Multimodality evoked potential (MEP) testing, including brainstem auditory, visual, and somatosensory evoked potentials, have been reported to be useful in predicting outcome in severe closed head injury. Brainstem auditory evoked potentials have been demonstrated to be abnormal in 10% to 40% of acute mild head injury. A prospective study of 18 patients with mild closed head injury was undertaken to determine the usefulness of MEP screening within two weeks of the acute event. Long latency event-related potentials (P300s), in response to auditory stimuli with an oddball paradigm, were included in the screening. The subjects had several symptoms consistent with the postconcussive syndrome at the time of the evoked potential testing. Only one patient had an abnormal evoked potential response (greater than three standard deviations from the mean) from all the testing done. The standard methods of MEP testing were insensitive to quantifying the possible physiologic changes that are associated with memory deficits, lethargy, and emotional irritability after mild closed head injury.
"To date, most of the literature on ERPs and MTBI has looked at the modulation of the classic P3 response as a result of concussion. Classic oddball paradigms typically yielded P300 amplitude reductions and latency delays after MTBI (Werner and Vanderzant, 1991; Solbakk et al., 1999; Dupuis et al., 2000; Reinvang et al., 2000; Potter et al., 2001; Lavoie et al., 2004; Gosselin et al., 2006). Recent studies specifically conducted with asymptomatic concussed athletes showed persistent P300 latency delays (Gaetz and Weinberg, 2000) and amplitude attenuation (Gosselin et al., 2006; De Beaumont et al., 2007a). "
[Show abstract][Hide abstract] ABSTRACT: Recent studies have shown that the detrimental effects of sports concussions on cognitive and motor function may persist up to a few years post-injury. The present study sought to investigate the effects of having sustained a sports concussion more than 30 years prior to testing on cognitive and motor functions. Nineteen healthy former athletes, in late adulthood (mean age = 60.79; SD = 5.16), who sustained their last sport-related concussion in early adulthood (mean age = 26.05; SD = 9.21) were compared with 21 healthy former athletes with no history of concussion (mean age = 58.89; SD = 9.07). Neuropsychological tests sensitive to age-related changes in cognition were administered. An auditory oddball paradigm was used to evoke P3a and P3b brain responses. Four TMS paradigms were employed to assess motor cortex excitability: (i) resting motor threshold; (ii) paired-pulse intracortical inhibition and intracortical facilitation; (iii) input/output curve and (iv) cortical silent period (CSP). A rapid alternating movement task was also used to characterize motor system dysfunctions. Relative to controls, former athletes with a history of concussion had: (i) lower performance on neuropsychological tests of episodic memory and response inhibition; (ii) significantly delayed and attenuated P3a/P3b components; (iii) significantly prolonged CSP and (iv) significantly reduced movement velocity (bradykinesia). The finding that the P3, the CSP as well as neuropsychological and motor indices were altered more than three decades post-concussion provides evidence for the chronicity of cognitive and motor system changes consecutive to sports concussion.
"Similar findings were reported by Unsal and Segalowitz (1995) and Olbrich et al. (1986). Other investigators, using auditory tasks, have reported either only prolonged latencies (Keren, Ben-Dror, Stern, Goldberg, & Groswasser, 1998; Pratap-Chand et al., 1988), only attenuated amplitudes (Ford & Khalil, 1996; Rugg et al., 1988; Solbakk, Reinvang, & Nielsen, 2000; Wirse´n, Stenberg, Rose´n, & Ingvar, 1992), or an absence of P300 abnormalities (Clark et al., 1992; Rugg et al., 1993; Sangal & Sangal, 1996; Werner & Vanderzant, 1991). ERP investigations of closed head injury have thus yielded conflicting results. "
[Show abstract][Hide abstract] ABSTRACT: We evaluated alterations in information processing after closed head injury as a function of task demands and stimulus modality. Visual and auditory discrimination tasks were administered to 11 survivors of a head injury and 16 matched healthy controls. In auditory tasks, compared with controls, the survivors had smaller N100s, smaller and later N200s, a more posterior scalp distribution of N200, and longer P300 and response latencies. Auditory N200 and P300 correlated highly with duration of unconsciousness. In contrast, in visual tasks, only a reduced N200 in the survivors differentiated the groups. Our results indicate that processing of auditory stimuli, including the perception and discrimination of stimulus features and the evaluation and categorization of stimuli, may be impaired after head trauma. Visual sensory processing may be spared, but higher-order visual processing involved in stimulus classification may be compromised.
