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At least 433 records · Page 24Linked to original sources

PubMed1996

Porcine gastroepiploic artery as an in vitro experimental model to study vasodilators in microsurgery.

Arterial vasospasm is a common problem in microsurgery. This pharmacological study compares seven vasodilators-lidocaine, papaverine, nicardipine, verapamil, diltiazem, sodium nitroprusside, and hydralazine-for their efficacy and potency in an experimental model of vasospasm. Porcine gastroepiploic arteries were cut into rings to measure isometric tension development in vitro. The arteries were preconstricted with endothelin-1, a stable thromboxane A2 analogue, norepinephrine, or potassium, and then exposed to increasing concentrations of each vasodilator. Every vasodilator except hydralazine and sodium nitroprusside was efficacious in producing near-maximal relaxation of arteries preconstricted with any vasospastic substance. The five efficacious vasodilators differed markedly in potency, as reflected in the concentrations producing half-maximal relaxation. The order of potency was nicardipine < or = verapamil or diltiazem < papaverine < lidocaine. This study suggests that nicardipine would be the most potent vasodilator for systemic or direct intra-arterial administration. Papaverine and lidocaine, in concentrations employed clinically, were both efficacious as topical vasodilators.

Animals↗

PubMed1998

Blood coagulation activity during microsurgery.

The authors investigated blood coagulation activity in patients who underwent microsurgery. Hemostatic parameters were measured in 9 patients (10 operations) who were undergoing free tissue transfers. These parameters included prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinopeptide A (FPA), prothrombin fragment 1 + 2 (F1 + 2), and thrombin-antithrombin complex (TAT). The flap totally necrosed owing to vasospasm in 1 patient with osteomyelitis of the heel, and the FPA, F1 + 2, and TAT values significantly increased. Reexploration was required because of flap cyanosis in 1 patient with a hemangioma on the wrist, and the F1 + 2 and TAT values increased during the salvage procedure. These molecular markers could be important in indicating hypercoagulable state sensitivity, and they serve as a warning of possible vascular compromise to a surgeon.

Adult↗

PubMed1980

The role of microsurgery in male infertility.

Microsurgery has become an important tool in the management of the infertile male. Although macrosurgical techniques are still required for preservation and protection of cryptorchid testes, microscopic techniques are also useful in the preservation of testicular tissue. We now use the microscope in all vasovasostomy and vasoepididyostomy procedures, but its final role in the treatment of male infertility has yet to be determined.

Child, Preschool↗

PubMed2000

Treatment of laryngeal carcinomas by laser endoscopic microsurgery.

OBJECTIVES: To determine if laser endoscopic microsurgery is a reliable and appropriate approach in the treatment of laryngeal cancers. STUDY DESIGN: Retrospective study of 160 patients treated from 1988 to 1996 at Liège. Analysis of indication, technique, and oncologic results. METHODS: Glottic tumors were treated with either type I, type II, or type III cordectomy, with or without conservation of an inferior muscular band, and extended if necessary to all or part of the contralateral cord. For supraglottic cancers, an excision limited to a part of the vestibule, a trans-preepiglottic resection, or a radical supraglottic resection was carried out. RESULTS: Our corrected actuarial survival at 5 years was 97% for the 98 infiltrative glottic tumors and 100% for the 18 infiltrative supraglottic and 27 in situ carcinomas. No local recurrences were noted, in either the group of 118 infiltrating cancers (in whom two precancerous lesions were treated with a further laser excision), or in the 27 in situ carcinomas. Local control was thus 100%. One patient died of his cancer, with lung metastases after neck recurrence. CONCLUSIONS: Like Steiner and Rudert, this series demonstrates the oncologic validity of this surgical approach to the treatment of unadvanced glottic tumors. Unlike these authors' study, however, strict case selection, as in cases with significant involvement of the anterior commissure, has allowed us to avoid local recurrences and consequently to avoid salvage total laryngectomies. Our experience with supraglottic cancers is too small to confirm the oncologic validity of this type of surgery but seems promising.

Adult↗

PubMed2000

A meta-analysis comparing outcomes of microsurgery and gamma knife radiosurgery.

