Head Impact Burden and Change in Neurocognitive Function During a Season of Youth Football.

OBJECTIVE: To determine the association of repetitive subconcussive head impacts with functional outcomes in primary and high school tackle football players. SETTING: Youth football fields and an outpatient sports neurology clinic. PARTICIPANTS: A total of 112 primary school (n = 55, age 9-12 years) and high school (n = 57, age 15-18 years) football players. DESIGN: A prospective cohort study. MAIN MEASURES: Helmet-based sensors were used to record head impacts during practices and games during the 2016 football season. Impact g-forces were summed to yield a measure of cumulative impact. History of self-reported premorbid medical diagnoses was obtained preseason. Players completed assessments of a variety of outcomes both pre- and postseason: neuropsychological test performance, symptoms, vestibular and ocular-motor screening, balance, parent-completed attention-deficit hyperactivity disorder (ADHD) symptoms, and self-reported behavioral adjustment. RESULTS: Average cumulative impact was 3700 (standard deviation = 2700) g-forces for the season and did not differ between age groups (P = .594). Cumulative impact did not predict pre- to postseason change scores on any outcome measures (all P > .05). Instead, younger age group and reported history of premorbid ADHD predicted change scores on several cognitive testing measures and parent-reported ADHD symptoms, while reported history of premorbid anxiety and depression predicted change scores on symptom reporting. CONCLUSIONS: In youth tackle football, subconcussive head impacts sustained over the course of a single season may not be associated with neurocognitive functional outcomes. The absence of a significant association may reflect the relatively short follow-up interval, and signals the need for studies across multiple seasons.

Brain calcifications induce neurological dysfunction that can be reversed by a bone drug.

Perivascular calcifications within the brain form in response to a variety of insults. While considered by many to be benign, these calcium phosphate deposits or "brain stones" can become large and are associated with neurological symptoms that range from seizures to parkinsonian symptoms. Here we hypothesize that the high concentrations of calcium in these deposits produce reversible, toxic effects on neurons that can be overcome with "bone" drugs that chelate solid phase calcium phosphates. We present preliminary findings that suggest a direct association between progressive neurological symptoms and brain calcification and the symptomatic improvement of seizures, headaches, and parkinsonian symptoms in patients treated with the bisphosphonate drug disodium etidronate, normally used to treat bone diseases. Future, longitudinal epidemiological studies and randomized trials will be needed to determine the true relationship between brain stones and neurological disorders as well as the utility of bisphosphonates in their prevention and treatment.

Word list generation performance in Alzheimer's disease and vascular dementia.

Word list generation (WLG) was examined among clinical samples of individuals with Alzheimer's disease (AD) (n = 73) or ischemic vascular dementia (IVD) (n = 85), equivalent in age, education, current and estimated premorbid intellectual functioning, and proportion of men and women. The AD group performed significantly better than did the IVD group on lexical WLG, and a trend was observed indicating superior performance among the IVD group on categorical WLG. Within-groups, comparisons of group means, and profile analyses of individual performance patterns all indicated that persons with AD demonstrated a lexical > categorical pattern significantly more often than did IVD participants. The absolute difference in average performance between the AD and IVD groups on lexical and categorical WLG was small; the findings, however, generally support the clinical utility of the lexical > categorical WLG pattern in the differential diagnosis of AD and IVD. The patterns of performance support the presence of relative impairment in semantic processing among the individuals with AD and global deficits in retrieval and processing speed in individuals with IVD.

High inter-reviewer variability of spike detection on intracranial EEG addressed by an automated multi-channel algorithm.

OBJECTIVE: The goal of this study was to determine the consistency of human reviewer spike detection and then develop a computer algorithm to make the intracranial spike detection process more objective and reliable. METHODS: Three human reviewers marked interictal spikes on samples of intracranial EEGs from 10 patients. The sensitivity, precision and agreement in channel ranking by activity were calculated between reviewers. A computer algorithm was developed to parallel the way human reviewers detect spikes by first identifying all potential spikes on each channel using frequency filtering and then block scaling all channels at the same time in order to exclude potential spikes that fall below an amplitude and slope threshold. Its performance was compared to the human reviewers on the same set of patients. RESULTS: Human reviewers showed surprisingly poor inter-reviewer agreement, but did broadly agree on the ranking of channels for spike activity. The computer algorithm performed as well as the human reviewers and did especially well at ranking channels from highest to lowest spike frequency. CONCLUSIONS: Our algorithm showed good agreement with the different human reviewers, even though they demonstrated different criteria for what constitutes a 'spike' and performed especially well at the clinically important task of ranking channels by spike activity. SIGNIFICANCE: An automated, objective method to detect interictal spikes on intracranial recordings will improve both research and the surgical management of epilepsy patients.

