Associations between physical fitness and cerebellar gray matter volume in adolescents

Despite the importance of the developing cerebellum on cognition, the associations between physical fitness and cerebellar volume in adolescents remain unclear. We explored the associations of physical fitness with gray matter (GM) volume of VI, VIIb and Crus I & II, which are cerebellar lobules related to cognition, in 40 (22 females; 17.9 ± 0.8 year-old) adolescents, and whether the associations were sex-specific. Peak oxygen uptake (V̇O2peak ) and power were assessed by maximal ramp test on a cycle ergometer, muscular strength with standing long jump (SLJ), speed-agility with the shuttle-run test (SRT), coordination with the Box and Block Test (BBT) and neuromuscular performance index (NPI) as the sum of SLJ, BBT and SRT z-scores. Body composition was measured using a dual-energy X-ray absorptiometry. Cerebellar volumes were assessed by magnetic resonance imaging. V̇O2peak relative to lean mass was inversely associated with the GM volume of the cerebellum (standardized regression coefficient (β) = -0.038, 95% confidence interval (CI) -0.075 to 0.001, p = 0.044). Cumulative NPI was positively associated with the GM volume of Crus I (β = 0.362, 95% CI 0.045 to 0.679, p = 0.027). In females, better performance in SRT was associated with a larger GM volume of Crus I (β = -0.373, 95% CI -0.760 to -0.028, p = 0.036). In males, cumulative NPI was inversely associated with the GM volume of Crus II (β = -0.793, 95% CI -1.579 to -0.008 p = 0.048). Other associations were nonsignificant. In conclusion, cardiorespiratory fitness, neuromuscular performance and speed-agility were associated with cerebellar GM volume, and the strength and direction of associations were sex-specific.

Navigated and individual α-peak-frequency-guided transcranial magnetic stimulation in male patients with treatment-refractory schizophrenia

BACKGROUND

Previous electroencephalography (EEG) studies have indicated altered brain oscillatory α-band activity in schizophrenia, and treatment with repetitive transcranial magnetic stimulation (rTMS) using individualized α-frequency has shown therapeutic effects. Magnetic resonance imaging-based neuronavigation methods allow stimulation of a specific cortical region and improve targeting of rTMS; therefore, we sought to study the efficacy of navigated, individual α-peak-frequency-guided rTMS (αTMS) on treatment-refractory schizophrenia.

METHODS

We recruited medication-refractory male patients with schizophrenia or schizoaffective disorder in this doubleblind, sham-controlled study. We randomized patients to a 3-week course of either active αTMS or sham stimulation applied to the left dorsolateral prefrontal cortex (DLPFC). We assessed participants with the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression Scale (CGI) at baseline and after treatment. We conducted a follow-up assessment with the PANSS 3 months after intervention.

RESULTS

We included 44 patients. After treatment, we observed a significantly higher PANSS total score (p = 0.029), PANSS general psychopathology score (p = 0.027) and PANSS 5-factor model cognitive-disorganized factor score (p = 0.011) in the αTMS group than the sham group. In addition, the CGI-Improvement score was significantly higher among those who received αTMS compared with sham stimulation (p = 0.048).

LIMITATIONS

The limited number of study participants included only male patients. Depression was not formally evaluated.

CONCLUSION

Navigated αTMS to the left DLPFC reduced total, general psychopathological, and cognitive-disorganized symptoms of schizophrenia. These results provide evidence for the therapeutic efficacy of individual α-peak-frequency-guided rTMS in treatment-refractory schizophrenia.

CLINICAL TRIAL REGISTRATION

NCT01941251; ClinicalTrials.gov.

Progressive myoclonic epilepsy type 1 (EPM1) patients present with abnormal 1H MRS brain metabolic profiles associated with cognitive function

PURPOSE

Progressive myoclonic epilepsy, type 1A (EPM1, Unverricht-Lundborg disease), is a rare neurodegenerative autosomal recessive disorder characterized by stimulus-sensitive and action myoclonus and tonic-clonic epileptic seizures. Patients develop neurological symptoms, including ataxia, intention tremor, and dysarthria, over time, with relatively limited and nonspecific MRI atrophy findings. The effects of the disease on brain metabolism are largely unknown.

METHOD

Eighteen EPM1 patients (9 M, 9F) underwent clinical evaluation and neuropsychological testing, which included the assessment of intellectual ability, verbal memory, and psychomotor and executive functions. Magnetic resonance spectroscopy (MRS) and imaging (MRI) were performed on a 1.5 T MRI system. 2D MRS chemical shift imaging (CSI) maps (TE = 270) were obtained from the following regions of the brain: basal ganglia, thalamus, insula, splenium, and occipital white and gray matter, and N-acetyl-aspartate (NAA)-, choline (Cho)-, and lactate (Lac)-to-creatine (Cr) ratios were analyzed. Ten healthy age-and sex-matched subjects (5M, 5F) were used as controls for MRS.

RESULTS

We found significant brain metabolic changes involving lactate, NAA, and choline, which are widespread in the basal ganglia, thalamic nuclei, insula, and occipital areas of EPM1 patients. Changes, especially in the right insula, basal ganglia, and thalamus, were associated with intellectual abilities and impairment of the psychomotor and executive functions of EPM1 patients.

CONCLUSION

Multiple brain metabolic alterations suggest the presence of neurodegeneration associated with EPM1 progression. The changes in metabolite ratios are associated with the neurocognitive dysfunction caused by the disease. However, the role of MRS findings in understanding pathophysiology of EPM1 warrants further studies.

Cortical thickness is inversely associated with transcranial magnetic stimulation-evoked N45 potential among young adults whose heavy drinking began in adolescence

BACKGROUND

Adolescence is a particularly vulnerable stage of development in terms of the deleterious effects of alcohol. Both lower gray matter (GM) volume and greater GABAergic activity have been associated with chronic alcohol consumption during adolescence. However, the association between these measures has not been investigated.

METHODS

In this exploratory study, we compared 26 young adults with a 10year history of heavy alcohol consumption with 21 controls who used little or no alcohol. Simultaneous transcranial magnetic stimulation and electroencephalography were used to assess transcranial magnetic stimulation-evoked N45 potentials, reflecting a balance between GABAergic inhibition and N-methyl-D-aspartate (NMDA) receptor-mediated glutaminergic excitation in the brain. GM thickness was measured from magnetic resonance images and GM and N45 potentials were then correlated.

RESULTS

Cortical thickness was significantly lower in several brain regions in the heavy-drinking group than the light-drinking group. The N45 amplitude was significantly larger frontally in the heavy-drinking group. Among heavy drinkers, there were several statistically significant correlations between thinner GM and larger frontal N45 amplitudes that were not detectable in the light-drinking group. The strongest correlations were detected in the frontal and parietal lobes, especially in the left superior frontal gyrus and the left supramarginal gyrus, and in both hemispheres in the superior parietal lobes.

CONCLUSIONS

These findings show that a thinner cortex and greater inhibitory neurotransmission are correlated in certain brain regions among young, long-term heavy alcohol users. Studies are needed to explore the possible causal mechanisms underlying these effects.