OBJECTIVES/HYPOTHESIS: Surgery has been the most common treatment for acoustic neuromas, but gamma knife radiosurgery has emerged as a safe and efficacious alternative to microsurgery. This meta-analysis compares the outcomes of the two modalities. STUDY DESIGN: A retrospective MEDLINE search was used to find all surgical and gamma knife studies published from 1990 to 1998 and strict inclusion criteria were applied. RESULTS: For tumors less than 4 cm in diameter, there is no difference in hearing preservation (P = .82) or facial nerve outcome (P = .2). Surgery on all sized tumors has a significantly lower complication rate than radiosurgery performed on tumors smaller than 4 cm (P = 3.2 x 10(-14)). Surgery also has a lower major morbidity rate than gamma knife radiosurgery (P = 2.4 x 10(-14)). Tumor control was defined as no tumor recurrence or no tumor regrowth. Surgery has superior tumor control when tumors are totally resected (P = 9.02 x 10(-11)). Assuming that all partially resected tumors will recur, surgery still retains a significant advantage over radiosurgery for tumor control (P = .028). CONCLUSION: Data from these studies date back to the late 1960s and do not completely reflect outcomes using current imaging and procedures. A major difficulty encountered in this study is inconsistent data reporting. Future surgical and radiation reports should use standardized outcomes scales to allow valid statistical comparisons. In addition, long-term results from gamma knife radiosurgery using lower dosimetry have not been reported. Surgery should remain the therapy of choice for acoustic neuromas until tumor control rates can be established.

Facial Nerve Injuries↗

PubMed2001

Robot-assisted microsurgery: a feasibility study in the rat.

OBJECTIVE: Telerobotic surgery is a novel technology that can improve a surgeon's manual dexterity as well as the results achieved with microsurgical procedures. METHODS: A prototype Robot-Assisted MicroSurgery (RAMS) microdexterity enhancement system developed by the Jet Propulsion Laboratory and MicroDexterity Systems, Inc., was tested in 10 rats. Carotid arteriotomies were created and closed using either the RAMS system or conventional microsurgical techniques. The time required, the technical quality (vessel patency and suture line integrity), the error rate, and subjective difficulty were compared. RESULTS: All procedures were successfully completed using the RAMS system to manipulate the vessel but not to hold the needle or place the sutures. The precision, technical quality, and error rate of telerobotic surgery were similar to those of conventional techniques. However, the use of the RAMS system was associated with a twofold increase in the length of the procedure. CONCLUSION: Surgery using a microdexterity enhancement system, or RAMS prototype, is feasible. With further development, such as a stereotelevisualization and haptic feedback system, this system could be used for telerobotic surgery in neurosurgical practice.

Animals↗

PubMed2002

Transsphenoidal microsurgery.

Transsphenoidal microsurgery is a well-established neurosurgical procedure that has become the standard of care in the management of the majority of pituitary tumors and a select group of other sellar lesions. The safety of the procedure depends on the surgeon's adherence to certain anatomic concepts. Foremost among these concepts is the necessity of preserving the integrity of the arachnoid membrane covering the tumor dome and avoiding vascular injuries in the cavernous sinus. The objective of this article is to demonstrate the sequential steps of a transsphenoidal microsurgical procedure for the removal of a pituitary tumor in light of the anatomic concepts discussed, with the goal of preventing complications and achieving the best possible outcome.

Adenoma↗

PubMed2002

Endoscope-assisted microsurgery for intracranial aneurysms.

OBJECTIVE: We discuss the role of the endoscope in the microsurgical treatment of intracranial aneurysms, analyzing its benefits, risks, and disadvantages. METHODS: This was a prospective study of 55 patients with 79 aneurysms, treated between July 1998 and June 2001, for whom the endoscope was used as an adjunct in the microsurgical treatment of their lesions. Seventy-one aneurysms were located in the anterior circulation, and eight were located in the posterior circulation. Thirty-seven patients presented with subarachnoid hemorrhage. Eighteen patients had unruptured aneurysms, of whom 5 presented with mass effect, 2 presented with transient ischemic attacks, and 11 were without symptoms. In all cases, the endoscope was used in addition to microsurgical dissection and clipping (sometimes before clipping, sometimes during clipping, and always after clipping), for observation of the neck anatomic features and perforators and verification of the optimal clip position. Intraoperative angiography was performed for all patients after aneurysm clipping. RESULTS: In the majority of cases, the endoscope was very useful for the assessment of regional anatomic features. It allowed better observation of anatomic features, compared with the microscope, for 26 aneurysms; in 15 cases, pertinent anatomic information could be obtained only with the endoscope. The duration of temporary clipping of the parent artery was significantly reduced for two patients. The clip was repositioned because of a residual neck or inclusion of the parent vessel during aneurysm clipping in six cases, and the clip position was readjusted because of compression of the optic nerve in one case. One patient experienced a small aneurysm rupture that was directly related to use of the endoscope, but this was easily controlled, with no sequelae. For many patients, the combination of the neuro-endoscope and the micro-Doppler probe made intraoperative angiography redundant. CONCLUSION: "Endoscope-assisted microsurgery" is a major advance in the microsurgical treatment of intracranial aneurysms; the endoscope allows better observation of regional anatomic features because of its magnification, illumination, and ability to "look around corners."

