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At least 217 records · Page 12Linked to original sources
PubMed1996

Laboratory testing of three intracranial pressure microtransducers: technical report.

Three comparatively priced intracranial pressure (ICP) microtransducers are now available, each characterized by the manufacturer as having very low zero drift over long periods, an excellent frequency response, and a low measurement error. The three microtransducers, coded Transducer A (Camino OLM ICP monitor; Camino Laboratories, San Diego, CA), Transducer B (Codman Microsensor ICP Transducer; Codman & Shurtlef Inc., Randolph, MA), and Transducer C (ICP Monitoring Catheter Kit OPX-SD [4F]; InnerSpace Medical, Irvine, CA), were examined in a pressure-flow test rig designed for assessment of hydrocephalus shunts. All three microtransducers compiled with the manufacturers' specifications and gave high-quality readings under test conditions. However, some differences were noted; Transducer C had the lowest 24-hour zero drift (drifts in all transducers were < 0.8 mm Hg). The temperature drift was very low in Transducer B and C, but Transducer A had a significantly higher drift (0.27 mm Hg/degrees C). Transducer A had a static error < 0.3 mm Hg, Transducer B < 2 mm Hg, and Transducer C < 8 mm Hg. Frequency detection in Transducers A and B were very good (bandwidth, > 30 Hz), whereas Transducer C had a limited bandwidth of 20 Hz. Transducer B scored the best overall, but all three scored satisfactorily during bench testing.

Cerebrospinal Fluid Pressure↗
PubMed1997

Use of a split bone graft to correct the cosmetic deformity associated with the transpetrosal-transtentorial surgical approach: technical report.

OBJECTIVE: Split bone graft reconstruction was performed after a standard transpetrosal-transtentorial approach to correct the cosmetic deformity in 18 patients. TECHNIQUE: The split bone graft was made by dividing the inner table of the temporosuboccipital bone graft and covered the bone effect created by petrosectomy and mastoidectomy. The split bone graft was created and shaped during closure of the dura, so that the operation was not prolonged. RESULTS: This technique produced excellent cosmetic results immediately after surgery; the results were maintained during the follow-up period of between 20 and 46 months. No complication associated with this technique was recognized. CONCLUSION: Split bone graft reconstruction is a simple and safe technique for preventing the cosmetic deformity associated with a transpetrosal-transtentorial approach.

Bone Transplantation↗
PubMed1997

Occipitotranstentorial approach for lesions of the superior cerebellar hemisphere: technical report.

OBJECTIVE: The occipitotranstentorial approach is well accepted for lesions of the pineal region, superior cerebellar vermis, or mesencephalon. Although evidently suitable, this approach has not, to our knowledge, been reported for lesions of the superior cerebellar hemisphere in adults. Experience with this approach is reported. METHODS: Four patients underwent surgery between August 1995 and March 1997. The findings obtained are evaluated. RESULTS: All lesions were situated in the quadrangular lobules (one extending into the vermis), and all were completely removed. Postoperative deficits, especially visual field deficits, did not occur. CONCLUSION: Lesions of the superior cerebellar hemispheres are easily approached by an occipitotranstentorial route. The major advantages over a supracerebellar approach are that the surgical route is nearly perpendicular to the lesion and to the tentorium instead of parallel, and wide exposure is thereby possible.

Adult↗
PubMed1998

Endovascular coil occlusion of a traumatic basilar-cavernous fistula: technical report.

OBJECTIVE AND IMPORTANCE: We describe an unusual case of an 8-year-old male patient presenting with a traumatic basilar artery aneurysm associated with a basilar-cavernous fistula. CLINICAL PRESENTATION: The fistula occurred as the result of an accident involving a vehicle and a pedestrian. The patient originally presented in a coma and with a dense left hemiparesis. INTERVENTION: The traumatic basilar aneurysm and basilar-cavernous fistula were successfully occluded by endovascular coil embolization in two sessions. By 6 months after injury, the patient had made an excellent neurological recovery, requiring only a left leg brace for walking. CONCLUSION: Endovascular coil embolization provided an effective treatment option in the case of this complex and unusual arteriovenous fistula. We discuss the radiological and clinical features of related traumatic neurovascular lesions.