Developmental models of motor-evoked potential features by transcranial magnetic stimulation across age groups from childhood to adulthood

To derive the maturation of neurophysiological processes from childhood to adulthood reflected by the change of motor-evoked potential (MEP) features. 38 participants were recruited from four groups (age mean in years [SD in months], number (males)): children (7.3 [4.2], 7(4)), preadolescents (10.3 [6.9], 10(5)), adolescents (15.3 [9.8], 11(5)), and adults (26.9 [46.2], 10(5)). The navigated transcranial magnetic stimulation was performed on both hemispheres at seven stimulation intensity (SI) levels from sub- to supra-threshold and targeted to the representative cortical area of abductor pollicis brevis muscle. MEPs were measured from three hand- and two forearm-muscles. The input-output (I/O) curves of MEP features across age groups were constructed using linear mixed-effect models. Age and SI significantly affected MEP features, whereas the stimulated side had a minor impact. MEP size and duration increased from childhood to adulthood. MEP onset- and peak-latency dropped in adolescence, particularly in hand muscles. Children had the smallest MEPs with the highest polyphasia, whereas I/O curves were similar among preadolescents, adolescents, and adults. This study illustrates some of the changing patterns of MEP features across the ages, suggesting developing patterns of neurophysiological processes activated by TMS, and to motivate studies with larger sample size.

Dynamic contrast-enhanced MRI to characterize angiogenesis in primary epithelial ovarian cancer: An exploratory study

PURPOSE

Angiogenesis is essential for tumor growth. Currently, there are no established imaging biomarkers to show angiogenesis in tumor tissue. The aim of this prospective study was to evaluate whether semiquantitative and pharmacokinetic DCE-MRI perfusion parameters could be used to assess angiogenesis in epithelial ovarian cancer (EOC).

METHOD

We enrolled 38 patients with primary EOC treated in 2011-2014. DCE-MRI was performed with a 3.0 T imaging system before the surgical treatment. Two different sizes of ROI were used to evaluate semiquantitative and pharmacokinetic DCE perfusion parameters: a large ROI (L-ROI) covering the whole primary lesion on one plane and a small ROI (S-ROI) covering a small solid, highly enhancing focus. Tissue samples from tumors were collected during the surgery. Immunohistochemistry was used to measure the expression of vascular endothelial growth factor (VEGF), its receptors (VEGFRs) and to analyse microvascular density (MVD) and the number of microvessels.

RESULTS

VEGF expression correlated inversely with K^trans (L-ROI, r = -0.395 (p = 0.009), S-ROI, r = -0.390, (p = 0.010)), V_e (L-ROI, r = -0.395 (p = 0.009), S-ROI, r = -0.412 (p = 0.006)) and V_p (L-ROI, r = -0.388 (p = 0.011), S-ROI, r = -0.339 (p = 0.028)) values in EOC. Higher VEGFR-2 correlated with lower DCE parameters K^trans (L-ROI, r = -0.311 (p = 0.040), S-ROI, r = -0.337 (p = 0.025)) and V_e (L-ROI, r = -0.305 (p = 0.044), S-ROI, r = -0.355 (p = 0.018)). We also found that MVD and the number of microvessels correlated positively with AUC, Peak and WashIn values.

CONCLUSIONS

We observed that several DCE-MRI parameters correlated with VEGF and VEGFR-2 expression and MVD. Thus, both semiquantitative and pharmacokinetic perfusion parameters of DCE-MRI represent promising tools for the assessment of angiogenesis in EOC.

Neoadjuvant chemotherapy induces an elevation of tumour apparent diffusion coefficient values in patients with ovarian cancer

OBJECTIVES

Multiparametric magnetic resonance imaging (mMRI) is the modality of choice in the imaging of ovarian cancer (OC). We aimed to investigate the feasibility of different types of regions of interest (ROIs) in the measurement of apparent diffusion coefficient (ADC) values of diffusion-weighted imaging in OC patients treated with neoadjuvant chemotherapy (NACT).

METHODS

We retrospectively enrolled 23 consecutive patients with advanced OC who had undergone NACT and mMRI. Seventeen of them had been imaged before and after NACT. Two observers independently measured the ADC values in both ovaries and in the metastatic mass by drawing on a single slice of (1) freehand large ROIs (L-ROIs) covering the solid parts of the whole tumour and (2) three small round ROIs (S-ROIs). The side of the primary ovarian tumour was defined. We evaluated the interobserver reproducibility and statistical significance of the change in tumoural pre- and post-NACT ADC values. Each patient's disease was defined as platinum-sensitive, semi-sensitive, or resistant. The patients were deemed either responders or non-responders.

RESULTS

The interobserver reproducibility of the L-ROI and S-ROI measurements ranged from good to excellent (ICC range: 0.71-0.99). The mean ADC values were significantly higher after NACT in the primary tumour (L-ROI p  < 0.001, S-ROIs p < 0.01), and the increase after NACT was associated with sensitivity to platinum-based chemotherapy. The changes in the ADC values of the omental mass were associated with a response to NACT.

CONCLUSION

The mean ADC values of the primary tumour increased significantly after NACT in the OC patients, and the amount of increase in omental mass was associated with the response to platinum-based NACT. Our study indicates that quantitative analysis of ADC values with a single slice and a whole tumour ROI placement is a reproducible method that has a potential role in the evaluation of NACT response in patients with OC.

TRIAL REGISTRATION

Retrospectively registered (institutional permission code: 5302501; date of the permission: 31.7.2020).

Greater increases in intratumoral apparent diffusion coefficients after chemoradiotherapy predict better overall survival of patients with cervical cancer

PURPOSE

To evaluate whether 1) the intratumoral apparent diffusion coefficients (ADCs) change during cervical cancer treatment and 2) the pretreatment ADC values or their change after treatment predict the treatment outcome or overall survival of patients with cervical cancer.

METHODS

We retrospectively enrolled 52 patients with inoperable cervical cancer treated with chemoradiotherapy, who had undergone diffusion weighted MRI before treatment and post external beam radiotherapy (EBRT) and concurrent chemotherapy. A subgroup of patients (n = 28) underwent altogether six consecutive diffusion weighted MRIs; 1) pretreatment, 2) post-EBRT and concurrent chemotherapy; 3-5) during image-guided brachytherapy (IGBT) and 6) after completing the whole treatment course. To assess interobserver and intertechnique reproducibility two observers independently measured the ADCs by drawing freehand a large region of interest (L-ROI) covering the whole tumor and three small ROIs (S-ROIs) in areas with most restricted diffusion.

RESULTS

Reproducibility was equally good for L-ROIs and S-ROIs. The pretreatment ADCs were higher in L-ROIs (883 mm2/s) than in S-ROIs (687 mm2/s, P < 0.001). The ADCs increased significantly between the pretreatment and post-EBRT scans (L-ROI: P < 0.001; S-ROI: P = 0.001). The ADCs remained significantly higher than pretreatment values during the whole IGBT. Using S-ROIs, greater increases in ADCs between pretreatment and post-EBRT MRI predicted better overall survival (P = 0.018).

