While we are now used to seeing images of people with COVID-19 on ventilators because of acute lung illnesses, debilitating and even deadly neurological illnesses may be affecting far more people with the novel severe acute respiratory syndrome coronavirus 2(SARS-CoV-2). COVID-19 causes neurological injury in 1 out of 7 patients hospitalized with the infection.1
EEG remains the most widely used investigation when epilepsy is suspected, but how and when does one use EEG in the diagnosis of epilepsy?
When not to use EEG to diagnose epilepsy
Epilepsy diagnosis is not always straightforward. Diagnosis depends on precise history taking, general medical and neurological examination, and prudent use of diagnostic tools. Depending on symptoms and examination a physician may order a variety of investigations including EEG, QEEG, ECG (to rule out heart problems like syncope), imaging techniques (including MRI, CT scan, and PET scan), lumbar puncture, prolactin study, blood tests and neuropsychological screening.
Routine electroencephalography (EEG) suffers from the same problem as a standard 12 lead electrocardiogram (ECG): it is limited in time. A standard ECG captures 10 seconds of the heart’s electrical activity while a standard EEG captures perhaps 10 to 20 minutes of the brain’s electrical activity. While these studies have their respective places in diagnostic medicine, they are limited in their ability to detect sporadic events such as paroxysmal atrial fibrillation in the former case, or a seizure event in the latter. Just as cardiologists have adopted Holter monitoring into clinical practice, so too have neurologists turned to ambulatory EEG for certain diagnostic purposes. We discuss the clinical indications for ambulatory EEG.
Reusable electroencephalographic (EEG) electrodes are under investigation as a potential source of hospital-acquired infection (HAI). Because the traditional EEG procedure involves abrasion of the skin, EEG electrodes are considered semi-critical devices, which require sterilization or high-level disinfection. Inadequately cleaned reusable cup electrodes may harbor bacteria, blood, and microscopic epithelial cells. Indeed, a break in the skin that occurs when applying EEG scalp electrodes creates the risk of infection from blood-borne pathogens such as HIV, Hepatitis-C, and Creutzfeldt-Jacob Disease.