Tsunehisa Tsubokawa

Predicting difficult intubation with indirect laryngoscopy

Background It is not always possible to predict when tracheal intubation will be difficult or impossible. The authors wanted to determine whether indirect laryngoscopy could identify patients in whom intubation was difficult. Methods Indirect laryngoscopy was done in 2,504 patients. The Wilson risk sum score and the modified Mallampati score were also studied in a different series of 3,680 patients for comparison. These predictive methods were compared according to three parameters: positive predictive value, sensitivity, and specificity. Results Of 6,184 patients studied, the trachea proved difficult to intubate in 82 (1.3%). Positive predictive value (31%) and specificity (98.4%) with indirect laryngoscopy were greater than the other two predictive methods (P < 0.01), whereas sensitivity with indirect laryngoscopy (69.2%) was greater than that of the Wilson risk sum score (55.4%) (P < 0.01). Conclusions Although in 15% of patients indirect laryngoscopy could not be performed because of excessive gag reflex, indirect laryngoscopy can serve as an effective method to predict difficult intubation.

Lateralized Theta Wave Connectivity and Language Performance in 2- to 5-Year-Old Children

Recent neuroimaging studies support the view that a left-lateralized brain network is crucial for language development in children. However, no previous studies have demonstrated a clear link between lateralized brain functional network and language performance in preschool children. Magnetoencephalography (MEG) is a noninvasive brain imaging technique and is a practical neuroimaging method for use in young children. MEG produces a reference-free signal, and is therefore an ideal tool to compute coherence between two distant cortical rhythms. In the present study, using a custom child-sized MEG system, we investigated brain networks while 78 right-handed preschool human children (32–64 months; 96% were 3-4 years old) listened to stories with moving images. The results indicated that left dominance of parietotemporal coherence in theta band activity (6-8 Hz) was specifically correlated with higher performance of language-related tasks, whereas this laterality was not correlated with nonverbal cognitive performance, chronological age, or head circumference. Power analyses did not reveal any specific frequencies that contributed to higher language performance. Our results suggest that it is not the left dominance in theta oscillation per se, but the left-dominant phase-locked connectivity via theta oscillation that contributes to the development of language ability in young children.

Left-molar Approach Improves the Laryngeal View in Patients with Difficult Laryngoscopy

Background The molar approach of laryngoscopy is reported to improve glottic view in sporadic cases of difficult laryngoscopy. The authors studied the effect of molar approaches and optimal external laryngeal manipulation (OELM) using the Macintosh blade. Methods A series of 1,015 adult patients who underwent general anesthesia and tracheal intubation was studied. Laryngoscopy was carried out using a Macintosh no. 3 or 4 standard blade. Three consecutive trials of direct laryngoscopy using the midline and left- and right-molar approaches were carried out under full muscle relaxation with optimal head and neck positioning. The best glottic views were recorded for each approach with and without OELM. Results Difficult laryngoscopy with a midline approach accounted for 6.5% (66 cases) before OELM and 1.97% (20 cases) after OELM. A left-molar approach with OELM further reduced difficult laryngoscopy to seven cases (P < 0.001 vs. midline approach with OELM); a right-molar approach with OELM reduced difficult laryngoscopy to 18 cases (P = 0.48). Conclusions The left-molar approach with OELM improves the laryngeal view in patients with difficult laryngoscopy.

A custom magnetoencephalography device reveals brain connectivity and high reading/decoding ability in children with autism

A subset of individuals with autism spectrum disorder (ASD) performs more proficiently on certain visual tasks than may be predicted by their general cognitive performances. However, in younger children with ASD (aged 5 to 7), preserved ability in these tasks and the neurophysiological correlates of their ability are not well documented. In the present study, we used a custom child-sized magnetoencephalography system and demonstrated that preserved ability in the visual reasoning task was associated with rightward lateralisation of the neurophysiological connectivity between the parietal and temporal regions in children with ASD. In addition, we demonstrated that higher reading/decoding ability was also associated with the same lateralisation in children with ASD. These neurophysiological correlates of visual tasks are considerably different from those that are observed in typically developing children. These findings indicate that children with ASD have inherently different neural pathways that contribute to their relatively preserved ability in visual tasks.