CONCLUSION

ADC values significantly increase during cervical cancer treatment. Greater increases in ADC values between pretreatment and post-EBRT predicted better overall survival using S-ROIs. Standardized methods for timing and delineation of ADC measurements are advocated in future studies.

The effect of shunt surgery on corticospinal excitability in idiopathic normal pressure hydrocephalus: a transcranial magnetic stimulation study

Background

Idiopathic normal pressure hydrocephalus (iNPH) is a multifactorial disease presenting with a classical symptom triad of cognitive decline, gait disturbance and urinary incontinence. The symptoms can be alleviated with shunt surgery but the etiology of the symptoms remains unclear. Navigated transcranial magnetic stimulation (nTMS) was applied to characterize corticospinal excitability and cortical motor function before and after shunt surgery in order to elucidate the pathophysiology of iNPH. We also aimed to determine, whether nTMS could be applied as a predictive tool in the pre-surgical work-up of iNPH.

Methods

24 patients with possible or probable iNPH were evaluated at baseline, after cerebrospinal fluid drainage test (TAP test) and three months after shunt surgery (follow-up). Symptom severity was evaluated on an iNPH scale and with clinical tests (walking test, Box & Block test, grooved pegboard). In the nTMS experiments, resting motor threshold (RMT), silent period (SP), input–output curve (IO-curve), repetition suppression (RS) and mapping of cortical representation areas of hand and foot muscles were assessed.

Results

After shunt surgery, all patients showed improved performance in gait and upper limb function. The nTMS parameters showed an increase in the RMTs (hand and foot) and the maximum value of the IO-curve increased in subject with a good surgical outcome. The improvement in gait correlated with an increase in the maximum value of the IO-curve. SP, RS and mapping remained unchanged.

Conclusion

The excitability of the motor cortex and the corticospinal tract increased in iNPH patients after shunt surgery. A favorable clinical outcome of shunt surgery is associated with a higher ability to re-form and maintain neuronal connectivity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-022-00385-1.

Association between breast cancer's prognostic factors and 3D textural features of non-contrast-enhanced T1 weighted breast MRI

OBJECTIVES

The aim of this exploratory study was to evaluate whether three-dimensional texture analysis (3D-TA) features of non-contrast-enhanced T₁ weighted MRI associate with traditional prognostic factors and disease-free survival (DFS) of breast cancer.

METHODS

3D-T₁ weighted images from 78 patients with 81 malignant histopathologically verified breast lesions were retrospectively analysed using standard-size volumes of interest. Grey-level co-occurrence matrix (GLCM)-based features were selected for statistical analysis. In statistics the Mann-Whitney U and the Kruskal-Wallis tests, the Cox proportional hazards model and the Kaplan-Meier method were used.

RESULTS

Tumours with higher histological grade were significantly associated with higher contrast (1 voxel: p = 0.033, 2 voxels: p = 0.036). All the entropy parameters showed significant correlation with tumour grade (p = 0.015-0.050) but there were no statistically significant associations between other TA parameters and tumour grade. The Nottingham Prognostic Index (NPI) was correlated with contrast and sum entropy parameters. A higher sum variance TA parameter was a significant predictor of shorter DFS.

CONCLUSION

Texture parameters, assessed by 3D-TA from non-enhanced T₁ weighted images, indicate tumour heterogeneity but have limited independent prognostic value. However, they are associated with tumour grade, NPI, and DFS. These parameters could be used as an adjunct to contrast-enhanced TA parameters.

ADVANCES IN KNOWLEDGE

3D-TA of non-contrast enhanced T₁ weighted breast MRI associates with tumour grade, NPI, and DFS. The use of non-contrast 3D-TA parameters in adjunct with contrast-enhanced 3D-TA parameters warrants further research.

Decreased Gray-White Matter Contrast of [11C]-PiB Uptake in Cognitively Unimpaired Subjects with Severe Obstructive Sleep Apnea

BACKGROUND

Very recently, cognitively normal, middle-aged adults with severe obstructive sleep apnea (OSA) were shown to have regional cortical amyloid-β deposits. In the normal brain, amyloid tracer (e.g., [11C]-PiB) uptake is observed in white matter (WM) but not in cortical gray matter (GM), resulting in clear GM-WM contrast. There are no reports on possible changes in this contrast in severe OSA.

OBJECTIVES

Evaluate changes in the global [11C]-PiB GM-WM contrast and study if factors reflecting clinical and imaging characteristics are associated with them.

DESIGN AND SETTING

Cross-sectional imaging study.

PARTICIPANTS

19 cognitively intact middle-aged (mean 44 years) patients with severe OSA (Apnea-Hypopnea Index >30/h), carefully selected to exclude any other possible factors that could alter brain health.

MEASUREMENTS

Detailed neuroimaging (amyloid PET, MRI). Signs of possible alterations in amyloid tracer GM-WM contrast and kinetics were studied with static and dynamic [11C]-PiB PET and WM structures with detailed 3.0T MRI.

RESULTS

Static [11C]-PiB PET uptake showed significantly decreased GM-WM contrast in 5 out of 19 patients. This was already clearly seen in visual evaluation and also detected quantitatively using retention indexes. Dynamic imaging revealed decreased contrast due to alterations in trace accumulation in the late phase of [11C]-PiB kinetics. Decreased GM-WM contrast in the late phase was global in nature. MRI revealed no corresponding alterations in WM structures. Importantly, decreased GM-WM contrast was associated with smoking (p = 0.007) and higher Apnea-Hypopnea Index (p = 0.001).

CONCLUSIONS

Severe OSA was associated with decreased GM-WM contrast in amyloid tracer uptake, with significant correlation with clinical parameters of smoking and AHI. The results support and further extend the current understanding of the deleterious effect of severe OSA on proper amyloid clearance, possibly reflecting dysfunction of the brain glymphatic system.

TMS-EEG Biomarkers of Amnestic Mild Cognitive Impairment Due to Alzheimer's Disease: A Proof-of-Concept Six Years Prospective Study

Background: Early and affordable identification of subjects with amnestic mild cognitive impairment (aMCI) who will convert to Alzheimer's disease (AD) is a major scientific challenge. Objective: To investigate the neurophysiological hallmarks of sensorimotor cortex function in aMCI under the hypothesis that some may represent the plastic rearrangements induced by neurodegeneration, hence predictors of future conversion to AD. We sought to determine (1) whether the sensorimotor network shows peculiar alterations in patients with aMCI and (2) if sensorimotor network alterations predict long-term disease progression at the individual level. Methods: We studied several transcranial magnetic stimulation (TMS)-electroencephalogram (EEG) parameters of the sensorimotor cortex in a group of patients with aMCI and followed them for 6 years. We then identified aMCI who clinically converted to AD [prodromal to AD-MCI (pAD-MCI)] and those who remained cognitively stable [non-prodromal to AD-MCI (npAD-MCI)]. Results: Patients with aMCI showed reduced motor cortex (M1) excitability and disrupted EEG synchronization [decreased intertrial coherence (ITC)] in alpha, beta and gamma frequency bands compared to the control subjects. The degree of alteration in M1 excitability and alpha ITC was comparable between pAD-MCI and npAD-MCI. Importantly, beta and gamma ITC impairment in the stimulated M1 was greater in pAD-MCI than npAD-MCI. Furthermore, an additional parameter related to the waveform shape of scalp signals, reflecting time-specific alterations in global TMS-induced activity [stability of the dipolar activity (sDA)], discriminated npAD-MCI from MCI who will convert to AD. Discussion: The above mentioned specific cortical changes, reflecting deficit of synchronization within the cortico-basal ganglia-thalamo-cortical loop in aMCI, may reflect the pathological processes underlying AD. These changes could be tested in larger cohorts as neurophysiological biomarkers of AD.

