Establishment of a Rat Model of Superior Sagittal-Sinus Occlusion via a Thread-Embolism Method

Due to the lack of an ideal animal model, the study of CVST is greatly limited. Now, a new type of SD-Rat CVST model was successfully established by inserting self-made thread-embolization centripetally at the initial site of SSS which standardized various or uncontrollable interference factors in clinical condition. After the rat was successfully anesthetized by intra peritoneal injection, apply gel ophthalmic eye lubricant after rat is put on stereotaxic frame to protect the corneas from drying during anesthesia.

Remove the hair on the top of the rat’s head. In order to perform this process more effectively the earlier step can be performed earlier in the preparation room. After the rat was successfully anesthetized by anesthetic machine, also apply sterile ophthalmic eye lubricant.

Sterilize surface on top of the rat’s head with 5%povidone iodine. Alternate this three times with 75%ethanol. Make a skin incision about two centimeters long in the middle of the head.

The fascia is cut open with a scalpel. And then, carefully peel off the top fascia and the periosteum to fully expose the skull. Confirm the position of the anterior fontanelle, A and the posterior fontanelle, B.Use the area between the coronal suture and the elbow suture, as the blood flow observational area.

To prevent the skull from affecting observation during laser-speckle blood flow imaging, thin the skull in the observation area until the blood vessels are clearly visible. During skull grinding use a normal temperature syringe to rinse the dura repeatedly, to avoid a high temperature burst to the cerebral cortex. This step and the following are all performed under a dissecting microscope.

In this figure, the red lined rectangular area is the blood flow observation area. The size of the thinned skull should be approximately one centimeter multiplied by one centimeter. And the blue lined rectangular area is the bone window.

About six millimeters multiplied by four millimeters. The red circular area is the parietal joint and the arrow points to the SSS. When the skull can be seen use tweezers to carefully the remaining bone pieces of the bone window.

Choose a suitable thread probe, use the front point or as the plug point. Carefully puncture it with a 2 millimeter syringe needle and quickly insert a thread probe into the prep point. At this time, the angle between the end of the thread probe end and the SSS should be approximately 30 to 45 degrees.

Then adjust the angle between the end of the thread probe and the SS to zero to 10 degrees. And slowly insert the SSS into the structure until the head reaches the posteria end of the sinus confluence. Rapid breathing may occur when the SSS is punctured.

If the end of the thread probe cannot be quickly inserted into the prep point at one time use a small gauze or cotton ball to gently press the probe point while slowly sliding down to expose the prep point carefully. That is done, quickly insert to the end of the wire brought into the SSS. The blue arrow shows the state of the probe insert into the SSS from the plug point.

White arrow shows the body of the probe and the red arrow shows that is the head. Thereafter cut off the excess part of the tail. Suture the rat’s skin.

Disinfect the skin three times and remove the rat from stereotaxic frame. Use the laser light source to uniformly illuminated the blood flow observational area. The image records the dynamic process of the thread probe into the SSS.

In this figure A and B shows a comparison of blood flow before and after thread embolization insertion. C shows that the blood flow in the SSS and brain veins were decreased significantly compared with both in the middle cerebral artery and capillaries. Fix the animal on the MRI scanning table.

Calibrate the brain position by positioning scanning and perform T2WI and MRI sequence scanning after confirming the position. In order to observe the state of the thread probe in the SSS more clearly the C2 head mounted method was used to display T2WI image of the rat brain. In this figure, A, B and C show the thread probe in the SSS from the horizontal position, sagittal position and the cranial position.

The image shows that the thread probe is in place which confirms embolization of the SSS. As the rat SSS thrombosis model is easily established minimizing the trauma, offered good stability and allowed for accurately controlling the chemical timing and the location, it is an ideal new type of CVST model.