Adult↗

PubMed1999

Internal mammary vessels as a model for power Doppler imaging of recipient vessels in microsurgery.

The aim of this interdisciplinary study was to evaluate power Doppler imaging as a method of collecting reliable preoperative data concerning the diameters and topography of exemplary internal mammary vessels as recipient vessels in reconstructive microsurgery. Thirteen female patients (range, 37 to 58 years; mean, 45.6 years) were examined preoperatively with power Doppler imaging from the first to the fifth intercostal space parasternally and bilaterally. These data are compared with measurements obtained intraoperatively in each individual. Mean velocity in the artery in the second intercostal space on the right side is 47.11 cm/sec (range, 15 to 90 cm/sec) and on the left side is 42.25 cm/sec (range, 18 to 95 cm/sec). Mean velocity in the vein in the second intercostal space on the right side is 17.80 cm/sec (range, 10 to 30 cm/sec) and on the left side is 13.06 cm/sec (range, 5.3 to 32 cm/sec). The topographic results are in close agreement with intraoperative measurements and previous anatomical studies. Sonographic preoperative data of arteries (mean, 1.88 mm) show slightly smaller diameters than intraoperative measurements (mean, 2.08 mm), whereas veins show slightly larger diameters in sonography (mean, 2.33 mm) than intraoperatively (mean, 2.12 mm). Mean sonographic diameter of artery ranges from 2.14 mm (second intercostal space) to 1.46 mm (fifth intercostal space), of the vein from 2.76 (second intercostal space) to 1.25 mm (fifth intercostal space). In one case, a vein was not detectable. This noninvasive method leads to confirmation of the preoperative choice of the optimal recipient vessels for free tissue transfer and does not harm the patient.

Adult↗

PubMed2001

Pharmacologic optimization of microsurgery in the new millennium.

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Understand the mechanisms by which the three most common antithrombotic agents work. 2. Be familiar with accepted dosing levels for the three agents. 3. Understand the rationale for their use and formulate an algorithmic approach to microvascular thrombosis. Microsurgical anastomoses are largely technically dependent; however, there exists a finite rate of failure, with often devastating consequences. Pharmacologic prophylaxis and intervention are used extensively in microsurgical cases, yet a unified algorithm does not exist among the various basic science and clinical studies in the literature. This results in a confusing and nonstandardized practice based on anecdotal experiences. The purpose of this article is to review the literature on this topic and synthesize a practical clinical management algorithm for pharmacologic therapy in microsurgery.

Anastomosis, Surgical↗

PubMed1988

Applications of a cannulated extrusion needle during vitreoretinal microsurgery.

A specially designed cannulated extrusion needle facilitates the internal drainage of subretinal fluid during vitreoretinal microsurgery. Case histories demonstrate the use of this instrument in the management of complex retinal detachments including eyes with preretinal and subretinal hemorrhage, proliferative vitreoretinopathy with open peripheral retinal breaks, retinal detachment with giant retinal tear, and combined traction-rhegmatogenous detachments due to diabetic retinopathy. This method of internal drainage appears to have specific advantages over standard techniques by allowing the removal of subretinal hemorrhage, the utilization of pre-existing peripheral breaks for internal drainage, and the complete reattachment of shallow posterior pole retinal detachments to allow laser endophotocoagulation.

Adult↗

PubMed2006

Carcinoma of the tongue base treated by transoral laser microsurgery, part one: Untreated tumors, a prospective analysis of oncologic and functional outcomes.

