Video-EEG Monitoring in Childhood Epilepsy M. Mohammadi MD Professor of Pediatric Neurology (TUMS) Former Fellow, Clinical Paediatric Neurophysiology, University College of London, GOS Hospital, London, UK. November 2006

Major Queries

Advantages of the Outpatient EEG Study? The outpatient "routine" EEG is the most commonly performed diagnostic procedure in the individual who has a suspected seizure disorder. For most patients, the routine EEG is sufficient for physicians to classify seizure types and initiate medical therapy.

Advantages of the Outpatient EEG Study? The neurologic history and examination and routine EEG indicate the probable seizure diagnosis in most patients. The outpatient sleeping and waking EEG study usually identifies interictal EEG activity, in patients with seizure disorders. Interictal epileptiform activity may be satisfactory in many instances to classify the seizure types.

Limitations of the Outpatient EEG Study? The brief duration of the EEG recordings may fail to identify epileptiform activity. The routine EEG may be repetitively normal and identify no epileptiform discharges.

Limitations of the Outpatient EEG Study? EEG may record nonspecific and nonepileptiform findings that may incorrectly suggest the diagnosis of epilepsy. Interictal EEG alone may lead to errors in diagnostic classification that result in ineffective treatment strategies. The interictal EEG pattern also may be an unreliable indicator of the classification of seizure type.

TYPES Outpatient vs. Inpatient Settings Ambulatory vs. Non-ambulatory EEG monitoring Analog vs. computer assisted digital video EEG monitoring

IMPLICATIONS Diagnosis of a seizure disorder Classification of seizure types Evaluation of precipitating factors Quantification of seizures Surgical localization

Does the Patient Have Epilepsy? Approximately 20% of patients who are referred to comprehensive epilepsy programs because of medically refractory "seizures" do not have epilepsy. Physiological and psychological disorders may cause diagnostic confusion with epilepsy and result in patients being inappropriately treated with antiepileptic medications. A normal scalp-recorded EEG during and after a "seizure" in an unresponsive patient virtually excludes an epileptic clinical event.

Nonepileptic Phenomena Confused with Epilepsy Autonomic Disorders Cardiac Arrhythmias Cerebrovascular Disease Drug Toxicity Metabolic Disorders Migraine Orthostatic Hypotension Valvular Heart Disease Vasovagal Syncope Vestibular Disorders Shuddering attacks Breath Holding Spells Sleep Disorders Day Dreaming GER

Nonepileptic Psychologic Phenomena Confused with Epilepsy Anxiety Depression Panic attacks Psychogenic seizures Psychosis Somatoform disorders Rage attacks

What is the Seizure Type? In one study, the diagnostic classification was altered in 19 (47.5%) of 40 patients by inpatient video-EEG monitoring. Studies also disclosed previously unrecognized seizures in 20% of patients monitored. Improved seizure control can occur in 60% to 70% of patients as a result of videoEEG monitoring. Prolonged EEG recordings are clearly superior to the routine EEG in detecting seizures (50%-70% with long-term monitoring compared with 2.5%-7% with routine EEG studies).

Is the Patient a Candidate for Epilepsy Surgery? The most effective treatment of intractable partial epilepsy is resection of the epileptic brain tissue. Of the nearly 800,000 patients with partial epilepsy in the United States, 45% have medically refractory seizure disorders. The most commonly performed and most effective procedure for treating intractable epilepsy is an anterior temporal lobectomy, after which nearly 60% of patients are seizure-free and 90% are substantially improved.

Is the Patient a Candidate for Epilepsy Surgery? The surgically remediable epileptic syndromes include medial temporal lobe epilepsy and partial epilepsy related to lesional pathology, eg, a primary brain tumor. Approximately 80% of patients with medial temporal lobe epilepsy associated with mesial temporal sclerosis have an excellent outcome.

Is the Patient a Candidate for Epilepsy Surgery? Confirmation of the localization of the epileptogenic area is critical to identifying appropriate candidates. An inability to localize the epileptogenic area sufficiently with noninvasive monitoring is an indication for long-term intracranial EEG monitoring, eg, subdural grid or implanted depth electrodes.

Limitations of Video-EEG Monitoring? Needs Special Training Technicians Interpretators Maintaining Personnel Logistically Difficult (Wi Fi Cordless Technology) Needs Patients’ Cooperation Needs Interdisciplinary Approach