This ERP technology is ready for prime time in TBI. The peer review and publication process is how science moves forward, and the use of ERP for TBI evaluations is now accepted by the peer review process, but not the EEG/qEEG yet fully, and definitely not EEG based discriminants for TBI, which are now counseled against in the peer reviewed literature.

Jay

ABSTRACT

Traumatic brain injuries are often associated with damage to sensory and cognitive processing pathways. Because evoked potentials (EPs) and event-related potentials (ERPs) are generated by neuronal activity, they are useful for assessing the integrity of neural processing capabilities in patients with traumatic brain injury (TBI). This review of somatosensory, auditory and visual ERPs in assessments of TBI patients is provided with the hope that it will be of interest to clinicians and researchers who conduct or interpret electrophysiological evaluations of this population. Because this article reviews ERP studies conducted in three different sensory modalities, involving patients with a wide range of TBI severity ratings and circumstances, it is dif!cult to provide a coherent summary of !ndings. However, some general trends emerge that give rise to the following observations and recommendations:

1) bilateral absence of somatosensory evoked potentials (SEPs) is often associated with poor clinical prognosis and outcome;

2) the presence of normal ERPs does not guarantee favorable outcome;

3) ERPs evoked by a variety of sensory stimuli should be used to evaluate TBI patients, especially those with severe injuries;

4) time since onset of injury should be taken into account when conducting ERP evaluations of TBI patients or interpreting results;

5) because sensory de!cits (e.g., vision impairment or hearing loss) affect ERP results, tests of peripheral sensory integrity should be conducted in conjunction with ERP recordings; and

6) patients’ state of consciousness, physical and cognitive abilities to respond and follow directions should be considered when conducting or interpreting ERP evaluations.

1. Introduction
Event-related potentials (ERPs) are types of electroencephalographic (EEG) recordings used to evaluate patients who experienced traumatic brain injury (TBI). “Potential” refers to the electrical potential difference (or voltage) between two points, de!ned as the electrical force that would drive an electric current between those points. In the case of ERPs and EEG, the “two points” are electrodes attached to the patient’s head that record voltages generated by neural activity from populations of neurons within a sensory pathway. These voltage changes result from movement of ions (e.g., K+, Ca++, Na+, and Cl?) and other charged particles within and between neurons in the brain. Evoked potentials (EPs), a subset of ERPs, are elicited by presenting stimuli (for example, light “ashes, sounds,electric shocks, images, words, odors or “avors) to the patient, then using a computer to average the EEG activity that is time-locked to the stimuli.

Traumatic brain injuries are often associated with damage to sensory organs and pathways. Because EPs are generated by neuronal activity, they are useful for assessing neural processing capabilities in TBI patients. Furthermore, EPs can provide information about the integrity of sensory pathways, including their ef!ciency for conducting input from the periphery to the central nervous system (CNS), the ability of CNS structures to process sensory input, and the ability of speci!c sensory systems to perceive and integrate stimuli. EPs and ERPs can also provide information about higher-order CNS processing, such as classi!cation and categorization of multi-modality stimuli, and decoding/interpretation of language, images and other complex stimuli. For TBI patients, EPs can provide valuable information related to the severity of injury and its impact on neuronal pathways. ERPs can
also provide information about patients’ states of consciousness and cognitive functions. In fact, one of the driving interests of using ERPs in TBI research is the possibility of predicting outcomes of these patients.

Read Full article – Electrophysiological assessments of cognition and sensory processing in TBI: Applications for diagnosis, prognosis and rehabilitation

Folmer, R.L., et al., Electrophysiological assessments of cognition and sensory processing in TBI: Applications for
diagnosis, prognosis and rehabilitation, Int. J. Psychophysiol. (2011), doi:10.1016/j.ijpsycho.2011.03.005

Robert L. Folmer a,b,!, Curtis J. Billings a,b, Anna C. Diedesch-Rouse a, Frederick J. Gallun a,b, Henry L. Lew c,d

a National Center for Rehabilitative Auditory Research, Portland VA Medical Center, Portland, OR, USA
b Department of Otolaryngology, Oregon Health & Science University, Portland, OR, USA
c Defense and Veterans Brain Injury Center (DVBIC), USA
d Department of Physical Medicine and Rehabilitation, Virginia Commonwealth University (VCU) School of Medicine, Richmond, VA, USA

Article history:
Received 29 September 2010
Received in revised form 4 March 2011
Accepted 8 March 2011

International Journal of Psychophysiology
journal homepage: www.el sevier.com/ locate/ i jpsycho

No traditional structural neuroimaging was able to see this damage (like CT or routine MRI). The NY Times recently reported on soldiers injuries evading the M.R.I and CT Scans

The brain areas involved included the orbital surfaces of the frontal lobe and the temporal areas.

These results point to the need for a clinical diagnosis, not a reliance on any given technology to answer the clinical question.

The endocrine changes from supposed pituitary injury, and the presence of micro-emboli due to pressure wave impact on the thorax that are reported in blast injury is not at all dismissible with these findings.

