Functional Connectivity Alterations in Patients with Post-stroke Epilepsy Based on Source-level EEG and Graph Theory.

We investigated the differences in functional connectivity based on the source-level electroencephalography (EEG) analysis between stroke patients with and without post-stroke epilepsy (PSE). Thirty stroke patients with PSE and 35 stroke patients without PSE were enrolled. EEG was conducted during a resting state period. We used a Brainstorm program for source estimation and the connectivity matrix. Data were processed according to EEG frequency bands. We used a BRAPH program to apply a graph theoretical analysis. In the beta band, radius and diameter were increased in patients with PSE than in those without PSE (2.699 vs. 2.579, adjusted p = 0.03; 2.261 vs. 2.171, adjusted p = 0.03). In the low gamma band, radius was increased in patients with PSE than in those without PSE (2.808 vs. 2.617, adjusted p = 0.03). In the high gamma band, the radius, diameter, average eccentricity, and characteristic path length were increased (1.828 vs. 1.559, adjusted p < 0.01; 2.653 vs. 2.306, adjusted p = 0.01; 2.212 vs. 1.913, adjusted p < 0.01; 1.425 vs. 1.286, adjusted p = 0.01), whereas average strength, mean clustering coefficient, and transitivity were decreased in patients with PSE than in those without PSE (49.955 vs. 55.055, adjusted p < 0.01; 0.727 vs. 0.810, adjusted p < 0.01; 1.091 vs. 1.215, adjusted p < 0.01). However, in the delta, theta, and alpha bands, none of the functional connectivity measures were different between groups. We demonstrated significant alterations of functional connectivity in patients with PSE, who have decreased segregation and integration in brain network, compared to those without PSE.

Risk of recurrent ischemic stroke in patients with patent foramen ovale: The role of D-dimer.

BACKGROUND: Paradoxical embolism under elevated thromboembolic conditions is known to be the primary mechanism of patent foramen ovale (PFO)-related stroke. We hypothesized that higher levels of D-dimer, a marker of thromboembolism, could increase the risk of stroke recurrence in patients with PFO. METHODS: We conducted a retrospective analysis of data from 1226 consecutive patients with acute ischemic cryptogenic stroke (CS) who underwent transesophageal echocardiography (TEE). D-dimer was assessed during admission. We used a multivariate Cox proportional hazards model to evaluate the association of long-term outcomes between the presence of PFO and levels of D-dimer. RESULTS: Of the 1226 patients, the study included 461 who underwent TEE. Among them, 242 (52.5%) had PFOs. Among PFO patients, those with a D-dimer level >1.0 mg/L had a significantly higher risk of stroke recurrence compared to those with <0.5mg/L (adjusted hazard ratio (aHR) 4.04, 95% confidence interval [CI] 1.63-10.02). A pattern of increased risk of event with increasing D-dimer levels was observed (Ptrend=0.008). However, there was no significant difference in the risk of stroke recurrence at any D-dimer level compared to D-dimer level <0.5 mg/L among patients without PFO. In these patients, there was little evidence of increased risk with increasing D-dimer levels (Ptrend=0.570). CONCLUSIONS: This study demonstrated that the elevated D-dimer level increased the recurrence of stroke in CS patients with PFO, particularly showing a dose-dependent relationship between D-dimer levels and recurrence. However, no such effect was observed in patients without PFO. These findings provide valuable insights into the potential benefits of anticoagulation for strokes related to PFO.

Monitored Anesthesia Care in Minimally Invasive Spine Surgery-A Retrospective Case Series Study.