Arteriovenous Fistula↗
PubMed1999

Fiberoptic delivery of laser energy to remove occlusions from ventricular shunts: technical report.

OBJECTIVES: Shunts frequently require surgical replacement because occlusions block the ventricular tubing. We have examined the hypothesis that a surgical laser coupled to an optical fiber can deliver sufficient energy to disrupt the occlusion in situ and thus afford a less invasive method of repair. METHODS: Choroid plexus tissue found in shunts explanted from patients, model tissues such as polyacrylamide gel, and animal tissues inserted into shunts were examined. Occlusions were fragmented by pulsed laser energy of 2.09-microm wavelength and 300-microsecond duration delivered via a flexible optical fiber several meters in length. The methods and conditions were similar to those likely to be used for preclinical in vivo studies. RESULTS: Short-lived vapor bubbles generated at the fiber tip disrupted occlusions within the shunt and expelled tissue blocking the inflow holes. Energy requirements to disrupt and remove occlusions in vitro were determined. Laser pulse energies and exposure thresholds that cause intentional damage to shunts also were determined. CONCLUSION: Laser energies needed to disrupt occlusions were below the energy needed to damage the shunt components. Our results show that a strategy using surgical lasers and optical fibers is feasible and suggest that the procedure could be used to repair blocked shunts without requiring surgical replacement.

Animals↗
PubMed1999

Use of hydroxyapatite bone cement to prevent cerebrospinal fluid leakage through the frontal sinus: technical report.

OBJECTIVE: To test the efficacy of a simple technique of frontal sinus obliteration during low frontal craniotomy using hydroxyapatite cement instead of more traditional methods, such as pericranial flaps, free muscle or adipose grafts, lumbar drainage, or fibrin glue. METHODS: Eight patients undergoing low frontal craniotomy for intradural surgery had the frontal sinus obliterated by careful removal of mucosa followed by filling of the sinus with hydroxyapatite bone cement. No other adjuncts for preventing cerebrospinal fluid leakage through the sinus were used. RESULTS: At an average follow-up of 9 months, there were no cerebrospinal fluid leaks, infections, instances of resorption, or cosmetic deformities. CONCLUSION: Hydroxyapatite bone cement seems to be a simple and effective method for frontal sinus obliteration and prevention of cerebrospinal fluid leakage.

Aged↗
PubMed1999

Use of mechanical thrombolysis via microballoon percutaneous transluminal angioplasty for the treatment of acute dural sinus thrombosis: case presentation and technical report.

OBJECTIVE AND IMPORTANCE: Although conventional superselective chemical thrombolysis is frequently successful for the treatment of severe acute dural sinus thrombosis, the technique has limitations and risks. This prompted us to develop a supplemental technique for achieving more rapid recanalization, using coronary microballoon percutaneous transluminal angioplasty catheters. We describe a successful application of this technique and technology that has not been previously reported. CLINICAL PRESENTATION: After several days of severe headaches, photophobia, and vomiting, a 29-year-old woman presented with rapidly progressive neurological deficits secondary to complete occlusion of the superior sagittal sinus (SSS) and right transverse/sigmoid sinus complex. Owing to her rapid neurological decline, she was referred for emergency endovascular intervention. TECHNIQUE: Initially, superselective chemical thrombolysis of the SSS was performed using urokinase. However, because of the extensive nature of the thrombus and lack of initial therapeutic response, we elected to attempt mechanical thrombolysis with various coronary percutaneous transluminal angioplasty microballoon catheters. This was accomplished by initial coaxial positioning of the device into an occluded segment, followed by gentle inflation and retraction of the device along the course of the right transverse sinus and/or SSS. These maneuvers were repeated with balloons of increasingly large diameter. Near-complete restoration of venous outflow was obtained within the SSS with preferential runoff into the left transverse sinus. The right transverse sinus was only partially recanalized. Despite the patient's rapid neurological decline on presentation, she experienced a dramatic clinical recovery with near-complete reversal of neurological deficits within 24 hours of intervention. CONCLUSION: This report shows the feasibility of performing safe and effective mechanical thrombolysis with percutaneous transluminal angioplasty coronary balloon microcatheters within the major dural sinuses. This technique can probably accelerate clot disruption and thrombolysis, possibly resulting in a more rapid restoration of venous flow.

