Transient vestibular balance dysfunction after primary blast injury.

Explosive munitions are used routinely in support of military operations. Moreover, service personnel are increasingly being deployed to regions where active conflict, terrorism, and land mines pose significant threats. Despite aggressive protective measures and safety practices, blast injury is an inherent risk. In contrast to secondary and tertiary blast injuries, primary blast injuries are generally limited to the air-filled organs of the respiratory, gastrointestinal, and auditory systems. We report the case of a Marine who entered the back-blast arc of a shoulder-launched multipurpose assault weapon at close range. Despite the magnitude of the blast, he sustained none of the classic findings suggestive of severe primary blast injury. However, he manifested unique vestibular balance abnormalities that precluded his return to full duty for several months. This suggests that personnel who sustain even a mild traumatic brain injury with vestibular manifestations may need prolonged observation and modified duty in certain military occupational specialties.

Biased responding: a case series demonstrating a relationship between somatic symptoms and impaired recognition memory performance for traumatic brain injured individuals.

Biased responding on the Sternberg Recognition Memory Test was observed in four patients with traumatic brain injury. None of these individuals met the Diagnostic and Statistical Manual's (DSM-IV) criteria for malingering. Individual recognition memory scores were high shortly after injury, declined to chance or below at the 6- and 12-month evaluations, and then showed substantial recovery by the 24-month evaluation. Recall memory performance actually declined slightly across this same 2-year period. Recognition memory scores were related to the extent to which the patients endorsed somatic items on the Hamilton Rating Scale for Depression (HAM-D). Poor performance was associated with high somatic scores. The relationship between memory and somatic scores on the HAM-D in this case series suggests that unconscious processes can influence memory performance and, because of this, that clinicians should not use such performance as a primary indicator of malingering. More importantly, biased responding and actual memory deficits may coexist. This is indicated in the current cases by the failure of recall memory to improve during the 2 years these patients were followed.

Factors predicting return to work following mild traumatic brain injury: a discriminant analysis.

Studies of mild traumatic brain injury (MTBI) suggest that most individuals recover rapidly and return to their everyday activities. However, a percentage of MTBI patients report persistent problems with cognitive, physical, and emotional symptoms. There is also evidence that some experience changes in occupational functioning following MTBI. The current study used a stepwise discriminant function analysis (DFA) to examine the role of injury severity variables, cognitive performance, and ratings of symptoms of TBI in predicting work status following MTBI. Subjects included 121 MTBI patients who were all active-duty military personnel. The stepwise DFA revealed that age and three cognitive variables (verbal memory, verbal fluency, and a speed test of planning and strategy) were predictive of work status 3-15 months following a documented MTBI, correctly classifying work status 68.8% of the time. A cross-validation DFA was conducted, with a 66.1% correct classification rate. These findings highlight the importance of cognitive impairments in identifying those at risk for occupational impairment following MTBI.

Verbal learning and memory in alcohol abusers and polysubstance abusers with concurrent alcohol abuse.

To define the combined effects of drug and alcohol abuse on verbal learning and memory, 70 alcoholic and 80 polysubstance abuse (PSA) individuals with concurrent alcohol abuse were compared on a list learning task, the California Verbal Learning Test (CVLT). Despite demonstrating similar learning strategies, response styles, and error patterns, the PSA group nontheless exhibited significantly greater recall deficits than the alcoholic group on the CVLT. These deficits were particularly evident in those who were heaviest abusers of cocaine. PSA participants did not, however, evidence greater recognition memory deficits. This pattern of greater deficits on recall than on recognition memory, as well as poor consolidation, is consistent with the initiation-retrieval difficulties of patient groups with subcortical dysfunction. It is concluded that the combined use of alcohol and drugs, cocaine in particular, may compound memory difficulties beyond what is typically observed in alcoholic individuals.

Cognitive recovery with abstinence and its relationship to family history for alcoholism.

OBJECTIVE: The relationship between drinking relapse and family history for alcoholism to cognitive functioning was investigated in alcoholics who completed a 28-day inpatient treatment program. METHOD: The current study examined 144 primary alcoholics who completed a battery of cognitive tests on admission to treatment and at a 3-4 month follow-up visit. Participants were classified as either family history positive (FH+) (n = 86) or family history negative (FH-) (n = 58) based on information on alcohol dependence in first degree relatives. The subjects were further classified as drinkers (n = 56) or abstainers (n = 88) at follow-up, based upon information gathered about their drinking practices during the interval. RESULTS: There were no differences between the groups based on family history status at admission to treatment. Comparisons made at follow-up revealed that the abstainers' (both FH+ and FH-) performance improved. The FH+ drinkers' performance was worse than that of both the FH- drinkers and the FH+ abstainers at follow-up. The poor performance of the FH+ drinkers relative to the FH- drinkers was not attributable to differences in drinking consumption during the test-retest interval. CONCLUSIONS: These results suggest that alcoholics who maintain abstinence following treatment show improvement on cognitive testing at follow-up; both FH+ and FH- abstainers showed improvement, indicating that a positive family history of alcoholism does not impede recovery that occurs with abstinence. The most important finding, however, is that the FH+ drinkers show greater deterioration at follow-up compared to the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Continuous recognition memory tests: are the assumptions of the theory of signal detection met?

Two continuous recognition memory tests were administered to 20 males and 20 females using the confidence rating procedure to determine if the underlying assumptions of the theory of signal detection (TSD) are met by these tasks. Z-score transformed ROC curves proved to be straight lines parallel to the positive diagonal of the ROC graph. These findings suggest that the distributions of familiarity for old and new stimuli are normal and of equal variance for the Continuous Recognition Memory and Continuous Visual Memory Tests. TSD interpretation of test data appears to be justified.

Effects of chronic alcoholism on hemispheric functioning: an examination of gender differences for cognitive and dichotic listening tasks.

A pattern of intact verbal abilities and impaired visuospatial abilities has led to a hypothesis of alcohol-induced right-hemisphere dysfunction in male chronic alcoholics. The applicability of this hypothesis to chronic female alcoholics was examined by administering the WAIS-R, Stark Paired Associates Tasks, and dichotic listening tasks to 15 male and 10 female alcoholics and 15 male and 10 female controls of similar age and education. Alcoholics had significantly lower Full Scale IQ scores on the WAIS-R but neither sex had a Verbal-Performance IQ difference indicative of right-hemisphere dysfunction. Male alcoholics showed deficits on both the Verbal and Visuospatial Stark Tasks, the deficit being greater on the Visuospatial Task. Male alcoholics showed an increased right-ear superiority on the verbal dichotic listening task and a decreased left-ear superiority on the musical dichotic listening task, both indicative of right-hemisphere dysfunction. The results, except for the WAIS-R, support the hypothesis that male but not female chronic alcoholics exhibit right-hemisphere dysfunction. Females, alcoholic or not, appear to be less lateralized in function.