Reduced long-range functional connectivity in young children with autism spectrum disorder

Autism spectrum disorder (ASD) is often described as a disorder of aberrant neural connectivity. Although it is important to study the pathophysiology of ASD in the developing cortex, the functional connectivity in the brains of young children with ASD has not been well studied. In this study, brain activity was measured non-invasively during consciousness in 50 young human children with ASD and 50 age- and gender-matched typically developing human (TD) children. We employed a custom child-sized magnetoencephalography (MEG) system in which sensors were located as close to the brain as possible for optimal recording in young children. We focused on theta band oscillations because they are thought to be involved in long-range networks associated with higher cognitive processes. The ASD group showed significantly reduced connectivity between the left-anterior and the right-posterior areas, exhibiting a decrease in the coherence of theta band (6 Hz) oscillations compared with the TD group. This reduction in coherence was significantly correlated with clinical severity in right-handed children with ASD. This is the first study to demonstrate reduced long-range functional connectivity in conscious young children with ASD using a novel MEG approach.

Altered brain connectivity in 3-to 7-year-old children with autism spectrum disorder.

Autism spectrum disorder (ASD) is often described as a disorder of aberrant neural connectivity and/or aberrant hemispheric lateralization. Although it is important to study the pathophysiology of the developing ASD cortex, the physiological connectivity of the brain in young children with ASD under conscious conditions has not yet been described. Magnetoencephalography (MEG) is a noninvasive brain imaging technique that is practical for use in young children. MEG produces a reference-free signal and is, therefore, an ideal tool for computing the coherence between two distant cortical rhythms. Using a custom child-sized MEG, we recently reported that 5- to 7-year-old children with ASD (n = 26) have inherently different neural pathways than typically developing (TD) children that contribute to their relatively preserved performance of visual tasks. In this study, we performed non-invasive measurements of the brain activity of 70 young children (3–7 years old, of which 18 were aged 3-4 years), a sample consisting of 35 ASD children and 35 TD children. Physiological connectivity and the laterality of physiological connectivity were assessed using intrahemispheric coherence for 9 frequency bands. As a result, significant rightward connectivity between the parietotemporal areas, via gamma band oscillations, was found in the ASD group. As we obtained the non-invasive measurements using a custom child-sized MEG, this is the first study to demonstrate a rightward-lateralized neurophysiological network in conscious young children (including children aged 3–4 years) with ASD.

Venous thromboembolism after spine surgery: changes of the fibrin monomer complex and D-dimer level during the perioperative period

OBJECT The goal of this study was to determine the incidence of deep venous thrombosis (DVT) and pulmonary embolism (PE) after spine surgery. Another purpose was to clarify the rapid changes of the fibrin monomer complex (FMC) and D-dimer levels during the perioperative period of spine surgery for early diagnosis of venous thromboembolism (VTE). METHODS The participants were 72 patients who underwent spine surgery between September 2007 and March 2008. The FMC and D-dimer levels were measured 6 times: 1) at induction of general anesthesia; 2) just after implantation or during surgery; 3) immediately following surgery; 4) 1 day after surgery; 5) 3 days postsurgery; and 6) 7 days after surgery. All patients received mechanical prophylaxis, including compression stockings and intermittent pneumatic compression devices, and all were examined with duplex ultrasonography assessments of both lower extremities and with lung perfusion scintigraphy 7-10 days after surgery. If DVT or PE was suspected, the patient underwent multidetector CT venography. RESULTS There were no patients with clinical signs of DVT and PE, but 6 (8.3%) showed VTE, among whom 5 had DVT and 3 had PE. Patients with VTE had significantly higher FMC levels 1 day after surgery, compared with those without VTE (55.9 ± 17.2 μg/ml vs 11.1 ± 2.89 μg/ml; p < 0.01). Patients with VTE had significantly higher D-dimer levels 7 days postsurgery, compared with those without VTE (12.5 ± 2.95 μg/ml vs 4.3 ± 0.39 μg/ml; p < 0.01). Receiver operating characteristic analysis showed that the FMC result was more useful than the D-dimer assay for diagnosis of VTE. When the cutoff value was set to 20.8 μg/ml for FMC, sensitivity was 100% and specificity was 86.3%. CONCLUSIONS In this study the prevalence of VTE after spine surgery was 8.3%. The FMC measured 1 day after spine surgery is considered to be useful as an indicator of VTE.

