TissueDB/Simulators/Superficial Temporal Artery-Middle Cerebral Artery Bypass Trainer

The Superficial Temporal Artery–Middle Cerebral Artery (STA-MCA) Bypass Trainer is a low-cost benchtop model — one that needs a 3D printer, basic force sensors and a microsurgical instrument set rather than only locally available materials — for practising the end-to-side STA-MCA microvascular anastomosis of cerebral bypass surgery.^[1] Described by Akdag et al. (2024) in World Neurosurgery 190:e665–e674 (doi:10.1016/j.wneu.2024.07.200), it pairs a 3D-printed hemispheric cranial mould and a silicone brain (cerebral parenchyma) cast with avian arterial simulants — turkey brachial artery as the donor STA and chicken brachial artery as the recipient MCA-M4 segment. To use it, the trainee performs the anastomosis under an operating microscope while embedded force sensors flag heavy contact with the brain, then pressurises the circulation loop to leak-test the finished join. It was developed by Beyza Alkis Akdag and colleagues at Dokuz Eylul University, Izmir, Turkey.

Build sequence traceable to Akdag et al. (2024) main text and figures. The 3D cranium, silicone parenchyma, force-sensor subsystem and circulation loop are built once; the avian vessels and dyed water are prepared per session.

1. Using a 3D printer, print a hemispheric cranial mould sized to a left cerebral hemisphere. The source does not publish the STL/CAD file or the mould dimensions — the geometry must be obtained from the authors (see Development Team Contact) to reproduce the apparatus.
2. Pour silicone into the mould and allow it to cure to form a cerebral parenchyma model of the left hemisphere.
3. Using a surgical drill, perform a left frontotemporoparietal craniotomy on the hardened silicone model to expose the region where the STA-MCA anastomosis will be performed.
4. Position the cranial model at 45° rotation to the right and 30° extension to simulate the intraoperative head position for cerebral bypass surgery.

1. Solder the (+) and (−) terminals of each of three force-sensitive resistors (S1, S2, S3; the source specifies an Interlink "0.500" sensor), with a 10-kΩ pull-down resistor on the (−) terminal.
2. Connect each sensor to a microcontroller analog input configured for a 5 V supply.
3. Calibrate each sensor by applying a stepped load over 0–200 N and recording the voltage response, then configure the microcontroller to convert the reading to force and to sound an audible alert each time a set touch-force threshold is crossed. The source publishes a separate second-order calibration curve for each of its three sensors (and a representative load/resistance/voltage table); these are sensor-specific and must be re-derived for your own sensors.
4. Position the three calibrated sensors (S1, S2, S3) around the sylvian fissure on the silicone parenchyma — corresponding to the frontal and temporal lobes — and fix them securely.
5. Connect all three sensors to a data receiver for continuous recording of touch-event timing and magnitude throughout the procedure.

1. Using dissection scissors, a scalpel, clamps and forceps, expose the brachial artery, vein and nerve bundle in a turkey wing (donor vessel for the STA).
2. Using a calliper, measure and dissect a 5–6 cm segment of the turkey brachial artery (about 1.0–1.5 mm in diameter) while preserving its integrity.
3. Under the surgical microscope, ligate all microvascular branches of the turkey brachial artery with 10-0 sutures so that only the main branch remains patent.
4. Dissect and separate the adventitia from the turkey brachial artery.
5. Repeat the dissection, measurement, branch-ligation and adventitial dissection on a chicken wing brachial artery (recipient vessel for the MCA-M4; about 1 mm in diameter).

1. Place the proximal end of the turkey STA simulant into an intravenous cannula and secure it with a 3-0 vicryl suture.
2. Place the distal end of the chicken MCA simulant into an intravenous cannula and secure it with a 3-0 vicryl suture.
3. Connect each cannula to an intravenous infusion set with an adjustable flow regulator.
4. Place the proximal ends of both infusion sets into a 1000-mL beaker reservoir.
5. Fill the beaker with water and add Rifocin ampoules to dye the water red for leak visualisation.
6. Connect the 80-GPH aquarium pump outlet via a third infusion set to the reservoir, creating a closed loop: donor → anastomosis → recipient → beaker → pump → donor.
7. Connect the pump to a power source and verify that liquid flows at a controlled speed through the donor simulant, through the (not-yet-anastomosed) recipient simulant, and back to the beaker.
8. Connect a perfusor and a calibrated manual manometer (mmHg) to the proximal end of the system for the post-anastomosis leak test.

1. Lay the prepared turkey brachial artery (STA simulant) so that it extends to the left temporal lobe of the silicone parenchyma.
2. Lay the prepared chicken brachial artery (MCA-M4 simulant) so that it extends from the left frontal lobe to the sylvian sulcus.
3. Apply methylene blue to the vessel ends to highlight the vessel wall under the microscope during the anastomosis.
4. Verify that the three force sensors remain securely fixed around the sylvian fissure and that the circulation system remains connected.

1. Perform a fish-mouth arteriotomy at the distal end of the turkey STA simulant (donor vessel).
2. Place one microvascular clip at the proximal end and one at the distal end of the chicken MCA simulant to isolate the recipient segment.
3. Using a scalpel, perform a linear arteriotomy on the chicken MCA simulant between the two clips.
4. Using an interrupted-suture technique, place the first two sutures at the "heel" and "toe" of the joined arteries, stitching outside-to-inside on the STA and inside-to-outside on the M4.
5. Continue the interrupted-suture anastomosis with about ten further sutures to complete the join.
6. Use either 9-0 or 10-0 polyamide (nylon) microsuture, with either a micro needle holder plus micro forceps or bilateral micro forceps.
7. Record the anastomosis completion time and the number of sensor touches (logged automatically by the data receiver).

1. With the anastomosis complete, release the two microclips from the chicken MCA simulant.
2. Activate the aquarium pump to start the dyed circulation through the completed anastomosis.
3. Confirm anastomotic continuity (visible red flow from the donor through the anastomosis into the recipient).
4. Clamp the distal ends of the system to hold pressure, and use the perfusor to pressurise it.
5. Titrate systolic pressure from hypotensive (<120 mmHg) through normotensive (120 mmHg) up to a maximum of 200 mmHg.
6. Record whether leakage occurs, the pressure at leak onset, and the number of leak points. If no leakage occurs at 200 mmHg, classify the anastomosis as patent.
7. If leakage is detected, identify and count the leak points and judge whether the leak is at a suture or at the vessel wall.

• Anastomotic continuity confirmed under dyed circulation — pass/fail
• Leak-test patency at 200 mmHg systolic — pass/fail (Akdag 2024 reports 66.7% patent across the 24-session series)
• Force-sensor data receiver records continuous touch events with no signal dropouts — pass/fail
• Manometer pressure titration covers the full hypotensive–normotensive–hypertensive range — pass/fail

1. Power down the aquarium pump and disconnect the power source.
2. Remove the turkey and chicken brachial-artery samples and discard them via standard biological-waste protocol.
3. Empty the beaker of dyed water and rinse the beaker, infusion sets and pump-outlet line with clean water to remove dye and biological residue.
4. Inspect the microsurgical instruments and clean them per institutional instrument-care protocol.
5. Inspect the silicone parenchyma for sensor displacement or wiring damage and re-anchor the sensors if needed; the silicone parenchyma is reusable across many sessions.
6. For the next session, harvest and prepare fresh vessels (Phase 3) and refill the beaker with fresh dyed water (Phase 4). The 3D cranium, silicone parenchyma and force-sensor subsystem are reused in place.

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