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

This article from the International Journal of Psychophysiology shows the full acceptance of the use of EP and ERP testing to evaluate TBI. The paper is co-authored from the Defence Veterans Brain Injury Center (DVBIC), and this paper shows none of the quibbling or caveats about a lack of specificity or sensitivity in TBI. It is a paper that looks at full adoption for use, not a call for plenty of more studies and funding!

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