OBJECTIVES: To report the oncologic and functional outcomes of transoral laser microsurgery (TLM) in the management of untreated primary carcinoma of the tongue base. STUDY DESIGN: A two center prospective case series analysis. METHODS: Fifty-nine patients with pathologically confirmed squamous cell carcinoma of the tongue base were treated with TLM between 1997 and 2005. The pathological T stage distribution was: T1, 16; T2, 23; T3, 12 and T4, 8. Thirty-six patients presented with stage IV disease, 12 with stage III, 7 with stage II and 4 with stage I disease. Neck dissections were performed in 49 patients (83%). Twenty-eight patients (47%) underwent adjuvant radiotherapy. End points analyzed were local control, loco regional control, disease specific survival, and overall survival. Organ function was assessed before and after treatment using a clinical Functional Outcome Swallowing Scale (FOSS) and Communication Scale (CS) staging system. RESULTS: The mean follow up for all patients was 31 months. The 2 and 5-year Kaplan-Meier estimates were: local control, both 90%; loco-regional control, both 88%; recurrence free survival, both 84% and overall survival 91% and 69% respectively. For all patients the median stay in hospital was 4 days. The median length of hospital visit for TLM alone was 2.5 days and 4 days for TLM with neck dissection. Three patients (5%) suffered minor post-operative hemorrhage. The median pre-operative FOSS stage was 0 (normal function.) The median post-operative FOSS stage was stage 1 (Normal function with episodic or daily symptoms of dysphagia.) There were no clinically significant changes in communication function after treatment. CONCLUSIONS: Transoral laser surgery is a safe and effective treatment for select early and advanced previously untreated squamous cell cancer of the tongue base. In addition, the low morbidity and mortality and shortened duration of hospitalization associated with TLM make it an attractive therapeutic alternative.

Aged↗

PubMed2006

Carcinoma of the tongue base treated by transoral laser microsurgery, part two: Persistent, recurrent and second primary tumors.

OBJECTIVES: To report the oncologic and functional outcomes of transoral laser microsurgery (TLM) in the treatment of persistent, recurrent, and second primary squamous cell carcinoma of the tongue base. STUDY DESIGN: A two-center prospective case series analysis. METHODS: Twenty-five patients with persistent, recurrent, or second primary squamous cell carcinoma of the tongue base were treated with TLM between 1997 and 2005. Four (16%) patients with persistent disease at the primary site were considered TX. Eleven (44%) patients with recurrent disease were pathologically staged rT1 3/11, rT2 2/11, rT3 4/11, T4 1/11, and TX 1/11. Ten (40%) patients with second primary tumors were staged pT1, 4/10; pT2, 3/10; pT3, 2/10; and pT4, 1/10. Eight (32%) patients underwent neck dissection. Three (12%) patients received adjuvant radiotherapy. Pre- and post-treatment organ function was assessed using a clinical Functional Outcome Swallowing Scale (FOSS) and Communication Scale. RESULTS: The mean follow-up period was 26 months. The 2-year Kaplan-Meier local control and locoregional control estimate was 69%. For those patients presenting with persistent/recurrent or second primary disease, the 2 year local control estimates were 75% and 68%, respectively. For all patients, the respective 2 and 5 year overall survival estimates were 54% and 26%. Two (8%) patients suffered postoperative hemorrhage. The average duration of hospitalization was 3.6 days. The median pretreatment and posttreatment FOSS stage was stage 2 and stage 3, respectively. CONCLUSIONS: Transoral laser surgery is a rational and effective treatment in appropriately selected patients with persistent, recurrent, or second primary tongue base cancer. The low morbidity and mortality and shortened duration of hospitalization associated with TLM make it an attractive therapeutic alternative.

Aged↗

PubMed2003

Dextran-related complications in head and neck microsurgery: do the benefits outweigh the risks? A prospective randomized analysis.

