The Use of Retraction Sutures in End-To-Side Microvascular Anastomosis-A Novel Technical Innovation in Experimental Rat Femoral Model with Successful Use in STA-MCA Bypass in Moyamoya Disease.

BACKGROUND: A narrow working space, small diameters, and the tendency to collapse with clamps make cerebral microvascular anastomosis challenging. A retraction suture (RS) is a novel technique to keep the recipient vessel lumen open during the bypass. OBJECTIVE: To provide a step-by-step overview of RS for end-to-side (ES) microvascular anastomosis on rat femoral vessels and successful use for superficial temporal artery to middle cerebral artery (STA-MCA) bypass in Moyamoya disease patients. METHODS: A prospective experimental study with approval from the Institutional Animal Ethics Committee. Femoral vessels ES anastomoses were performed on Sprague Daley rats. The rat model used 3 types of RS (adventitial, luminal, and flap RSs). An ES-interrupted anastomosis was done. The rats were observed for an average period of 16.18 ± 5.65 days; the patency was assessed by reexploration. The immediate patency on the STA-MCA bypasses was confirmed with intraoperative indocyanine green angiography and micro-Doppler; delayed patency with magnetic resonance imaging and digital subtraction angiography after 3-6 months. RESULTS: In the rat model, 45 anastomoses were performed, 15 each using the 3 subtypes. The immediate patency was 100%. Delayed patency was 42/43 (97.67%), and 2 rats died during observation. In the clinical series, 59 STA-MCA bypasses were done in 44 patients (average age, 18.14 ± 11.09 years) using RS. The follow-up imaging was available for 41/59 patients. Both immediate patency and delayed patency (41/41 at 6 months) were 100%. CONCLUSION: The RS allows continuous visualization of the vessel lumen, reduces the handling of intimal edges, and avoids incorporating the back wall in sutures, thus improving anastomosis patency.

Histopathological Validation of Microvascular Anastomosis using Two-Throw Reef Knots - An Experimental Study.

Background: Knot configuration is an important but relatively neglected topic in microvascular anastomosis literature. Objective: To study the differences between end-to-end microvascular anastomosis performed with two-throw reef knots as compared to traditional three-throw knots in a rat femoral artery model at the histological level. Material and Methods: Sprague Dawley rats underwent end-to-end microvascular anastomosis of the right femoral artery (one-way-up method). The rats were divided into two groups: two-throw reef knots versus traditional three-throw knots. The patency was checked by the standard empty refill method. After 2 weeks, the rats underwent re-exploration. An anastomotic segment was sent for histological analysis. Histological alterations including luminal patency and changes in Tunica intima, Tunica media, and Tunica adventitia were compared between the two groups. Results: Twenty-nine rats were operated on by the senior author (17 by three-throw and 12 by two-throw reef knots). In the two-throw reef knot group versus the traditional three-throw knot group, the immediate patency rates were 100% versus 82.4%, and the delayed patency rates were 90.9% versus 62.5%, respectively. The histopathological patency rates were concordant with delayed patency rates. Subintimal proliferation and fibrosis were comparable in both groups. Adventitial granulomas were noted in all, irrespective of the knotting technique. Tunica media preservation rates for the two-throw reef knot versus the traditional three-throw knot group were 63.6% versus 0%. Five rats were operated by the beginner in the field, all by two-throw reef knots (to assess the safety of this new method in the hands of a beginner). Conclusion: Microvascular anastomosis performed with two-throw reef knots appears not only feasible but better in terms of anastomosis patency. Histological superiority in terms of Tunica media preservation further validates the technique.

Toe-First Technique for End to Side Microvascular Anastomosis.

