An Experimental Platform Generating Simulated Blunt Impacts to the Head Due to Rearward Falls.

Impacts to the back of the head due to rearward falls, also referred to as "backfall" events, represent a common source of TBI for athletes and soldiers. A new experimental apparatus is described for replicating the linear and rotational kinematics of the head during backfall events. An anthropomorphic test device (ATD) with a head-borne sensor suite was configured to fall backwards from a standing height, inducing contact between the rear of the head and a ground surface simulant. A pivoting swing arm and release strap were used to generate consistent and realistic head kinematics. Backfall experiments were performed with the ATD fitted with an American football helmet and the resulting linear and rotational head kinematics, as well as calculated injury metrics, compared favorably with those of football players undergoing similar impacts during games or play reconstructions. This test method complements existing blunt impact helmet performance experiments, such as drop tower and pneumatic ram test methods, which may not be able to fully reproduce head-neck-torso kinematics during a backfall event.

Responses of the Human Brain to Mild Dehydration and Rehydration Explored In Vivo by 1H-MR Imaging and Spectroscopy.

BACKGROUND AND PURPOSE: As yet, there are no in vivo data on tissue water changes and associated morphometric changes involved in the osmo-adaptation of normal brains. Our aim was to evaluate osmoadaptive responses of the healthy human brain to osmotic challenges of de- and rehydration by serial measurements of brain volume, tissue fluid, and metabolites. MATERIALS AND METHODS: Serial T1-weighted and (1)H-MR spectroscopy data were acquired in 15 healthy individuals at normohydration, on 12 hours of dehydration, and during 1 hour of oral rehydration. Osmotic challenges were monitored by serum measures, including osmolality and hematocrit. MR imaging data were analyzed by using FreeSurfer and LCModel. RESULTS: On dehydration, serum osmolality increased by 0.67% and brain tissue fluid decreased by 1.63%, on average. MR imaging morphometry demonstrated corresponding decreases of cortical thickness and volumes of the whole brain, cortex, white matter, and hypothalamus/thalamus. These changes reversed during rehydration. Continuous fluid ingestion of 1 L of water for 1 hour within the scanner lowered serum osmolality by 0.96% and increased brain tissue fluid by 0.43%, on average. Concomitantly, cortical thickness and volumes of the whole brain, cortex, white matter, and hypothalamus/thalamus increased. Changes in brain tissue fluid were related to volume changes of the whole brain, the white matter, and hypothalamus/thalamus. Only volume changes of the hypothalamus/thalamus significantly correlated with serum osmolality. CONCLUSIONS: This is the first study simultaneously evaluating changes in brain tissue fluid, metabolites, volume, and cortical thickness. Our results reflect cellular volume regulatory mechanisms at a macroscopic level and emphasize that it is essential to control for hydration levels in studies on brain morphometry and metabolism in order to avoid confounding the findings.

Magic angle effect: a relevant artifact in MR neurography at 3T?

BACKGROUND AND PURPOSE: MRN is an emerging diagnostic method for disorders of peripheral nerves. However, it is unclear whether the influence of the MA on intraneural T2 signal is severe enough to provoke false-positive findings. MATERIALS AND METHODS: Twenty-five healthy subjects underwent MRN of the sciatic nerve of the proximal thigh at 3T. The T2(app) was calculated from a DE-TSE sequence (TR = 3000 ms, TE1 = 12 ms, TE2 = 69 ms) at 7 angles of the sciatic nerve relative to B0 = 0°, 30°, 35°, 40°, 45°, 50°, and 55°. Precise angle adjustments were performed with a dedicated in-bore positioning aid. Qualitative evaluation of intraneural T2-weighted contrast between this group of healthy subjects and 14 patients with neuropathic lesions was performed by comparing CNRs of a TIRM sequence (TR = 5000 ms, TE = 76 ms, TI = 180 ms). RESULTS: In healthy subjects, the prolongation of T2(app) from 0° to 55° was from 74.5 ± 13.4 to 104.0 ± 16.9 ms (P < .001). The increase in T2(app) relative to baseline (0°) was 9.6% (30°), 18.4% (35°), 25% (40°), 27.6% (45°), and 37% (55°). Intraneural CNR increased by 1.98 ± 0.69 at 40° and 2.93 ± 0.46 at 55°. Nevertheless, the mean CNR of healthy subjects was substantially lower than that in patients at 40° (P < .0001) and even at the position of maximum MA (55°: 20.6 ± 5.11 versus 52.6 ± 7.12, P < .0001). CONCLUSIONS: Neuropathic lesions are clearly distinguishable from an artificial increase of intraneural T2 by the MA. Even at a maximum MA (55°), the false-positive determination of a neuropathic lesion is unlikely.