Acute Disease↗
PubMed2000

Multicolumn infusion of gene therapy cells into human brain tumors: technical report.

OBJECTIVE: Effective gene therapy for brain tumors may require saturation of the tumors with tumoricidal doses of the therapeutic gene. Safe, precise, and efficient delivery of gene therapy vectors is required. Most reported cases of and published protocols for gene therapy for brain tumors involve freehand injection of retroviral vector-producing cells (VPCs) into the brain. Major disadvantages of this method include the inaccuracy of hand-guided needle placement and limited control of injection parameters. These factors can result in failure to deliver the viral vectors to specifically targeted sites within the brain, extensive tissue disruption resulting from excessively forceful injection, and reflux of the injectate along the needle tract. METHODS: We describe a novel stereotactic strategy for saturating tumor volumes with tumoricidal doses of gene therapy vectors and a new, more precise method of infusing VPCs. With our new instrument, the multicolumn stereotactic infusion system, needle placement is stereotactically guided and both VPC infusion and needle withdrawal are mechanically controlled. RESULTS: This technique, which has been used effectively for six patients, permits precise deposition of columns of VPCs throughout the targeted tumor volume. CONCLUSION: This technique should facilitate saturation of tumors with tumoricidal doses of gene therapy vectors and should improve the results of gene therapy protocols that rely on intraparenchymal injection for delivery.

Biopsy↗
PubMed2002

Hand-assisted laparoscopic ultrasound-guided radiofrequency thermal ablation of liver tumors: a technical report.

Ultrasound-guided radiofrequency thermal ablation has been performed for liver tumors by percutaneous, laparoscopic, or open surgical approaches. Each approach has specific advantages and disadvantages. Herein we describe a new technique for hand-assisted laparoscopic ultrasound-guided radiofrequency thermal ablation of liver tumors. A hand-access device is placed at the right or central portion of the abdomen, in addition to standard trocars. A conventional intraoperative ultrasound probe, with an ultrasound guidance system attached, is inserted into the peritoneal cavity together with the surgeon's hand. After pneumoperitoneum is established, an electrode-cannula for thermal ablation is introduced subcostally or intercostally, and advanced into a liver tumor under direct guidance by intraoperative ultrasound. We have used this technique in eight patients with unresectable liver tumors. Precise guidance of the cannula into tumors was possible. All tumors were well ablated. The postoperative recovery of patients was of shorter duration compared with that of an open surgical approach. A hand-assisted laparoscopic ultrasound-guided method has advantages of both laparoscopic and open surgical approaches for radiofrequency thermal ablation treatment of liver tumors. Accurate cannula insertion is possible with the ultrasound guidance system. The hand-assisted laparoscopic approach can become an additional useful technique, particularly as a valuable alternative to an open surgical method, for performing radiofrequency thermal ablation.

Carcinoma, Hepatocellular↗
PubMed2005

Chronic Abdominal Pain In Children: a Technical Report of the American Academy of Pediatrics and the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition.