BACKGROUND: The use of the classic 2-ends anchoring technique is common in end-to side (ES) microvascular anastomosis. The literature on the toe-first (TF) technique is limited. In the current study we present the successful outcomes with the TF technique in ES anastomoses in rat femoral vessels model. METHODS: ES microvascular anastomosis with the tf technique was performed in the femoral vessels of 10 Sprague Dawley rats. Two-throw reef knot interrupted sutures were used in all cases. Individual parameters during the procedure were recorded for analysis. The immediate and delayed (cut open technique after 2 weeks) patencies were confirmed. An illustrative case showing the use of this technique in superficial temporal artery to middle cerebral artery bypass in a pediatric moyamoya disease case is included. RESULTS: The average suturing time was 40.14 ± 5.30 minutes, the procedures were completed with an average of 14.57 ± 1.90 sutures. The average time per suture was 2.78 ± 0.43 minutes. The immediate patency was 100% (10 of 10 cases). Two rats died of unknown cause in the observation period. The delayed patency was 100% in the remaining 8 cases (average observation: 29.6 days). CONCLUSIONS: The TF interrupted suture technique of ES microvascular anastomosis with 2-throw reef knots is feasible with excellent immediate and delayed patency rates. The distinct advantages of the TF are the continuous visualization of the recipient lumen during anastomoses, avoiding back-wall bites, and the ability to correct any discrepancy in the recipient-donor lumens during the procedure.

Removal of Perirolandic Cavernoma with Direct Cortical Stimulation and Neuronavigation with DTI.

BACKGROUND AND INTRODUCTION: Intraoperative neuromonitoring for eloquent cortical lesions is irreplaceable in present-day neurosurgery. OBJECTIVE: We report a novel technique of combining awake craniotomy with direct cortical stimulation of the motor cortex using the NIM© nerve monitoring system. TECHNIQUE: A 17-year-old boy presenting with focal motor seizures, diagnosed with left perirolandinc cavernoma, underwent awake craniotomy and complete excision under direct cortical stimulation with NIM monopolar stimulator electrode to locate the motor cortex. RESULT: The patient developed transient weakness of handgrip during surgery, which improved by the same day evening. At 3 months follow-up, he could perform all the activities with his dominant right hand. CONCLUSION: Cortical stimulation using a nerve monitoring system is a useful technique in case of nonavailability of standard evoked potential monitoring system for motor cortex mapping.

End-to-Side Microvascular Anastomosis on Rat Femoral Vessels Using Only 2-Throw Knot Interrupted Sututres - Evaluation of Feasibility and Patency Rates on Rat Femoral Vessels Model.

BACKGROUND: The use of a 3-throw knot for anastomosis by microvascular neurosurgeons is the usual standard. There is an inherent belief that the third throw adds extra security to the knot; however, the third throw can make the knot heavy and unbalanced and can exert undue extra pressure on the opposing walls of the small-caliber intracranial vessels. This study evaluated the feasibility and efficiency of 2-throw reef knot interrupted sutures for an end-to-side microvascular anastomosis. METHODS: A prospective observational study of end-to-side anastomosis using a femoral artery-to-vein model was performed in 30 Sprague-Dawley rats. All anastomoses were done using 2-throw reef knot interrupted sutures. Ten procedures each were done by the heel-first, toe-first, and classic 2-ends techniques. Individual parameters were recorded for analysis. The delayed patency was confirmed by reexploration after a mean duration of 19.82 ± 8.12 days. RESULTS: The overall patency rates were 100% in the immediate period and 96.43% (27 of 28) in the delayed period. The average clamping time, average suturing time, and the average time per suture were 65.48 ± 16.93 minutes, 40.94 ± 11.22 minutes, and 3.18 ± 1.10 minutes, respectively. Two rats died in the postoperative period. CONCLUSIONS: The end-to-side microvascular anastomosis with 2-throw reef knots is feasible, with excellent immediate and delayed patency rates.

Microvascular Anastomosis Using Only 2-Throw Reef-Knots: A Technical Note.

In macrosurgery creating a knot with at least three throws is an established practice. The potential disadvantages of this practice in microsurgery include the following: the direction of the cut ends interfere with the suture line, unbalanced nature of knot disturbs the apposition of delicate vessel ends and the excessive knot weight. A reef knot with only 2 throws may thus be a better alternative. We have described our technique of end to end anastomosis with 2-throw reef knots in a rat femoral artery model using one way up method. Judging from the surgical outcome the practice of two throw reef knot seems feasible and appealing.

Predictors of outcome of subdural empyema in children.

