Mechanical instability as a cause of gait disturbance in high-grade spondylolisthesis: a pre- and postoperative three-dimensional gait analysis.

Mechanical instability of the spinopelvic junction is a suspected cause of abnormal gait in high-grade spondylolisthesis. Computerized three-dimensional gait analysis was performed on a 10-year-old with grade III spondylolisthesis at L-5. Preoperatively, the gait pattern was characterized by posterior pelvic tilt, decreased hip flexion, increased knee flexion, and decreased stride length and walking speed. All temporal and kinematic parameters of gait normalized after laminectomy and instrumented, in situ arthrodesis (L-4-S-1). The absence of any neurologic abnormalities on preoperative imaging, intraoperative somatosensory-evoked potentials (SSEP) monitoring, and nerve-root exploration, together with the observed improvement after stabilization of the spinopelvic junction, suggests a mechanical basis for the gait changes in high-grade spondylolisthesis.

Surgical treatment of acoustic neuroma (vestibular schwannoma) in the United States: report from the Acoustic Neuroma Registry.

In 1989, the Acoustic Neuroma Association established a multisurgeon, multi-institutional registry to collect data related to the treatment of patients with acoustic neuroma. This report analyzes information from the 1579 surgically treated patients who were entered in the registry between January 1, 1989, and February 28, 1994.

Assessment of cryoprecipitate-thrombin solution for dural repair.

BACKGROUND: After resection of cranial and skull base tumors, fibrin-thrombin solutions can provide a temporary biologic seal of dural closures until final healing occurs. We investigated several variables affecting the strength of these "tissues glues" for repair of dural defects using in vitro methods to model clinical repairs. METHODS: The competence of human cryoprecipitate-thrombin (CPT) "tissue glues" in providing a watertight seal for patched rat fascia and human cadaveric dural defects was assessed. A saline column was fabricated to allow for controlled pressure (up to 700 mm) to be applied over an open aperature containing the repaired defect. Variables of repair included time after repair, defect size, and mixing temperature. RESULTS: Wide variations in the strength of different cryoprecipitate glues were found. Time allowed after repair did not significantly affect the repair strength. Cooling the components of the glue solution prior to mixing significantly increased repair strength. Similar results were found for different defect sizes. CONCLUSIONS: Under controlled in vitro conditions, integrity of fibrin glue repairs varied widely. This was not attributable to differences in solution fibrinogen concentration. Cooling the "tissue glue" components prior to mixing significantly increased repair strength of patched tissue defects.

Development of the bi-directional ultrasound system for base of tongue imaging.

The use of conventional ultrasound systems to image the upper airway has been limited because ultrasound energy is attenuated by the air column. In an attempt to study upper airway geometry, we developed a computer controlled bi-directional ultrasound system which combines two conventional ultrasound devices with computer image processing to yield images of upper airway structures. Human studies and cadaver studies were performed to evaluate the system. Images acquired by the bi-directional ultrasound system were comparable to images from 3D volume rendered CT scans. This system may provide valuable data in the study of upper airway physiology and pathology.

Investigation of a coaxial bipolar nerve stimulator for intraoperative motor nerve monitoring.

Intraoperative cranial motor nerve monitoring has improved the preservation of cranial nerve function during cerebellopontine angle and skull base surgery. Further improvements are needed to provide greater selectivity and sensitivity during intraoperative motor nerve stimulation. Use of bipolar stimulator probes has been recommended by previous investigators. The authors hypothesized that a coaxial bipolar stimulator design might provide important advantages over existing designs. This study compared the results of bipolar and monopolar stimulation using a coaxial stimulator probe in a rat model and during neurotologic procedures. The coaxial bipolar probe was superior in selectivity, thereby permitting useful multichannel monitoring. The coaxial design may also offer advantages over previous bipolar stimulator designs.

A rat model to study hypercalcemia-induced acute pancreatitis.

