Wavelet-crosscorrelation analysis: Non-stationary analysis of neurophysiological signals.

OBJECTIVE: Wavelet-crosscorrelation analysis is a new application of wavelet analysis used to show the propagation of epileptiform discharges and to localize the corresponding lesions. We have shown previously that this analysis can help predict brain conditions statistically (Mizuno-Matsumoto et al. 2002). Our objective was to assess whether wavelet-crosscorrelation analysis reveals the initiation and propagation of epileptiform activity in human patients. METHODS: The data obtained from three patients with simple partial seizures (SPS) using whole-head magnetoencephalography (MEG) were analyzed by the wavelet-crosscorrelation method. Wavelet-crosscorrelation coefficients (WCC), the coherent structure of each possible pair of signals from 64 MEG channels forvarious periods, and the time lag (TL) in two related signals, were ascertained. RESULTS: We clearly demonstrated both localization of the irritative zone and propagation of the epileptiform discharges. CONCLUSIONS: Wavelet-crosscorrelation analysis can help reveal and visualize the dynamic changes of brain conditions. The method of this analysis can compensate for other existing methods for the analysis of MEG, electroencephalography (EEG) or Elecotrocorticography (ECoG). SIGNIFICANCE: Our proposed method suggests that revealing and visualizing the dynamic changes of brain conditions can help clinicians and even patients themselves better understand such conditions.

NMR second moment imaging using Jeener-Broekaert dipolar signals.

It is demonstrated that imaging of the 1H NMR second moment can be achieved by using the Jeener-Broekaert (JB) dipolar signal instead of the Zeeman FID signal commonly employed. The JB dipolar signal can be induced by applying a JB pulse sequence, 90 degrees (x)-tau-45 degrees (y)-tau(')-45 degrees (y), which is followed by the time-suspension magic echo sequence, TREV-16TS, for imaging detection. Scanning the imaging detection to cover the whole evolution of the JB dipolar signal finally results in producing spatially resolved JB dipolar signals. The local value of the quantity called the "JB second moment," M(2(JB)), is then estimated from the initial slope of each resolved JB dipolar signal. The M(2(JB)) can be regarded as the "weighted" powder average of the usual second moment. The "weighting" effect due to the JB sequence leads to the tau dependent M(2(JB)) value. The tau dependence is potentially useful for characterizing the second moment distribution resulting from the crystal orientation dependence: For example, in addition to the usual powder average, an approximate distribution range can be deduced by a simple analysis of the tau dependence, serving as a new contrast for materials imaging. This is illustrated by preliminary experiments performed on test samples.

Theta rhythm increases in left superior temporal cortex during auditory hallucinations in schizophrenia: a case report.

Auditory hallucinations (AH), the perception of sounds and voices in the absence of external stimuli, remain a serious problem for a large subgroup of patients with schizophrenia. Functional imaging of brain activity associated with AH is difficult, since the target event is involuntary and its timing cannot be predicted. Prior efforts to image the patterns of cortical activity during AH have yielded conflicting results. In this study, MEG was used to directly image the brain electrophysiological events associated with AH in schizophrenia. We observed an increase in theta rhythm, as sporadic bursts, in the left superior temporal area during the AH states, whereas there was steady theta band activity in the resting state. The present finding suggests strong association of the left superior temporal cortex with the experience of AH in this patient. This is consistent with the hypothesis that AH arises from areas of auditory cortex subserving receptive language processing.

Imaging of the (1)H NMR second moment with (13)C chemical-shift resolution

A method of (13)C chemical-shift-resolved (1)H second moment imaging is proposed for molecular mobility imaging of heterogeneous materials. For evaluating the (1)H second moment, the method relies on the curve fitting procedure using spin-echo shapes indirectly: The information of (1)H echo shapes is transferred to the (13)C signal amplitude through (1)H-(13)C cross polarization and then the curve fitting is made using the (13)C signal amplitude. The (13)C signal is detected under (1)H dipolar decoupling and magic angle spinning, resulting in the incorporation of (13)C chemical-shift resolution. Imaging information is included in the (13)C signal by application of phase-encoding gradients. The second moment images obtained can reflect the molecular mobility at every molecular site separated by (13)C chemical shifts, yielding detailed information on the molecular mobility. The method is demonstrated by spatially 1D experiments performed on a model sample. Copyright 2000 Academic Press.