Chronic abdominal pain, defined as long-lasting intermittent or constant abdominal pain, is a common pediatric problem encountered by primary care physicians, medical subspecialists and surgical specialists. Chronic abdominal pain in children is usually functional-that is, without objective evidence of an underlying organic disorder. The Subcommittee on Chronic Abdominal Pain of the American Academy of Pediatrics and the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition has prepared this report based on a comprehensive, systematic review and rating of the medical literature. This report accompanies a clinical report based on the literature review and expert opinion. The subcommittee examined the diagnostic and therapeutic value of a medical and psychologic history, diagnostic tests, and pharmacological and behavioral therapy. The presence of alarm symptoms or signs (such as weight loss, gastrointestinal bleeding, persistent fever, chronic severe diarrhea and significant vomiting) is associated with a higher prevalence of organic disease. There was insufficient evidence to state that the nature of the abdominal pain or the presence of associated symptoms (such as anorexia, nausea, headache and joint pain) can discriminate between functional and organic disorders. Although children with chronic abdominal pain and their parents are more often anxious or depressed, the presence of anxiety, depression, behavior problems or recent negative life events does not distinguish between functional and organic abdominal pain. Most children who are brought to the primary care physician's office for chronic abdominal pain are unlikely to require diagnostic testing. Pediatric studies of therapeutic interventions were examined and found to be limited or inconclusive.

Abdominal Pain↗
PubMed2003

Validation of in vivo assessment of facial soft-tissue volume changes and clinical application in midfacial distraction: a technical report.

The purpose of this study was to validate the assessment of visible volume changes of the facial soft tissue with an optical three-dimensional sensor and to introduce new parameters for the evaluation of the soft-tissue shape achieved from three-dimensional data of selected cases of midfacial distraction. Images of a truncated cone of known volume were assessed repeatedly with an optical three-dimensional sensor based on phase-measuring triangulation to calculate the volume. Two cubic centimeters of anesthetic solution was injected into the right malar region of 10 volunteers who gave their informed consent. Three-dimensional images were assessed before and immediately after the injections for the assessment of the visible volume change. In five patients who underwent midfacial distraction after a high quadrangular Le Fort I osteotomy, three-dimensional scans were acquired before and 6 and 24 months after the operation. The visible soft-tissue volume change in the malar-midfacial area and the mean distance of the accommodation vector that transformed the preoperative into the postoperative surface were calculated. The volume of the truncated cone was 235.26 +/- 1.01 cc, revealing a measurement uncertainty of 0.4 percent. The injections of anesthetic solution into the malar area resulted in an average visible volume change of 2.06 +/- 0.06 cc. The measurement uncertainty was 3 percent. In the five patients, the average distance of maxillary advancement was 6.7 +/- 2.3 mm after 6 months and 5.4 +/- 3.0 mm after 2 years. It was accompanied by a mean visible volume increase of 8.92 +/- 5.95 cc on the right side and 9.54 +/- 4.39 cc on the left side after 6 months and 3.54 +/- 3.70 cc and 4.80 +/- 3.47 cc, respectively, after 2 years. The mean distance of the accommodation vector was 4.41 +/- 1.94 mm on the right side and 4.74 +/- 1.32 mm on the left side after 6 months and 1.62 +/- 1.96 mm and 2.16 +/- 1.52 mm, respectively, after 2 years. The assessment of visible volume changes by optical three-dimensional images can be carried out with considerable accuracy. The determination of volume changes and accompanying accommodation vectors completes the cephalometric analysis during the follow-up of patients undergoing midfacial distraction. The new parameters will help to assess normative soft-tissue data on the basis of three-dimensional imaging with a view to an improved three-dimensional prediction of the operative outcome of orthognathic surgery.

Adolescent↗
PubMed2005

Technical report and preliminary clinical data of a novel catheter for luminal re-entry after subintimal dissection.