Atlas-informed computational processing pipeline for individual targeting of brain areas for therapeutic navigated transcranial magnetic stimulation

OBJECTIVE

Navigated transcranial magnetic stimulation (nTMS) is targeted at different cortical sites for diagnostic, therapeutic, and neuroscientific purposes. Correct identification of the cortical target areas is important for achieving desired effects, but it is challenging when no direct responses arise upon target area stimulation. We aimed at utilizing atlas-based marking of cortical areas for nTMS targeting to present a convenient, rater-independent method for overlaying the individual target sites with brain anatomy.

METHODS

We developed a pipeline, which fits a brain atlas to the individual brain and enables visualization of the target areas during the nTMS session. We applied the pipeline to our previous nTMS data, focusing on depression and schizophrenia patients. Furthermore, we included examples of Tourette syndrome and tinnitus therapies, as well as neurosurgical and motor mappings.

RESULTS

In depression and schizophrenia patients, the visually selected dorsolateral prefrontal cortex (DLPFC) targets were close to the border between atlas areas A9/46 and A8. In the other areas, the atlas-based areas were in agreement with the treatment targets.

CONCLUSIONS

The atlas-based target areas agreed well with the cortical targets selected by experts during the treatments.

SIGNIFICANCE

Overlaying atlas information over the navigation view is a convenient and useful add-on for improving nTMS targeting.

Severe Obstructive Sleep Apnea and Increased Cortical Amyloid-β Deposition

BACKGROUND

The suggested association between severe obstructive sleep apnea (OSA) and risk of Alzheimer's disease (AD) needs further study. Only few recent reports exist on associations between brain amyloid-β (Aβ) burden and severe OSA in middle-aged patients.

OBJECTIVE

Examine the possible presence of cortical Aβ accumulation in middle-aged patients with severe OSA.

METHODS

We performed detailed multimodal neuroimaging in 19 cognitive intact patients (mean 44.2 years) with severe OSA (Apnea-Hypopnea Index >30 h-1). Known etiological factors for possible Aβ accumulation were used as exclusion criteria. Aβ uptake was studied with [11C]-PiB-PET, glucose metabolism with [18F]-FDG-PET, and structural imaging with 3.0T MRI.

RESULTS

When analyzed individually, in [11C]-PiB-PET a substantial number (∼32%) of the patients exhibited statistically significant evidence of increased cortical Aβ uptake based on elevated regional Z-score values, mostly seen bilaterally in the precuneus and posterior cingulum regions. Cortical glucose hypometabolism in [18F]-FDG-PET was seen in two patients. MRI did not show structural changes suggestive of AD-related pathology.

CONCLUSION

Increased [11C]-PiB uptake was seen in middle-aged cognitively intact patients with severe OSA. These findings are similar to those described in cognitive unimpaired older OSA patients. The changes in cortical Aβ uptake suggest that severe OSA itself may predispose to alterations related to AD already in middle-age. Aβ clearance may be compromised without simultaneous evidence of metabolic or structural alterations. The results emphasize the importance of early diagnostics and proper treatment of severe OSA in cognitively intact middle-aged subjects, possibly diminishing the individual risk for later cognitive dysfunction.

Primary hand motor representation areas in healthy children, preadolescents, adolescents, and adults

The development of the organization of the motor representation areas in children and adolescents is not well-known. This cross-sectional study aimed to provide an understanding for the development of the functional motor areas of the upper extremity muscles by studying healthy right-handed children (6-9 years, n = 10), preadolescents (10-12 years, n = 13), adolescents (15-17 years, n = 12), and adults (22-34 years, n = 12). The optimal representation site and resting motor threshold (rMT) for the abductor pollicis brevis (APB) were assessed in both hemispheres using navigated transcranial magnetic stimulation (nTMS). Motor mapping was performed at 110% of the rMT while recording the EMG of six upper limb muscles in the hand and forearm. The association between the motor map and manual dexterity (box and block test, BBT) was examined. The mapping was well-tolerated and feasible in all but the youngest participant whose rMT exceeded the maximum stimulator output. The centers-of-gravity (CoG) for individual muscles were scattered to the greatest extent in the group of preadolescents and centered and became more focused with age. In preadolescents, the CoGs in the left hemisphere were located more laterally, and they shifted medially with age. The proportion of hand compared to arm representation increased with age (p = 0.001); in the right hemisphere, this was associated with greater fine motor ability. Similarly, there was less overlap between hand and forearm muscles representations in children compared to adults (p<0.001). There was a posterior-anterior shift in the APB hotspot coordinate with age, and the APB coordinate in the left hemisphere exhibited a lateral to medial shift with age from adolescence to adulthood (p = 0.006). Our results contribute to the elucidation of the developmental course in the organization of the motor cortex and its associations with fine motor skills. It was shown that nTMS motor mapping in relaxed muscles is feasible in developmental studies in children older than seven years of age.

Brain Response Induced with Paired Associative Stimulation Is Related to Repetition Suppression of Motor Evoked Potential

Repetition suppression (RS), i.e., the reduction of neuronal activity upon repetition of an external stimulus, can be demonstrated in the motor system using transcranial magnetic stimulation (TMS). We evaluated the RS in relation to the neuroplastic changes induced by paired associative stimulation (PAS). An RS paradigm, consisting of 20 trains of four identical suprathreshold TMS pulses 1 s apart, was assessed for motor-evoked potentials (MEPs) in 16 healthy subjects, before and following (at 0, 10, and 20 min) a common PAS protocol. For analysis, we divided RS into two components: (1) the ratio of the second MEP amplitude to the first one in RS trains, i.e., the “dynamic” component, and (2) the mean of the second to fourth MEP amplitudes, i.e., the “stable” component. Following PAS, five subjects showed change in the dynamic RS component. However, nearly all the individuals (n = 14) exhibited change in the stable component (p < 0.05). The stable component was similar between subjects showing increased MEPs and those showing decreased MEPs at this level (p = 0.254). The results suggest the tendency of the brain towards a stable state, probably free from the ongoing dynamics, following PAS.

Corticospinal excitability in idiopathic normal pressure hydrocephalus: a transcranial magnetic stimulation study

Background

Idiopathic normal pressure hydrocephalus (iNPH) is a neurodegenerative disease with an unknown etiology. Disturbed corticospinal inhibition of the motor cortex has been reported in iNPH and can be evaluated in a noninvasive and painless manner using navigated transcranial magnetic stimulation (nTMS). This is the first study to characterize the immediate impact of cerebrospinal fluid (CSF) drainage on corticospinal excitability.

