Neuromagnetic assessment of pathophysiologic brain activity induced by minor head trauma

BACKGROUND AND PURPOSE: Patients with mild traumatic brain injury (TBI) oft en show significant neuropsychological dysfunction despite the absence of a bnormalities on traditional neuroradiologic examinations or EEG, Our object ive was to determine if magnetic source imaging (MSI), using a combination of MR imaging and magnetoencephalography (MEG), is more sensitive than EEG and MR imaging in providing objective evidence of minor brain injury. METHODS: Four subject groups were evaluated with MR, MSI, and EEG, Group A consisted of 20 neurologically normal control subjects without histories of head trauma, Group B consisted of 10 subjects with histories of mild head trauma but complete recovery, Group C consisted of 20 subjects with histori es of mild head injury and persistent postconcussive symptoms. The 15 subje cts included in group D underwent repeat examinations at an interval of 2 t o 4 months. RESULTS: No MR abnormalities were seen in the normal control group or the a symptomatic group, but five (20%) of the patients with persistent postconcu ssive symptoms had abnormal MR findings. EEG was abnormal for one subject ( 5%) from the normal control group, one (10%) from the asymptomatic group, a nd five (20%) from the group with persistent postconcussive symptoms, MSI w as abnormal for one subject (5%) from the normal control group, one (10%) f rom the asymptomatic group, and 13 (65%) from the group with persistent pos tconcussive symptoms, There was a direct correlation between symptom resolu tion and MSI findings for the symptomatic head trauma group, CONCLUSION: MSI indicated brain dysfunction in significantly more patients with postconcussive symptoms than either EEG or MR imaging (P <.01). The pr esence of excessive abnormal low-frequency magnetic activity provides objec tive evidence of brain injury in patients with postconcussive syndromes and correlates well with the degree of symptomatic recovery.