Range of sensory gating values and test-retest reliability in normal subjects.

This article characterizes gating in normal subjects using P50, N100, and P200 components in a paired-click paradigm and compares the test-retest reliabilities of the three components. Sixty-seven normal subjects had gating data from a standard paired-click paradigm; 30 had test-retest data. The test-retest reliability of the amplitudes, latencies, and sensory gating indices derived from the P50, N100, and P200 responses were compared. Measured gating ratios showed either normal or positively skewed distributions. Test-retest reliability of the P50 gating ratio did not reach significance, but N100 and P200 ratios showed better reliability (.50 and .64). The P50 difference score was more reliable (.61), and the N100 and P200 test-retest reliabilities of difference scores were high (.83 and .81, respectively). N100 and P200 attenuation is reliable; further work is needed to develop more reliable P50 gating measures.

Comparison of the psychosocial typology of children with below average IQ to that of children with learning disabilities.

This study investigates the subtypal patterns of psychosocial functioning of children with below average IQ (BAIQ) using the application of both Q-factor analysis and profile-matching. The results suggest that the psychosocial dimensions of children with BAIQ are quite similar to those of children with LD in a general sense. Many of the same subtypes were derived, and the proportions of children displaying normal, mild, and severe levels of psychopathology were not significantly different from those of children with LD. There were some minor differences, however: For example, children with BAIQ exhibited a greater tendency to display psychopathology with internalizing features. Consistent with previous research involving children with LD, there were no changes in either type or severity of psychopathology with advancing years.

Motor unit number estimate of distal and proximal muscles in Charcot-Marie-Tooth disease.

In order to determine the utility of motor unit number estimation (MUNE) in assessing axonal loss in chronic inherited neuropathies, we determined MUNEs in 54 patients with Charcot-Marie-Tooth (CMT) disease (29 patients with CMT-1A, 13 with CMT-X, and 12 with CMT-2) by using spike-triggered averaging (STA) of the ulnar-innervated abductor digiti minimi/hypothenar muscles (ADM) and the musculo-cutaneous innervated biceps/brachialis (BB) muscles. MUNEs were analyzed in relationship to the corresponding compound muscle action potential (CMAP) amplitudes as well as to clinical strength. Proximal muscles, which appeared strong clinically, had evidence of chronic denervation/reinnervation, although to a lesser extent than weak distal hand muscles, supporting the concept that axonal loss in CMT occurs in a length-dependent fashion. The reduction in ADM-MUNE strongly correlated with clinical weakness in the hand. Both the ADM-MUNE and BB-MUNE were abnormal more often than CMAP amplitude, probably reflecting extensive motor unit reconfiguration and enlargement that maintains CMAP amplitude despite severe motor unit loss. This study suggests that MUNE can assess motor unit loss in CMT and may better reflect axonal loss than CMAP amplitude. The STA technique of MUNE may be useful in longitudinal studies of proximal and distal motor unit changes in CMT.

Psychosocial status after pediatric traumatic brain injury: a subtype analysis using the Child Behavior Checklist.

This study identified subtypes of psychosocial functioning in children who had sustained traumatic brain injury (TBI). Child Behavior Checklist (CBCL) profiles for 92 participants, aged 12 to 18 years, who had sustained a mild, moderate, or severe TBI were subjected to Q-Factor analysis. Sixty-four of the participants (75%) were classified into a four-category psychosocial typology labelled Normal (n = 32), Attention (n = 14), Delinquent (n = 10), and Withdrawn-Somatic (n = 8). This typology was found to overlap in part with previous TBI psychosocial typology (Butler et al., 1997), and with three of the clinical profile types derived by Achenbach (1993) for the CBCL. The majority of participants, including those who sustained severe TBI, were assigned to the Normal subtype and the overall level of psychosocial deviance was relatively mild in the other three subtypes. The results of this study support previous typology efforts and confirm the heterogeneous presentation of social and emotional functioning following TBI.