Methods

Twenty patients with possible or probable iNPH (16 women and 4 men, mean age 74.4 years, range 67–84 years), presenting the classical symptom triad and radiological findings, were evaluated with motor function tests (10-m walk test, Grooved Pegboard and Box & Block test) and nTMS (silent period, SP, resting motor threshold, RMT and input–output curve, IO-curve). Evaluations were performed at baseline and repeated immediately after CSF drainage via lumbar puncture.

Results

At baseline, iNPH patients presented shorter SPs (p < 0.001) and lower RMTs (p < 0.001) as compared to normative values. Positive correlation was detected between SP duration and Box & Block test (rho = 0.64, p = 0.002) in iNPH patients. CSF drainage led to an enhancement in gait velocity (p = 0.002) and a steeper IO-curve slope (p = 0.049).

Conclusions

Shorter SPs and lower RMTs in iNPH suggest impaired corticospinal inhibition and corticospinal hyperexcitability. The steeper IO-slope in patients who improve their gait velocity after CSF drainage may indicate a higher recovery potential. Corticospinal excitability correlated with the motor function of the upper limbs implying that the disturbance in motor performance in iNPH extends beyond the classically reported gait impairment.

Effects of long-term adolescent alcohol consumption on white matter integrity and their correlations with metabolic alterations

Alcohol-related white matter (WM) microstructural changes have not been fully elucidated in adolescents. We aimed to investigate influences of subclinical alcohol use during adolescence on WM microstructure and to characterize those with serum metabolic alterations. 35 moderate-to-heavy drinkers (15 males, 20 females) and 27 controls (12 males, 15 females) were selected based on their ten-year Alcohol Use Disorders Identification Test scores measured at three time points. Magnetic resonance imaging was conducted at endpoint time. Whole brain analysis of fractional anisotropy (FA) was performed. Diffusivity indices in the significant regions were computed for between-group comparisons and correlation analyses with serum metabolite concentrations. Decreased FA was found in moderate-to-heavy drinking men in anterior corpus callosum, superior/anterior corona radiata and right inferior fronto-occipital fasciculus, accompanied by increased radial diffusivity and a smaller area of reduced axial diffusivity, which correlated with serum metabolites playing roles in energy metabolism, myelination and axonal degeneration. No significant difference in FA was detected between female or mixed-gender moderate-to-heavy drinking subjects and controls, supporting gender differences in the relationship between adolescent alcohol use and neurodevelopmental trajectories. Future researches with longitudinal imaging data are warranted for comprehensive evaluation on potentially reversible effects of alcohol use over adolescent brain.

The effect of coil placement and orientation on the assessment of focal excitability in motor mapping with navigated transcranial magnetic stimulation

BACKGROUND

Navigated transcranial magnetic stimulation (nTMS) is used for mapping muscle representations in the primary motor cortex. We used sulcus-aligned mapping and electric field (E-field) modeling to investigate the excitability of the motor hand area for further understanding the methodological limitations of nTMS.

NEW METHOD

We studied 10 healthy volunteers to locate the cortical target eliciting the largest responses (the hotspot) in the first dorsal interosseous (FDI) muscle. Six additional targets were placed along the central sulcus at 5-mm distances. Resting motor thresholds (rMTs) and optimal coil orientations were determined at all targets, and a conventional motor mapping was conducted. The cortical E-fields, induced by stimulating the targets with rMT intensities and optimal coil orientations, were modeled in a realistic head geometry to estimate the activated cortical sites.

RESULTS

The rMTs increased with increasing distance from the hotspot (p < 0.001). The greatest motor-evoked potential (MEP) amplitudes occurred with the coil perpendicular to the sulcus and with the coil pointing towards the hotspot or the center of gravity of the motor map. The E-field strengths at the hotspot (99±26 V/m) remained above previously estimated thresholds for activation.

COMPARISON WITH EXISTING METHODS

Depending on the target location, optimal coil orientations may deviate significantly from the conventional perpendicular-to-sulcus angle, which is often assumed optimal. These orientations seem to maintain the E-field stable in the hand knob, regardless of the sulcal shape near the stimulated target.

CONCLUSIONS

The coil orientation is crucial for the accuracy of motor mapping, and the apparent motor map may extend due to remote hotspot activation.

Interaction between repetition suppression in motor activation and long-interval intracortical inhibition

Repetition suppression (RS) is the adaptation of the neural activity in response to a repeated external stimulus. It has been proposed that RS occurs at the thalamo-cortical level, hence activating a feedback loop to the cortex in order to counteract with the repeated motor cortical activation. In this study, to elucidate the common modulators between the RS and the inhibitory/facilitatory cortical networks, two TMS paradigms were applied, i.e. the characteristic long-interval intracortical inhibition (LICI) and the I1-wave timed short-interval intracortical facilitation (SICF). Since LICI is a local intracortical inhibitory phenomenon affecting cortical excitation over a long interval like the RS, the interaction between RS and LICI was tested. As the I1-wave timed SICF is likely not affected by inhibitory modulation, the appearance of the RS with respect to SICF was investigated. Non-linear interaction between LICI and RS was observed, while I1-wave timed SICF facilitated all MEP responses of RS by a common offset still preserving the RS. These findings implicate that the underlying mechanism for the observed interaction is likely contributed to the activation of the negative thalamo-cortical feedback loop represented by the RS, most likely at the cortical level.

Maturation changes the excitability and effective connectivity of the frontal lobe: A developmental TMS-EEG study

The combination of transcranial magnetic stimulation with simultaneous electroencephalography (TMS-EEG) offers direct neurophysiological insight into excitability and connectivity within neural circuits. However, there have been few developmental TMS-EEG studies to date, and they all have focused on primary motor cortex stimulation. In the present study, we used navigated high-density TMS-EEG to investigate the maturation of the superior frontal cortex (dorsal premotor cortex [PMd]), which is involved in a broad range of motor and cognitive functions known to develop with age. We demonstrated that reactivity to frontal cortex TMS decreases with development. We also showed that although frontal cortex TMS elicits an equally complex TEP waveform in all age groups, the statistically significant between-group differences in the topography of the TMS-evoked peaks and differences in current density maps suggest changes in effective connectivity of the right PMd with maturation. More generally, our results indicate that direct study of the brain's excitability and effective connectivity via TMS-EEG co-registration can also be applied to pediatric populations outside the primary motor cortex, and may provide useful information for developmental studies and studies on developmental neuropsychiatric disorders.

Changes in the serum metabolite profile correlate with decreased brain gray matter volume in moderate-to-heavy drinking young adults

Our aim was to analyze metabolite profile changes in serum associated with moderate-to-heavy consumption of alcohol in young adults and to evaluate whether these changes are connected to reduced brain gray matter volumes. These study population consisted of young adults with a 10-year history of moderate-to-heavy alcohol consumption (n = 35) and light-drinking controls (n = 27). We used the targeted liquid chromatography mass spectrometry method to measure concentrations of metabolites in serum, and 3.0 T magnetic resonance imaging to assess brain gray matter volumes. Alterations in amino acid and energy metabolism were observed in the moderate-to-heavy drinking young adults when compared to the controls. After correction for multiple testing, the group of moderate-to-heavy drinking young adults had increased serum concentrations of 1-methylhistamine (p = 0.001, d = 0.82) when compared to the controls. Furthermore, concentrations of 1-methylhistamine (r = -0.48, p = 0.004) and creatine (r = -0.52, p = 0.001) were negatively correlated with the brain gray matter volumes in the females. Overall, our results show association between moderate-to-heavy use of alcohol and altered metabolite profile in young adults as well as suggesting that some of these changes could be associated with the reduced brain gray matter volume.

