Comprehensive Video EEG monitoring JWM Neurology Kate Kobza, MD August 2006

Why do we need it?

Limitations of routine EEG:  Limited sampling An EEG is a sampling of brain activity occurring at the time of the recording An EEG is a sampling of brain activity occurring at the time of the recording Seizures and spells are paroxysmal and may be missed on a short study Seizures and spells are paroxysmal and may be missed on a short study  No video to correlate patient behavior with suspicious EEG changes

Limitations of routine EEG:  Yield of a single routine scalp EEG is 50%  Certain artifacts and normal variants can be confused with epileptiform discharges  Some EEG abnormalities do not have a close correlation with clinical seizures

Limitations of routine EEG:  Pathophysiologically – epileptic seizures are characterized by an excessive, disorderly, neuronal discharge  An EEG study may disclose epileptiform abnormalities which have a high correlation with occurrence of epileptic seizures  The only way to definitively prove epilepsy is to record a seizure

What does a video EEG study consist of?

Methodology  EEG electrodes are attached to the scalp with glue  ECG electrodes are placed  Patient is moved to a room with video monitoring  Patient and family are given an alarm to push with any spell  Trained nurses and staff respond to alarms to observe patient and treat if necessary

Methodology  Miscellaneous options: Antiepileptic medications may be discontinued or decreased Antiepileptic medications may be discontinued or decreased Known inducers of events may be performed Known inducers of events may be performed Sleep deprivationSleep deprivation Suggestion (important in nonepileptic events)Suggestion (important in nonepileptic events) Extra electrodes may be added Extra electrodes may be added SphenoidalSphenoidal Foramen ovaleForamen ovale

Methodology  Multi-channel long term EEG recording with split screen video recording  Digital storage of EEG and video data that can be reviewed later  Performed under close monitoring of trained technologists and nurses  Study is reviewed by a trained neurologist or epileptologist

Outpatient settings  Represents a partially controlled environment  Useful for: Minor or non-convulsive seizures Minor or non-convulsive seizures Diagnostic purposes only Diagnostic purposes only  Benefits: Less costly Less costly  Drawbacks: Invasive electrodes not possible Invasive electrodes not possible No medication withdrawal possible No medication withdrawal possible

Inpatient settings  Completely controlled environment  Useful for: Major or convulsive seizures Major or convulsive seizures Medication withdrawal possible Medication withdrawal possible  Benefits: Other tests: Blood sugars, SPECT possible Other tests: Blood sugars, SPECT possible Inducers can be used, if present Inducers can be used, if present Invasive electrode monitoring possible Invasive electrode monitoring possible Intracranial EEG possible Intracranial EEG possible  Drawbacks: Expensive Expensive

Who orders a study? What patients might be candidates?

 Primarily neurologists order video EEG studies  Video EEG can be ordered on infants, children, and adults

Indications for video EEG monitoring

Common indications:  Follow up of borderline or nonconclusive routine EEGs  Diagnosis of recurrent spells  Classification of seizure type  Quantification of interictal epileptiform activity  Preoperative evaluation of surgical candidates  Evaluation of patient in coma as treatments for status epilepticus

Follow-up borderline EEG  Allows for prolonged collection of digital EEG  Areas of uncertainty (i.e. artifact vs. abnormality) can be correlated with video material for clarification

Aids in diagnosis of spells:  Causes other than epileptic seizures: Syncope Syncope Sleep apnea Sleep apnea Periodic movements of sleep Periodic movements of sleep Non-epileptic seizures Non-epileptic seizures Breath-holding spells Breath-holding spells Migraine Migraine

Other uses:  Characterization or any repetitive or stereotyped behavior autonomic changes in infants repetitive behaviors in the ICU setting unexplained nocturnal events

Characterization of seizures  Accurate diagnosis and classification of seizures is essential for proper therapeutic intervention  Medication choices are driven by seizure classification

