Henry Merkin

Sensitivity and Specificity of QEEG in Children with Attention Deficit or Specific Developmental Learning Disorders

The sensitivity and specificity of QEEG-based discriminant functions were evaluated in populations of children diagnosed with specific developmental learning disorders and those with attention deficit disorders. Both populations of children could be distinguished from each other, and from the normal population, with high levels of accuracy. Pretreatment QEEG could be utilized to distinguish ADD/ADHD children who responded to dextroamphetamine from those who responded to methylphenidate, again with high levels of accuracy. This paper provides a replication of all presented discriminant functions, and should provide the research basis for the generalized utilization of QEEG in the initial evaluation of children with learning and/or attention disorders.

Quantitative electroencephalographic characteristics of crack cocaine dependence

This study replicates preliminary findings reporting a quantitative electroencephalographic (QEEG) profile of crack cocaine dependence in abstinence. All subjects (n = 52) met criteria for DMS-III-R cocaine dependence (in the form of crack), and were residing in a drug-free therapeutic community. Baseline QEEG evaluations were conducted at intake (5-10 days after last use of crack, and at follow-up (1 month after last reported use). Previous findings of significant excess of relative alpha power and deficit of absolute and relative delta and theta power were replicated in this expanded group. Abnormalities were greater in anterior than posterior regions, and disturbances in interhemispheric relationships were also observed. Further, QEEG showed little change in the interval between the first and second evaluations. This QEEG profile may reflect persistent alterations in neurotransmission as a possible consequence of chronic cocaine exposure.

Outcome Related Electrophysiological Subtypes of Cocaine Dependence

We previously described the existence of two quantitative EEG (QEEG) subtypes of cocaine dependent males, identified at baseline, displaying differential pronenessto relapse. The current study expands the population to include females and enhances the measure set to include both QEEG and somatosensory EP (SEP) features. Fifty-seven cocaine dependent adults (16 F, 41 M) were evaluated 5–14 days after last cocaine use, while in residence at a drug-free therapeutic community. The median length of stay in treatment (continued abstinence) was 25 weeks. Using a small subset of QEEG and SEP baseline features, three subtypes (CLUS) were identified. CLUS 2 (n=25) and CLUS 3 (n=23) replicated the published subtypes, while CLUS 1 (n=9) was previously undescribed. Cluster membership was significantly associated with length of stay in treatment (χ2=13.789, P<0.001), but not with length of exposure to crack cocaine or to any demographic or clinical features. Seventy-eight percent of CLUS 1 and 65% of CLUS 3 left treatment ≤ 25 weeks, whereas 80% of CLUS 2 remained in treatment > 25 weeks. The existence of outcome related subtypes may reflect: [1] differential neurophysiological vulnerability, “traits,” predisposing individuals to cocaine addiction; or [2] differential neurosensitivity, “states,” due to the effects of chronic cocaine exposure, and associated differences in treatment outcome. Using Variable Resolution Electrical Tomographic Analysis (VARETA), the mathematically most probable neuroanatomical source of the scalp recorded EEG data was localized. Computation of VARETA on the baseline Cluster profiles suggest significant differences in the underlying pathophysiology of these subtypes.

Toward a better understanding of the pathophysiology of OCD SSRI responders: QEEG source localization.

Objective:  To demonstrate the utility of three‐dimensional source localization of the scalp‐recorded electroencephalogram (EEG) for the identification of the most probable underlying brain dysfunction in patients with obsessive–compulsive disorder (OCD).

Prediction of treatment outcome in cocaine dependent males using quantitative EEG

This study investigates the existence of outcome related neurophysiological subtypes within a population of abstinent cocaine dependent adults. We have previously reported and replicated the existence of a distinctive quantitative EEG (QEEG) profile in such a population, and demonstrated the persistence of this pattern at one and six month follow-up evaluations. This profile is characterized by significant deficits of absolute and relative delta and theta power, and excess of relative alpha power, as compared with age expected normal values. Abnormalities were greater in anterior than posterior regions, and disturbances in interhemispheric relationships were also observed. In the current study, 35 adult males with DSM-III-R cocaine dependence, were evaluated while residents of a drug-free residential therapeutic community, 5-15 days after last use of crack cocaine. Using multivariate cluster analysis, two neurophysiological subtypes were identified from the baseline QEEGs; Cluster 1 characterized by significant deficits of delta and theta activity, significant excess of alpha activity and more normal amounts of beta activity (alpha CLUS) and Cluster 2 characterized by deficits of delta, more normal amounts of theta and anterior excess of alpha and beta activity beta CLUS). No significant relationships were found between QEEG subtype membership and length of exposure to cocaine, time since last use of cocaine or any demographic characteristics. Further, no significant relationships were found between the commonly reported comorbid clinical features of depression and anxiety and subtype membership. However, a significant relationship was found between QEEG subtype membership and length of stay in treatment, with members of the alpha CLUS retained in treatment significantly longer than members of the beta CLUS.

