Surgical Anatomy of Rats for the Training of Microvascular Anastomosis

Deep learning-based video-analysis of instrument motion in microvascular anastomosis training

PURPOSE

Attaining sufficient microsurgical skills is paramount for neurosurgical trainees. Kinematic analysis of surgical instruments using video offers the potential for an objective assessment of microsurgical proficiency, thereby enhancing surgical training and patient safety. The purposes of this study were to develop a deep-learning-based automated instrument tip-detection algorithm, and to validate its performance in microvascular anastomosis training.

METHODS

An automated instrument tip-tracking algorithm was developed and trained using YOLOv2, based on clinical microsurgical videos and microvascular anastomosis practice videos. With this model, we measured motion economy (procedural time and path distance) and motion smoothness (normalized jerk index) during the task of suturing artificial blood vessels for end-to-side anastomosis. These parameters were validated using traditional criteria-based rating scales and were compared across surgeons with varying microsurgical experience (novice, intermediate, and expert). The suturing task was deconstructed into four distinct phases, and parameters within each phase were compared between novice and expert surgeons.

RESULTS

The high accuracy of the developed model was indicated by a mean Dice similarity coefficient of 0.87. Deep learning-based parameters (procedural time, path distance, and normalized jerk index) exhibited correlations with traditional criteria-based rating scales and surgeons' years of experience. Experts completed the suturing task faster than novices. The total path distance for the right (dominant) side instrument movement was shorter for experts compared to novices. However, for the left (non-dominant) side, differences between the two groups were observed only in specific phases. The normalized jerk index for both the right and left sides was significantly lower in the expert than in the novice groups, and receiver operating characteristic analysis showed strong discriminative ability.

CONCLUSION

The deep learning-based kinematic analytic approach for surgical instruments proves beneficial in assessing performance in microvascular anastomosis. Moreover, this methodology can be adapted for use in clinical settings.

Seven bypasses simulation set: description and validity assessment of novel models for microneurosurgical training

OBJECTIVE

Microsurgical training remains indispensable to master cerebrovascular bypass procedures, but simulation models for training that accurately replicate microanastomosis in narrow, deep-operating corridors are lacking. Seven simulation bypass scenarios were developed that included head models in various surgical positions with premade approaches, simulating the restrictions of the surgical corridors and hand positions for microvascular bypass training. This study describes these models and assesses their validity.

METHODS

Simulation models were created using 3D printing of the skull with a designed craniotomy. Brain and external soft tissues were cast using a silicone molding technique from the clay-sculptured prototypes. The 7 simulation scenarios included: 1) temporal craniotomy for a superficial temporal artery (STA)-middle cerebral artery (MCA) bypass using the M4 branch of the MCA; 2) pterional craniotomy and transsylvian approach for STA-M2 bypass; 3) bifrontal craniotomy and interhemispheric approach for side-to-side bypass using the A3 branches of the anterior cerebral artery; 4) far lateral craniotomy and transcerebellomedullary approach for a posterior inferior cerebellar artery (PICA)-PICA bypass or 5) PICA reanastomosis; 6) orbitozygomatic craniotomy and transsylvian-subtemporal approach for a posterior cerebral artery bypass; and 7) extended retrosigmoid craniotomy and transcerebellopontine approach for an occipital artery-anterior inferior cerebellar artery bypass. Experienced neurosurgeons evaluated each model by practicing the aforementioned bypasses on the models. Face and content validities were assessed using the bypass participant survey.

RESULTS

A workflow for model production was developed, and these models were used during microsurgical courses at 2 neurosurgical institutions. Each model is accompanied by a corresponding prototypical case and surgical video, creating a simulation scenario. Seven experienced cerebrovascular neurosurgeons practiced microvascular anastomoses on each of the models and completed surveys. They reported that actual anastomosis within a specific approach was well replicated by the models, and difficulty was comparable to that for real surgery, which confirms the face validity of the models. All experts stated that practice using these models may improve bypass technique, instrument handling, and surgical technique when applied to patients, confirming the content validity of the models.

CONCLUSIONS

The 7 bypasses simulation set includes novel models that effectively simulate surgical scenarios of a bypass within distinct deep anatomical corridors, as well as hand and operator positions. These models use artificial materials, are reusable, and can be implemented for personal training and during microsurgical courses.

Low cost and easy acquisition: corn grain in microsurgery training

OBJECTIVES

develop an easily accessible model for training the initial motor practice in microsurgery using corn kernels.

METHODS

ten corn kernels (Zea mays) were used. A 7mm longitudinal cut was made on one side of the corn grain. The training consisted of performing 4 simple knots between the edges of the incision, using 10-0 mononylon thread. The parameters analyzed were 1) cost of the model; 2) assembly time of the model test system; 3) time for performing the knots; 4) distance between the knots.

RESULTS

in all corn kernels tested, it was possible to perform the proposed microsurgical suture training, without any difficulty in the procedure. The average time to perform the 4 knots was 6.51±1.18 minutes. The total cost of the simulator model was R$3.59. The average distance between the knots was 1.7±0.3mm. The model developed from corn grains has an extremely low cost when compared to the use of animals or high-tech simulators. Other advantages are the easy availability of canned corn kernels and the possibility of making more than four knots along the 7mm incision.

CONCLUSION

the training model developed has low cost, is easy to acquire and viable for training basic manual skills in microsurgery.