[Show abstract][Hide abstract] ABSTRACT: Questions : Cette thèse visait à répondre à deux questions fondamentales : 1) Est-ce que les athlètes qui présentent un historique de commotions cérébrales du sport en conservent des effets délétères à long terme? ; et 2) Est-ce que les effets néfastes des commotions cérébrales récurrentes sur le fonctionnement tant cognitif que moteur sont cumulatifs? Devis expérimental : À l’aide d’un plan d’investigation double-cohorte réalisé avec un groupe d’athlètes évoluant au niveau universitaire et un autre formé d’anciens athlètes universitaires testés plus de trois décennies plus tard, les quatre études qui composent cette thèse ont employé des méthodes raffinées d’investigation des fonctions cognitives et motrices pour en déceler des atteintes persistantes. Méthodologie : Les potentiels évoqués cognitifs ainsi que les tests neuropsychologiques ont permis de sonder le fonctionnement cognitif de ces athlètes alors que la stimulation magnétique transcrânienne, une plateforme de force permettant de mesurer la stabilité posturale ainsi qu’un système d’enregistrement tridimensionnel des mouvements rapides alternatifs ont servi à l’évaluation de l’intégrité du système moteur. Résultats : Cette thèse a permis de déceler des altérations persistentes et cumulatives des fonctions cognitives et motrices. De plus, ces subtiles atteintes observées chez les jeunes athlètes, affectant essentiellement des marqueurs neurophysiologiques sous-cliniques du fonctionnement cognitif et moteur, s’étaient accentuées chez les anciens athlètes universitaires qui montraient un déclin quantifiable tant des fonctions cognitives que motrices. Discussion : Ces résultats suggèrent d’une part que les commotions cérébrales du sport entraînent des altérations cognitives et motrices chroniques qui s’accentuent en fonction du nombre de commotions cérébrales subies. D’autre part, les effets délétères des commotions cérébrales du sport sur le fonctionnement cognitif et moteur combinés à ceux associés au processus de vieillissement entraînent un déclin cognitif et moteur quantifiable en comparaison aux anciens athlètes n’ayant jamais subi de commotions cérébrales. Question: This thesis aimed to address two fundamental issues: 1) Are there long-lasting effects of sports-related concussion on cognitive and motor functions? and 2) Are the adverse effects of recurrent concussions cumulative? Experimental Design: The cross-sectional thesis design included a group of active university-level athletes as well as a group of former athletes recruited more than three decades after their university years who were tested on neurophysiological measures of both cognitive and motor system functions. Methods: Event-Related potentials and neuropsychological tests were used to assess cognitive functions while transcranial magnetic paradigms were used to assess motor cortex excitability, a force platform was used to assess postural stability and a 3-dimensional recording device was used to track hand position when performing a rapid alternating movement task. Results: This thesis disclosed persistent and cumulative alterations of both cognitive and motor functions after sports concussions. Furthermore, subclinical, neurophysiological alterations found in young concussed athletes were exacerbated in former athletes with concussions who displayed quantifiable cognitive and motor functions decline more than three decades post-concussion. Discussion: These results suggest that sports concussions induce cognitive and motor functions abnormalities that worsen as a function of the number of concussions sustained. Moreover, findings from the present thesis indicate that the deleterious effects of sports concussion on cognitive and motor system functions combined to those associated with the aging process lead to quantifiable decline on both cognition and motor functions.
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