Patients Ask: Can an EEG Show Brain Damage?

model of the human brain

Some patients may know what an EEG is used for, but even fewer know the extent of its neurodiagnostic capabilities. An EEG is a diagnostic tool that provides information which, along with additional tests, assists the doctor form the diagnosis for the patient.

An EEG may show an area of the brain that reveals unexpected activity which would allow the doctor to order additional tests to investigate the cause. EEG is one of many tests performed to provide information to the doctor to assist in forming a diagnosis.

Today we hope to answer questions that patients often wonder about by looking at their top 3 concerns regarding the brain and EEG:


  • Can an EEG show brain damage?

  • Can an EEG detect a brain tumor?

  • Can an EEG detect brain death?


To shed some light on how powerful a neurodiagnostic tool EEG really is, let’s explore its effectiveness. Keep in mind that the EEG by itself would not conclusively determine any of these diagnoses.

Can an EEG Show Brain Damage?

Since an electroencephalogram reads brain waves, it is generally true that an EEG can show technologists and doctors signs of brain damage. However, the injuries covered under the blanket term “brain damage” are extensive. There are other factors that play a role in the discoverability of brain damage, such as the location of the injury and its severity. 

Brain damage can include but is not limited to, concussions, hemorrhaging (bleeding), and contusions. 

Concussions can occur even when wearing a helmet or with no visible signs of damage. An EEG is recommended soon after a concussion because the quicker a check is done, the higher the chance of detecting damage. Abnormalities seen in the data can provide clues for technologists, but brains are resilient and may return to relatively normal functioning quickly, making it harder to find signs of abnormalities.

Brain contusions are more obvious to the naked eye. There may be bruising, swelling, or open wounds with bleeding. While it may appear evident that there is brain damage, an EEG can be used to determine the severity. Seizure activity detection during this time, convulsive or subclinical, does not bode well for the patient’s chance at recovery.

Typically the lower the patient’s level of consciousness, the more extensive the brain damage.

football player wearing a helmet

Can an EEG detect a brain tumor?

Yes, an EEG can help detect brain tumors. Similar to brain injuries, the detectability depends on its size, location, and type. For example, tumors can be more easily found in the temporal lobe but are more difficult to find in the parietal lobe. This is again determined by the presence of abnormalities in the EEG data. These abnormalities tend to be confined to the temporal lobe part of the brain even if the tumor is physically present in a different part of the brain. Fast-growing malignant tumors can be more detectable than their slower, more benign counterparts.

Can an EEG detect brain death?

Depending on your definition of brain death – yes. An EEG can help determine if a patient’s brain is no longer functioning. 

Brain death has been defined as the “complete loss of brain function, including involuntary activity necessary to sustain life.” It may mean different things to different people, depending on your religious or social beliefs. 

An EEG isn’t necessary in the United States to determine brain death if the patient is showing the proper symptoms and medical conditions that can cause symptoms similar to brain death have been ruled out. Regardless, an EEG may be used to provide additional evidence of brain death. It is easier said than done.

According to the American Clinical Neurophysiology Society EEG brain death criteria, “Electrocerebral inactivity (ECI) or electrocerebral silence (ECS) is defined as no EEG activity over 2 uV when recording from scalp electrode pairs 10 or more cm apart with interelectrode impedances under 10,000 Ohms (10 KOhms), but over 100 Ohms.” 

The ICU is an electrically “noisy” place and acquiring a clean EEG with minimal artifact will be challenging, especially when an EKG or EMG is also present in addition to the other medical equipment in the room. To add further adversity, some patients who technically meet the criteria for brain death can still show electrocerebral activity up to three days later. 

an intensive care unit

Luckily, EEG technology is also able to provide more understanding as to the effects of an injury and a patient’s progress towards improvement over time. As a species, we still have much to learn about the brain.

At Lifelines Neuro, we make EEG equipment and software to supply hospitals, neurology clinics, and providers the tools they need to care for their patients. We helped pioneer the first ambulatory EEG amplifiers in the world, and imagine a world where neurodiagnostics can be accessed without boundaries. If you would like to learn more about what our particular EEG devices are capable of, schedule a chat with a member of our sales team, who are experienced, Registered EEG Technologists.