Bifrontal active and sham rTMS in treatment-resistant unipolar major depression

BACKGROUND AND AIM

Prevention of the recurrence of major depression and its residual symptoms requires effective treatment. Our aim was to study the effects of bifrontal active rTMS controlled by sham rTMS in treatment-resistant unipolar major depressive disorder (MDD).

METHODS

Thirty-seven patients with treatment-resistant MDD were randomized into two groups. One group received a total of 30 sessions of active bifrontal rTMS (10 Hz rTMS on left dorsolateral prefrontal cortex (DLPFC) and 1 Hz rTMS on right DLPFC) and the other group received bilateral sham rTMS on five days a week for six weeks.

RESULTS

Depressive symptoms significantly improved in both the groups, but without a significant group difference. Furthermore, patients with psychotic depression improved similarly to those with moderate or severe depression.

CONCLUSIONS

The results of present study indicate a large sham effect of stimulation treatment. The intensive structured treatment protocol may explain the positive outcome in both the groups. It is important to recognize, appreciate, and utilize placebo effects as a significant means of rehabilitation in psychiatric care.

Feasibility of mapping breast cancer with supine breast MRI in patients scheduled for oncoplastic surgery

OBJECTIVES

To prospectively determine the feasibility of preoperative supine breast MRI in breast cancer patients scheduled for oncoplastic breast-conserving surgery.

METHODS

In addition to a diagnostic prone breast MRI, a supplementary supine MRI was performed with the patient in the surgical position including skin markers. Tumours' locations were ink-marked on the skin according to findings obtained from supine MRI. Changes in tumours' largest diameter and locations between prone and supine MRI were measured and compared to histology. Nipple-to-tumour and tumour-to-chest wall distances were also measured. Tumours and suspicious areas were surgically removed according to skin ink-markings. The differences between MRI measurements with reference to histopathology were evaluated with the paired-sample t test.

RESULTS

Fourteen consecutive patients, 15 breasts and 27 lesions were analysed. Compared to histology, prone MRI overestimated tumour size by 47.1% (p = 0.01) and supine MRI by 14.5% (p = 0.259). In supine MRI, lesions' mean diameters and areas were smaller compared to prone MRI (- 20.9%, p = 0.009 and - 38.3%, p = 0.016, respectively). This difference in diameter was more pronounced in non-mass lesions (- 31.2%, p = 0.031) compared to mass lesions (- 9.2%, p = 0.009). Tumours' mean distance from chest wall diminished by 69.4% (p < 0.001) and from nipple by 18.2% (p < 0.001). Free microscopic margins were achieved in first operation in all patients.

CONCLUSIONS

Supine MRI in the surgical position is feasible and useful in the precise localisation of prone MRI-detected lesions and provides a helpful tool to implement in surgery. Supine MRI more accurately determines tumours' size and location and might have an important role to diminish overestimations.

KEY POINTS

• Breath-hold supine breast MRI is feasible using commercially available coils and sequences. • Size and area of lesions on MRI were consistently smaller when measured from the supine position as compared to the prone position. • Supine breast MRI is useful in the precise preoperative localisation of prone MRI-detected lesions. •.

Effects of knee flexion and extension on the tibial tuberosity-trochlear groove (TT-TG) distance in adolescents

Background

Measurement of the tibial tubercle–trochlear groove (TT–TG) distance is used to assess patellofemoral instability and rotation. Since patellofemoral instability and acute patellar dislocation are common among adolescents, it is important to clarify the relationship between TT–TG distance and various flexion and extension angles in asymptomatic children. The purpose of the present study was to determine how knee flexion and extension influence TT–TG-distance values measured using 3D imaging in an anatomic axial plane among asymptomatic adolescents.

Methods

We performed magnetic resonance imaging (MRI) of 26 knees in 13 adolescents (8 boys and 5 girls) of 11–17 years of age, with no known patellofemoral disorders. Imaging was performed with 3.0 T MRI with the knee at four separate angles of flexion between 0° and 30°. Measurements were made by two independent blinded raters.

Results

The mean TT–TG distance in millimetres was 11.1–0.29 × the angle in degrees. TT–TG distance decreased with greater flexion, showing a mean decrease of 0.29 mm (SD, 0.04) per degree of increased flexion (p < 0.001). We found significant inter-observer (Pearson’s r = 0.636, p = 0.03) and intra-observer (Pearson’s r = 0.792, p ≤ 0.001) correlations. TT–TG values were not significantly correlated with age, length, weight, or body mass index. The rate of TT–TG change (change between consecutive TT–TG values/change between consecutive angles) was significantly negatively correlated with length (p = 0.014), weight (p = 0.004), and body mass index (p = 0.025).

Conclusions

Our data revealed that TT–TG distance assessed in the anatomic axial plane decreased with greater flexion in adolescent. Moreover, this effect of knee angle was stronger in smaller subjects. These findings support the need for a standardized protocol for TT–TG distance measurement in adolescents.

Heavy alcohol use in adolescence is associated with altered cortical activity: a combined TMS-EEG study

Long-term alcohol use affects cognitive and neurophysiological functioning as well as structural brain development. Combining simultaneous electroencephalogram (EEG) recording with transcranial magnetic stimulation (TMS) enables direct, in vivo exploration of cortical excitability and assessment of effective and functional connectivity. In the central nervous system, the effects of alcohol are particularly mediated by alterations in gamma-aminobutyric acid (GABA)ergic neurotransmission, and TMS-evoked potentials (TEPs) N45 and N100 in EEG are known to reflect GABAergic function. However, no previous studies have examined the effects of long-term alcohol use in adolescence on TEPs. In this study, a total of 27 young adults with heavy alcohol use in adolescence and 25 age-matched, gender-matched and education-matched controls with little or no alcohol use participated in TMS-EEG measurements. The motor cortex (M1) was stimulated with an intensity of 90 percent of the resting motor threshold of the abductor pollicis brevis muscle. No significant differences were found in the resting motor threshold, TEP latencies or neuropsychological functioning between the groups. We observed an increase in the global mean field power in the time window of 54- to 75-millisecond post-TMS, as well as significant topographical differences in the P60 and N100 in those with a history of heavy drinking. Furthermore, there was a marked increase in the GABAergic N45 amplitude in alcohol users. These findings suggest that long-term alcohol use in adolescence, even when not meeting the diagnostic criteria for a disorder, is associated with changes in connectivity and cortical excitability.