Enhanced cortical reperfusion protects coagulation factor XII-deficient mice from ischemic stroke as revealed by high-field MRI.

Intrinsic coagulation factor XII deficient (FXII(-/-)) mice are protected from ischemic stroke. To elucidate underlying mechanisms we investigated the early ischemic period in vivo by multimodal magnetic resonance imaging (MRI) at 17.6 Tesla. Cerebral ischemia was induced by either transient (60 min) or permanent occlusion of the middle cerebral artery (t/pMCAO). 10 FXII(-/-) mice underwent t- , 10 FXII(-/-) mice p- and 10 Wildtype (Wt) mice tMCAO. Cerebral blood flow (CBF), diffusion-weighted-imaging (DWI) and T2-relaxometry were measured at 2 h and 24 h after MCAO. Outcome measures were evaluated after motion correction and normalization to atlas space. 2 h after tMCAO CBF reduction was similar in FXII(-/-) and Wt mice extending over cortical (CBF (ml/100 g/min) 33.6+/-6.9 vs. 35.3+/-4.6, p=0.42) and subcortical regions (25.7+/-4.5 vs. 31.6+/-4.0, p=0.17). At 24 h, recovery of cortical CBF by +36% was observed only in tMCAO FXII(-/-) mice contrasting a further decrease of -30% in Wt mice after tMCAO (p=0.02, F((1,18))=6.24). In FXII(-/-) mice in which patency of the MCA was not restored (pMCAO) a further decrease of -75% was observed. Cortical reperfusion in tMCAO FXII(-/-) mice was related to a lower risk of infarction of 59% vs. 93% in Wt mice (p=0.04). Subcortical CBF was similarly decreased in both tMCAO groups (Wt and FXII(-/-)) relating to a similar risk of infarction of 89% (Wt) vs. 99% (FXII(-/-), p=0.17). Deficiency of FXII allows neocortical reperfusion after tMCAO and rescues brain tissue by this mechanism. This study supports the concept of FXII as a promising new target for stroke prevention and therapy.

CT perfusion predicts secondary cerebral infarction after aneurysmal subarachnoid hemorrhage.

OBJECTIVE: To prospectively assess the diagnostic accuracy of CT perfusion (CTP) and transcranial Doppler sonography (TCD) for the prediction of secondary cerebral infarction (SCI) after aneurysmal subarachnoid hemorrhage (SAH). METHODS: During 2 weeks after SAH, 38 consecutive patients completed an average of 3.5 CT/CTP and 10.7 TCD examinations at regular intervals as required by the study protocol. SCI was defined as delayed infarction on native CT between 3 and 14 days after SAH and developed in n = 14 patients (n = 24 without SCI). Analysis was based on examination dates before SCI. Common measures of diagnostic accuracy were calculated for qualitative CTP (visual color-map ratings from two blinded observers) and TCD assessments (mean flow velocity >120 cm/s in anterior, middle, and posterior cerebral artery territories). Quantitative measures, which for CTP were obtained from cortical a priori regions of interest corresponding to the vascular territories, were analyzed by binary logistic regression. RESULTS: Time of prediction for SCI by CTP was at a median of 3 days (range 2 to 5 days) before manifestation of complete infarction on native CT. Visual assessment of time-to-peak (TTP) color maps performed best for the prediction of SCI with 0.93 sensitivity (95% CI: 0.7 to 1.0) and 0.67 specificity (95% CI: 0.53 to 0.7). On quantitative analysis, the odds ratio (OR) for 1 second of side-to-side delay in TTP was 1.4 (p = 0.01, Wald chi(2) = 8.57, CI: 1.07 to 1.82). Daily TCD measures were not significantly related to SCI at any time before complete infarction on native CT. CONCLUSIONS: Time to peak as indicated by CT perfusion is a sensitive and early predictor of secondary cerebral infarction.