Telemedicine for evaluation of brain function by a metacomputer.

A method of evaluating brain function using the metacomputer concept of the Globus system combined with a message-passing interface is described. The proposed method has the ability to exploit various geographically distributed resources and parallel computing linked to a high-technology medical instrumentation system, magnetoencephalography, to analyze the functional state of the brain. It is envisaged that the method will lead to the realization of an efficient telemedicine system for health care.

Laser surgery for allergic and hypertrophic rhinitis.

Laser surgery, which is one type of surgical treatment for allergic and hypertrophic rhinitis, was investigated basically and clinically. The basic investigation showed morphological changes in the nasal mucosa before and after laser surgery. Before laser surgery, hyperplasia of the mucous epithelium, thickening of the basement membrane, edema of the lamina propria mucosa, eosinophilic infiltration, and enlargement of the nasal glands were noted. After laser surgery, the nasal mucosa was covered with 1) epithelium that was squamatized or cuboidal and/or 2) columnar epithelium that was stratified. Granulation-like tissue or cicatricial tissue was found in the lamina propria mucosa. Clinically, we performed laser surgery in 204 cases. Regarding the short-term results, laser surgery was effective in 87%. In the long term, the short-term results persisted in 81% of cases treated for sneezing, 78% for nasal discharge, and 76% for nasal obstruction. From these results, we concluded that laser surgery was a useful surgical treatment for allergic and hypertrophic rhinitis.

Magic echo solid-state NMR imaging without a rapidly switchable field gradient

To relax the high-speed requirement imposed on the gradient system used in solid-state proton imaging, we propose two simple modifications of the magic echo imaging sequence, TREV-16TS. In the first modification, the applied gradient is inverted in the middle of the RF irradiation; the second modification utilizes a sinusoidal gradient synchronized with the RF sequence. It is estimated by experiments that as long as the RF amplitude is at least about 10 times stronger than the resonance offset induced by the gradient, the spatial resolution is not degraded significantly by the line narrowing deterioration due to the gradient applied during the on-resonance RF irradiation. The modifications allow commercially available standard gradients to be used for the magic echo imaging of solids. Copyright 1999 Academic Press.

Medial prefrontal cortex generates frontal midline theta rhythm.

Frontal midline theta rhythm (Fm theta) is a distinct theta activity of EEG in the frontal midline area that appears during concentrated performance of mental tasks in normal subjects and reflects focused attentional processing. To tomographically visualize the source current density distributions of Fm theta, we recorded Fm theta by using a 64-channel whole-head MEG system from four healthy subjects, and applied a new analysis method, synthetic aperture magnetometry (SAM), an adaptive beam forming method. Fm theta was observed in the MEG signals over the bilateral frontal regions. SAM analysis showed bilateral medial prefrontal cortices, including anterior cingulate cortex, as the source of Fm theta. This result suggests that focused attention is mainly related to medial prefrontal cortex.

Cross polarization for 1H NMR image contrast in solids

A novel 1H imaging method for solids, yielding images reflecting 1H-13C dipolar interactions through cross relaxation time TIS, is presented. Phase-alternating multiple-contact cross polarization (PAMC CP) was incorporated into the magic-echo frequency-encoding imaging scheme; the PAMC CP sequence may partly but efficiently destroy the initial 1H magnetization depending on the TIS values. A theory describing the effects of the PAMC CP sequence was developed, which was used for the assessment of the sequence as well as the analysis for the experimental results. It was demonstrated that the TIS-weighted 1H image and the TIS mapping for a phantom, constituted of adamantane and ferrocene, can distinguish these compounds clearly. Copyright 1998 Academic Press.

Palliative radiotherapy for lingual metastasis of renal cell carcinoma.