Atypical brain lateralisation in the auditory cortex and language performance in 3- to 7-year-old children with high-functioning autism spectrum disorder: a child-customised magnetoencephalography (MEG) study

BackgroundMagnetoencephalography (MEG) is used to measure the auditory evoked magnetic field (AEF), which reflects language-related performance. In young children, however, the simultaneous quantification of the bilateral auditory-evoked response during binaural hearing is difficult using conventional adult-sized MEG systems. Recently, a child-customised MEG device has facilitated the acquisition of bi-hemispheric recordings, even in young children. Using the child-customised MEG device, we previously reported that language-related performance was reflected in the strength of the early component (P50m) of the auditory evoked magnetic field (AEF) in typically developing (TD) young children (2 to 5 years old) [Eur J Neurosci 2012, 35:644–650]. The aim of this study was to investigate how this neurophysiological index in each hemisphere is correlated with language performance in autism spectrum disorder (ASD) and TD children.MethodsWe used magnetoencephalography (MEG) to measure the auditory evoked magnetic field (AEF), which reflects language-related performance. We investigated the P50m that is evoked by voice stimuli (/ne/) bilaterally in 33 young children (3 to 7 years old) with ASD and in 30 young children who were typically developing (TD). The children were matched according to their age (in months) and gender. Most of the children with ASD were high-functioning subjects.ResultsThe results showed that the children with ASD exhibited significantly less leftward lateralisation in their P50m intensity compared with the TD children. Furthermore, the results of a multiple regression analysis indicated that a shorter P50m latency in both hemispheres was specifically correlated with higher language-related performance in the TD children, whereas this latency was not correlated with non-verbal cognitive performance or chronological age. The children with ASD did not show any correlation between P50m latency and language-related performance; instead, increasing chronological age was a significant predictor of shorter P50m latency in the right hemisphere.ConclusionsUsing a child-customised MEG device, we studied the P50m component that was evoked through binaural human voice stimuli in young ASD and TD children to examine differences in auditory cortex function that are associated with language development. Our results suggest that there is atypical brain function in the auditory cortex in young children with ASD, regardless of language development.

Language performance and auditory evoked fields in 2- to 5-year-old children

Language development progresses at a dramatic rate in preschool children. As rapid temporal processing of speech signals is important in daily colloquial environments, we performed magnetoencephalography (MEG) to investigate the linkage between speech‐evoked responses during rapid‐rate stimulus presentation (interstimulus interval < 1 s) and language performance in 2‐ to 5‐year‐old children (n = 59). Our results indicated that syllables with this short stimulus interval evoked detectable P50m, but not N100m, in most participants, indicating a marked influence of longer neuronal refractory period for stimulation. The results of equivalent dipole estimation showed that the intensity of the P50m component in the left hemisphere was positively correlated with language performance (conceptual inference ability). The observed positive correlations were suggested to reflect the maturation of synaptic organisation or axonal maturation and myelination underlying the acquisition of linguistic abilities. The present study is among the first to use MEG to study brain maturation pertaining to language abilities in preschool children.

The effects of arm position on central spread of local anesthetics and on quality of the block with axillary brachial plexus block

BACKGROUND AND OBJECTIVES Spread of local anesthetic solution in axillary brachial plexus block is thought to be influenced by the position of the arm and the use of compression maneuvers. We investigated how these two factors affected central local anesthetic spread and block quality. METHODS Radiographic spread of local anesthetic was studied in 80 adult patients. They received mepivacaine mixed with contrast agent through an indwelling catheter with the arm abducted to either 0 or 90 degrees , and with or without local digital compression. Central and peripheral spread of the contrast agent was evaluated with anteroposterior radiographs of the axilla. Block quality was studied in a separate series of 70 adult patients. They received mepivacaine with the arm abducted 0 degrees or 90 degrees . The degree of sensory and motor block was assessed 20 minutes after the injection. RESULTS Arm position at 0 degrees abduction promoted central spread of the contrast agent. Although digital compression suppressed peripheral spread effectively, it did not improve the central spread of the solution. Sensory block was comparable in all terminal nerves of the arm in both arm positions, whereas motor block of the radial nerve was promoted with no abduction. CONCLUSIONS The central spread of local anesthetics is facilitated by injection without abduction of the arm but not by the use of compression at the injection site. This, however, did not alter the quality of the block.