Neuropsychological principia brevita: an application to traumatic (acquired) brain injury

Emergence of complex partial epilepsy-like experiences following closed head injuries: personality variables and neuropsychological profiles

To pursue Richard Roberts' epileptic spectrum disorder (ESD) and the emergence of complex partial epilepsy-like experiences, items and total scores for the ESD Inventory were examined for 185 patients who had sustained mechanical impacts (and were diagnosed with or without neuropsychological impairment) and a reference group (n=68) of university students. Results from neuropsychological, personality, neurological screening, and interview data supported the role of temporal lobe origins for these experiences. The incidences of these experiences were sufficient to adversely affect adaptation and to produce psychiatric profiles. Although only 70% of the patients who were impaired versus not impaired could be differentiated by items from the ESD Inventory, >95% of the patients with scores >100 on the ESD Inventory displayed abnormal scores on more than four Minnesota Multiphasic Personality Inventory scales. These results support Roberts' ESD concept and strongly suggest that persistent, subclinical occurrence of these experiences could be the cause or major correlate of neuropsychological impairment for these patients.

Mechanical impacts to the skulls of rats produce specific deficits in maze performance and weight loss: evidence for apoptosis of cortical neurons and implications for clinical neuropsychology

The purpose of this experiment was to induce closed head injuries that might be applicable to clinical neuropsychology. Six adult female albino rats were struck over the right dorsal skull by a 200-gm weight that fell through a 0.9-m tube while another six rats served as controls. The rats that received the impact to the skulls displayed significantly more weight loss and fewer completions of the maze during the subsequent two to four days (effect size about 40%) while their open field behaviors, response latencies to thermal stimulation of the feet, and immobility within a conditioned fear setting did not differ significantly from those of controls. Histological analyses of the brains about 35 days after the impact indicated striking alterations in the morphology of cerebral cortical neurons, strongly suggestive of an apoptotic-like process, within the dorsal cerebral cortices below the likely impact site. Distributions of clusters of these aberrant-looking cells were also evident opposite to the impact site within the ventral cerebrum. Because apoptosis is involved with minimal inflammation and edema, detection of diffuse apoptosis by MRI and CT would be unlikely even though the influence on adaptability would be significant.

A brief (one-hour) quantitative neuropsychological assessment with three performance-based tests: strong concordance with proficiency scores for a more extensive test battery

Raw scores for each of several dozens of traditional and more recently developed neuropsychological tests were correlated with an impairment index composed of all of these scores from the records of 162 patients who had been assessed following impacts of substantial mechanical energies. A score of either less than 20 correct binaural responses for a dichotic word listening task, more than 99 sec. for Trails B, and more than 3.8 min. to complete the Tactual Performance Test with both hands correctly classified 85% of patients whose z scores were less than -1.0 (below average) or -1.0 or above (average) for a composite neurocognitive index. The results suggest that these three tests, administrable within about one hour, may be employed as a more objective criterion rather than "clinical impressions" for discerning if patients require more extensive neuropsychological testing.

Discrepancies between standardized measures of cognitive level and Halstead-Reitan impairment indices as inferences of brain damage following head injuries

z scores for measures of intelligence, memory, educational achievement, and neuropsychological impairment were obtained for 193 patients who had sustained impacts of mechanical energy to their skulls. Two sets of normative data, adjusted for age and sex and not adjusted for these variables, were employed to compute indices of neurocognitive proficiency (the inverse of impairment). 80% or 76 of the 96 patients whose Halstead-Reitan Indices were greater than 0.4 displayed scores for neurocognitive proficiency that were two or more standard deviations below the averages of their scores for intelligence, memory, and educational achievement. None of the patents whose Impairment Indices were 0.4 or less displayed this discrepancy. There were no statistically significant differences between these two groups of patients with respect to the presence of unconsciousness following the injury or the duration of posttraumatic memory disruptions. The results indicate that quantitative scores for neuropsychological impairments are still the most accurate criteria to discern brain dysfunction within the mild to moderate range.

Infiltration of lymphocytes in the limbic brain following stimulation of subclinical cellular immunity and low dosages of lithium and a cholinergic agent

This experiment was designed to investigate the hypothesis that single small dosages of lithium (1.5 mEq/kg), the muscarinic agent pilocarpine (15 mg/kg) and spinal cord emulsion encourage perivascular infiltration of lymphocytes into the brain even when overt symptoms of experimental allergic encephalomyelitis are not apparent. The brains of rats that had received this small dosage of lithium and pilocarpine exhibited discernable infiltrations of lymphocytes within limbic tracts but no discernable neuronal loss. Although the brains of the rats that displayed overt seizures following larger dosages of lithium (3 mEq/kg) and pilocarpine (30 mg/kg) exhibited the usual pattern of neuronal loss within multiple thalamic and limbic structures and conspicuous foci of lymphocytic infiltration (particularly within the hippocampal formation) the correlation between the numbers of foci and the proportions of neuronal damage in these structures was not significant statistically. These results indicate that infiltrations of lymphocytes into brain parenchyma are not simple artifacts of the amount of neuronal damage and may be sensitive toxicological markers for subclinical interactions between drugs and immune responses.

PERSONALITY NOT INTELLIGENCE OR EDUCATIONAL ACHIEVEMENT DIFFERENTIATE UNIVERSITY STUDENTS WHO ACCESS SPECIAL NEEDS FOR “LEARNING DISABILITIES”

University students who had been referred over a three year period from a special needs office because of putative learning disabilities were compared to randomly selected cohorts. There was no evidence of learning disabilities. Standardized scores for intelligence memory and educational achievement were all within the average range for both groups. Although there was no evidence of significant psychopathology in either group, the special needs group was significantly more immature, dependent, attention seeking and emotionally sensitive than the reference group. Only four of these variables were required to classify accurately 94% of all of the students (canonical correlation = 0.82). The results indicated that standardized norm-referenced assessment is essential to determine the actual etiologies for university students who request “special needs” because of putative learning disabilities. Implications of strategies for counselling these students are discussed.

