Diagnosis

Physical ExaminationIn most cases, the diagnosis of traumatic brain injury (TBI) will be obvious. What might remain uncertain, especially early on, is the type and extent of brain damage present. Both the physical examination and special testing can help in making this clearer. Early on, the physical examination focuses on determining the depth of coma. This is done through the use of the Glasgow Coma Scale.

Table 1. Glasgow Coma Scale (GCS)

 

Range of Eye Response	Range of Verbal Response	Range of Motor Response
1. No eye opening	1. No verbal response	1. No motor response
2. Eye opening to pain	2. Incomprehensible sounds	2. Extension to pain
3. Eye opening to verbal command	3. Inappropriate words	3. Flexion to pain
4. Eyes open spontaneously	4. Confused	4. Withdrawal from pain
	5. Oriented	5. Localizing pain
		6. Obeys commands

This scale rates the patient’s response to stimulation in three different areas: moving their arms or legs, opening their eyes, and talking. One of the most important questions is to determine when a person has come out of coma. There are several different ways of defining when someone is out of coma. One is when the patient’s GCS score is 9 or above. Another would be when the patient’s eyes open by themselves. However, the most common standard used to mark the end of coma is when a patient is able to follow instructions such as to squeeze a hand. More information about coma and other forms of altered consciousness follow.

After someone has emerged from a coma, much of the focus of the physical examinations will be to determine what problems a person might have as the result of the brain injury. This would include testing all the normal functions of the body that are directly controlled by the brain such as sensing, moving, thinking and feeling.  

Tests
In addition to the physical examination, several tests can be done to help identify which parts of the brain are injured and possibly even the extent of the brain damage. The most commonly performed tests are described here.

1. Computed Tomography (CT):  CT scans are the most widely used tests after brain injury. They are essentially x-rays that have been modified so that they show a picture of the brain itself (and not just the skull like normal x-rays). They are quick and easy to obtain and will often show potentially dangerous conditions. However, it is important to realize that CT scans do not show all of the brain damage. In particular, the most important and common type of injury after TBI, diffuse axonal injury (DAI), is not often seen on a CT scan. For this reason, CT scans are not necessarily very reliable in determining the true extent of brain injury.
2. Magnetic Resonance Imaging (MRI):  MRI scans provide much more detail about the brain than do CT scans. In particular, injuries that might not show up on a CT scan will often be visible on an MRI. However, MRIs are much harder to obtain than CT scans. They take longer and obtaining them is difficult to impossible if the patient is connected to any type of metal equipment. Even though MRIs show more information than CT scans, their ability to predict outcome after TBI is still limited (see Section IX. Prognosis).
3. Electroencephalography (EEG):  EEGs measure the electrical activity of the brain. The test is non-invasive and simply involves the placement of recording electrodes on a person’s scalp. EEGs are not always obtained after TBI. They are most useful when there is a concern that a patient might have had or is at risk of having seizures. They are also sometimes used for patients who are still unconscious or just regaining consciousness to see if he might be having subtle seizures (called sub-clinical seizures) that are slowing down recovery. EEGs have very little ability to predict outcome after a TBI.
4. Evoked Potentials (EP):  While EEGs measure the brain’s natural or spontaneous electrical activity, evoked potentials measure the brain’s electrical activity in response to stimulation. This stimulation can be visual (visual evoked potentials), sounds (auditory evoked potentials) or electrical stimuli to the skin (somatosensory evoked potentials). The results can provide information about the nerves in the body as well as the brain’s ability to detect the stimulation. This test is most useful in patients who are still unconscious; there is evidence that, in these situations, the test can provide some information about future outcome.
5. Magnetic Resonance Spectroscopy (MRS):  This test, which uses the same equipment as normal MRIs, measures the concentration of various chemicals in the brain. Although still primarily used for research, it is possible that it will be more useful in the future, especially in helping to predict outcome.
6. Functional neuroimaging:  This category includes such tests as functional MRI (fMRI), single photon computed tomography (SPECT) and positron emission tomography (PET). These tests are primarily used in research and are not often used in the actual clinical care of patients.