Neurologic Practice in a Video-EEG Monitoring Unit

Introduction

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Neurologists working on a video-electroencephalography monitoring (VEM) unit are part of a large team comprising ward nurses and an epilepsy advanced practice nurse (APN), EEG technologists with special expertise in VEM, and usually personnel who monitor the video-EEG continuously, as well as a biomedical engineer and ancillary health care personnel. The neurologists, APN, and chief technologist take responsibility for establishing protocols and overseeing quality control. This chapter will deal specifically with the role of neurologists on VEM units. Nursing and technical issues are covered in other chapters.

Guidelines for Specialized Epilepsy Centers

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The National Association of Epilepsy Centers (NAEC) has established guidelines for four levels of epilepsy care, as outlined in Chapter 5.¹ Third-level centers can be medical, which do not perform surgical treatment for epilepsy, or medical-surgical, which are able to perform surgical resections of structural lesions and standard anterior temporal resections. Fourth-level centers also perform more complicated diagnostic surgical procedures, including placement of depth, subdural grid, and strip electrodes. Not all fourth-level centers offer corpuscallosotomy, hemispherectomy, and other specialized therapeutic surgical procedures; however, they are expected to have referral arrangements with fourth-level centers offering these services. These guidelines stipulate that a third-level medical center for epilepsy provide minimum 8-hour VEM with surface electrodes and supervision by an EEG technologist, with assistance by an epilepsy staff nurse or monitoring technician when necessary. Third-level medical-surgical centers provide 24-hour (continuous) VEM with surface electrodes, including sphenoidal or other appropriate additional electrodes, and continuous supervision by EEG technologists or epilepsy staff nurses, supported by monitoring technicians, or automated seizure detection programs when appropriate. Fourth-level centers additionally provide 24-hour video-EEG recording with intracranial electrodes under continuous supervision and observation, as well as functional cortical mapping and evoked potential recording, using intracranial electrodes, which may be performed extraoperatively on the VEM unit. Additional details regarding NAEC guidelines and certification may be found in Chapter 5.

The International League Against Epilepsy (ILAE) has also published recommended standards for epilepsy surgery centers, but guidelines for VEM are not detailed.² Finally, the American Clinical Neurophysiology Society (ACNS) and the International Federation of Clinical Neurophysiology Societies (IFCNS) have issued a series of guidelines for long-term monitoring for epilepsy (LTME), the most recent published in 2008.³ These include indications for long-term monitoring, qualifications and responsibilities for long-term monitoring personnel, long-term monitoring equipment and procedures, equipment and procedures for long-term monitoring of behavior and correlation with EEG, technical and methodological considerations, recommended uses of specific long-term monitoring systems, and guidelines for writing reports. This chapter covers neurologic practice on a VEM unit for a fourth-level epilepsy center, which is most comprehensive, but information should also apply for third-level centers. The chief neurologist of the monitoring unit should be familiar with all of these guidelines.

Personnel

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The most recent ACNS guidelines state that the chief or medical supervisor of a VEM unit and other neurologists working on a VEM unit have the qualifications and responsibilities listed in Table 6-1.³

Table 6-1Qualifications and Responsibilities of LTME Lab Chief and Neurologists

	Qualifications	Responsibilities
Chief of Lab	Physician qualified to be chief of an EEG laboratory as outlined in Guidelines for Laboratory Accreditation, Standard One, published by the ACNS Certification from the appropriate national EEG group Training in the operation of LTME equipment and special knowledge of the technical aspects of data recording, storage, and retrieval. Formal training or equivalent experience in electronics and/or computer science is strongly recommended. Training in the interpretation of EEG and video data generated in an LTME laboratory. Experience beyond routine EEG interpretation is necessary, as much of the analysis involves complex ictal and interictal features, as well as artifacts, seldom encountered in a standard EEG laboratory. Experience in the practical use of specialized LTME equipment and in data interpretation to be gained by working in a major LTME laboratory, preferably under the direction of individuals who meet the qualifications for chief or medical supervisor of an LTME laboratory	The same responsibilities and authority as the chief of an EEG laboratory. To have the training and necessary skills needed to care for a person having seizures. Final interpretive synthesis of LTME data with diagnostic and pathophysiological formulations.
Neurologists on lab service	A physician with the qualifications to be a clinical electroencephalographer as outlined in Standards of Practice in Clinical Electroencephalography, Guideline Four, published by the ACNS. Training and experience in the use of LTME equipment and the interpretation of LTME data, preferably under the direction of an individual who meets the qualifications for chief or medical supervisor of an LTME laboratory.	Analysis of, at minimum, pertinent segments of collected electrographic and behavioral data reviewed in all appropriate formats The writing of LTME reports The final interpretive synthesis of LTME data with diagnostic and pathophysiological formulations in the absence or in lieu of the chief or medical supervisor

