Cortical representation of swallowing in normal adults: functional implications

OBJECTIVE

Dysphagia of neurogenic or postsurgical origin presents management and therapeutic challenges to the otolaryngologist. Improvements in management and therapeutic approaches may be facilitated by understanding how the central nervous system controls swallowing. The purpose of this investigation was to utilize functional magnetic resonance imaging to determine patterns of cortical activity during swallowing in normal, healthy adult subjects.

STUDY DESIGN

Functional magnetic resonance imaging (fMRI) was performed on eight healthy adult subjects using conventional BOLD (blood oxygenation level dependent) techniques.

METHODS

Subjects performed three different swallowing tasks including dry and bolus swallows, and performed a control finger movement task. Statistical maps of cortical activation were generated using a cross-correlation analysis. One-way and two-way ANOVA statistical analyses were performed to compare activated areas among the different tasks and to determine the effects of task sequence.

RESULTS

Activation during the three swallowing tasks occurred in the primary motor cortex, primary somatosensory cortex, and other cortical and subcortical sites. Cortical representation of swallowing and finger movement followed somatotopic maps. Differential distribution of cortical activation was observed for the different swallowing tasks.

CONCLUSIONS

Activation of the primary motor and somatosensory cortices, as well as other sensory-motor areas, occurs with swallowing in normal adults. Differential distribution of cortical activity with different swallowing tasks suggests differential functional organization for different swallowing tasks. Understanding these mechanisms may facilitate improved management and therapeutic intervention for neurogenic and postsurgical dysphagia.

Water-suppression MRI: role in the evaluation of osseous lesions

The efficacy of chemical shift based water-suppression MRI in the evaluation of bone marrow lesions has not been previously reported. T1-weighted images without and with water suppression were compared in five patients with 16 lesions. There was a significant improvement in the contrast-to-noise ratio (from 4.32 to 5.95, P < 0.01) and contrast ratio (from 1.71 to 5.69, P < 0.004) with water suppression. Water suppression may be useful clinically by increasing the conspicuity of bone marrow lesions.

Lateralization of cortical function in swallowing: a functional MR imaging study

BACKGROUND AND PURPOSE

While functional MR imaging and other techniques have contributed to our knowledge of functional brain localization, these methods have not been extensively applied to the complex and incompletely understood task of swallowing. We used functional MR imaging to investigate motor cortex activity during swallowing in healthy human adults.

METHODS

Eight subjects were imaged on a 1.5-T MR system using blood oxygen level-dependent contrast mechanisms. Subjects performed three swallowing tasks and a finger-tapping task. Areas of activation in the cortex and subcortical areas were tabulated, and a laterality index, defined as LI = [sigmas left - sigmas right]/[sigmas left + sigmas right] x 100, was computed for the three tasks.

RESULTS

Activation was observed in the primary motor and sensory cortices, motor processing and association areas, and subcortical sites. This activity was dominant for one hemisphere with left hemispheric dominance more prevalent among the subjects. Right hemispheric dominance, however, showed stronger lateralization than the left hemisphere.

CONCLUSION

Our data indicate that specific sites in the motor cortex and other cortical and subcortical areas are activated with swallowing tasks and that hemispheric dominance is a feature of swallowing under these conditions. In addition, we demonstrate the utility of functional MR imaging in the study of the cortical representation of swallowing and suggest a role for functional MR imaging in the diagnosis of dysphagia of cerebral origin.

Vector diffraction from subwavelength optical disk structures: two-dimensional modeling of near-field profiles, far-field intensities, and detector signals from a DVD

Rigorous two-dimensional vector-diffraction patterns of a focused beam incident on an optical disk, specifically, a digital versatile disk (DVD), are examined both in the near field and in the far field. An efficient finite-difference frequency-domain method is developed for calculating the electromagnetic fields in the neighborhood of subwavelength dielectric and metallic structures. The results of vector-diffraction theory are compared with those of scalar-diffraction theory for pressed DVD features that consist of pits or of bumps. The sum (data) and difference (tracking) signals from a split photodetector are also calculated for different disk features and for different polarizations. The subwavelength features of a DVD result in considerable vector-diffraction effects both in the near-field profiles and in the detector signals, depending not only on the polarization of illumination but also on whether the features are pits or bumps. This paper provides important insight into the vector-diffraction effects encountered in high-density optical data storage systems.

