Bedside EEG

Determining the Medical Necessity of a Routine Bedside EEG:
By Charles Wang M.D. – Neurologist– Chicago, IL

Accurately assessing a patient’s mental status and/or potential for seizures is a critical factor in deciding the best course of action in terms of treatment, referral to a specialist or transfer to a higher-level facility. Many times, a 30-60 minute bedside routine EEG can be the determining element, especially when a patient is cannot communicate or accurately describe his/her medical symptoms.   A routine EEG test is medically necessary:

  1. To help identify the etiology (cause) of a patient’s altered mental status
  2. To determine whether seizure activity is present, and to identify the type of seizure
  3. To further define the prognosis of comatose patients

How can an EEG help in the diagnosis of mental status?

An EEG test provides an objective measure of brain activity. Patients with an encephalopathy (brain disease or injury) typically have an abnormal EEG result, characterized by diffuse slowing; clinically observed as a notable change in mental status. Other times the EEG test abnormalities are very specific and can lead to a clear diagnosis – especially in cases of hepatic encephalopathy, intoxication, Creutzfield-Jakob disease, acute lesions such as stroke, and subclinical status epilepticus. Even a normal EEG test result can be extremely helpful in making an accurate diagnosis, and to rule out other neurological symptoms.  A normal EEG result can be expected in patients suffering from generalized depression, agitation, or confusion, not linked to a specific brain disorder.

How can an EEG be used to diagnose and treat seizures?

An EEG is the best diagnostic tool available to diagnosis seizures. An EEG can pinpoint the source and frequency of electrical activity within the brain. Based on the findings of the EEG, the most effective anticonvulsant (anti-seizure) medication can be prescribed immediately. Typically, a follow-up outpatient EEG is recommended after discharge to verify effectiveness of the medications in minimizing seizures which may not otherwise be observed or detected.

How is an EEG used to evaluate the prognosis of comatose patients?

Physicians can use an EEG to predict the outcomes of patients who decline into a coma following cardiac arrest or head injury. An EEG can also be used to determine electrocerebral silence (brain death). Finally, an EEG can be used in comatose patients to rule out non-convulsive status epilepticus, which can be potentially treatable and reversible.

When is an outpatient EEG recommended in place of a routine bedside EEG?

There are three situations where an outpatient EEG is recommended instead of a bedside EEG:

  1. When a patient is discharged from the hospital in a safe, stable and coherent condition
  2. When a patient’s seizure symptoms have stopped, and the EEG can be completed within 24 hours of discharge
  3. When a patient regains consciousness and is no longer in a comatose state