Background and Objectives: Minimally invasive spine surgery (MISS) under monitored anesthesia care (MAC) has emerged as a treatment modality for spinal radiculopathy. It is essential to secure the airway and guarantee spontaneous respiration without endotracheal intubation during MISS in a prone position. Materials and Methods: To evaluate the feasibility and safety of MAC with dexmedetomidine during MISS, we retrospectively reviewed clinical cases. A retrospective review of medical records was conducted between September 2015 and June 2016. A total of 17 patients undergoing MISS were included. Vital signs were analyzed every 15 min. The depth of sedation was assessed using the bispectral index (BIS) and the frequency of rescue sedatives. Adverse events during anesthesia, including bradycardia, hypotension, respiratory depression, postoperative nausea, and vomiting, were evaluated. Results: All cases were completed without the occurrence of airway-related complications. None of the patients needed conversion to general anesthesia. The median maintenance dosage of dexmedetomidine for adequate sedation was 0.40 (IQR 0.40-0.60) mcg/kg/hr with a median loading dose of 0.70 (IQR 0.67-0.82) mcg/kg. The mean BIS during the main procedure was 76.46 ± 10.75. Rescue sedatives were administered in four cases (23.6%) with a mean of 1.5 mg intravenous midazolam. After dexmedetomidine administration, hypotension and bradycardia developed in six (35.3%) and three (17.6%) of the seventeen patients, respectively. Conclusions: MAC using dexmedetomidine is a feasible anesthetic method for MISS in a prone position. Hypotension and bradycardia should be monitored carefully during dexmedetomidine administration.

Brain networks in migraine with and without aura: An exploratory arterial spin labeling MRI study.

OBJECTIVES: The aim of this exploratory study was to investigate the underlying pathomechanisms of migraine with aura (MA) and migraine without aura (MO) in the interictal phase using a connectivity analysis. METHODS: We prospectively enrolled patients who were newly diagnosed with migraine. All patients underwent brain MRI, including diffusion tensor imaging and arterial spin labeling perfusion MRI. We analyzed the differences between patients with MA and those with MO in structural connectivity based on diffusion tensor imaging and functional connectivity based on arterial spin labeling perfusion MRI using a graph theoretical analysis. RESULTS: We enrolled 58 patients with migraine (11 patients with MA and 47 patients with MO). There were no differences between patients with MA and those with MO in the network measures of global structural connectivity. However, differences in global functional connectivity were found between the two groups. The assortative coefficient was lower in patients with MA than in those with MO (-0.050 vs. -0.012, p = .017). There were no differences in local structural and functional connectivity between patients with MA and those with MO. CONCLUSION: We found differences in global functional connectivity between patients with MO and those with MA. The study of MA and MO using a connectivity analysis may shed light on migraine pathophysiology. We suggest it is worthwhile to investigate if changes in functional connectivity may serve as novel biomarkers in MA. In this regard, ASL MRI appears to be valuable in the context of network analysis, but further studies are needed to confirm our findings.

Sleep structure and electroencephalographic spectral power of middle-aged or older adults: Normative values by age and sex in the Korean population.

The fine structure of sleep electrocortical activity reflects health and disease. The current study provides normative data for sleep structure and electroencephalography (EEG) spectral power measures derived from overnight polysomnography (PSG) and examines the effect of age and sex among Korean middle-aged and older adults with or without obstructive sleep apnea (OSA). We analysed home PSG data from 1,153 adult participants of an ongoing population-based cohort study, the Korean Genome and Epidemiology Study. Sleep stages were visually scored and spectral power was measured on a single-channel EEG (C4-A1). We computed spectral power for five frequency ranges. The EEG power was reported in relative (%) and log-transformed absolute values (µV2 ). With ageing, the proportion of N1 sleep increased, whereas N3 decreased, which is more noticeable in men than in women. The amount of N3 was relatively low in this cohort. With ageing, relative delta power decreased and alpha and sigma power increased for the whole sleep period, which was more pronounced during REM sleep in non-OSA. For men compared with women, relative theta power was lower during REM and sigma and beta were higher during N1 sleep. The differences of relative powers by age and sex in OSA were comparable to those in non-OSA. In a community-based Korean population, we present normative data of sleep structure and spectral power for middle-aged or older adults of a non-Caucasian ethnicity. The values varied with age and sex and were not influenced by sleep apnea.

Existence and Significance of Internal Border Zone Infarcts with Accessory Lesions Located in the Anteromedial Temporal Lobe.

