The BrainScopeTM , (BrainScope Company, Inc., St. Louis, MO) is a handheld EEG monitoring device which acquires data from five frontal head leads instead of the usual 21 electrodes of the Standard International 10/20 system. The BrainScope device is currently in a research and development phase. The current research protocol requires data to be collected for a ten (10) minute period of time. The device indicates whether the patient’s EEG exhibits “normal” or “abnormal” features. If the device indicates “abnormal”, a further assessment is made as to whether the abnormalities are “global” or “lateralized”. For example, a patient with an acute left subdural hematoma would be expected to be: abnormal, lateralized. Such classifications are made based on an automatic algorithm which uses quantitative EEG features combined with wavelet analysis to recognize patterns in electrical signals. The current, prototype device requires the use of a laptop to perform off-line analyses. In future models of the BrainScope device, the analysis will be internalized so that a bedside result can be immediately available to clinicians for interpretation. Future models will also incorporate alerts for non-convulsive status, burst suppression (common in drug overdoses where respiratory compromise is imminent) and brainstem dysfunction.
The current research version of the BrainScope has been used at Washington University in 225 patients. The device provides the normal/abnormal reading which has been correlated with clinical outcomes. The sensitivity for determining abnormal in our subset of patients was 93%. The specificity for determining abnormal was 95%. These numbers were obtained by having cases reviewed by a neurologist at Washington University specializing in EEGs. After reviewing the clinical scenario, and in some cases the hospital acquired standard EEG, he determined that the patients that received an abnormal BrainScope reading would have been determined to be abnormal on standard EEG testing.
The BrainScope device will be most useful when it finds a normal EEG. For example, in one of our research subjects, the patient presented with left arm weakness after a fall. The CT scan or the head and cervical spine xrays were normal. The BrainScope finding was also normal which prompted the clinician to investigate extracranial causes of the patient’s weakness. The patient was subsequently sent for a Magnetic Resonance Imaging (MRI) study of the neck which revealed a central cord contusion. Normal BrainScope results have also been found in the study in patients with myoclonus and pseudoseizures.
When the BrainScope device results in an “abnormal” reading, it is not always clear if the anormality was caused by the current illness. For example, a patient with a past medical history of an old stroke may produce an abnormal reading on the BrainScope device and not be indicative of new pathology. The same would be true for standard EEGs where the brain’s electrical signals may return to normal after a stroke, but not necessarily so. This “false-positive” result may be a limitation of the device for future applications.
In conclusion, while the BrainScope device is still in research and development, it can be a useful tool for the emergency department in the near future. The device may play a role in triaging patients where if the BrainScope results are normal, there is a high likelihood that the patient does not have significant brain pathology. The device is intriguing because it is a functional test and has given an “abnormal” reading in several patients with concussions where conventional imaging was normal. This may be important since concussions are often missed in the ED. Although still in the development phase, the BrainScope may become a useful adjunct to the conventional imaging available for ED patients.
Dr. Naunheim is an associate professor at Washington University School of Medicine in St. Louise, MO, and has done extensive work with BrainScope since 2005.