The report is of a 50-year-old man with renal cell carcinoma (RCC) who had rapidly progressing metastasis to the tongue at 10 months after the left radical nephrectomy. The metastatic lingual tumor was not resectable, therefore treated with radiation (50 Gy). The tumor disappeared macroscopically after the radiation therapy, but enlarged again 4 months later. The patient died of respiratory failure due to multiple lung metastases 12 months after the appearance of the lingual metastasis. Radiation therapy is an acceptable palliative strategy for advanced lingual metastasis of RCC.

Effects of head rotation on pharyngeal function during normal swallow.

This study quantified the effects of head rotation on pharyngeal swallowing in healthy subjects. Videofluoroscopic and oropharyngeal manometric examinations of pharyngeal swallowing were performed on seven volunteers with the head in neutral and rotated positions. Videofluoroscopic study revealed that head rotation swallow causes the bolus to lateralize away from the direction of head rotation. Pharyngeal manometric study indicated that the pharyngeal peak pressures toward the side of head rotation were significantly increased, whereas the pharyngeal pressures opposite the side of head rotation were not affected. Head rotation swallow produced a significant fall in upper esophageal sphincter (UES) resting pressure and a delay in UES closing. We concluded that the head rotation swallow in normal subjects not only alters the bolus pathway, but also has a useful effect on both pharyngeal clearance and UES dynamics.

Occurrences of electroencephalographic (EEG) patterns that resemble epileptiform discharges in background EEG in epileptic patients.

The relationships of background EEG to epileptiform discharge development were studied in 9 epileptic patients having generalized spike and wave complexes (SWCs) with a maximum at the frontal location on either side. The instantaneous power spectrum of EEGs at F3, F4, C3, C4, P3, P4, O1, O2, T3 and T4 was estimated with wavelet transform. Subsequently, the similarity of power spectra between SWCs and background EEG was determined by use of Kullback-Leibler information and artificial neural network in each patient. Both similarity measures revealed that EEG patterns similar to SWCs occurred in the background activity just before SWCs at frontal locations. These findings suggested that these SWC-like EEG events occurred as poorly developed epileptiform discharges buried in the background activity.

[Effect of posture strategies on preventing aspiration].

The purpose of this study was to determine the effect of postural change on preventing aspiration, and the types of swallowing disorder that were influenced by posture. Ninety-five patients that were examined by aspiration of barium during videofluoroscopic examination of oropharyngeal swallow assumed one of four postures (chin down, head rotation, chin down + head rotation, and head back to chin down). Postural strategies were successful in eliminating aspiration in 68(72%) of the 95 patients. Twenty five of the 68 patients, however, needed an additional change in bolus volume to eliminate aspiration. Effective postures eliminating aspiration were chin down for 43 patients, head rotation for 10 patients, chin down + head rotation for 12 patients, and head back to chin down for 3 patients. The successes rates of posture changes for each swallowing abnormality were 76% for reduced tongue base retraction, 74% for delay in triggering pharyngeal swallow, 74% for reduced laryngeal elevation, 73% for laryngeal paralysis, 68% for inefficient oral transit, and in 57% for cricopharyngeal dysfunction. Among individuals with cricopharyngeal dysfunction or with than three swallowing motility problems, the frequency of unsuccessful swallow despite postural change was significantly higher than that of successful swallow. These results indicated that the posture strategies in addition to control of bolus volume could prevent aspiration in more than 70% of patients, but the efficacy of posture techniques differed with the different types of swallowing disorder identified as causing the aspiration, and suggested that the posture strategies were less beneficial in individuals with cricopharyngeal dysfunction or exhibiting multiple swallowing disorders.

Fast imaging of the second moment using magic echo trains.

Approaches are discussed to imaging of the second moment of proton NMR dipolar spectra. Two methods are proposed using the peak shapes of the magic echo trains for evaluation of the second moment. One is a quasi-multidimensional FT approach where the peak shapes of the magic echoes are spatially resolved, and the other is the fast version of the former approach, collecting the same data in a much shorter measurement time. Preliminary results of spatially 2D, as well as 1D, experiments are reported.

Inhibition of head and neck metastatic and/or recurrent cancer by local administration of multi-cytokine inducer OK-432.