Source imaging of QEEG as a method to detect awareness in a person in vegetative state

Background: Assessment of awareness in patients with severe brain injury remains subjective, although patients with even limited awareness (e.g. minimal conscious state, MCS) have different prognoses and treatment than those in vegetative state (VS). Recently, task appropriate differential regional activation in VS has been reported using fMRI during mental imagery. Primary objective: Demonstration of conscious awareness in reproducible differential EEG source localization images in a VS patient reflecting requested mental imagery was performed. Methods: A VS patient (with re-test) and a normal control were requested to imagine singing and to mentally perform serial subtraction, while EEG was recorded. QEEG source localization was performed to identify regions of brain activation in response to tasks. Results: Replicable distinctive activation of brain areas appropriate for each task was seen in the VS patient and control. Frequency spectra shifted to beta, with significant source activation in regions including the bilateral anterior cingulate, insula, left caudate and dorsolateral pre-frontal cortex to singing and the putamen, insula, left pre-frontal cortex and right temporal gyrus to subtraction by 7s. Conclusions: Results from this single case suggests the potential utility of QEEG source localization images to detect awareness in patients clinically diagnosed as being in VS. This indicates the possibility that EEG may serve as an important adjunct to the assessment of awareness in patients with disorders of consciousness in the clinical setting.

The Diagnostic Utility of Dermatomal Evoked Potentials

A study was completed to evaluate the diagnostic utility of dermatomal evoked potentials (EPs) for identifying single and multiple sensory nerve root compromise. We examined the clinical records of 37 patients referred for neck and lower back pain with particular attention paid to presenting clinical symptoms, magnetic resonance (MR) imaging results, and cervical and/or lumbar dermatomal EP results. The primary object of this study was to determine whether or not dermatomal EPs provided useful diagnostic information about nerve root function that would supplement the structural information provided by the MR imaging. We evaluated an outpatient population presenting with neck and lower back pain. These patients had detailed clinical evaluations, MR images, and EP evaluations, each done by independent sources. EP studies included mixed nerve EPs (ulnar and median or tibial nerve), and either C6 and C8 or L4, L5, and S1 dermatomal EPs for cervical and lumbar disorders, respectively. Mixed nerve and dermatomal EPs provided reliable information about nerve root function that corresponded to clinical symptoms more closely than did the MR findings. Specifically, these EPs often provided additional information about lateralized nerve root dysfunction beyond that given by the MR imaging. In some cases, EPs identified disturbances in nerve root function in the absence of MR-imaging-identified structural abnormality.

Exploration of the Pathophysiology of Chronic Pain Using Quantitative EEG Source Localization

Chronic pain affects more than 35% of the US adult population representing a major public health imperative. Currently, there are no objective means for identifying the presence of pain, nor for quantifying pain severity. Through a better understanding of the pathophysiology of pain, objective indicators of pain might be forthcoming. Brain mechanisms mediating the painful state were imaged in this study, using source localization of the EEG. In a population of 77 chronic pain patients, significant overactivation of the “Pain Matrix” or pain network, was found in brain regions including, the anterior cingulate, anterior and posterior insula, parietal lobule, thalamus, S1, and dorsolateral prefrontal cortex (DLPFC), consistent with those reported with conventional functional imaging, and extended to include the mid and posterior cingulate, suggesting that the increased temporal resolution of electrophysiological measures may allow a more precise identification of the pain network. Significant differences between those who self-report high and low pain were reported for some of the regions of interest (ROIs), maximally on left hemisphere in the DLPFC, suggesting encoding of pain intensity occurs in a subset of pain network ROIs. Furthermore, a preliminary multivariate logistic regression analysis was used to select quantitative-EEG features which demonstrated a highly significant predictive relationship of self-reported pain scores. Findings support the potential to derive a quantitative measure of the severity of pain using information extracted from a multivariate descriptor of the abnormal overactivation. Furthermore, the frequency specific (theta/low alpha band) overactivation in the regions reported, while not providing direct evidence, are consistent with a model of thalamocortical dysrhythmia as the potential mechanism of the neuropathic painful condition.