Song development by chipping sparrows and field sparrows

When, where and from whom young songbirds learn their songs have been controversial issues in the study of song development. We chose to study some of these issues in two migratory and closely related songbirds, the chipping sparrow, Spizella passerina, and field sparrow, Spizella pusilla. Nestlings of both species were collected in western Massachusetts and hand-reared in the laboratory. There, juveniles were placed in separate cages and assigned to one of three rooms; in each room were eight young chipping sparrows, eight young field sparrows and two adult tutors of each species, arranged so that most of the young males were adjacent to adult tutors of the same species. During mid-winter, adult tutors were moved from one room to another, so that the young birds heard different song types from different tutors during their hatching year and the following spring. From spectral analysis of our extensive tape recordings, we found that most juvenile males imitated the songs of their hatching-year tutors but then gradually modified their songs to match more closely either their adult tutors or other pupils the next spring. One chipping and one field sparrow clearly imitated a new song syllable from a spring live tutor; that is, these yearling males learned songs by 'instruction'. Other sparrows improvised extensively, and one chipping sparrow learned a field sparrow's song syllable. Our results reveal great individual variation in how songs are developed, and we expect similar flexibility among birds in nature. Copyright 1999 The Association for the Study of Animal Behaviour.

Decreased BOLD functional MR activation of the motor and sensory cortices adjacent to a glioblastoma multiforme: implications for image-guided neurosurgery

A patient with a glioblastoma multiforme and mild sensorimotor deficits had significantly less activation of the motor and sensory cortices on the side with the tumor than on the contralateral side on blood oxygen level-dependent (BOLD) functional MR images. This difference, which may be due to pressure effects or loss of vascular autoregulation, should be considered in preoperative planning in which BOLD functional MR imaging is used to identify eloquent cortices to be avoided during brain tumor surgery.

Single-shot echo-planar imaging of multiple sclerosis: effects of varying echo time

Our aim was to determine the relative merits of short and long echo times (TE) with single-shot echo-planar imaging for imaging cerebral lesions such as multiple sclerosis. We examined seven patients with clinically definite multiple sclerosis were imaged at 1.5 T. Patients were scanned with spinecho, single-shot echo-planar imaging, using TEs of 45, 75, 105, and 135 ms. Region of interest (ROI) measurements were performed on 36 lesions at or above the level of the corona radiata. The mean image contrast (IC) was highest (231.1) for a TE of 45 ms, followed by 75 ms (218.9), 105 ms (217.9), and 135 ms (191.6). When mean contrast-to-noise ratios (C/N) were compared, the value was again highest (29.7) for TE 45 ms, followed by 75 ms (28.9), 105 ms (28.5), and 135 ms (26.3). In a lesion-by-lesion comparison, TE 45 ms had the highest IC and C/N in the largest number of cases (50 % and 47.2 %, respectively). IC and C/N for TE 45 ms were superior to those of 75 ms in 64% and 58%, respectively. These results support the use of relatively short TEs for single-shot echo-planar imaging in the setting of cerebral lesions such as multiple sclerosis.