How can we live a fuller and healthier lifestyle as we get older? Perhaps keeping our body and brain engaged can help. That seems to be the case in Japan where the number of centegenarians is greater than 20,000.

THE ART OF AGING:THE LIMITLESS POTENTIAL OF THE BRAIN introduces a number of these “super-seniors” who lead healthy lives at nearly 100-years-old and, through them,searches for the “keys” to living a healthy and vital life regardless of age.

Click here to view the embedded video.

We are honored to welcome several high-profile speakers, including:

• Personalized Medicine in the Age of Technology - Vilayanur S. Ramachandran, MD, PhD; Director of the Center for Brain and Cognition and Professor with the Psychology Department and Neurosciences Program at the University of California, San Diego, and Adjunct Professor of Biology at the Salk Institute

• Regeneration and Stress at Work: Strategies for Improved Employee Health - Tores Theorell, MD, PhD; Professor Emeritus at the University of Stockholm, Sweden

• An Overview of Mind Body Healing - C. Norman Shealy, MD, PhD; founder of the American Holistic Medical Association, and past president of the International Society for the Study of Subtle Energies and Energy Medicine

• Neurotherapy in the Treatment of Traumatic Brain Injury: A Physiological Hypothesis – Paul Rapp, PhD; Professor in the Department of Military and Emergency Medicine at the Uniformed Services University of the Health Sciences

The Boy with the Incredible Brain

This is the breathtaking story of Daniel Tammet. A twenty-something with extraordinary mental abilities, Daniel is one of the world’s few savants. He can do calculations to 100 decimal places in his head, and learn a language in a week. This documentary follows Daniel as he travels to America to meet the scientists who are convinced he may hold the key to unlocking similar abilities in everyone.


Secrets of the Mind

Click here to view the embedded video.

Phantoms in the Brain: V. S. Ramchandran from T.E.D.

This is a 25 minute video of Ramchandran’s talk presented at TED.

Phantoms in the Brain Part 1 Full Documentary in parts on YouTube


Phantoms in the Brain Part 2

I put two and two together, and figured he had a big likelihood of a subdural hematoma putting pressure on his language and speech motor areas on the left frontal dorso-lateral area. Subdurals are common in elderly individuals who fall and hit their head, and need to be ruled out if there is a recurrent or persistent complaint following TBI. He complained of headaches which were unrelenting, but they had not scanned him even with his returns to their medical plan 2-3 times in the weeks following the fall.

I figured it would be impossible for him to tell the ER what he needed (as CT or MRI to look for the subdural), so I wrote him an e-mail summary of the findings and pertinent history for my mother to print out and take with them. I sent my elderly father and mother off to the ER, and my dad didn’t want to go because he figured he would miss football games. By Sunday noon, he was in the neurosurgeon’s hands, and they removed a LARGE subdural of 150 Ccs. He is now fine, with all his language skills returned. He even caught the late game on the tube.

After the surgical prep my mother called, and I was asked to “call the doctor”, and I rang in on the neurosurgeon’s headset when he had my dad’s head open. It was a pretty routine evacuation of a subdural, but they were very happy to be handed the case on a platter with the e-mail. He said he was surprised at the “diagnosis” done via telephone and gut instinct, but even more by the accuracy of the localization of the subdural to the left dorso-lateral frontal as well as left temporal areas. The subdural was very large, and encompassed the entire area described.

I’ve had enough drama for the holidays. You would think maybe he will stop bugging me to be a doctor now.

Damage is seldom restricted to merely being exclusively either white or gray matter, and mixed findings are seen commonly.  There are studies showing the correlation of quantitative EEG findings with quantitative MRI findings that are instructive in identifying the nature of the effect on the EEG of the different types of damage.

The EEG changes following brain injury are spectrally different between white and gray matter damage, which helps when evaluating the nature of the damage with the EEG.  The white matter is a high speed relay system that innervates the cortex, both with primary sensory input relayed from the thalamus, and with cortical-cortical input via various fasciculi.

When the cortex has decreased innervation, delta content emerges, according to the IFCN’s position paper on the basic mechanisms of cerebral rhythmic EEG**.  Thus, traumatic brain injury resulting in white matter damage is associated with slower spectral increases in the areas cortically where decreased innervation is present.  These slow spectral increases are seen primarily as delta, and may also be seen as a slower band including theta, especially with larger increases in the slow spectra.

White matter also carries signals across the cortex, and from the cortex through subcortical structures to other cortical locations, resulting in the neural network’s “connectivity”.    There has been a small case series showing that in some direct frontal injuries, there is a decrease in correlation from the left to the right frontal lobe, seen as decreased spectral correlation, also referred to as co-modulation (M.B. Sterman and D. Kaiser’s SKIL software).  This is identical to the changes seen with damage to the anterior portions of the corpus callosum following surgery.  This data was presented by Dr. Sterman, and published by the Journal of Neurotherapy as a technical paper describing their co-modulation metric.