Cycloid psychoses -- from clinical concepts to biological foundations.

The modern concept of cycloid psychoses is primarily based upon the clinical delineation of their phenotypes according to Leonhard. By settling the dilemma of Kraepelinean "atypical psychoses", their description may be considered one of the major achievements of clinical psychiatry in the last century. In particular, this had been facilitated by the work of Wernicke and Kleist. Albeit not yet generally recognized, cycloid psychoses have already stimulated great efforts of research yielding remarkable results. In this article, we elucidate the concept of cycloid psychoses and present recent findings pertaining to their putative biological foundations. Finally, future perspectives for the field of biological psychiatry are proposed fostering the heuristics of Leonhard's nosology.

Electrophysiological measurements of anterior cingulate function.

Based on recent findings from various areas of brain research the anterior cingulate cortex (ACC) within the prefrontal cortex is increasingly considered as a brain region activated during tasks requiring conflict-monitoring and allocation of attention. In the present study with event-related potentials (ERPs) the question has been addressed, whether the NoGo-condition of the Continuous Performance Test is associated with enough conflict-monitoring and allocation of attention in order to activate the ACC in healthy controls. Low Resolution Electromagnetic Tomography (LORETA), a new three-dimensional source localization method, revealed significantly increased brain electrical activity during the NoGo-ERP as compared to the Go-ERP with its maximum located exactly within the ACC in four independent samples of healthy subjects. These results relate the conflict-monitoring requirements associated with inhibition of a prepared motor response (NoGo-condition) to a powerful brain electrical ACC-activity. This non-invasive, easy to perform and inexpensive electrophysiological measurement, therefore, provides a new method for the assessment of ACC-function in healthy subjects.

Sequential MRI and MR spectroscopy in embolized meningiomas: correlation with surgical and histopathological findings.

The preoperative embolization of meningiomas is commonly used to facilitate surgery. The purpose of this study was to evaluate the morphological and metabolic changes in embolized meningiomas and to correlate the results with surgical and histopathological findings. In a prospective study, 36 patients with intracranial meningiomas were included. The extent of devascularization was assessed by angiography and MR volumetry. MRI and MR spectroscopy (MRS) were performed before and sequentially after embolization. At surgery, blood loss was measured and intraoperative duplex-mode ultrasound was applied to identify avascular tumor portions. Histopathological specimens were evaluated for the histological subtype, localization and extent of necrotic tumor portions. Postembolization MRI revealed a variable pattern of secondary revascularization and devascularization with an early onset following embolization. In all patients, peripheral secondary enhancement was present which histopathologically represented a thin layer of vital tumor tissue. MRS revealed lactate in devascularized areas immediately after embolization. Lipids were not observed before the 3rd day after embolization and were always associated with avascular and soft tissue at the time of surgery. Embolized meningiomas feature a variable dynamic with the potential for revascularization and secondary devascularization. Lipid signals indicate avascular and soft tissue at surgery. In case of delayed surgery, MRI and MRS should be performed in order to exclude revascularization and to establish the fatty degeneration of the meningioma.

Long-term reliability of electrophysiologic response control parameters.

The execution (Go) and the inhibition (NoGo) of a motor response are basic cognitive processes that can be assessed by means of a simple neuropsychological Go-NoGo task: the Continuous Performance Test (CPT). Simultaneous electrophysiologic investigations revealed that the NoGo condition of the CPT is associated with a clearly more anterior brain electrical activity compared with the Go condition. Recently, it has been shown that this NoGo anteriorization effect during a response control paradigm can be measured quantitatively with the electrophysiologic centroid method. The objective of the current study, therefore, was to determine the long-term reliability of the topographic measures of cognitive response control (i.e., location of the Go and the NoGo centroid and the NoGo anteriorization). For this purpose, a 21-channel EEG was recorded twice from 13 healthy volunteers during their execution of a cued CPT (O-X version). The time interval between test and retest was 2.74 years (range, 2.41 to 2.97 years). Statistical analysis of the event-related Go and NoGo potentials revealed an excellent test-retest reliability, as expressed by Pearson's product moment correlation coefficients of more than 0.85 (P < or = 0.0005) and intraclass correlation coefficients of more than 0.90 (P

Sequential MR imaging and proton MR spectroscopy in patients who underwent recent detoxification for chronic alcoholism: correlation with clinical and neuropsychological data.