Hypercalcemia causes acute pancreatitis in humans, a phenomenon reproduced experimentally in cats and guinea pigs. Because the rat is the most frequently used animal for the study of experimental pancreatitis, the present studies were performed to evaluate the effects of hypercalcemia in the rat. In in vitro studies, pancreatic lobules were prepared from fasted Wistar rats (200-250 g) and incubated in HEPES bicarbonate-buffered medium (pH 7.4) containing 0, 0.6, 1.2, 2.5, 5, and 10 mM CaCl2 with or without carbachol 10(-6) M. Amylase was measured in the medium after 30 min to 3 h, and expressed as percent of total amylase. In in vivo studies, fasted male Wistar rats (300-400 g) received calcium (CaCl2; 0.6 mmol/kgh) into the tail vein for 12 h. Control animals received NaCl 0.9% infusion. Histologic slides (H&E-stained) were evaluated in a blinded fashion. Pancreatic lobules showed a higher basal amylase output when incubated in higher calcium medium. The largest, significant difference (2.6-fold) was between 0.6 and 5 mM medium CaCl2 (p < 0.05). Carbachol-stimulated amylase release was again higher with increasing medium calcium with the most pronounced difference (1.3-fold) between 0.6 and 2.5 mM CaCl2 (p < 0.05). In vivo calcium-treated animals showed accumulation of zymogen granules in the cytoplasm, cytoplasmic vacuolization, focal acinar cell depolarization, acinar necrosis, and edema. Calcium causes amylase release from rat pancreatic lobules in vitro. Higher medium calcium levels both significantly increase amylase release from unstimulated and carbachol stimulated lobules. Twelve-hour in vivo calcium infusion leads to accumulation of zymogen granules in acinar cells and acinar injury.(ABSTRACT TRUNCATED AT 250 WORDS)

[The use of nonpathogenic leptospira as diagnostic antigens for the diagnosis of leptospira infections in cattle]. / Zur Nutzung apathogener Leptospiren als Suchantigene in der Diagnostik der Leptospireninfektion des Rindes.

The seroprevalence of leptospira antibodies was determined in 4377 bovine sera by microagglutination assay using 11 Leptospira interrogans serovars. In 10% (439 samples) of the sera, a positive reaction was detected. These included 275 sera (62.6%) with reaction to L. grippotyphosa, 159 (36.2%) to L. saxkoebing and 5 (1.1%) sera with reactions to other serovars. Multiple reactions were found in 9.8% of the 439 positive sera, whereby the Sejroe group dominated (65%) within the possible combinations of crossreactions. To determine the suitability of nonpathogenic strains as polyvalent diagnostic antigens, two L. biflexa serovar patoc strains were compared with the above-mentioned 11 L. interrogans serovars in microagglutination testing of 1995 screen sera. The sensitivity of the test was found to be 0.3% and the specificity was 80.3%. Using the two L. patoc strains, all of the 415 positive field sera and 11 positive control sera yielded negative reactions. Based on these results, the use of L. biflexa serovar patoc cannot be recommended as polyvalent antigen in the diagnosis of bovine leptospirosis by microagglutination.

The surgical workstation: surgical planning using generic software.

Computer software for rendering and display of three-dimensional data is becoming readily available for all types of computers. Such programs typically accept data from any source, compute a three-dimensional volume of data, and display it with a variety of rendering options. Although not specifically designed for medical image processing, these programs can provide very detailed and finely rendered images that are useful for surgical planning. We use one such program to display data from standard computed tomography scans, which gives us a photorealistic three-dimensional view of patient anatomy. This view can be modified to render tissues transparent, translucent, or opaque, and thus allows the surgeon to selectively enhance bony architecture, tumors, or other details. Images can be rotated, sliced, and displayed in the surgical position. Image animation can be added to facilitate the display of complex anatomic relationships. Our experience with this technology suggests that such programs can provide the basis for personal surgical workstations for medical image analysis and surgical planning. Further development of such generic imaging systems should allow this useful technology to become widely available for surgical planning and education. We discuss our experience with a typical generic imaging workstation.