Coherence changes may also be seen with head injury, with both hypercoherence and Hypocoherence reported, depending on the nature of the specific case’s damage.  Isolated areas may become hypercoherent due to the lack of input, though separated areas will be hypocoherent due to the damage to their connective network.

Damage may be seen in gray matter, which is highly “plastic”, unlike white matter, where damage persists.  The neural plasticity allows for regeneration of the cortical gray matter following injury, so the spectral changes associated with gray matter damage may change over time, from the more acute stages, through a transition phase into a static phase, which may allow for re-integration into functional relationships with neural network activity.

The immediate changes seen spectrally with gray matter injury is a decrease in the function of the thalmo-cortical neural network activity, seen spectrally as decreased alpha and beta, as well as decreased gamma in the affected gray matter.  These changes last for the period of the healing, commonly seen across a period from 6 months to a year.

As the gray matter heals, but is not integrated into the neural network function, the idling rhythm in alpha may return and even be seen as an excessive value in database comparisons, since the cortical area is not “working”.  The beta and gamma remain low during this phase, since they are not seen at normal levels in the idled cortical areas.  Beta is generated in local gray matter network activity, and gamma is seen in functionally bound and active networks only.

Once the neural network of the local gray matter is re-integrated into the functional processing, the alpha will then be reduced, and the faster activity seen associated with local function will also be seen as returning to more normal levels.  This may not happen spontaneously, and may require specific interventions, such as neurofeedback, physical therapy, and/or various cognitive-behavioral interventions.

The work of Dr. Kirtley Thornton showed that the gamma and beta remain low, even when the alpha return has occurred.  These faster patterns returned following successful clinical therapy to re-integrate the neural tissue into the functional neural network of the cortical gray matter and white matter.

Some software provides multivariate discriminant analysis, differentiating normal controls from mild traumatic brain injured clients.  These were collected retrospectively, with clients in a specific state of the dynamically changing gray matter’s plasticity, within a 9 month range in one product that is commercially available.  Their prospective use clinically, like all other classification systems, provide false positive and false negative results (type 1 and type 2 errors).

When used indiscriminately, discriminants provide a significant “red herring” problem clinically.  They are not appropriately used as a screening test for individuals, but rather they are only appropriate when used to answer a specific clinical question: “Has my client who has had an actual head injury actually suffered a brain injury?”

I personally do not find them useful clinically, since they do not provide a full evaluation of a client’s brain’s specific injury, and have an unacceptable false negative rate in know head injured clients.  The dismissal of clinically significant findings by the relatively blind use of a head trauma discriminant would tell 20%-30% of those who have had a real brain injury that they are “normal”.  This is not acceptable in the real world when a better clinical judgment would be provided by a careful analysis of the EEG and qEEG by experts in this specific application area.  We have also found a 50% false positive rate when applied to a general clinical population (though this is not the intended use of the discriminant).

The neurological professional groups are divided on the use of traumatic brain injury discriminant classification, with the American Academy of Neurology (AAN) refusing to accept discriminant use clinically, but the 1994 position paper of AMEEGA, published in EEG and Clinical Neurophysiology, provides for the clinical acceptability of the technique in the hands of experts.  ECNS (EEG and Clinical Neuroscience Society)  has reiterated the AMEEGA position paper, and the AAN position paper has had specific responses to it from those who use discriminants.

I find the detailed evaluation of the client’s EEG and qEEG, and an understanding of the dynamics of the brain’s response to trauma, provide a superior working understanding of the client’s specific injury.  This is far superior compared with a simplistic sorting into classifications of “normal” or “TBI” by software that admittedly misses 20% of the actual cases of brain injury and 50% of other clinical cases would be classified positive for brain injury in the absence of any history of head injury in an open clinical series.

Therapeutic intervention is not specified by TBI discriminants, nor is it reasonably possible to customize a therapeutic approach using discriminants due to their sensitivity to artifact.  By contrast, the EEG and qEEG data can be used for both understanding the brain injury, as well as to help the clinician customize a therapeutic approach to the specific neural network areas injured traumatically.

**   M. Steriade, P. Gloor, R.R. Llinas, F.H. Lopes da Silva, and M.M. Mesulam (1990)
Report of IFCN Committee on Basic Mechanisms:  Basic mechanisms of Cerebral Rhythmic Activities,
Electroencephalography and Clinical Neurophysiology; 1990, 76: 481-508

References:

Nuwer, M, et al, Routine and Quantitative EEG in Mild Traumatic Brain Injury; Clinical Neurophysiology, 116 (2005) 2001-2025

Thatcher, R.W., Camacho, M,, Salazar, A, Linden, C., Biver, C. and Clarke, L.: Quantitative MRI of Gray-White Matter Distribution in Traumatic Brain Injury. Journal of Neurotrauma, Volume 14, No. 1, 1-14, 1997

Thatcher, R.W., Moore, N, John, E.R., et al.: QEEG and Traumatic Brain Injury: Rebuttal of the American Academy of Neurology 1997. A Report by the EEG and Clinical Neuroscience Society, Clinical Electroencephalography, 30(3): 94-98, 1999