RATIONALE AND OBJECTIVES: The objective of this study was to evaluate the safety and the effectiveness of the Outback catheter for intraluminal re-entry after subintimal dissection in the crossing of chronic arterial occlusions. METHODS: This study was a proof-of-concept feasibility. Ten patients with totally occluded arteries in the iliac artery to the distal femoral artery (mean occlusion length, 13.1 cm; range, 5-25 cm) were treated with the novel catheter. After successful re-entry, PTA or PTA plus stenting was performed. RESULTS: No perforations, dissections, lacerations, or device complications occurred. The procedural re-entry success rate with the Outback catheter was 50% (5/10 patients). CONCLUSIONS: Although the Outback catheter is safe, the percentage of intraluminal reaccess should be ameliorated through engineering improvements because there is some evidence to suggest that subintimal recanalization could produce improved long-term results.

Aged↗
PubMed1995

Technical report: results of immunological tests on faecal extracts are likely to be extremely misleading.

Clinical investigation of gut immunity is difficult because of the need to study intestinal tissues or secretions directly. Others have reported that immunoglobulins, antibodies and cytokines can be detected in saline extracts of faeces. We have assessed the validity of this approach by measuring immunoglobulins, albumin, alpha 1-antitrypsin and isotype-specific antibodies in matched samples of faeces and whole gut lavage fluid. Results were compared as estimated output per day, and by using haemoglobin as a common reference substance. Samples were obtained from 10 patients with active inflammatory bowel disease and 10 with other benign GI diseases. For immunoglobulins, albumin and antibodies, the amount detected in faeces varied from < 0.01% to 35.5% (based on estimated daily output) and < 0.01% to 18.5% (based on haemoglobin) of the amount known to be produced in the gut from results of assays on whole gut lavage fluid (WGLF); there were significantly higher rates of recovery in faecal specimens from patients with active gut inflammation than from other patients. Detection rates and titres of specific antibody in faeces were even lower than those for immunoreactive IgA. These data indicate that immunological tests on saline extracts of faeces do not represent the true status of the gut humoral immune system, and such studies should be strongly discouraged.

Adult↗
PubMed1992

Technical report: fallopian tube recanalization facilitated by a hydrophillic glide wire.

Fallopian tube recanalization is now a well established radiological procedure (1). We describe a case in which the tubal obstruction was resistant to the standard technique of recanalization by the passage of a platinum tipped wire but in which we were able to achieve success with the aid of a hydrophillic "glide" wire (Radifocus angled tip, Terumo Corporation, Tokyo, Japan).

Adult↗
PubMedDate not supplied

The visible human male: a technical report.

The National Library of Medicine's Visible Human Male data set consists of digital magnetic resonance (MR), computed tomography (CT), and anatomic images derived from a single male cadaver. The data set is 15 gigabytes in size and is available from the National Library of Medicine under a no-cost license agreement. The history of the Visible Human Male cadaver and the methods and technology to produce the data set are described.

Adult↗
PubMed1997

Laboratory testing of the Spiegelberg brain pressure monitor: a technical report.

OBJECTIVES: The Spiegelberg brain pressure monitor is a low cost intracranial pressure monitoring system that has been used clinically for some time, mainly in Germany. To provide a rigorous bench comparison of the Spiegelberg monitor with the Camino pressure monitor an evaluation programme has been carried out in the UK Shunt Evaluation Laboratory. DESIGN: Drift over 72 hours and with temperature, a frequency response, and the accuracy of measurement of both static and pulsatile pressures have been tested simultanously in Camino and Spiegelberg transducers using a computerised rig. RESULTS: Long term zero drift was less than 0.7 mm Hg in both transducers. The Spiegelberg monitor showed no temperature drift whereas the Camino monitor had a drift of around 0.3 mm Hg/degrees C. The Spiegelberg monitor underread mean pressures <40 mm Hg by <1 mm Hg, but the error increased to 4.7 mm Hg at 100 mm Hg. The frequency bandwidth of the Spiegelberg monitor was 4 Hz at a low pressure. Underreading of the amplitude increased with the mean pressure, with a delay of about 0.1 s in the detection of the peaks of pulse waveform. CONCLUSION: The Spiegelberg transducer had excellent accuracy for static intracranial pressure measurement, but complex waveform analysis may be biased by its limited dynamic response.

Clinical Laboratory Techniques↗