Green Spring criteria for medical necessity of outpatient treatment and its use in a mental health utilization review program.

The authors have developed a two-tiered method for utilization review of outpatient mental health services. The methodology looks at initial and continued treatment evaluation and uses diagnosis, symptoms, plan of treatment, and the Global Assessment Scale (GAS) among other indicators to determine appropriateness of treatment. Preliminary program experience has been positive and is included.

Effect of geniohyoid and sternohyoid muscle contraction on upper airway resistance in the cat.

Previous investigators (van Lunteren et al. J. Appl. Physiol. 62: 582-590, 1987) have suggested that the geniohyoid and sternohyoid muscles may act as upper airway dilators in the cat. To investigate the effect of geniohyoid and sternohyoid contraction on inspiratory upper airway resistance (UAR), we studied five adult male cats anesthetized with ketamine and xylazine during spontaneous room-air breathing. Inspiratory nasal airflow was measured by sealing the lips and constructing a nose mask. Supraglottic pressure was measured using a transpharyngeal catheter placed above the larynx. Mask pressure was measured using a separate catheter. Geniohyoid and sternohyoid lengths were determined by sonomicrometry. Geniohyoid and sternohyoid contraction was stimulated by direct muscle electrical stimulation with implanted wire electrodes. Mean inspiratory UAR was determined for spontaneous breaths under three conditions: 1) baseline (no muscle stimulation), 2) geniohyoid contraction alone, and 3) sternohyoid contraction alone. Geniohyoid contraction alone produced no significant reduction in inspiratory UAR [unstimulated, 17.75 +/- 0.86 (SE) cmH2O.l-1.s; geniohyoid contraction, 19.24 +/- 1.10]. Sternohyoid contraction alone also produced no significant reduction in inspiratory UAR (unstimulated, 15.74 +/- 0.92 cmH2O.l-1.s; sternohyoid contraction, 14.78 +/- 0.78). Simultaneous contraction of the geniohyoid and sternohyoid muscles over a wide range of muscle lengths produced no consistent change in inspiratory UAR. The geniohyoid and sternohyoid muscles do not appear to function consistently as upper airway dilator muscles when UAR is used as an index of upper airway patency in the cat.

Facial reanimation after acoustic neuroma excision: the patient's perspective.

Facial reanimation after acoustic neuroma excision is currently accomplished using a variety of surgical techniques. A multi-institutional survey of patient perceptions of facial reanimation success was accomplished by mailing a questionnaire to 809 randomly selected members of the Acoustic Neuroma Association. Four hundred sixty patients who underwent 296 reanimation procedures responded. Facial to hypoglossal nerve anastomosis, tarsorrhaphy, and upper eyelid implants were most frequently performed. The patient's estimations of initial deficit, spontaneous recovery, and overall satisfaction with the reanimation procedures are discussed.

Changes in upper airway muscle activation and ventilation during phasic REM sleep in normal men.