OBJECTIVES: To examine the existence and significance of internal border zone (IBZ) infarcts with accessory lesions in the anteromedial temporal lobe (ATL). MATERIALS AND METHODS: IBZ infarcts located at the corona radiata were selected based on diffusion-weighted imaging of 2535 consecutive patients with ischemic stroke and the presence of lesions in the ATL was identified. The Mann-Whitney U test, Student t-test, Pearson χ2 test, or Fisher exact test was used to analyze differences between the IBZ infarct groups with and without accessory lesions in the ATL. RESULTS: Thirty-six of 2535 patients (1.4%) had IBZ infarcts. The IBZ group with accessory lesions in the ATL (17 cases, 47.2%) showed a higher portion of occluded middle cerebral arteries than the IBZ group without accessory lesions in the ATL (p = 0.02). The initial National Institutes of Health Stroke Scale score (odds ratio, 2.03; 95% confidence interval, 1.04-3.99;   = 0.039) and progression after admission (odds ratio, 25.43; 95% confidence interval, 2.47-261.99; p = 0.007) were independently associated with poor prognosis in patients with IBZ infarcts. There were no differences in the progression rate and clinical outcomes, regardless of the presence of lesions in the ATL. CONCLUSIONS: Our study suggests the existence of a distinct type of IBZ infarct characterized by accessory lesions in the ATL, which is associated with different arterial features but has a similar clinical course to IBZ infarcts without accessory lesions in the ATL.

Stimulation Emission Depleted Photoacoustic.

We demonstrate that the Stimulated Emission Depletion (STED) concept, which is usually invoked for fluorescence, can be extended to photoacoustic effects. When two-nanosecond pulses of exciting and stimulating light are synchronized, 80% of the acoustic signal generated through excited state absorption (ESA) can be quenched. Regarding the cross-sections for stimulated emission and ESA, a model gives a good order of magnitude in the depletion efficiency. The transient molecular orientation, usually measured via the fluorescence anisotropy, can be accessed in photoacoustic when STED is implemented.

Prevalence and Characteristics of Restless Legs Syndrome in Korean Adults: A Study in Two Independent Samples of the General Population.

BACKGROUND: Restless legs syndrome (RLS) is a common sleep disorder, although it has a low prevalence in Asian populations. However, the reported RLS prevalence in -Korean adults is mostly 4.5-12.1%, which is higher than that reported in other Asian populations. This study aimed to diagnose RLS and exclude mimicking conditions in 2 independent samples of Korean adults, and to compare its prevalence to that from previous studies performed in Asian countries. METHODS: Study populations included a (1) nationwide stratified random sample (n = 2,824; age 19-79 years) and (2) community-based cohort (n = 2,685; age 47-79 years). We applied the Cambridge-Hopkins diagnostic questionnaire to diagnose RLS and differentiate it from RLS mimics. Sleep-related symptoms, mood, and medical conditions were compared between the RLS and non-RLS groups. Prior studies of the RLS prevalence in Asia were systematically reviewed and compared to our findings. RESULTS: The adjusted RLS prevalence was 0.4 and 1.3% in populations 1 and 2, respectively. In both populations, subjects with RLS had more depression. The prevalence of RLS mimics was 5.1 and 2.6%, in populations 1 and 2, respectively. The RLS prevalence in Asia was higher when RLS was defined by the presence of essential clinical features and lower when a differential diagnosis was additionally implemented. CONCLUSIONS: The RLS prevalence in Korean adults considering RLS mimics is comparable to that in adults from other Asian countries (< 2%). The reported RLS prevalence varies depending on the diagnostic method employed.

Light Controlled Optical Aharonov-Bohm Oscillations in a Single Quantum Ring.

We found that optical Aharonov-Bohm oscillations in a single GaAs/GaAlAs quantum ring can be controlled by excitation intensity. With a weak excitation intensity of 1.2 kW cm-2, the optical Aharonov-Bohm oscillation period of biexcitons was observed to be half that of excitons in accordance with the period expected for a two-exciton Wigner molecule. When the excitation intensity is increased by an order of magnitude (12 kW cm-2), a gradual deviation of the Wigner molecule condition occurs with decreased oscillation periods and diamagnetic coefficients for both excitons and biexcitons along with a spectral shift. These results suggest that the effective orbit radii and rim widths of electrons and holes in a single quantum ring can be modified by light intensity via photoexcited carriers, which are possibly trapped at interface defects resulting in a local electric field.

