of training. Physicians with higher levels of training were more confident with diagnosis based on observation. In summary, reviewing videos of paroxysmal spells may improve diagnostic accuracy and enhance the evaluation of patients. Neurologists at all levels of training should encourage the recording and review of videos of recurrent spells to aid in medical decision-making especially when there is high concern that the spells in question are NEBS.

Paroxysmal nonepileptic events in children with epilepsy

OBJECTIVE

The aim of this study was to clarify the characteristics of paroxysmal nonepileptic events (PNEs) suspected as being epileptic seizures by families of children with epilepsy.

METHODS

The video-EEG (vEEG) recordings of habitual paroxysmal events in children with epilepsy at Nagoya University Hospital between October 2006 and January 2016 were reviewed. Based on the doctor's suspicion before the vEEG, the PNEs were divided into two groups that included PNEs suspected as epileptic seizures and PNEs suspected as PNEs. PNEs in the former group were classified based on the suspected seizure type.

RESULTS

Of 886 habitual paroxysmal events, vEEG confirmed that 83 events (68 children) were PNEs. The median age of the 68 children was 3.2 years. Concurrent epilepsies included focal epilepsies (n=33), infantile spasms (n=16), and other types (n=19). The most common types of PNEs were sleep myoclonus (n=11), followed by stereotypies (n=9), awake myoclonus (n=8), paroxysmal ocular deviations (PODs, n=8), and tonic posturing (n=8). Even after direct observation or video viewing, the doctors suspected epileptic seizures in all three of the PODs and two of the tonic posturing children. Before the vEEG, however, the accurate visual information led to the speculation that the four psychogenic and two sleep myoclonus events were all PNEs. Myoclonus, stereotypies, and head drops were often misdiagnosed as epileptic spasms, while PODs and tonic posturing were often misdiagnosed as focal seizures with motor components. Additionally, staring and motion arrest during a drowsy state were often misdiagnosed as focal dyscognitive seizures. Seven of eight patients with PODs had epileptic spasms that were concurrent with epileptic seizures. A diffuse cerebral lesion or reduced visual acuity was seen in seven patients with PODs.

CONCLUSION

We re-emphasize that vEEG is essential for accurate diagnosis and provides evidence for listing POD in the differential diagnosis of oculomotor paroxysmal events.