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. 2020 May 26;11(6):3288–3300. doi: 10.1364/BOE.394649

Table 1. Procedure and substance lookup table for the chronic cranial window surgery.

Step Procedure description Materials & substance Remarks
1 One hour prior to surgery, administer buprenorphine SR subcutaneously. Prepare sterile supplies and instruments.
  • Buprenorphine-sustained release (SR) (ZooPharm, 0.5 mg/ml). Dosage: 1.0 mg/kg.

Buprenorphine SR can provide analgesia for sustained period of 72 hours. Alternatively, standard buprenorphine (0.05 mg/kg) can be used here and then 8-12 hours after the surgery for 3 days.

2 Induce anesthesia to the animal by isoflurane inhalation in oxygen enriched air (0.2 L/min O2 and 0.8 L/min air), firstly at 5% dose in an induction chamber, and then adjust to 1.5-2% after transferring the animal to the nose cone on the stereotaxic frame.
  • Isoflurane (FORANE, Baxter, USA). Dosage: 5% initially, and then 1.5∼2% throughout the surgery.

 

3 Administer dexamethasone subcutaneously, and mount the mouse head using an ear bar adapter. Apply eye ointment to prevent the cornea from drying out.
  • Dexamethasone sodium phosphate injection (Fresenius USA, 4 mg/ml). Dose: 2.0 mg/kg

  • Refresh P.M. Lubricant Eye Ointment

Dexamethasone reduces the cortical stress response and prevents cerebral edema. It is critical for successful surgeries.

4 Remove the scalp hair by Nair cream. Sterilize the surgical site by alternating betadine and 70% alcohol at least three times. Drape the animal and set up a sterile field.
  • Nair™ hair lotion

  • Betadine surgical scrub (Avrio Health LP)

  • 70% isopropanol (Fisher Co., USA)

Going to a sterile field after this step.

5 Make an incision to remove the scalp covering the cranium, gently retract the skin and scrap off the periosteum. Use small drops of 1% xylocaine to minimize bleeding of the skin and periosteum tissue. Xylocaine liquid (lidocaine 1% + epinephrine 1:100,000 solution, Hospira, USA) Removing the periosteum tissue will later help the dental cement adhere to the bone and better secure the cranial implant.

6 Use a dental drill with a round carbide bur to create circular groove in the right parietal bone, 1 mm posterior and lateral to the bregma. Pause drilling every 15 sec to apply 0.9% sterile saline to avoid heating. Leave the central island of skull (dia. 4-mm) intact.
  • High-speed surgical hand drill (Foredom, USA) with #2 round FG carbide burs (0.5 mm).

  • Sterile saline 0.9% (Mountainside Medical, USA)

Extra cautions should be taken not to apply excessive pressure with the drill that may puncture the skull and injure the dura. Check the readiness of the craniotomy by gently pushing on the center island with forceps. If the island moves when lightly touched, then it is ready to be lifted/removed.

7 Apply saline drops, then gently insert the tip of an angled-fine-tipped forceps into the trabecular (spongy) bone of the center island, horizontally, from the side of the groove, and slowly lift/remove the center island. If bleeding occurs, use saline-soaked Gelfoam to clean up the blood or keep the exposed dura moist.
  • Sterile Gelfoam sponges (Pfizer, USA)

Saline is important here to help with lifting the center island and have it removed without excessive bleeding. Some meningeal capillaries might tear and cause focal bleeding during the removal. Use only Gelfoam to soak up the blood and clean the exposed dura, cotton swabs or Kimwipes are discouraged.

8 Replace the center island of skull with a 5-mm circular coverglass, apply a drop of saline as a coupling media in between, and then use cyanoacrylate glue to seal the coverglass.
  • Krazyglue (Krazy Glue, USA)

It is important to use saline here as a coupling media between the glass and dura, so that glue materials were not in direct contact with brain tissue.

9 Apply a thin layer of dental cement to cover the rest of the skull surface, resulting in a cement headcap. After drying this layer, apply another layer of cement to install the medal plate.
  • Dental cement (Stoelting Co., USA)

Check to make sure all areas are covered with dental cement with no exposed muscle and flesh in the surgical opening.