Baixo custo e fácil aquisição: grãos de milho no treinamento microcirúrgico

RESUMO Objetivo: desenvolver um modelo facilmente acessível para o treinamento da prática motora inicial em microcirurgia a partir da utilização de grãos de milho. Métodos: foram utilizados dez grãos de milho (Zea mays). Realizou-se um corte longitudinal de 7mm em uma das faces do grão de milho. O treinamento consistiu na realização de 4 pontos simples entre as bordas da incisão, utilizando fio de mononáilon 10-0. Os parâmetros analisados foram 1) custo do modelo; 2) tempo de montagem do sistema de teste do modelo; 3) tempo de realização dos nós; 4) distância entre os pontos. Resultados: em todos os grãos testados foi possível realizar o treinamento de sutura microcirúrgica proposto, sem dificuldade ao procedimento. O tempo médio para a realização dos 4 pontos foi de 6,51±1,18 minutos. O custo total do modelo simulatório foi de R$3,59. A distância média entre os pontos foi de 1,7±0,3mm. O modelo desenvolvido a partir de grãos de milhos apresenta custo extremamente baixo quando comparado ao uso de animais ou de simuladores de alta tecnologia. Outras vantagens são fácil disponibilidade de grãos de milho em conserva e possibilidade de serem realizados mais de quatro pontos ao longo da incisão de 7mm. Conclusão: o modelo de treinamento desenvolvido é de baixo custo, de fácil aquisição e viável para o treinamento de habilidades manuais básicas em microcirurgia.

Side-to-Side Microvascular Anastomosis Using Rat Cervical Vessels

BACKGROUND

Side-to-side anastomosis is the most challenging anastomosis owing to the difficult intraluminal suturing technique, which requires practice in the microsurgical laboratory before application in patients in the operating room. The objective of this study was to describe 2 side-to-side microvascular anastomosis training models using rat cervical vessels.

METHODS

Two side-to-side microvascular anastomosis training models, one with rat cervical vessels between bilateral common carotid arteries (CCAs) (CCA-CCA anastomosis) and one with a unilateral CCA and the anterior facial vein of the external jugular vein (EJV) (CCA-EJV anastomosis), were studied. Diameters of CCA and anterior facial vein, distances between temporary clips and length of arteriotomies, and vascular clipping time were recorded. Patency rates were evaluated immediately and 7 days after the procedure.

RESULTS

Diameters of CCA and anterior facial vein were 1.00-1.20 mm and 1.40-1.80 mm, respectively. A segment of vessel slightly longer than the arteriotomy or venotomy was temporarily clipped; mean lengths between temporary clips in CCA-CCA anastomosis and CCA-EJV anastomosis of 6.48 ± 0.66 mm and 8.02 ± 0.45 mm, respectively, were used in the study. The minimum distance between the corner of the arteriotomy or venotomy and the clip was 1 mm. The mean vascular temporary clipping times in CCA-CCA anastomosis and CCA-EJV anastomosis were 40.05 ± 3.92 minutes and 42.50 ± 4.82 minutes, respectively. Patency rates of 100% were achieved in all anastomoses.

CONCLUSIONS

CCA-CCA and CCA-EJV side-to-side anastomosis models using rat cervical vessels are feasible and effective side-to-side anastomosis training models.

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.

The "STARS-CASCADE" Study: Virtual Reality Simulation as a New Training Approach in Vascular Neurosurgery

OBJECTIVE

Surgical clipping has become a relatively rare procedure in comparison to endovascular exclusion of cerebral aneurysms. Consequently, there is a declining number of cases where young neurosurgeons can practice clipping. For this reason, we investigated the application of a new 3-dimensional (3D) simulation and rehearsal device, Surgical Theater, in vascular neurosurgery.

METHODS

We analyzed data of 20 patients who underwent surgical aneurysm clipping. In 10 cases, Surgical Theater was used to perform the preoperative 3D planning (CASCADE group), while traditional imaging was used in the other cases (control group). Preoperative 3D simulation was performed by 4 expert and 3 junior neurosurgeons (1 fellow, 2 residents). During postoperative debriefings, expert surgeons explained the different aspects of the operation to their younger colleagues in an interactive way using the simulator. Questionnaires were given to the surgeons to get qualitative feedback about the simulator, and the junior surgeons' performance at simulator was also analyzed.

RESULTS

There were no differences in surgery outcomes, complications, and surgical duration (P > 0.05) between the 2 groups. Senior neurosurgeons performed similarly when operating at the simulator as compared with in the operating room, while junior neurosurgeons improved their performance at the simulator after the debriefing session (P < 0.005).

CONCLUSIONS

Surgical Theater proved to be realistic in replicating vascular neurosurgery scenarios for rehearsal and simulation purposes. Moreover, it was shown to be useful for didactic purposes, allowing young neurosurgeons to take full advantage and learn from senior colleagues to become familiar with this demanding neurosurgical subspecialty.

3D-printed cranial models simulating operative field depth for microvascular training in neurosurgery

BACKGROUND

The skills required for neurosurgical operations using microsurgical techniques in a deep operating field are difficult to master in the operating room without risk to patients. Although there are many microsurgical training models, most do not use a skull model to simulate a deep field. To solve this problem, 3D models were created to provide increased training in the laboratory before the operating room, improving patient safety.

METHODS

A patient's head was scanned using computed tomography. The data were reconstructed and converted into a standard 3D printing file. The skull was printed with several openings to simulate common surgical approaches. These models were then used to create a deep operating field while practicing on a chicken thigh (femoral artery anastomosis) and on a rat (abdominal aortic anastomosis).

RESULTS

The advantages of practicing with the 3D printed models were clearly demonstrated by our trainees, including appropriate hand position on the skull, becoming comfortable with the depth of the anastomosis, and simulating proper skull angle and rigid fixation. One limitation is the absence of intracranial structures, which is being explored in future work.

CONCLUSION

This neurosurgical model can improve microsurgery training by recapitulating the depth of a real operating field. Improved training can lead to increased accuracy and efficiency of surgical procedures, thereby minimizing the risk to patients.

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.