Forensic Update From the Desk of Dr. Sam Goldstein

How office-based neurophysiological testing strengthens forensic opinions regarding causation while comprehensive neuropsychological evaluation defines functional consequences.

One of the greatest challenges in the forensic evaluation of mild traumatic brain injury (mTBI) and concussion has always been distinguishing between proving that an injury occurred and demonstrating how it affects an individual's daily functioning. These are related but fundamentally different forensic questions. The first concerns medical causation, namely, did the traumatic event produce measurable injury to the brain? The second concerns functional consequences, namely, how that injury has altered the person's cognitive, emotional, behavioral, vocational, and interpersonal functioning.

Historically, these questions have relied on various forms of evidence. Emergency department records, witness statements, accident reconstruction, biomechanical analyses, neurological examinations, and contemporaneous medical documentation help establish that a traumatic event occurred and that it had sufficient force to cause injury. In contrast, comprehensive neuropsychological assessment evaluates the cognitive, emotional, behavioral, educational, and vocational consequences of that injury.

Recent advances in neurophysiology are narrowing the historical gap between these two stages of forensic analysis. Emerging office-based neurophysiological technologies can provide objective physiological evidence of altered brain function, strengthening medical opinions on causation and complementing, rather than replacing, the comprehensive functional evaluations conducted by forensic neuropsychologists.

Moving Beyond Structural Imaging

The recently published review, Office-Based Neurophysiological Assessments for Diagnosis and Prognosis of Concussion, describes advances in portable electroencephalography (EEG) and Event-Related Potential (ERP) technology that now enable sophisticated neurophysiological testing in outpatient clinical settings rather than in specialized university laboratories. This is a significant advancement because clinicians can now obtain objective measurements of brain function quickly, noninvasively, and cost-effectively in an office setting. Unlike CT or conventional MRI, which primarily assess brain structure, EEG and ERP testing assess brain function. This distinction is critically important in concussion.

Modern neuroscience increasingly recognizes concussion as a physiological disturbance characterized by disrupted neuronal signaling, altered neural connectivity, impaired communication among cortical networks, metabolic dysfunction, and changes in synaptic transmission. These abnormalities often occur without visible structural lesions on conventional neuroimaging. Consequently, patients may experience persistent cognitive symptoms despite "normal" MRI or CT findings.

EEG and ERP technology address this diagnostic gap by directly measuring the brain's electrical activity and its responses to carefully standardized auditory and cognitive stimuli. The resulting data provide quantitative measures of sensory processing, attentional allocation, cognitive efficiency, processing speed, working memory, executive control, and neural communication across cortical regions.

Objective Biomarkers of Brain Dysfunction

The reviewed research demonstrates that abnormalities in ERP components, including P50, N100, P200, P300, N400, and other latency and amplitude measures, are frequently observed after concussion. Importantly, many of these abnormalities persist long after acute symptoms would typically resolve. An ERP is a measurable electrical response of the brain, recorded with EEG, that occurs in response to a specific sensory, cognitive, or motor event. For example, seeing a picture, hearing a tone, recognizing a word, or detecting an unexpected stimulus can produce ERPs. A useful distinction is: Evoked potentials (EPs) are often associated with relatively early sensory pathway responses, whereas ERPs can include later responses reflecting processes such as attention, recognition, memory, and decision-making.

Among the most intriguing findings is the growing evidence on the P50 sensory gating response. This electrophysiological marker reflects the brain's ability to filter out redundant sensory information. Deficits in sensory gating have been linked to inefficient cortical processing and may help explain why many patients report cognitive overload, distractibility, slowed thinking, and difficulty functioning in busy environments, even when neuroimaging studies are normal.

Because ERP measurements are objective physiological recordings rather than subjective symptom reports, they are largely independent of patient effort, symptom exaggeration, or reporting bias. This feature makes them particularly attractive in forensic settings, where objective corroboration is often highly valued. The review further suggests that these neurophysiological abnormalities have both diagnostic value and prognostic significance. Certain electrophysiological profiles appear to be associated with prolonged recovery trajectories, allowing clinicians to identify patients who may require closer monitoring, more intensive rehabilitation, or longer recovery periods.

Strengthening the Analysis of Medical Causation

The expanding neurophysiological literature has significant implications for forensic evaluations, where causation questions often become central to litigation. Legal causation requires more than showing that an accident occurred. The evaluator must determine whether the traumatic event produced physiological brain dysfunction consistent with the individual's current presentation. Historically, this determination relied heavily on clinical history, temporal relationships, symptom evolution, and the exclusion of alternative explanations.

Objective neurophysiological biomarkers now provide additional scientific evidence. Quantitative EEG and ERP studies can demonstrate measurable alterations in cortical processing shortly after traumatic injury. When these objective findings are interpreted alongside documented mechanisms of injury, emergency medical documentation, neurological examinations, accident reconstruction, and accepted neurological principles, they strengthen the medical opinion that observed brain dysfunction is causally related to trauma rather than to unrelated neurological or psychological conditions.

A comprehensive electrophysiological report exemplifies this integrated approach. Rather than relying solely on subjective complaints, the report synthesizes accident history, acute medical findings, neurological examination, symptom chronology, EEG analysis, ERP measures, and current neuroscience to conclude that traumatic brain injury is medically probable and directly related to the identified traumatic event.

Importantly, such reports clearly distinguish among etiology, medical causation, physiological brain dysfunction, and functional impairment. This structured framework is especially valuable in forensic settings because it separates objective evidence of injury from subsequent analyses of disability and damages.