Normal multiplanar movement of the spinal cord during unilateral and bilateral straight leg raise: Quantification, mechanisms, and overview

The purpose of this investigation was to provide a full set of normal data describing neural biomechanics within the vertebral canal in all three planes with unilateral and bilateral SLR tests to allow for clinical comparison with clinical cases. This is done following the notion that, due to neural continuum, tensile forces are transmitted through the lumbosacral nerve roots and dura to the conus medullaris (linear dependency principle). In this controlled radiologic study 10 asymptomatic volunteers were scanned with 1.5T magnetic resonance scanner (Siemens Magnetom Aera, Erlangen, Germany) using different scanning sequences for planning and for measurement purposes. Conus displacement in both antero-posterior direction (sagittal slices) and lateral direction (axial slices) was quantified during unilateral passive left, right SLR, and bilateral SLR and compared with the position of the conus in the neutral (anatomic) position. It is shown that the conus medullaris displaced laterally and anteroposteriorly in response to unilateral and bilateral SLRs. Pearson's correlations were higher than 0.95 for both intra- and inter-observer reliability. The observed power was higher than 0.99 for all the variables tested. Following this, the authors conclude that lateral and antero-posterior displacement of conus medullaris into the vertebral canal occurs consistently with unilateral and bilateral SLRs following directions predicted by tension vectors. Summative information collected in this line of research in neuroradiology is here presented. We believe we have presented the first conclusive and complete full set of normal data on non-invasive, in vivo, normative measurement of spinal cord displacement with the SLR ever presented. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1335-1342, 2017.

Alcohol consumption during adolescence is associated with reduced grey matter volumes

BACKGROUND AND AIMS

Cognitive impairment has been associated with excessive alcohol use, but its neural basis is poorly understood. Chronic excessive alcohol use in adolescence may lead to neuronal loss and volumetric changes in the brain. Our objective was to compare the grey matter volumes of heavy- and light-drinking adolescents.

DESIGN

This was a longitudinal study: heavy-drinking adolescents without an alcohol use disorder and their light-drinking controls were followed-up for 10 years using questionnaires at three time-points. Magnetic resonance imaging was conducted at the last time-point.

SETTING

The area near Kuopio University Hospital, Finland.

PARTICIPANTS

The 62 participants were aged 22-28 years and included 35 alcohol users and 27 controls who had been followed-up for approximately 10 years.

MEASUREMENTS

Alcohol use was measured by the Alcohol Use Disorders Identification Test (AUDIT)-C at three time-points during 10 years. Participants were selected based on their AUDIT-C score. Magnetic resonance imaging was conducted at the last time-point. Grey matter volume was determined and compared between heavy- and light-drinking groups using voxel-based morphometry on three-dimensional T1-weighted magnetic resonance images using predefined regions of interest and a threshold of P < 0.05, with small volume correction applied on cluster level.

FINDINGS

Grey matter volumes were significantly smaller among heavy-drinking participants in the bilateral anterior cingulate cortex, right orbitofrontal and frontopolar cortex, right superior temporal gyrus and right insular cortex compared to the control group (P < 0.05, family-wise error-corrected cluster level).

CONCLUSIONS

Excessive alcohol use during adolescence appears to be associated with an abnormal development of the brain grey matter. Moreover, the structural changes detected in the insula of alcohol users may reflect a reduced sensitivity to alcohol's negative subjective effects.

Development of cortical motor circuits between childhood and adulthood: A navigated TMS-HdEEG study

Motor functions improve during childhood and adolescence, but little is still known about the development of cortical motor circuits during early life. To elucidate the neurophysiological hallmarks of motor cortex development, we investigated the differences in motor cortical excitability and connectivity between healthy children, adolescents, and adults by means of navigated suprathreshold motor cortex transcranial magnetic stimulation (TMS) combined with high-density electroencephalography (EEG). We demonstrated that with development, the excitability of the motor system increases, the TMS-evoked EEG waveform increases in complexity, the magnitude of induced activation decreases, and signal spreading increases. Furthermore, the phase of the oscillatory response to TMS becomes less consistent with age. These changes parallel an improvement in manual dexterity and may reflect developmental changes in functional connectivity. Hum Brain Mapp 38:2599-2615, 2017. © 2017 Wiley Periodicals, Inc.

Localization of cortical primary motor area of the hand using navigated transcranial magnetic stimulation, BOLD and arterial spin labeling fMRI

BACKGROUND

Although the relationship between neuronavigated transcranial magnetic stimulation (nTMS) and functional magnetic resonance imaging (fMRI) has been widely studied in motor mapping, it is unknown how the motor response type or the choice of motor task affect this relationship.

NEW METHOD

Centers of gravity (CoGs) and response maxima were measured with blood-oxygen-level dependent (BOLD) and arterial spin labeling (ASL) fMRI during motor tasks against nTMS CoGs and response maxima, which were mapped with motor evoked potentials (MEPs) and silent periods (SPs).

RESULTS

No differences in motor representations (CoGs and response maxima) were observed in lateral-medial direction (p=0.265). fMRI methods localized the motor representation more posterior than nTMS (p<0.001). This was not affected by the BOLD fMRI motor task (p>0.999) nor nTMS response type (p>0.999). ASL fMRI maxima did not differ from the nTMS nor BOLD fMRI CoGs (p≥0.070), but the ASL CoG was deeper in comparison to other methods (p≤0.042). The BOLD fMRI motor task did not influence the depth of the motor representation (p≥0.745). The median Euclidean distances between the nTMS and fMRI motor representations varied between 7.7mm and 14.5mm and did not differ between the methods (F≤1.23, p≥0.318).

COMPARISON WITH EXISTING METHODS

The relationship between fMRI and nTMS mapped excitatory (MEP) and inhibitory (SP) responses, and whether the choice of motor task affects this relationship, have not been studied before.

CONCLUSIONS

The congruence between fMRI and nTMS is good. The choice of nTMS motor response type nor BOLD fMRI motor task had no effect on this relationship.

Radiographic Changes in the Condyle of the Temporomandibular Joint in Psoriatic Arthritis

One hundred and ten patients with psoriatic arthritis (PA) and 100 matched control patients were examined by using ***orthopan-tomography to discover radiographic changes in the condyle of the temporomandibular joint (TMJ). Thirty-one per cent of the PA patients and 13 per cent of the control patients had radiographic changes in the condyle of the TMJ. The most common radiographic finding in PA patients was unilateral erosion of the condyle. Of the radiographic changes in the PA group, cortical erosions correlated negatively with age, whereas osteophytes correlated positively with the duration of PA.

Increased Inhibition in Non-Primary Motor Areas of String-Instrument Players: A Preliminary Study with Paired-Pulse Transcranial Magnetic Stimulation

Background: The muscle representations in non-primary motor area (NPMA) are located in the dorsal premotor area (PMd) and in the border region between the premotor area and the supplementary motor area (SMA).

Objective: We characterized the plasticity of intracortical inhibitory and excitatory circuits in muscle representations in primary motor cortex (M1) and in NPMA related to acquired fine motor skills. We compared local cortical inhibition and facilitation balance in M1 and in NPMA between control subjects (n = 6) and right-handed string-instrument players (n = 5).