The multi-cytokine inducer OK-432 is a pulverized preparation of the low-virulence SU strain of Streptococcus pyogenes of human origin. A reduction of the tumour mass in the OK-432-injected areas was observed in 11 out of 13 patients with metastatic and/or recurrent head and neck cancer. Complete response (CR), partial response (PR) and minor response (MR) were noted in six, three and two cases respectively. OK-432 local administration therapy could create a new strategy for cancer therapy.

Large radiolucent tracheal foreign body found by CT scan caused dyspnea: an admonition on flexible fiberscopic foreign body removal.

A 25-year-old male patient with a sharp, large, and radiolucent tracheobronchial foreign body which was inhaled at the time of a traffic accident is reported on. CT scan was quite useful in finding this radiolucent foreign body. The patient had no respiratory disturbance because the foreign body was located in the level between bifurcation and left main bronchus; however, a flexible fiberscopic procedure performed to remove the body caused an airway obstruction and a dyspnea because the foreign body lodged in the subglottis. Remarkable progress has been made in the development of the flexible fiberscope system. Almost all medical facilities in Japan have flexible systems. However, the opportunities for young physicians to learn about rigid systems may now become limited. This case may warn us not to have too much confidence in the ability of flexible fiberscope system to remove this kind of large foreign body and remind us of the need to continue adequate training in the rigid systems.

[Tonsillectomy in a boy liver transplant].

As of 1995, organ transplantation from cadaver donors is under debate in the Japanese Diet. Depending on what the Diet decides, more organ transplantations may be performed. Since cases of orthotopic liver transplantation (OLT) may increase, the need to perform surgical operations in post-OLT patients may arise. The purpose of this report is to enlighten Japanese otorhinolaryngologists on the post-transplant state. An 8-year-old boy who underwent OLT in Australia 7 years previously underwent successful tonsillectomy, adenoidectomy and insertion of ventilation tubes into both ears under general anesthesia (GA) to treat habitual angina, hypertrophy of the nasopharyngeal and palatine tonsils, and secretory otitis media. The optimal circumstances for operation require adequate but not excessive immunosuppression and a well-functioning graft. Vascular complications (VCs) such as hepatic artery thrombosis become rare after a few years post-OLT. However, once VCs occur the mortality rate of OLT patients is high, and excessive perioperative changes in circulation must be avoided. Immunosuppressive agents should be continued throughout the perioperative period and perioperative antibiotic prophylaxis should be employed, just as in non-transplant patients. Tonsillectomy is an effective means of prophylaxis for upper respiratory infection in habitual angina patients. Infection of an OLT patient may become critical because immunosuppressive agents to prevent rejection lower immune barriers and increase the risk of infection, and dose reduction may increase the risk of rejection. Tonsillectomy may also prevent a possible lympho-proliferative disorder (LPD). Tonsillar hypertrophy in OLT patients may be due to life-threatening LPD. Thus, tonsillectomy serves both as a prophylactic and curative measure against possible complications OLT may cause later, and therefore may improve the outcome of OLT.

The 3-dimensional representation of EEG distance by use of Shannon-Gelfand-Yaglom information measure during mental arithmetic.

EEG relationships in delta, theta, alpha and beta frequency bands as well as the whole frequency range among 12 electrode locations during resting and mental arithmetic were examined by use of Shannon-Gelfand-Yaglom information measure (SGY) in 10 normal subjects. The EEG relationships were represented in a 3-dimensional (3-D) feature space with multidimensional scaling (MDS). MDS resulted in an anterior-posterior, a left-right and an upper-lower axis. In all 5 frequency bands, the 12 electrodes on the anterior-posterior and left-right axes resembled their actual positions on the scalp during resting and mental arithmetic. During mental arithmetic, prominent changes in the 3-D representation of electrode sites were visualized for activity. The isolation of left and right mid-temporal locations, together with greater EEG distances between left and right mid-temporal locations, were notable during mental arithmetic, suggesting the simultaneous activation possibly in dominant and non-dominant hemispheres and contralateral influences from left to right mid-temporal locations.