Optical sectioning in optical resolution photo acoustic microscopy.

We report a novel optical resolution photoacoustic microscopy concept to obtain an axial resolution only by optical methods. The photoacoustic signal is generated through a non-radiative relaxation from a level that is populated by excited state absorption. This two-step excitation process of a single laser enables to achieve an optical sectioning without any acoustic selectivity, whereby a full optical resolution photoacoustic microscopy is obtained. We bring a proof of this concept using Rhodamine and Zinc Tetraphenylporphyrin dyes known for their efficient excited state absorption process.

Associations of impaired sleep quality, insomnia, and sleepiness with epilepsy: A questionnaire-based case-control study.

PURPOSE: The purpose of this study was to document the frequency of sleep problems including poor sleep quality, excessive daytime sleepiness, and insomnia in subjects with epilepsy compared with healthy controls and to determine the factors associated with these sleep disturbances. METHODS: We recruited 180 patients with epilepsy (age: 43.2 ± 15.6 years, men: 50.0%) and 2836 healthy subjects (age: 44.5 ± 15.0 years, men: 49.8%). Sleep and the anxiety/mood profiles were measured using the Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, Insomnia Severity Index, Goldberg Anxiety Scale, and Patient Health Questionnaire-9 depression scale. Associations of sleep problems with epilepsy and other factors were tested by multiple logistic regression analysis, adjusted for age, gender, body mass index, alcohol intake, smoking, perceived sleep insufficiency, and habitual snoring. RESULTS: Sleep disturbances were more common in the group with epilepsy than in the controls (53.3% vs. 25.5%; p<0.001). Poor sleep quality, excessive daytime sleepiness, and insomnia were significantly associated with epilepsy (odds ratio [95% confidence interval]: 3.52 [2.45-5.05], 2.10 [1.41-3.12], 5.91 [3.43-10.16], respectively). Depressive mood, anxiety, and perceived sleep insufficiency contributed to the presence of sleep disturbances. In the group with epilepsy, seizure remission for the past year related to a lower frequency of insomnia, whereas age, sex, type of epilepsy, and number of antiepileptic drugs were not correlated with sleep problems. CONCLUSION: Epilepsy was significantly associated with the higher frequency of sleep disturbances, which supports the importance of screening sleep problems in patients with epilepsy and providing available intervention.

Central Trochlear Palsy: Report of Two Patients With Ipsilesional Palsy and Review of the Literature.

BACKGROUND: The trochlear (fourth) nerve is the only cranial nerve that decussates before emerging from the posterior aspect of the brainstem. Lesions involving the trochlear nucleus or fascicles mostly give rise to contralesional superior oblique palsy (SOP). METHODS: We report 2 patients with SOP on the side of intraaxial lesions with a literature review on central trochlear palsy. RESULTS: The lesions are more commonly located posterior to the cerebral aqueduct in patients with ipsilesional SOP than in those with contralesional SOP. CONCLUSIONS: Intraaxial lesions may cause ipsilesional or contralesional SOP depending on the lesion location along the course of trochlear fascicle in the brainstem.

Dorsal Medullary Infarction: Distinct Syndrome of Isolated Central Vestibulopathy.

BACKGROUND AND PURPOSE: The characteristics of infarctions restricted to the dorsal medulla have received little attention. This study aimed to define the distinct clinical features of dorsal medullary infarction. METHODS: Of the 172 patients with a diagnosis of medullary infarction at Seoul National University Bundang Hospital from 2003 to 2014, 18 patients with isolated dorsal medullary infarction were subjected to analyses of clinical and laboratory findings. RESULTS: All patients presented acute isolated vestibular syndrome with dizziness/vertigo and imbalance. Almost all patients (17/18, 94%) showed the signs from involvements of the vestibular nuclei, nucleus prepositus hypoglossi, or inferior cerebellar peduncle, which included direction-changing gaze-evoked nystagmus (n=12), negative head-impulse tests (n=8), skew deviation (n=7), central patterns of head-shaking nystagmus (n=6), and spontaneous nystagmus (n=2). Initial magnetic resonance imagings including diffusion-weighted images were negative in 7 patients (39%). Twelve patients (67%) showed a progression and developed additional neurological abnormalities, but the neurological outcomes were favorable. CONCLUSIONS: The presence of central vestibular signs allows bedside differentiation of isolated vestibular syndrome because of dorsal medullary infarction from acute peripheral vestibular disorders. Because initially false-negative magnetic resonance imagings and subsequent progression are frequent in dorsal medullary infarction, early recognition through scrutinized evaluation is important for proper managements.