Classification of seizure types  Generalized Absence Absence Generalized tonic, clonic, or atonic Generalized tonic, clonic, or atonic Myoclonic Myoclonic  Partial onset Simple or complex Simple or complex Secondary generalization Secondary generalization  Non epileptic

Examples of seizure types  Complex partial  Generalized tonic-clonic  Nonepileptic

Complex partial

Generalized tonic-clonic

Nonepileptic

Diagnosis of non-epileptic events: Pseudoseizures  Studies 1 have shown that 22% of patients with medically intractable seizures studied by video EEG monitoring had nonepileptic events  Approximately 1/3 of patients studied at video monitoring centers have nonepileptic events  The majority of patients with nonepileptic events have been inappropriately treated with antiepileptic medications for years  1 Matson et al.

Nonepileptic events  Video EEG monitoring provides evidence to support medication choices Allows safe discontinuation of antiepileptic drugsAllows safe discontinuation of antiepileptic drugs  Information can be used when discussing a diagnosis of pseudoseizure with patients Many patients are relieved by diagnosisMany patients are relieved by diagnosis Many others are doubtful as they have been told for many years that they have epilepsyMany others are doubtful as they have been told for many years that they have epilepsy  This is used to as a treatment modality

Nonepileptic events  Majority of patients with nonepileptic events also experience epileptic seizures  Video EEG can quantitate frequency of each type Aids in education of family members about clinical differences Aids in education of family members about clinical differences Avoid abuse of resourcesAvoid abuse of resources Limit health provider callsLimit health provider calls Avoid abuse (overuse) of antiepileptic drugsAvoid abuse (overuse) of antiepileptic drugs

Quantification of interictal epileptiform activity  Quantify the number of seizures per day  Helpful for: Absence seizures Absence seizures Helpful in decision to stop medicationsHelpful in decision to stop medications Nonconvulsive seizures Nonconvulsive seizures Document efficacy of suppressive medications Document efficacy of suppressive medications

Things we don’t like to hear as a passenger.

Localization of epileptogenic focus  Useful in patients with intractable epilepsy as part of a presurgical evaluation  Focus of study is to correlate EEG findings with lesion on MRI

Preoperative evaluation of surgical candidates  Usually for intractable temporal or extra-temporal epilepsy  Can be performed with sphenoidal or foramen ovale electrodes  Subdural grid placements can be used in conjunction with a neurosurgeon

Evaluation of patient in coma as treatments for status epilepticus

Status epilepticus  Patients often demonstate continued subclinical seizure discharges after the clinical behaviors have cease  EEG monitoring is necessary in all patients in drug induced coma as a treatment for status epilepticus Need to document burst suppression pattern induced by medsNeed to document burst suppression pattern induced by meds

Long term EEG monitoring: Other uses  Intraoperatively: Functional stimulation during resections Functional stimulation during resections Intraoperative surface EEG monitoring Intraoperative surface EEG monitoring carotid endarterectomycarotid endarterectomy

Other monitoring modalities:  Digital ambulatory monitoring Patient wears a digital EEG recorder home Patient wears a digital EEG recorder home Records 24 hours of digital EEG Records 24 hours of digital EEG Patient records symptoms in a diary Patient records symptoms in a diary

In Summary: Video EEG monitoring  Captured 50-96% of epileptic and nonepileptic events (Legatt AD and Ebersole JS, 1998).  Established a diagnosis in 88-95% (Legatt AD and Ebersole JS, 1998).  Improved outcome in 30-74% of patients (Legatt AD and Ebersole JS, 1998).

St. Vincent Hospital  Routine EEG – outpatient or inpatient  Ambulatory EEG – 24 hour outpatient study  Video EEG monitoring 3 adult rooms (hardwired) 3 adult rooms (hardwired) 1 portable unit (adult or pediatric) 1 portable unit (adult or pediatric) 1 ICU monitoring room 1 ICU monitoring room

A neurologist