Qualifications and responsibilities of EEG technologists and monitoring technicians are also specified, and the chief neurologist on the VEM unit is responsible for ensuring that the technologists and technicians are appropriately qualified and adequately perform their assigned duties, which are detailed elsewhere in this textbook. The chief neurologist is also responsible, with the clinical nurse specialist, for ensuring that nurses are properly qualified and performing their duties appropriately, as discussed in the previous chapter, and for ensuring necessary support from a biomedical engineering facility, to ensure that equipment is functioning properly and that personnel are available to troubleshoot problems on an around-the-clock basis.

Access to psychiatrists and clinical psychologists is essential, particularly for patients diagnosed with psychogenic nonepileptic seizures (PNES). Other medical and surgical specialists are often required for necessary diagnostic or therapeutic advice, and services of occupational therapists and social workers are desirable. The VEM neurologists are responsible for coordinating these consultations.

Purposes of Video-EEG Monitoring

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Table 6-2 lists the ACNS guidelines for long-term monitoring.³

Table 6-2Indications for Use of Long-Term Video-EEG Monitoring

Diagnosis

Identification of epileptic paroxysmal electrographic and/or behavioral abnormalities. These include epileptic seizures, overt and subclinical, and documentation of interictal epileptiform discharges. EEG and/or behavioral abnormalities may assist in the differential diagnosis between epileptic disorders and conditions associated with intermittent symptoms because of nonepileptic mechanisms (e.g., syncope, cardiac arrhythmias, transient ischemic attacks, narcolepsy, other sleep disturbances, psychogenic seizures, other behavioral disorders).
Verification of the epileptic nature of the new “spells” in a patient with previously documented and controlled seizures

Classification/Characterization

Classification of clinical seizure type(s) in a patient with documented or poorly characterized epilepsy
Characterization (lateralization, localization, distribution) of EEG abnormalities, both ictal and interictal, associated with seizure disorders. Characterization of epileptiform EEG features, including both ictal discharges and interictal transients, is essential in the evaluation of patients with intractable epilepsy for surgical intervention.
Characterization of the relationship of seizures to specific precipitating circumstances or stimuli (e.g., nocturnal, catamenial, situation-related, activity-related). Verification and/or characterization of temporal patterns of seizure occurrence, either spontaneous or with respect to therapeutic manipulations (e.g., drug regimens).
Characterization of the behavioral consequences of epileptiform discharges as measured by specific tasks

Quantification

Quantification of the number or frequency of seizures and/or interictal discharges and their relationship to naturally occurring events or cycles
Quantitative documentation of the EEG response (ictal and interictal) to a therapeutic intervention or modification (e.g., drug alteration)
Monitoring objective EEG features is useful in patients with frequent seizures, particularly with absence and other seizures having indiscernible or minimal behavioral manifestations.

In practice, approximately one third of patients admitted to third- and fourth-level VEM units are referred for differential diagnosis of possible PNES. These patients are usually referred from community neurologists who require diagnostic verification in patients with suspicious ictal events that do not respond to antiepileptic drugs (AEDs). Occasionally, patients are transferred from other hospitals for differential diagnosis of unusual status epilepticus, which more often than not turns out to be PNES. The other two thirds are usually admitted for presurgical evaluation, and 10 to 20% of these, at fourth-level centers, will require a second admission for intracranial monitoring. Classification of epileptic seizures and epilepsy syndromes is not usually a primary reason for VEM unit admission, but it is important that neurologists be familiar with the current ILAE classifications^4,5 and more recent amendments.^6,7

Equipment

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The chief neurologist of the VEM unit is responsible for choosing the equipment when the unit is created and has overall responsibility for seeing that this equipment is maintained and replaced as appropriate. This includes both noninvasive and invasive electrodes, as well as equipment necessary for recording, storing, and retrieving EEG and video data. It is necessary, therefore, to be familiar with the various types of equipment available and understand the most cost-effective methods necessary for the type of monitoring that will be done. Technological advances are occurring rapidly, and research on epilepsy results in observations that drive technology. For instance, there is increasing interest in the ability of high-frequency oscillations to localize epileptogenic tissue.⁸ Consequently, many telemetry vendors will upgrade equipment with an increased sampling rate that permits recording frequencies to 600 Hz or higher. Although it is the responsibility of the EEG technologists and biomedical engineering facility to maintain and repair equipment on the VEM unit, the chief neurologist must have sufficient knowledge of the monitoring needs and equipment capabilities to provide ultimate oversight.

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