Isolated unilateral infarction of the cerebellar tonsil: ocular motor findings.

The oculomotor abnormalities with isolated infarction of the cerebellar tonsil are unknown. In a patient with acute infarction of the right tonsil, we found (1) nearly completely abolished ipsilateral smooth pursuit and impaired contralateral pursuit, (2) a low-amplitude ipsilesional right-beating nystagmus without fixation, (3) gaze-holding deficits, and (4) normal vestibulo-ocular reflex. These findings contrast with striking vestibular abnormalities reported with unilateral flocculus and anterior tonsil infarction. Taken together, these findings allow more diagnostic certainty in cerebellar patients, help resolve controversies about interpretation of experimental findings in monkeys, and clarify homologies between the monkey and human cerebellum.

Vestibular Performance During High-Acceleration Stimuli Correlates with Clinical Decline in SCA6.

In spinocerebellar ataxia type 6 (SCA6), the vestibular dysfunction and its correlation with other clinical parameters require further exploration. We determined vestibular responses over a broad range of stimulus acceleration in 11 patients with SCA6 (six men, age range=33-72 years, mean age±SD=59±12 years) using bithermal caloric irrigations, rotary chair, and head impulse tests. Correlations were also pursued among disability scores, as measured using the International Cooperative Ataxia Rating Scale, disease duration, age at onset, cytosine-adenine-guanine (CAG) repeat length, and the gain of the vestibulo-ocular reflex (VOR). In response to relatively low-acceleration, low-frequency rotational and bithermal caloric stimuli, the VOR gains were normal or increased regardless of the severity of disease. On the other hand, with relatively high-acceleration, high-frequency head impulses, there was a relative increase in gain in the mildly affected patients and a decrease in gain in the more severely affected patients and gains were negatively correlated with the severity of disease (Spearman correlation, R=-0.927, p<0.001). Selective decrease of the vestibular responses during high-acceleration, high-frequency stimuli may be ascribed to degeneration of either the flocculus or vestibular nuclei. The performance of the VOR during high-acceleration, high-frequency head impulses may be a quantitative indicator of clinical decline in SCA6.

Early statin use in ischemic stroke patients treated with recanalization therapy: retrospective observational study.

BACKGROUND: We aimed to determine whether early statin use following recanalization therapy improves the functional outcome of ischemic stroke. METHODS: Using a prospective stroke registry database, we identified a consecutive 337 patients within 6 h of onset who had symptomatic stenosis or occlusion of major cerebral arteries and received recanalization therapy. Based on commencement of statin therapy, patients were categorized into administration on the first (D1, 13.4%), second (D2, 20.8%) and third day or later (D ≥ 3, 15.4%) after recanalization therapy, and no use (NU, 50.4%). The primary efficacy outcome was a 3-month modified Rankin Scale score of 0-1, and the secondary outcomes were neurologic improvement, neurologic deterioration and symptomatic hemorrhagic transformation during hospitalization. RESULTS: Earlier use of statin was associated with a better primary outcome in a dose-response relationship (P for trend = 0.01) independent of premorbid statin use, stroke history, atrial fibrillation, stroke subtype, calendar year, and methods of recanalization therapy. The odds of a better primary outcome increased in D1 compared to NU (adjusted odds ratio, 2.96; 95% confidence interval, 1.19-7.37). Earlier statin use was significantly associated with less neurologic deterioration and symptomatic hemorrhagic transformation in bivariate analyses but not in multivariable analyses. Interaction analysis revealed that the effect of early statin use was not altered by stroke subtype and recanalization modality (P for interaction = 0.97 and 0.26, respectively). CONCLUSION: Early statin use after recanalization therapy in ischemic stroke may improve the likelihood of a better functional outcome without increasing the risk of intracranial hemorrhage.