Where Neurophysiology Ends and Forensic Neuropsychology Begins

Although objective neurophysiological testing substantially strengthens the analysis of causation, it represents only the beginning of a comprehensive forensic evaluation. My role as a forensic neuropsychologist differs fundamentally from that of neurophysiological testing.

EEG and ERP technology may objectively demonstrate that traumatic injury has altered brain function. However, these physiological findings alone cannot determine how those abnormalities affect an individual's capacity to function in everyday life. They cannot fully explain whether a person can return to work, complete complex academic tasks, manage finances independently, maintain interpersonal relationships, regulate emotions, or safely perform occupational responsibilities.

That is where comprehensive forensic neuropsychological assessment becomes indispensable. A thorough forensic evaluation integrates extensive clinical interviewing, medical record review, educational and occupational history, standardized neuropsychological testing, psychological assessment, performance validity testing, collateral interviews, behavioral observations, symptom validity measures, and functional history. Together, these data answer questions that electrophysiological testing alone cannot.

For example:

• Has sustained attention declined?
• Is new learning impaired?
• Has processing speed slowed?
• Are executive functions less efficient?
• Has emotional regulation deteriorated?
• Has vocational capacity changed?
• Are interpersonal relationships suffering?
• What accommodations, treatment, rehabilitation, or future care will likely be necessary?

These questions address functional consequences, not merely physiological abnormalities.

Complementary Rather Than Competitive Technologies

The distinction is analogous to orthopedic medicine. An MRI may objectively demonstrate a torn anterior cruciate ligament, thereby establishing the presence of a structural injury. Functional evaluation then determines whether the individual can walk, climb stairs, return to employment, participate in sports, or resume independent daily activities. Neither assessment replaces the other.

Similarly, neurophysiological testing helps determine whether traumatic brain dysfunction exists, whereas forensic neuropsychological assessment explains what that dysfunction means for cognition, behavior, emotional functioning, educational achievement, vocational performance, independent living, and overall quality of life. These approaches are therefore complementary rather than competitive. Together, they provide a far more complete understanding of traumatic brain injury than either discipline could alone.

Looking Toward the Future

Objective neurophysiological evidence may also help resolve one of the longstanding controversies in concussion litigation, namely the frequent absence of abnormalities on conventional structural imaging. Many individuals with persistent post-concussive symptoms have normal CT and MRI findings despite ongoing cognitive complaints. EEG and ERP testing offer another scientifically grounded method for documenting altered neural functioning that might otherwise go undetected.

The growing literature extends beyond concussion itself. Research on ERP markers in traumatic brain injury has demonstrated measurable alterations in cortical processing, particularly in early sensory responses such as the P50 component. Additional work on repetitive head trauma and chronic traumatic encephalopathy (CTE) suggests that electrophysiological biomarkers may eventually help identify individuals at elevated risk for later neurodegenerative disease, although longitudinal validation remains necessary before such applications become standard clinical practice.

ERPs may ultimately be particularly important in concussion evaluation because they provide an objective, physiologic measure of brain function, rather than requiring an examiner to infer the presence or absence of brain dysfunction primarily from symptoms, medical history, or neuropsychological test performance. In forensic cases, those traditional sources of evidence can lead qualified experts to different conclusions. One expert may interpret the history and neuropsychological findings as supporting a concussion or persistent cognitive impairment, while another may attribute the same findings to pre-existing conditions, psychological factors, variability in effort, or the limited specificity of neuropsychological test performance for traumatic brain injury. A validated electrophysiological biomarker could provide objective evidence of whether characteristic abnormalities in neural processing are present, potentially reducing reliance on competing interpretations of behavioral test results. In that sense, the technology could move concussion assessment away from a predominantly inferential dispute between experts and toward a question informed by reproducible physiological measurements.

The Take-Home Message

For attorneys and forensic practitioners, the message is straightforward. Objective EEG and ERP technologies provide increasingly persuasive scientific evidence regarding whether traumatic brain injury occurred and whether measurable physiological alterations in brain function are present. These findings strengthen the case for medical causation by documenting changes in neural function consistent with traumatic injury.

Comprehensive forensic neuropsychological assessment, however, remains essential for explaining the consequences of those physiological changes. It determines how altered brain function affects cognition, emotional regulation, behavior, educational performance, vocational capacity, independent living, interpersonal relationships, and future functioning. In other words, objective neurophysiology helps answer the question, "Did the trauma produce measurable brain dysfunction?" My forensic neuropsychological evaluation answers the equally important question, "What has that brain dysfunction cost this individual in everyday life?"

Together, these complementary approaches provide courts, attorneys, physicians, rehabilitation professionals, and patients with the most scientifically comprehensive understanding currently available. Objective physiology strengthens the evidence of causation, while comprehensive forensic assessment explains the human consequences. Integrating both disciplines represents the future of evidence-based forensic brain injury evaluation. ◆

References

• Bashuk, R. G., Scranton, S. L., Allen, R. S., & Cecchi, M. (2025). Office-based Neurophysiological Assessments for Diagnosis and Prognosis of Concussion. Innovations in Clinical Neuroscience, 22(7-9), 18-23.
• Marin, A., Turk, K. W., Price, A., Palumbo, R., & Budson, A. E. (2018). Event-Related Potentials as Potential Biomarkers of Traumatic Brain Injury and Chronic Traumatic Encephalopathy. Scientific poster, Department of Neurology, Boston University School of Medicine and VA Boston Healthcare System.
• Centers for Disease Control and Prevention. (2024). What Is a Concussion? https://www.cdc.gov/traumatic-brain-injury/

*Disclosure: Dr. Goldstein serves on the Scientific Advisory Board of Xenter, a company that provides equipment and services in connection with EEG+ERP assessments and receives compensation for this role.