Prevalence of back discomfort and estimates of back load in two manufacturing facilities

This study evaluated the association between the prevalence of back discomfort and estimates of back load posed by nine jobs in two manufacturing facilities. Prevalence of back discomfort experienced was estimated through self-administered questionnaires. A total of 266 questionnaires were distributed to workers randomly selected from nine jobs in two factories. Workers were asked to rate on a 0-5 scale the discomfort level they experienced in the back for a one-month period before and at the time of the survey. The return rate for each job ranges from 57% to 100%. Overall, 14.5% of the survey respondents experienced some discomfort in the back. With the assistance of a checklist, nine supervisors rated each task of the job they supervised by the magnitude of the force (low, moderate, or high) and by the duration, (less than 30% time, 30% to 50% time, and greater than 50% time) that workers typically spent in awkward back postures, such as back flexion, extension, twisting, and lateral bending. An additional total back load estimate was provided independently by an ergonomist. Logistic regression analysis found a positive association between the back discomfort prevalence observed in the present study and the load estimates both by the ergonomist and by task information based on back twisting. Significant concordance was found between the ergonomist's load estimates and the supervisors' estimate of the duration of twisted back. This study demonstrated not only that a checklist approach could provide useful task information for deriving exposure estimates, but also that exposure estimate for a job could be derived from its constituent tasks. Though in this study it was the supervisor who utilized the checklist to estimate the back loads, there is no reason why experienced workers could not use the checklist to provide similar estimates. A large-scale study should be conducted to improve the design of this checklist approach.

Functional image-guided surgery of intracranial tumors located in or near the sensorimotor cortex

OBJECT

The purpose of this study was to evaluate the efficacy of noninvasive preoperative functional imaging data used in an interactive fashion in the operating room. The authors describe a method of registering preoperative functional magnetic resonance (fMR) imaging localization of sensorimotor cortex with a frameless stereotactic surgical navigation device.

METHODS

The day before surgery, patients underwent blood oxygen level-dependent fMR imaging while performing a finger-tapping motor paradigm. Immediately afterward an anatomical stereotactic MR image was acquired. Raw fMR imaging data were analyzed offline at a separate workstation, and the resulting functional maps were registered to a high-resolution anatomical scan. The fused functional-anatomical images were then downloaded onto a surgical navigation computer via an ethernet connection. At surgery, the brain was exposed in the standard fashion, and the sensorimotor cortex was identified by direct cortical stimulation, the use of somatosensory evoked potentials, or both. This localization was then compared with that predicted by the registered fMR study. Thirteen procedures were performed in 12 patients. The mean registration error was 2.2 mm. The predicted location of motor and/or sensory cortex matched that found on intraoperative mapping in all 12 patients tested. Maximal tumor resection was accomplished in each case and no new permanent neurological deficits resulted.

CONCLUSIONS

Compared with conventional brain mapping techniques, fMR image-guided surgery may allow for smaller brain exposures, localization of the language cortex with the patient under general anesthesia, and the mapping of multiple functional sites. The scanning equipment used in this method may be more readily available than for other functional imaging techniques such as positron emission tomography or magnetoencephalography.

Functional MRI-guided surgery of intracranial tumors

We describe a technique of registering functional magnetic resonance image (fMRI) data sets with the anatomical images used for intraoperative navigation. Three patients with supratentorial tumors were studied, 2 with astrocytomas and 1 with a meningioma. The day before surgery, a functional blood-oxygen-level-dependent MR scan was done. During the same imaging session, an anatomic stereotactic MR scan was performed. The raw data were reconstructed off line on a workstation, and the fMR maps were then registered to the anatomic studies using image header information. Fused images were then transferred to the navigational workstation over an Ethernet connection. At surgery, brain exposure was performed in a standard manner. In each case, the registered scans accurately localized the motor and/or sensory cortex. No new permanent neurological deficits resulted from surgery. The potential advantages of fMRI-guided surgery include: (1) smaller brain exposures; (2) localization of language cortex under general anesthesia; (3) mapping of multiple functional sites, with decreased time and increased case of surgery.

Vector diffraction from subwavelength optical disk structures: Two-dimensional near-field profiles

An efficient finite-difference frequency-domain method is developed for calculating electromagnetic fields in the neighborhood of subwavelength dielectric and metallic structures. The method is used to investigate two-dimensional near-field and far-field patterns of a focused beam diffracted from an optical disk, specifically from a DVD (Digital Versatile Disk). It is shown that the polarization of illumination has a significant impact on diffraction patterns as expected and that scalar theory does not provide an accurate analysis of diffraction from a DVD.

