Frequency-dependent changes of local resting oscillations in sleep-deprived brain.

Sleep deprivation (SD) adversely affects brain function and is accompanied by frequency dependent changes in EEG. Recent studies have suggested that BOLD fluctuations pertain to a spatiotemporal organization with different frequencies. The present study aimed to investigate the frequency-dependent SD-related brain oscillatory activity by using the amplitude of low-frequency fluctuation (ALFF) analysis. The ALFF changes were measured across different frequencies (Slow-4: 0.027-0.073 Hz; Slow-5: 0.01-0.027 Hz; and Typical band: 0.01-0.08 Hz) in 24 h SD as compared to rested wakeful during resting-state fMRI. Sixteen volunteers underwent two fMRI sessions, once during rested wakefulness and once after 24 h of SD. SD showed prominently decreased ALFF in the right inferior parietal lobule (IPL), bilateral orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC), while increased ALFF in the visual cortex, left sensorimotor cortex and fusiform gyrus. Across the Slow-4 and Slow-5, results differed significantly in the OFC, DLPFC, thalamus and caudate in comparison to typical frequency band; and Slow-4 showed greater differences. In addition, negative correlations of behavior performance and ALFF patterns were found mainly in the right IPL across the typical frequency band. These observations provided novel insights about the physiological responses of SD, identified how it disturbs the brain rhythms, and linked SD with frequency-dependent alterations in amplitude patterns.

Spinal cystic schwannoma: an MRI evaluation.

Spinal cystic schwannomas are a very rare entity and have been reported in only a few case reports in literature; its diagnosis and management has remained a challenge. This study reviewed the results of magnetic resonance imaging (MRI) of 12 patients (7 men and 5 women; aged 37 - 67 years; mean age: 52.75 years) with pathologically proven cystic schwannoma of the spine and discussed their differential diagnosis. All patients underwent surgery at our institutions between June 2000 and April 2012. MRI showed well-delineated intradural and extramedullary lesion of iso- to low signal intensity on T1 weighted images, high signal intensity on T2 weighted images, and rim enhancement on contrast-enhanced images. A precise understanding of the MRI features of spinal schwannomas, especially the typical characteristic of enhancement, may help clinicians in their pre-operative diagnoses and surgical planning.

A pharmaco-fMRI study on pain networks induced by electrical stimulation after sumatriptan injection.

Sumatriptan, a drug widely used to alleviate migraine headaches, has several somatosensory adverse effects, including tactile allodynia. To understand whether sumatriptan affects sensory and affective circuitries simultaneously, we investigated the responses of 12 healthy volunteers to electrical stimuli after infusion with either sumatriptan or saline. Using a double-blind crossover study design, we used functional magnetic resonance imaging (fMRI) to measure brain activation in different areas during electrical stimulation. The visual analog scale (VAS) and short-form McGill pain questionnaire (SF-MPQ) were used to rate stimulation-evoked sensations and affections after drug administration. VAS rating, SF-MPQ, and block fMRI were all performed in each subject during sumatriptan and saline injection. Echo-planar imaging sequences were used to determine the whole-brain blood oxygenation level-dependent signal of the entire brain. Our results showed that sumatriptan predominantly activated regions in the medial pain system and smaller regions in the lateral pain system. These regions included the secondary somatosensory cortex (SII), anterior insular cortex, orbitofrontal cortex, medial thalamus, cerebellar supravermis, dentate nucleus, and the majority of the anterior cingulate cortex (ACC). In contrast, activation following saline administration was observed primarily in the lateral pain system, including the primary sensory cortex, lateral SII, posterior insular cortex, anterior ACC, and lateral thalamus. Importantly, we found that VAS ratings and MPQ scores were increased after sumatriptan infusion, but not after saline administration. Our fMRI, VAS, and SF-MPQ findings suggest that sumatriptan plays a significant role in the affective dimension of pain and a minor role related to sensory discrimination.

A preliminary study of the dysregulation of the resting networks in first-episode medication-naive adolescent depression.

Recent developments in depression studies have heightened the need for investigating adolescent major depressive disorder (MDD). Many previous neuroimaging studies used task designs and found consistent results in the dysfunction of brain regions in depressed adolescent patients. In this study, we aimed to evaluate the topological properties of brain functional networks of adolescents with MDD from an integrated view. Using resting state functional magnetic resonance imaging (fMRI), graph theory was applied to construct the resting networks in 16 first-episode and unmedicated adolescents with MDD and 16 healthy controls (HC). Our results showed that the topological properties of depressed adolescents' networks were significantly disrupted compared with HC. Dysregulation of brain regions were found in the anterior cingulate cortex, dorsolateral, medial and inferior prefrontal cortex, insula, amygdala, and the temporal cortices. Furthermore, the connectivity degree of amygdala related functional connection was positively correlated with the duration of depression. Detection and estimation of these functional impairments may advance our current understanding of the pathophysiological mechanism of adolescent MDD.

Spinal extradural meningeal cysts: an MRI evaluation of a case series and literature review.

STUDY DESIGN: Case series and literature review. OBJECTIVE: To analyze the characteristics of extradural spinal meningeal cysts (SMCs) by magnetic resonance imaging (MRI) and discuss their classifications and etiology, as well as exploring the choice of treatment. SUMMARY OF BACKGROUND DATA: Spinal extradural meningeal cysts are a rare type of SMC. They are also known as extradural/epidural spinal arachnoid cysts. According to Nabors' classification, they belong to the category of types I and II meningeal cysts. The etiology of spinal extradural cysts remains unclear. MATERIALS AND METHODS: We retrospectively analyzed the MRI scans of 18 cases of extradural arachnoid cyst, which were consecutively treated surgically at our institutions between June 1990 and November 2009. All cases were confirmed by surgery. Disonics 0.35T and Philips Gyroscan Intera 1.5T scanner with surface coils were used for patient scanning. MRI examination included routine sagittal T1-weighted/spin-echo , sagittal, and transverse T2-weighted scanning. The above scans were repeated after the administration of intravenous contrast 3 medium (gadolinium) in 12 patients. RESULTS: Seven of the 18 cases were located in the middle and lower thoracic spine, 3 in the lumbar spine, and 8 in the thoracolumbar junction. All cystic lesions were isointense compared with cerebrospinal fluid on the T1 and T2-weighted images. The lesions showed no enhancement after gadolinium administration. CONCLUSIONS: MRI had great sensitivity to and specificity for extradural arachnoid cysts and seemed to be the diagnostic procedure of choice before and after surgery. Accurate understanding of MRI features helps clinicians make preoperative diagnoses and guides the operation. The definitive treatment of SMCs involves total removal of the cyst and repair of the dural defect.