Several investigators have observed that irregular breathing occurs during rapid-eye-movement (REM) sleep in healthy subjects, with ventilatory suppression being prominent during active eye movements [phasic REM (PREM) sleep] as opposed to tonic REM (TREM) sleep, when ocular activity is absent and ventilation more regular. Inasmuch as considerable data suggest that rapid eye movements are a manifestation of sleep-induced neural events that may importantly influence respiratory neurons, we hypothesized that upper airway dilator muscle activation may also be suppressed during periods of active eye movements in REM sleep. We studied six normal men during single nocturnal sleep studies. Standard sleep-staging parameters, ventilation, and genioglossus and alae nasi electromyograms (EMG) were continuously recorded during the study. There were no significant differences in minute ventilation, tidal volume, or any index of genioglossus or alae nasi EMG amplitude between non-REM (NREM) and REM sleep, when REM was analyzed as a single sleep stage. Each breath during REM sleep was scored as "phasic" or "tonic," depending on its proximity to REM deflections on the electrooculogram. Comparison of all three sleep states (NREM, PREM, and TREM) revealed that peak inspiratory genioglossus and alae nasi EMG activities were significantly decreased during PREM sleep compared with TREM sleep [genioglossus (arbitrary units): NREM 49 +/- 12 (mean +/- SE), TREM 49 +/- 5, PREM 20 +/- 5 (P less than 0.05, PREM different from TREM and NREM); alae nasi: NREM 16 +/- 4, TREM 38 +/- 7, PREM 10 +/- 4 (P less than 0.05, PREM different from TREM)]. We also observed, as have others, that ventilation, tidal volume, and mean inspiratory airflow were significantly decreased and respiratory frequency was increased during PREM sleep compared with both TREM and NREM sleep. We conclude that hypoventilation occurs in concert with reduced upper airway dilator muscle activation during PREM sleep by mechanisms that remain to be established.

Sternohyoid muscle biopsy. A diagnostic technique in respiratory failure of neuromuscular origin.

Patients with neuromuscular disease may develop respiratory failure requiring mechanical ventilation. We describe a sternohyoid muscle biopsy technique as a diagnostic aid in such patients undergoing tracheostomy for prolonged ventilatory support. The biopsy procedure is quick and without added discomfort or morbidity for the patient. Our preliminary observations in three patients suggest that the sternohyoid muscle biopsy may be a useful diagnostic tool in this selected group of patients.

Detection of intraoperative laser injury to the facial nerve by electromyographic monitoring of facial muscles.

Injury to the facial nerve is a significant risk during resection of cerebellopontine angle tumors. To minimize the risk of facial nerve injury, intraoperative electromyographic monitoring of facial musculature is frequently used. However, the reliability of such monitoring systems for detection of thermal nerve injury resulting from the use of carbon dioxide lasers has not been systematically evaluated. We determined the sensitivity of a computerized electromyographic monitor for detection of laser facial nerve injury in an anesthetized rat model. The mandibular and buccal branches of the facial nerve were isolated in 12 rats. A carbon dioxide laser was used to create controlled sites of thermal injury to both nerves over a 3-hour period. When a laser injury was created distal to previous injury sites, electromyographic discharge was noted in 72% to 82% of injuries. Laser injury proximal to previous injury sites was detected with 33% efficiency. These detection rates did not change significantly over a 3-hour period. This preliminary data suggests that electromyographic monitoring of facial musculature allows detection of facial nerve injury caused by carbon dioxide lasers.

Salmonella abscess of the pharynx.

Salmonella abscess in the head and neck is an uncommon occurrence. Such abscesses most often present in patients with underlying systemic processes or in those receiving iatrogenic immunosuppression. We report a 53-year-old woman with a retropharyngeal abscess treated with clindamycin and ampicillin. Treatment required surgical debridement and long-term antibiotics. There is a predilection for salmonella to affect tissue having underlying pathology, so that local tissue biopsy and long-term follow-up to document tissue reversions to normal are required.

Upper airway resistance and geniohyoid muscle activity in normal men during wakefulness and sleep.