Unexpected left endobronchial intubation in a case of Turner's syndrome

Patients with Turner's syndrome present a multiplicity of cardiovascular and airway abnormalities. We describe a case of Turner's syndrome with pericardial effusion who experienced an inadvertent endobronchial intubation due to displacement of the endotracheal tube immediately after the pericardial drainage. A sudden increase of airway pressure and decrease of oxygen saturation in the presence of breathing sound audible via the chest piece placed on the left hemithorax first misled us to call our attention to sputum impaction. No sputum was obtainable from airway suction. Inadvertent bronchial intubation was highly suspected at the post-anesthesia room when a decrease of right side breathing sound was noted together with a progressive fall of oxygen saturation. Emergent chest x-ray confirmed the diagnosis. It was thought that the mishap took place early in the act of or following the pericardial drainage. Our case serves as evidence once again to emphasize the possibility of endobronchial intubation due to displacement of endotracheal tube during anesthesia and the importance of monitoring to guard against inadvertent bronchial intubation, particularly in patients with associated problems such as Turner's syndrome with huge pericardial effusion.

The chromosomal effect of birchen dust as determined by the micronucleus test

In a wood processing factory, the measured air concentration of birchen dust was 1.26 +/- 0.41 mg/m3, and the micronucleus frequency of peripheral blood lymphocytes in 83 workers exposed to wood dust was 1.13 +/- 2.83/1000, which was significantly higher (P < 0.01) than that of control group (0.51 +/- 1.41/1000). The number of exposed workers with positive micronucleus test was 9.6%, which was higher than that of control group (4.5%), but the difference was not significant (P > 0.05). The micronucleus test in mice treated with water extracts of unsteamed and unbaked birchen dust showed that the micronucleus frequencies in all treated groups were significantly higher than that of control group (P < 0.01) and there was also a dose response correlation (r = 0.96, P < 0.0005). The results of steamed and baked birchen dust extracts were significantly lower than those of the unsteamed and unbaked ones at the same doses (P < 0.001). This suggests that when the birchen dust is steamed at the temperature of 100 degrees C for 24 h or baked at the temperature of 80 degrees C, its inducing effect in micronucleus test could be lowered.

Intraoperative functional MRI using a real-time neurosurgical navigation system

A 42-year-old-man had focal left hand motor seizures. MR studies demonstrated a right posterior frontal brain tumor. Functional MRI was performed, localizing the motor cortex posterior to the lesion. The functional images were integrated with a neurosurgical navigation computer. A real-time intraoperative display of the anatomic and functional images was produced, registered to a neurosurgical probe. Excellent correlation was demonstrated between the functional maps and invasive electrophysiologic mapping performed at the time of craniotomy.

Wavelet transform-based image compression for transmission of MR data

OBJECTIVE

The purpose of this study was to develop an effective, inexpensive teleradiology image-transmission system for transfer of MR studies using wavelet transform image compression.

CONCLUSION

We describe an efficient system for implementing teleradiology capability for transmission of diagnostic MR images. The system uses the wavelet transform to achieve greater than 90% image compression, with standard modern transmission times of less than 5 sec per compressed image. The method is inexpensive and can be implemented using commonly available workstation and MR scanner capabilities.

Fast inversion recovery for myelin suppression (FIRMS). A new magnetic resonance pulse sequence

Fast inversion recovery for myelin suppression is a new magnetic resonance sequence with the ability to increase gray-white matter contrast. This can improve the definition of normal anatomical structures.