Accelerated degeneration of the discoid lateral meniscus after medial opening wedge high tibial osteotomy.

PURPOSE: This study was undertaken to report clinical outcomes after high tibial osteotomy (HTO) in patients with a discoid lateral meniscus and to determine (1) whether discoid lateral meniscus degeneration by magnetic resonance imaging (MRI) progresses after HTO and (2) whether this progression adversely affects clinical results. METHODS: The records of 292 patients (292 knees) who underwent medial opening HTO were retrospectively reviewed, and discoid types and grades of lateral meniscus degeneration as determined by MRI were recorded preoperatively. Of the 292 patients, 17 (5.8%) had a discoid lateral meniscus, and postoperative MR images were obtained at least 2 years after HTO for 15 of these 17 patients. RESULTS: American Knee Society (AKS) pain, knee and function scores significantly improved in the 15 patients after surgery (p < 0.001). Eight (53%) had an incomplete and 7 (47%) had a complete discoid lateral meniscus. By preoperative MRI, the distribution of meniscal degeneration was as follows: grade 1, 4 patients; grade 2, 7 patients; and grade 3, 4 patients. At the final follow-up, the distribution of degeneration was as follows: grade 1, 2 patients; grade 2, 5 patients; and grade 3, 8 patients. Two patients with grade 3 degeneration who did not undergo partial meniscectomy showed tear progression. Thus, 8 of the 15 patients (53%) experienced progressive discoid meniscal degeneration after HTO. Median AKS pain score was significantly lower in the progression group than in the non-progression group (40 vs 45, respectively). CONCLUSION: The results of this study suggest that increased load on the lateral compartment after HTO can accelerate discoid lateral meniscus degeneration by MRI and caution that when a discoid lateral meniscus is found by preoperative MRI, progressive degeneration may occur after HTO and clinical outcome may be adversely affected. LEVEL OF EVIDENCE: Therapeutic study, Level IV.

The impact of stent design on the structural mechanics of the crossing Y-stent: an in vitro study.

INTRODUCTION: Crossing Y-stent technique is a valid option for coiling wide-necked bifurcation aneurysms. Two main designs of stents, the closed- (CCS) and open-cell (OCS), are used in combination for a crossing Y-construct. This in vitro study was conducted to assess the mechanical characteristics of each stent-combination and to suggest an optimal combination for clinical practice. METHODS: The Enterprise and the Neuroform3 stents were used as closed-cell and open-cell stents, respectively. Four different Y-stent combinations; double CCSs (CCS-CCS; Enterprise-Enterprise), OCS followed by CCS (OCS-CCS; Neuroform-Enterprise), CCS followed by OCS (CCS-OCS; Enterprise-Neuroform), and double OCSs (OCS-OCS; Neuroform-Neuroform) were tested in a bifurcation aneurysm model. Images of the model were obtained by digital subtraction angiography (DSA), and morphological changes of Y-constructs caused by interaction between stents were compared. RESULTS: Double OCSs showed the best stent apposition to model branches and no collapse of the second stent at the intersection, whereas Y-stent combinations using a CCS as the second stent showed tubular collapse of the second stent at the crossing point. These combinations revealed unsatisfactory apposition to the model branch in which the second stent was deployed. Most narrowing of the second stent was noted in the double CCSs construct, which resulted in poorest stent apposition. CONCLUSION: Based on a simple in vitro experiment, we suggest that double OCSs Y-construct is optimal for achieving best stent-wall apposition. Furthermore, our findings suggest that Y-stent combinations utilizing a CCS as the second stent may increase the risk of thromboembolic complications due to poor stent-wall apposition.

Positional suppression of periodic alternating nystagmus.

A 43-year-old man with a high-grade glioma involving the cerebellar nodulus showed a near-complete suppression of periodic alternating nystagmus (PAN) in the lateral decubitus position to either side. This positional modulation of PAN is consistent with suppression of the velocity storage mechanism by head position changes (tilt dumping) and is supportive of the role of the velocity storage mechanism in generating PAN.