Methods: Navigated transcranial magnetic stimulation (TMS) was used to compare motor thresholds (MTs), motor evoked potentials (MEPs), short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) in non-dominant hand muscle representations in M1 and NPMA.

Results: String-instrument players showed reduced SICI in M1 in the actively used left hand abductor digiti minimi (ADM) muscle representation at 3 ms inter-stimulus interval (ISI) with a conditioning stimulus (CS) intensity of 80% of MT and increased SICI in NPMA in ADM representation at 2 ms ISI and CS intensity of 50% of MT in comparison with controls. No differences between string-instrument players and controls were found for the SICI in the left hand opponens pollicis (OP) muscle representation, which is a muscle not intensively trained in string-instrument players.

Conclusions: These preliminary results indicate that the stronger inhibition in motor representations outside M1 in string-instrument players may be crucial when accurate movements of single muscles must be performed. In contrast, weaker inhibition in M1 in string-instrument players may benefit the performance of fast finger movements.

In Vivo MRI Measurement of Spinal Cord Displacement in the Thoracolumbar Region of Asymptomatic Subjects with Unilateral and Sham Straight Leg Raise Tests

Background

Normal displacement of the conus medullaris with unilateral and bilateral SLR has been quantified and the "principle of linear dependence" has been described.

Purpose

Explore whether previously recorded movements of conus medullaris with SLRs are i) primarily due to transmission of tensile forces transmitted through the neural tissues during SLR or ii) the result of reciprocal movements between vertebrae and nerves.

Study design

Controlled radiologic study.

Methods

Ten asymptomatic volunteers were scanned with a 1.5T magnetic resonance (MR) scanner using T2 weighted spc 3D scanning sequences and a device that permits greater ranges of SLR. Displacement of the conus medullaris during the unilateral and sham SLR was quantified reliably with a randomized procedure. Conus displacement in response to unilateral and sham SLRs was quantified and the results compared.

Results

The conus displaced caudally in the spinal canal by 3.54±0.87 mm (mean±SD) with unilateral (p≤.001) and proximally by 0.32±1.6 mm with sham SLR (p≤.542). Pearson correlations were higher than 0.99 for both intra- and inter-observer reliability and the observed power was 1 for unilateral SLRs and 0.054 and 0.149 for left and right sham SLR respectively.

Conclusions

Four relevant points emerge from the presented data: i) reciprocal movements between the spinal cord and the surrounding vertebrae are likely to occur during SLR in asymptomatic subjects, ii) conus medullaris displacement in the vertebral canal with SLR is primarily due to transmission of tensile forces through the neural tissues, iii) when tensile forces are transmitted through the neural system as in the clinical SLR, the magnitude of conus medullaris displacement prevails over the amount of bone adjustment.

Functional and structural cortical characteristics after restricted focal motor cortical infarction evaluated at chronic stage - Indications from a preliminary study

OBJECTIVE

To assess the inter-hemispheric differences in neuronal function and structure of the motor cortex in a small group of chronic stroke patients having suffered a restricted ischemic lesion affecting hand motor representation. GABAergic intracortical inhibition, known to be affected by stroke lesion, was also investigated.

METHODS

Eight patients exhibiting little or no motor impairment were studied using transcranial magnetic stimulation (TMS) and diffusion weighted imaging (DWI) >15months from diagnosis. Resting motor threshold (MT) for 50μV and 2mV motor evoked potentials, and short-interval intracortical inhibition (SICI) were measured from hand muscles. Apparent diffusion coefficients (ADCs) were analyzed from the DWI for the primary motor cortex (M1), the supplementary motor area (SMA) and thalamus for reflecting changes in neuronal organization.

RESULTS

The MTs did not differ between the affected (AH) and unaffected hemisphere (UH) in 50μV responses, while the MTs for 2mV responses were higher (p=0.018) in AH. SICI was weakened in AH (p=0.008). ADCs were higher in the affected M1 compared to the unaffected M1 (p=0.018) while there were no inter-hemispheric differences in SMA or thalamus.

CONCLUSIONS

Inter-hemispheric asymmetry and neuronal organization demonstrated abnormalities in the M1. However, no confident inference can be made whether the observed alterations in neurophysiological and imaging measures have causal role for motor rehabilitation in these patients.

SIGNIFICANCE

Neurophysiological changes persist and are detectable using TMS years after stroke even though clinical symptoms have normalized.

Locating and Outlining the Cortical Motor Representation Areas of Facial Muscles With Navigated Transcranial Magnetic Stimulation

BACKGROUND

Navigated transcranial magnetic stimulation (nTMS) has become established as an accurate noninvasive technique for mapping the functional motor cortex for the representation areas of upper and lower limb muscles but not yet for facial musculature.

OBJECTIVE

To characterize the applicability and clinical impact of using nTMS to map cortical motor areas of facial muscles in healthy volunteers and neurosurgical tumor patients.

METHODS

Eight healthy volunteers and 12 patients with tumor were studied. The motor threshold (MT) was determined for the abductor pollicis brevis and mentalis muscles. The lateral part of the motor cortex was mapped with suprathreshold stimulation intensity, and motor evoked potentials were recorded from several facial muscles. The patient protocol was modified according to the clinical indication.

RESULTS

In all healthy subjects, motor evoked potentials were elicited in the mentalis (mean latency, 13.4 milliseconds) and orbicularis oris (mean latency, 12.6 milliseconds) muscles. At 110% of MT of the mentalis, the motor evoked potentials of facial muscles were elicited mainly in the precentral gyrus but also from one gyrus anterior and posterior to it. The cortical areas applicable for mapping were limited by an artifact attributable to direct peripheral nerve stimulation. The mapping protocol was successful in 10 of 12 tumor patients at locating the representation area of the lower facial muscles. The MT of the facial muscles was significantly higher than that of the abductor pollicis brevis.

CONCLUSION

nTMS is an applicable and clinically beneficial noninvasive method to preoperatively map the cortical representation areas of the facial muscles in the lower part of the face. Instead of using the MT of the abductor pollicis brevis, the stimulus intensity during mapping should be proportioned to the MT of a facial muscle.

Sensorimotor cortex excitability and connectivity in Alzheimer's disease: A TMS-EEG Co-registration study

Several studies have shown that, in spite of the fact that motor symptoms manifest late in the course of Alzheimer's disease (AD), neuropathological progression in the motor cortex parallels that in other brain areas generally considered more specific targets of the neurodegenerative process. It has been suggested that motor cortex excitability is enhanced in AD from the early stages, and that this is related to disease's severity and progression. To investigate the neurophysiological hallmarks of motor cortex functionality in early AD we combined transcranial magnetic stimulation (TMS) with electroencephalography (EEG). We demonstrated that in mild AD the sensorimotor system is hyperexcitable, despite the lack of clinically evident motor manifestations. This phenomenon causes a stronger response to stimulation in a specific time window, possibly due to locally acting reinforcing circuits, while network activity and connectivity is reduced. These changes could be interpreted as a compensatory mechanism allowing for the preservation of sensorimotor programming and execution over a long period of time, regardless of the disease's progression. Hum Brain Mapp 37:2083-2096, 2016. © 2016 Wiley Periodicals, Inc.