Increased experience with free-tissue transfer has minimized flap loss secondary to microvascular thrombosis, yet pharmacologic antithrombotic prophylaxis continues to be used routinely. Currently there is no consensus on the ideal pharmacologic agent, dosing, or efficacy. Low-molecular-weight dextran has been widely used for prophylaxis due to its properties of volume expansion and enhanced microrheology. Significant systemic morbidity (pulmonary morbidity, cardiac morbidity, anaphylaxis) is known to occur with use of low-molecular-weight dextran. The purpose of this study was to evaluate morbidity associated with postoperative low-molecular-weight dextran and aspirin prophylaxis in head and neck microsurgery patients. This study was a randomized prospective analysis of 100 consecutive patients undergoing microvascular reconstruction for head and neck malignancy during a 2-year period. Patients were randomized into one of three postoperative antithrombotic prophylaxis treatment groups: low-molecular-weight dextran 20 cc/hour for 48 hours (n = 35), low-molecular-weight dextran 20 cc/hour for 120 hours (n = 32), or aspirin 325 mg/day for 120 hours (n = 27). Six patients were excluded intraoperatively due to the need for systemic heparin therapy. Treatment groups were compared for age, sex, prior medical problems, duration of anesthesia, and intraoperative fluid intake. Flap outcome and the incidence of local and systemic complications were evaluated in the treatment groups. Patient ages ranged from 12 to 84 years (mean age, 58 years). No significant difference was found among the treatment groups with respect to age, sex, prior medical problems, duration of anesthesia, intraoperative fluid intake, and the distribution of donor and recipient sites. There were no total flap losses and two partial flap losses in this series. Three flaps were reexplored and all were salvaged. The incidence of systemic complications (congestive heart failure, myocardial infarction, pulmonary edema, pleural effusion, and pneumonia) was as follows: low-molecular-weight dextran 120 hours, 51 percent; low-molecular-weight dextran 48 hours, 29 percent; and aspirin, 7 percent. Analysis of these data suggests that the method of prophylaxis had no effect on overall flap survival. However, the incidence of systemic complications was significantly related to the method of prophylaxis, with patients receiving low-molecular-weight dextran 120 hours and 48 hours at a 7.2 and 3.9 times greater relative risk, respectively, of developing a systemic complication compared with patients receiving aspirin. The results of this study have eliminated the routine use of low-molecular-weight dextran prophylaxis at our institution in an effort to reduce morbidity in head and neck microsurgical reconstruction.

Adolescent↗

PubMed1998

Adaptive canceling of physiological tremor for improved precision in microsurgery.

Physiological hand tremor impedes microsurgery. We present both a novel adaptive algorithm for tremor estimation and a new technique for active real-time canceling of physiological tremor. Tremor is modeled online using the weighted-frequency Fourier linear combiner (WFLC). This adaptive algorithm models tremor as a modulating sinusoid, and tracks its frequency, amplitude, and phase. Piezoelectric actuators move the surgical instrument tip in opposition to the motion of tremor, effectively subtracting the tremor from the total motion. We demonstrate the technique in one dimension using a cantilever apparatus as a benchtop simulation of the surgical instrument. Actual hand motion, prerecorded during simulated surgery, is used as input. In 25 tests, WFLC tremor compensation reduces the rms tip motion in the 6-16 Hz tremor band by 67%, and reduces the rms error with respect to an a posteriori estimate of voluntary motion by 30%. The technique can be implemented in a hand-held microsurgical instrument.

Algorithms↗

PubMed1977

Anaesthetic technique for microsurgery of the larynx.

The problems of anaesthesia for microsurgery of the larynx are reviewed and the disadvantages of some current techniques are discussed. A modified headrest, laryngoscope, dental protector, laryngostat, and a technique of ventilation based on insufflation, which prevents tracheal soiling and allows visibility and room for instrumentation, are described.

Anesthesia, Endotracheal↗

PubMed1979

Anaesthesia for microsurgery of the larynx using a carbon dioxide laser.

Microsurgery of the larynx using the carbon dioxide laser is becoming popular and provides many advantages. The anaesthetic management described here has proved successful in clinical use. Anaesthesia is induced with thiopentone and maintained by nitrous oxide and oxygen with or without halothane. Muscle relaxation is maintained using a continuous infusion of suxamethonium. Emphasis is laid on the need to protect the tracheal tube against the fire risk from the laser beam.

Anesthesia, General↗

PubMed1982

Hypotensive anaesthesia for microsurgery of the middle ear. A comparison between enflurane and halothane.

One hundred patients undergoing microsurgery of the ear were anaesthetised using thiopentone, nitrous oxide, oxygen and either halothane or enflurane with spontaneous respiration. Blood pressure was reduced to approximately 70 mmHg by the use of hypotensive agents. The efficacy of halothane and enflurane in producing good operating conditions was compared during this technique. Haemostasis was assessed by the surgeon who was unaware which volatile agent was being used. Both agents were found to be satisfactory and enflurane was shown to be a safe and reliable agent with this technique should an alternative to halothane be required. No impairment of renal function was seen with either agent in combination with hypotension.

Adolescent↗