SPECT (HMPAO) support for activation of the medial prefrontal cortices during toe graphaesthesia

This experiment was designed to test the construct validity of psychometric analyses that suggested a strong functional association between the accuracy for toe graphaesthesia and selective activation of neurons within the medial prefrontal regions. Single Photon Emission Computerized Tomography (SPECT) profiles were obtained for three volunteers (2 men, 1 woman) after they had been exposed to a toe graphaesthesia task or had been exposed to the control setting. The two measurements for each participant were separated by at least one week. Qualitative evaluation, using criteria employed for clinical diagnoses, of serial coronal, sagittal, and horizontal sections clearly indicated a specific increase in uptake of tracer within the rostral one-third to one-half of the medial prefrontal cortices of all three subjects during the toe graphaesthesia task compared to that during baseline conditions. The results are consistent with our neuropsychological research which indicates that toe graphaesthesia may be an accurate and useful indicator of the functional integrity of the medial surfaces of the anterior cerebral hemispheres.

Emergent properties following brain injury: the claustrum as a major component of a pathway that influences nociceptive thresholds to foot shock in rats

Flinch (pain) thresholds for electric current delivered to the feet were correlated with the amount of necrosis within the diencephalon and telencephalon for rats in which seizures had been induced by lithium and pilocarpine about two months before the testing. The shared variance of the quantitative damage within the claustrum, the anterior part of the paraventricular nucleus of thalamus, (central) mediodorsal thalamus, and lateral amygdala (ventromedial part) explained 81% of the variance in the nociceptive (flinch) thresholds. A primary role of the claustrum within the neuropathways that mediate the response to the interoceptive and "painful" characteristics of stimuli is indicated. The concept of primary pathways versus "emergent" pathways subsequent to excitotoxic damage within the neuromatrix is discussed.

Depression following brain trauma is enhanced in patients with mild discrepancies between intelligence and impairment on neuropsychological scores

Analysis of the MMPI (Minnesota Multiphasic Personality Inventory) scores from 135 (20 years to 60 years old) patients who had sustained closed head injuries supported the hypothesis of a nonlinear relationship between the severity of depression and the magnitude of the discrepancy between intelligence and neuropsychological proficiency. Although the MMPI Depression T scores for all groups of patients were elevated (M = 78, SD = 13), patients with the least and greatest discrepancies between intelligence and neuropsychological proficiency scored lower on Depression than patients with discrepancies within the z-score ranges -2.0 and -1.1. The results of symmetrical covariance for either depression or complex partial epileptic-like experiences before comparisons between groups suggested depression and the epileptic-like experiences share the same source of variance.

Long-term consequences of subtle stimuli during the first twenty-four hours of seizure-induced brain injury

Chronically epileptic (induced by a single systemic injection of lithium and pilocarpine about 30 days before the experiment began) male rats were trained within a radial maze while they were administered either GABA-pentin (Neurontin), or prednisolone or given no treatment. There was no significant improvement in learning or memory between the groups. Numbers of trials per day were positively correlated with the time required to display the overt stereotyped forelimb clonus after the single pilocarpine injection. The numbers of correct trials completed during the first few days of acquisition were significantly greater for the rats that had receive weak (1 microT) complex, pulsed magnetic fields over the right hemisphere during the first 24 hr. after seizure induction than for those who received the same field over the left hemisphere or that had been exposed to reference conditions. Implications of the enhanced sensitivity of limbic neurons to subtle electromagnetic interaction during electrical lability are discussed.

Demands during maze. learning in limbic epileptic rats: selective damage in the thalamus?

A qualitatively evident enhancement of chromolytic neurons within the lateral posterior thalamus of rats in which limbic seizures had been induced by lithium and pilocarpine and who were later trained for spatial memory was assessed quantitatively. The significant increase in the numbers of chromolytic neurons and the decrease in the numbers of normal neurons for these rats compared to the reference brains suggested these morphological changes were recent. The hypothesis that excessive stimulation of the lateral posterior nucleus by daily training in a radial maze may have facilitated the necrosis was supported by the inverse relationship between a linear combination of the numbers of normal neurons and oligodendroglia and the rate of learning during the earlier but not the later sessions. An implication for iatrogenic effects from rehabilitation of humans following brain injury was suggested.

Clinical neurological indicators are only moderately correlated with quantitative neuropsychological test scores in patients who display mild-moderate brain impairment following closed-head injuries

Quantitative comparisons were completed between mean scores for standardized neuropsychological tests (requiring 6 hr.), numbers of neurological signs (tests requiring 15 min.), anomalies within the electroencephalogram, subjective symptoms during a structured interview (requiring 20 min.), and an indicator of an organic brain syndrome for 81 patients who had sustained significant mechanical impacts to their skulls. The composite of neuropsychological scores was correlated 0.70 with a composite of neurological indicators and EEG anomalies. There were no significant correlations between neuropsychological or neurological scores and the numbers of subjective complaints, abnormal personality indicators, duration of coma or the interval of posttraumatic dysmnesia. However, the scores for the severity of the organic brain syndrome, partial complex epileptic symptoms, and subjective complaints were inversely correlated (rho = -0.35) with the duration of coma, the period of posttraumatic amnesia, and the numbers of qualitative electroencephalographic anomalies.