OBJECTIVE: The aim of this study was to report the etiology, clinical features, microbiology, surgical outcome, and predictors of outcome of spontaneous subdural empyema (SDE). METHODS: The authors conducted a retrospective study in a tertiary hospital. Children up to 18 years of age, with a diagnosis of SDE with infective etiology, were included in the present cohort. Patients with posttraumatic, postsurgery, and tubercular origin of SDE were excluded from the study. The Glasgow Outcome Scale was used for outcome assessment at the end of 3 months. For analysis purposes, the demographic data, clinical features, radiological data, microbiology, type of surgery, and complication data were categorized, and univariate and multivariable logistic regression analyses were performed to identify the factors associated with outcome. RESULTS: Ninety-eight children were included in the study and the mean age was 10.9 years. Otogenic origin (34.7%) was the most common source of infection, followed by meningitis (14.3%). The mean duration of symptoms was 12 days. Seventy-six children presented with Glasgow Coma Scale (GCS) score > 8 and the supratentorial location was the most common location. Almost 75% of the children underwent craniotomy or craniectomy and the rest had burr-hole evacuation. Beta-hemolytic Streptococcus (10%) was the most common organism isolated. Cerebral venous thrombosis (CVT; 10.2%) was the most frequent complication in this cohort. The other complications were infarction (6.1%), new-onset seizure (4.1%), and bone flap osteomyelitis (4.1%). Thirteen cases had a recurrence of pus collection, which was more common in the craniotomy group than in the burr-hole group. Age (p = 0.02), GCS score ≤ 8 (OR 8.15, p = 0.001), CVT (OR 15.17, p = 0.001), and presence of infarction (OR 7, p = 0.05) were strongly associated with unfavorable outcome. In multivariable logistic regression analysis, only GCS score ≤ 8 (p = 0.01), CVT (p = 0.02), and presence of infarction (p = 0.04) had a significant impact on unfavorable outcome. CONCLUSIONS: Prompt diagnosis and immediate intervention is the goal of management of SDE, especially in children as a delay in diagnosis can result in unconsciousness and secondary complications such as CVT and infarction, which adversely affect outcome.

Inverted (Buried) Reef Knot in Microsurgery - A Technical Note.

In side to side anastomosis and end to end (one way up) microvascular anastomosis, the back wall of the vessel is sutured first with inverted/buried knots. A common mistake made by surgeons during this step is the formation of a granny knot. In inverted suturing, cut ends of granny knot points inside the vessel lumen and interfere with the suture line. This additional Intraluminal thread may promote foreign body reaction and may act as a nidus for thrombus formation. Hence, this subtle mistake in knot formation may cause immediate and/or delayed anastomosis failure. The purpose of the study was to describe principles of inverted/buried reef knot formation. We describe in detail the methodology to form an inverted reef knot in microsurgery using paracords and a glove model.

Successful Development by Design of Experiments of a Gas Chromatography Method for Simultaneous Analysis of Residual Solvents of Classes 1 and 2.

In this study, design of experiments (DoE) was employed to develop a single injection method using a headspace gas chromatograph with flame ionization detector for resolution of residual solvents of United States Pharmacopeia (USP) listed classes 1 and 2, against current recommendation of independent injections. G43 column (6% cyanopropylphenyl and 94% dimethylpolysiloxane) and nitrogen were used as the stationary phase and carrier gas, respectively. Initial temperature, hold time, temperature ramp and carrier gas velocity were the critical method parameters. Resolution of 1,1,1-trichloroethane and tetrahydrofuan (THF); THF and chloroform; benzene and 1,2-dichloroethane (DCE), and 1,2-dimethoxyethane and DCE were selected as critical quality attributes. These were optimized by DoE that resulted in resolution of >1.34 among various solvents. The separation of all the solvents was achieved within total run time of 77 min. A better resolution of 2.66 was observed in the case of acetonitrile and methylene chloride; there was improved Signal/Noise ratio of 8.86 for 1,1,1-trichloroethane; tailing factor for pyridine was 1.00, and the method showed acceptable repeatability of peak areas (%RSDmax = 11.53) and retention times (%RSDmax = 0.45). Thus, while system suitability criteria and validation results very well met the USP requirements, the optimized method proposed in this study proved advantageous additionally in terms of single injection; short run time, and use of nitrogen as a carrier gas instead of costly helium in the USP method.