Absorption of irrigating fluid during transcervical resection of endometrium--a report of two cases

It has been recognized for many years that the use of hypotonic solution for the irrigation of the bladder cavity during transurethral resection of the prostate (TURP) may result in hyponatremia and water intoxication due to rapid and excessive absorption of the solution from the exposed prostatic bed, the clinical manifestation of which is termed "TURP syndrome". A similar condition termed "female TURP syndrome" following hysteroscopic transcervical endometrial resection (TCR) has been reported. Since the frequency of TCR continues to increase the increased rate of "TCR syndrome" would come in its wake. Here, we present two cases who developed severe hyperglycemia and hyponatremia while underwent TCR with 10% dextrose in water as the irrigation fluid and the same time emphasize the potential risk of this complication.

The role of vasopressin on the effect of U-50,488 to block the development of morphine tolerance and physical dependence

U-50,488, a selective kappa-opioid receptor agonist, has been reported to inhibit the development of antinociceptive tolerance to morphine in mice, rats and guinea pigs, but the mechanism involved in this action remains unknown. Since U-50,488 has been reported to suppress the plasma vasopressin level, we investigated the role of vasopressin with U-50,488 in the male Sprague Dawley rat in this study. Animals (230-270 g) were chronically treated with morphine (10 mg/kg, i.p.) twice a day for 6 days in order to induce tolerance to antinociceptive effect measured by tail-flick test. Withdrawal symptoms were precipitated by naloxone (10 mg/kg, i.p.) on day 7. U-50,488 (i.p.) or AVP (i.p. or i.c.v.) or U-50,488 and AVP was (were) coadministered with chronic morphine to investigate their effects on morphine tolerance and dependence. We found that coadministration of 8 mg/kg U-50,488 (i.p.) with morphine almost completely block morphine tolerance and partially block withdrawal symptoms. In contrast, coadministration of AVP (0.3 microgram/kg, i.p., or 0.01 microgram, i.c.v.) with morphine and U-50,488, the effects of U-50,488 to block morphine tolerance and dependence were reversed. In addition, treatment of AVP antagonist (dPTyr(Me)AVP, 0.5 microgram/kg, i.p. or 0.5 microgram, i.c.v.) has the similar effect as U-50,488 to block morphine tolerance. In summary, the effect of U-50,488 to block morphine tolerance and dependence may relate to its inhibitory effect on AVP release.

Percutaneous intratumoral injection of cisplatin microspheres in tumor-bearing rats to diminish acute nephrotoxicity

Poly(D,L-lactide) microspheres loaded with cisplatin (PLA-CDDP MS) were prepared by a solvent evaporation technique for direct intratumoral injection. The microspheres, 50-100 microns, containing 40.04% of cisplatin produce sustained release in vitro. PLA-CDDP MS (6 mg/kg body weight of cisplatin) suspensions were injected intratumorally into mammary tumors in rats. Cisplatin solution (6 mg/kg body weight) was injected either intratumorally or intraperitoneally in two groups. After treatments, the tumor size decreased in each of the groups as a function of time. Sixteen days post-injection, the tumors had either disappeared or significantly shrunk. PLA-CDDP MS had a similar antitumor effect compared with cisplatin aqueous solution. Blood urea nitrogen, serum creatinine and histopathology examinations revealed that the renal toxicity in the PLA-CDDP MS group was significantly less than in the control groups. These results indicate that intratumoral injection of PLA-CDDP MS maintains anticancer potency and reduces acute renal toxicity.

10'-Desmethoxystreptonigrin, a novel analog of streptonigrin

10'-Desmethoxystreptonigrin, a novel analog of streptonigrin produced by Streptomyces albus, was discovered in a screen for inhibitors of farnesylation of RAS p21 protein. The compound was isolated from the fermentation broth and its structure determined. It is markedly cytotoxic to several human tumor cell lines and also exhibits potent broad-spectrum antibacterial activity.

Aerocavin, a new antibiotic produced by Chromobacterium violaceum

A new antibiotic, aerocavin, has been isolated from fermentation broths of a non-pigmented strain of Chromobacterium violaceum. The structure 1 was deduced from its spectroscopic properties and X-ray diffraction analysis. Aerocavin exhibits activity in vitro against Gram-positive and Gram-negative bacteria.