BACKGROUND AND PURPOSE: Chronic alcohol abuse may cause neuropsychological disorders and result in brain atrophy. The purpose of this study was to evaluate the metabolic, morphologic, and functional cerebral changes in the early stage of abstinence from chronic alcoholism. METHODS: Seventeen alcohol-dependent patients underwent MR imaging and MR spectroscopy on days 1 through 3 and days 36 through 39 of abstinence. In addition, psychological performance measures testing intelligence, concentration, attention, and memory were applied. Neuropsychological data were correlated with spectroscopic and volumetric results by using a Pearson's product moment correlation. The same measurements were also performed in 12 healthy, age-matched control subjects. Peak integral values for N-acetylaspartate (NAA) and choline (Cho) were referred to the peak integral value of creatine (Cr) as the internal reference. RESULTS: NAA/Cr was decreased in the patients in both the frontal lobes and cerebellum immediately after cessation of drinking (days 1 through 3). After 36 to 39 days of abstinence, NAA/Cr had significantly increased in the patients and corresponded to performance on psychological tests. The Cho/Cr ratio was decreased in the cerebellum during early abstinence but was recovered on days 36 through 39. The patients had enlarged CSF spaces 1 to 3 days after detoxification, which decreased during sobriety. The extent of brain atrophy did not correspond to performance on psychological performance tests. CONCLUSION: Regression of brain atrophy and metabolic recovery occurs at an early stage after abstinence from chronic alcohol abuse. MR spectroscopy findings return to normal metabolic levels within weeks after detoxification. The recovery of NAA/Cr is associated with improved performance on neuropsychological tests.

Differences in substantia nigra echogenicity of nosological subtypes within the schizophrenic spectrum. A preliminary transcranial ultrasound study.

OBJECTIVE: Schizophrenic patients treated with neuroleptic drugs often develop neuroleptic-induced parkinsonism (NIP). Here, transcranial sonography (TCS) was used to test for differences in the susceptibility to NIP related to the echogenicity of the substantia nigra (SN) in different schizophrenic subforms. METHODS: 79 patients with schizophrenic spectrum psychoses treated by neuroleptic drugs and diagnosed according to ICD-10 and Leonhard's nosology were examined independently by TCS and, clinically, for NIP. RESULTS: Patients with larger echogenic SN had more severe NIP (p < 0.05). Diagnostic categories according to ICD-10 did not differ significantly in SN echogenicity (p > 0.2), whereas Leonhard's did (p < 0.05). CONCLUSIONS: These findings suggest altered SN echogenicity in subtypes of the schizophrenic spectrum. The putative role of the nigrostriatal system in the etiology of schizophrenic subtypes is discussed.

[Reliability of electrophysiological measurements of motor control]. / Fiabilidad de las medidas electrofisiológicas del control motor.

OBJECTIVES: The aim of the study was the short term test-retest-reliability of electrophyisiological correlates of simple processes of the motor control, i.e. the execution (go) and the inhibition (no go) of a prepared motor response, evoked during the Continuous Performance Test (CPT). Our interest was centered in the reliability of the topographical P300-parameters described in previous studies, i.e. the localizations of the go and no go centroids and the no go anteriorization (NGA), which is the difference between the two centroid locations. A sufficient reliability is a basic requirement for the application of these new topographical parameters for the investigation of different psychiatric illnesses with suspected dysfunctions of prefrontal motor control, e.g. schizophrenias and affective illnesses, obsessive-compulsive disorders, personality disorders with deficits in impulse control, and in children with attention deficit hyperactivity disorder. PATIENTS AND METHODS: We examined 23 healthy subjects who executed two versions of the CPT with an interval of 30 minutes. After averaging the obtained evoked potentials of each subject, we determined the latencies, amplitudes and positive centroids, at the moment of the peak of the Global Field Power in a P300 time window. RESULTS: Statistical analysis revealed sufficient test-retest-reliabilities in comparison to other electrophysiological paradigms, mainly for the localizations of the go (r = 0.93; p = 10(-10)) and no go centroid (r = 0.85; p = 10(-4)), as well as for the no go anteriorization (r = 0.63; p = 10(-3)). CONCLUSION: These results are a prerequisite for the application of these topographical parameters as measures of the prefrontal motor control in different healthy and psychiatric populations.