Sleep-related reduction in geniohyoid muscular support may lead to increased airway resistance in normal subjects. To test this hypothesis, we studied seven normal men throughout a single night of sleep. We recorded inspiratory supraglottic airway resistance, geniohyoid muscle electromyographic (EMGgh) activity, sleep staging, and ventilatory parameters in these subjects during supine nasal breathing. Mean inspiratory upper airway resistance was significantly (P less than 0.01) increased in these subjects during all stages of sleep compared with wakefulness, reaching highest levels during non-rapid-eye-movement (NREM) sleep [awake 2.5 +/- 0.6 (SE) cmH2O.l-1.s, stage 2 NREM sleep 24.1 +/- 11.1, stage 3/4 NREM sleep 30.2 +/- 12.3, rapid-eye-movement (REM) sleep 13.0 +/- 6.7]. Breath-by-breath linear correlation analyses of upper airway resistance and time-averaged EMGgh amplitude demonstrated a significant (P less than 0.05) negative correlation (r = -0.44 to -0.55) between these parameters in five of seven subjects when data from all states (wakefulness and sleep) were combined. However, we found no clear relationship between normalized upper airway resistance and EMGgh activity during individual states (wakefulness, stage 2 NREM sleep, stage 3/4 NREM sleep, and REM sleep) when data from all subjects were combined. The timing of EMGgh onset relative to the onset of inspiratory airflow did not change significantly during wakefulness, NREM sleep, and REM sleep. Inspiratory augmentation of geniohyoid activity generally preceded the start of inspiratory airflow. The time from onset of inspiratory airflow to peak inspiratory EMGgh activity was significantly increased during sleep compared with wakefulness (awake 0.81 +/- 0.04 s, NREM sleep 1.01 +/- 0.04, REM sleep 1.04 +/- 0.05; P less than 0.05). These data indicate that sleep-related changes in geniohyoid muscle activity may influence upper airway resistance in some subjects. However, the relationship between geniohyoid muscle activity and upper airway resistance was complex and varied among subjects, suggesting that other factors must also be considered to explain sleep influences on upper airway patency.

Geniohyoid muscle activity in normal men during wakefulness and sleep.

Reduction in the activity of upper airway "dilator" muscles during sleep may allow the pharyngeal airway to collapse in some individuals. However, quantitative studies concerning the effect of sleep on specific upper airway muscles that may influence pharyngeal patency are sparse and inconclusive. We studied seven normal men (mean age 27, range 22-37 yr) during a single nocturnal sleep study and recorded sleep staging parameters, ventilation, and geniohyoid muscle electromyogram (EMGgh) during nasal breathing throughout the night. Anatomic landmarks for placement of intramuscular geniohyoid recording electrodes were determined from a cadaver study. These landmarks were used in percutaneous placement of wire electrodes, and raw and moving-time-averaged EMGgh activities were recorded. Sleep stage was determined using standard criteria. Stable periods of wakefulness and non-rapid-eye-movement (NREM) and rapid-eye-movement (REM) sleep were selected for analysis. The EMGgh exhibited phasic inspiratory activity during wakefulness and sleep in all subjects. In six of seven subjects, mean and peak inspiratory EMGgh activities were significant (P less than 0.05) reduced during stages 2 and 3/4 NREM sleep and REM sleep compared with wakefulness. This reduction of EMGgh activity was shown to result from a sleep-related decline in the level of tonic muscle activity. Phasic inspiratory EMGgh activity during all stages of sleep was not significantly different from that during wakefulness. Of interest, tonic, phasic, and peak EMGgh activities were not significantly reduced during REM sleep compared with any other sleep stage in any subject. In addition, the slope of onset of phasic EMGgh activity was not different during stage 2 NREM and REM sleep compared with wakefulness in these subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of five different methods for routine diagnosis of rabies.

Brain tissue from 187 animals of different species was investigated by means of fluorescent antibody test, peroxidase anti-peroxidase technique, mouse inoculation test and cell culture technique for a diagnosis of rabies. With peroxidase anti-peroxidase technique the rabies specific reaction comprised inclusion bodies and a granular staining of the cytoplasm of affected cells. A specific positive reaction was found only in neurons, in which perikaryon as well as cell processes were affected. Fluorescent antibody test and peroxidase anti-peroxidase technique detected 98% each, mouse inoculation test 95% and cell culture technique 81% of the rabies positive animals. In conclusion, peroxidase anti-peroxidase technique allows a highly reliable diagnosis of rabies when only formalin-fixed and paraffin-embedded material is available. Histopathological alterations comprising Negri bodies, inflammatory and degenerative lesions were encountered in 53% of the rabies positive brains.