Following the guidelines of the NOM- 062- ZOO- 1999 and the International Council for Laboratory Animals (ICLAS).
Step 1: Sylastic® plates insertion.
Preoperative fasting for 12 hours is indicated. Ketamine anesthesia be performed with a dose of ( 30 mg / kg IM or 12 mg / kg IM ) + Xylazine (3 mg / kg ) to achieve Stage 3: Level 2 ( eye movements stop but breathing movements are preserved ) anesthesia . Corroborating with plantar ( foot of the animal is stretched, it stimulated the interdigital trying to induce pain, if the animal removes the foot, still is not at optimal levels to initiate the procedure )
Care during anesthesia:
• Temperature control: 100 watt lamps to 20 cm away.
• Respiratory Function: Noting tissues in search of cyanosis and directly observing the breathing movements.
• Cardiovascular Function: monitored with capillary refill. In case you are delayed data hypovolemia.
• If stop CPR 5 compressions 2 breaths (which may be by pipette to the nostril of the subject).
Antisepsis: with iopovidone iodine in a spiral (the center to the periphery) and trichotomy is performed. Sterile fields are placed.
Surgical technique:
With a 1 cm incision in the dorsal interscapular region subcutaneous dissection is performed to make enough space for the 4 sylastic® plates. The 4 plates are inserted subcutaneously. (Image 1). Then de skin is sutured with nylon 4-0 USP. Elizabethan collar is placed to prevent the subject withdraws the suture.
Step 2: Harvesting the implants with the fibrous tissue, and grafting it with duralplasty.
Implant removal: preoperative fasting for 12 hrs be indicated. Anesthesia for this procedure will be with Propofol infusion (alternative anesthesia can be used). Antisepsis: Clean with povidone iodine in a spiral (the center to the periphery) and trichotomy is performed. Sterile fields are placed.
Care during anesthesia:
• Temperature control: 100 watt lamps to 20 cm away.
• Respiratory Function: Noting tissues in search of cyanosis and directly observing the breathing movements.
• Cardiovascular Function: monitors with capillary refill. In case you are delayed data hypovolemia.
• If stop CPR 5 compressions 2 breaths (which may be by pipette to the nostril of the animal).
Surgical technique:
Subcutaneous dissection: a wider to dissect the fibrous capsule and remove the implants incision is made. Should take special care to preserve at all costs the fibrous capsule. The edges are everted and placed in physiological solution for later use. The incision is sutured with Nylon 4-0 USP.
The subject is repositioned in ventral decubitus. (Surgical Loupes are strongly suggested) A sagittal incision 5 cm long midline of the subject´s head is performed. The subcutaneous tissue exposing the skull is removed (Image 2). Lidocaine is placed 10 IU (locally spray Unipharm Laboratories) and a scraping is done properly to expose the skull of the rat. An initial trepan is performed with a craniotome (or dentist minidrill) and spread to expose the dura. During the craniotomy must constantly irrigate the region to avoid trauma friction increasing temperature. The bone is kept in a container with saline.
Durotomy is performed dimensions 1.5x1.5 cm, central dura is extracted (May be a good pathology specimen for control, comparing neodura and original dura). The thicker fibrous capsule is selected and used as autologous graft. It is cut to the size of the defect. It is sutured with 4 points on every corner and the edges are sutured with continuous single point (suture Neurolon® 7-0 USP alternative Nylon 7-0 UPS). Gentamicin (2.5mg / kg) is placed locally single dose. Four drill holes are carried out with a smaller drill to pass a suture and to secure the bone graft (earlier prepared) to the skull (Image 3). Once the bone in place the skin is closed with Nylon 4-0 USP and.
Aftercare:
- Recovery of anesthesia: warm between 27-30 ° C without noise or things that increase stress.
- Recovery: Same conditions until it recovers its physiological state.
- Long-term care: Once recovered the physiological state. An Elizabethan collar is placed so that the points are not removed. Points after 10 days and the Elizabethan collar is removed.
- Analgesia: diclofenac (50 mg / kg) every 24 hours and Buprenorphine (0.01-0.05 mg / kg) every 12 hours by reason necessary (animals with signs of pain).
Monitoring for signs of complications will be given: epileptic episodes, Signs of infection, CNS impairment.
Inflammatory response should be minimal. Compatibility is unquestionable. The functionality of the tissue will probably be the challenge in this experimental model.
After 3 weeks, the rat will be sacrificed and histological sections of hard graft and compared with the dura excised in the second procedure.