Notes for Surgical Implantation for Intracranial Pressure in Mice

The basic surgical technique is derived from the procedure used for measuring ECG in small animals, alongside a technique used for measuring intracranial pressure in nonhuman primates.

Surgical Description for Mouse:

• Place animal in stereotaxic frame
• Incise skin on head and place device in a subcutaneous pocket on the flank
• Remove periosteum from skull and dry the surface of the skull
• Drill hole in skull at desired placement
  • Position the hole in an area where the catheter is less likely to kink
  • The hole may be drilled at a slight angle to help prevent the risk of catheter kinking
• Etch the skull with a scalpel blade around hole
• Tie a loose throw in a length of non-absorbable suture around the catheter
• Place catheter in hole so the tip rests between the skull and dura
  • Position the loose throw so it lies flat against the skull, and complete a square knot
  • Add 1-2 finger-trap throws down the catheter away from the skull and finish with two square knots
• Apply dental acrylic around hole and catheter, ensuring suture is covered as well to prevent catheter from migrating
• Suture head using 5-0 suture on a taper needle with interrupted horizontal mattress (or other tension-relieving) suture pattern
• Calculate the head pressure as follows:
  • At 37C, every 1 cm in height will have 1.4 mmHg of head pressure

Using the technique above in non-human primates, pressures were demonstrated to be stable over the course of one year. Physical or chemical alterations were required to induce changes in ICP.