[Hypochondriacal euphoria as a special form of monopolar affective psychosis]. / Die hypochondrische Euphorie als Sonderform einer monopolaren affektiven Psychose.

BACKGROUND: In contemporary concepts of affective psychoses the existence of monopolar manias is widely questioned. Nevertheless, cases of manias with monomorphous symptomatology are reported repeatedly from all over the world. Based upon subtle observation of signs and course over many years, Karl Leonhard developed a concept of affective psychoses that permits a distinction of monopolar from bipolar forms, e.g. monopolar manias and euphoric euphorias. METHODS: As an example for the pure forms of euphorias we present two cases of hypochondriacal euphoria. CONCLUSION: We discuss some of the literature relevant to the issue and propose the application of a differentiated psychopathological analysis for the discrimination of monopolar from bipolar manias.

Test-retest reliability of electrophysiological parameters related to cognitive motor control.

Previously, the continuous performance test was demonstrated to elicit distinct electrophysiological correlates of cognitive response during execution (Go) and inhibition (NoGo) of an anticipated motor response. A robust method for topographical quantification of these brain electrical microstates has been established recently. Test reliability is crucial to allow application in the assessment of neuropsychiatric disorders. The present study evaluates the reliability of the Go and NoGo centroid locations as well as the NoGo anteriorisation (NGA) in 23 healthy individuals. Our results show supreme test-alternate retest reliabilities of Pearson's product moment correlations and intraclass correlation coefficients of r> or =0.63 (P< or =0.001) for these parameters which assert a quality well within the range reported for those of other electrophysiological standard paradigms. Go and NoGo centroid locations as well as the NGA are, therefore, reliable correlates of prefrontal motor control and may contribute to the understanding of disorders with allied impairments.

[Anorexia nervosa--the triad of metric index, BMI age-specific percentile curve and goal weight]. / Anorexia nervosa--Die Trias von Metrik-Index, BMI-Altersperzentilenkurve und Zielgewicht.

Cross sectional and longitudinal data from the Berlin Anorexia Study on the inpatient treatment of n = 133 adolescent females with the principal axis I diagnosis of an eating disorder (n = 104 anorexia nervosa, n = 19 bulimia nervosa, n = 10 eating disorders not otherwise specified; according to ICD-10 and DSM-IV criteria) indicate a significant shift in the frequency distribution of somatometrically assessed types of body shape among patients as categorized by the Metric Index, towards the leptomorphic phenotype (p < 0.050, chi 2/Fisher's). Three explanatory models are discussed. Diagnostic and therapeutic implications, particularly of the determination of target weight in anorexia nervosa based on the individual's type of body shape, are emphasized, and an operational algorithm is proposed which uses the Metric Index and sex-specific BMI age percentiles adjusted for type of body shape.

[Anorexia nervosa and "anorexia athletica"]. / Anorexia nervosa und "Anorexia athletica"?

Available evidence supports the assumption that stressors in vulnerable adolescence potentially lead to restrictive dieting and imbalances of serotonergic metabolic particularly in females. In conjunction with idealized body images and developmentally characteristic bodily perceptions prone to distortion pathogenetic mechanisms of eating disorders are released. The entities of eating disorders are dimensionally viewed as points of continua a functions and categorized according to ICD-10 or DSM-IV, respectively. Data of our studies on grammar school students, ballet dancers and anorexia nervosa patients emphasize the necessity to differentiate different types of body shape by using the metric index. Facing this background a distinction of "anorexia athletica" appears unreasonable.