User:Neurosurgeons corner

For hundreds of years severe head injuries had a very bad prognosis. Despite them being the biggest killers in Neurosurgery, not much in the way of surgical advancements came along in trauma Neurosurgery compared to other subspecialties of Neurosurgery. The Monro Kellie Doctrine which is a simple way of explaining head injuries has been cited in almost all head injury models. Since the cranium is a "fixed" box and the three components inside namely brain, CSF and blood are not compressible, the only option before was to open the cranium as wide as possible with a surgery termed Decompressive hemicraniectomy. However, Dr. Cherian etal proposed that the CSF shifted to within the brain from the cisterns in acute stages of head injury and this was the reason for the severe brain swelling seen at this stage. They proposed that the opening of cisterns to atmospheric pressure will decrease the intracranial pressure. This surgery was tried out in over 1000 patients in many centres over the world and was found to decrease the intraoperative brain swelling, mortality and morbidity. The surgical technique of Cisternostomy Cisternostomy is a new way of surgical treatment for head injury with the same indications as that for decompressive hemicraniectomy, selected cases of severe pediatric head injuries and acute subdural hematomas with severe brainswelling, sometimes even when the GCS corresponds to a moderate head injury. Time interval It is very important not to waste any time and allow cytotoxic brainswelling or hypoxic injury which will not respond to Cisternostomy. The decision making and transport to theatre for the surgery should be as fast as possible. Positioning The patient is not positioned on any headrest. However, Leyla retractors are sometimes very helpful in the procedure. The positioning is with the head extended to 15 degrees, turned to the opposite side to 15 degrees and the malar prominence should be facing towards the roof. This positioning (especially the extension) helps one in getting into the interoptic cistern without any delay. Later on, changing the microscope angle and slightly moving the head and adjusting the table can help in visualizing the basilar quad without much difficulty. Craniotomy A pterional flap with or without FTOZ extension is used as the craniotomy. It is very important to go as basal as possible in a tight brain so as to be able to open the cisterns. A limited FTOZ will be very helpful in this aspect sometimes. For this, the frontal aspect of the skin flap has to be dissected upto the orbit and the inferior orbital fissure is identified with a dissector from the orbit into the inferior orbital fissure. A burr hole is each made in the keyhole and just above the root of the zygoma. From the keyhole, first cut is made into the burr hole above the zygomatic root and then the second cut is made from the keyhole to the inferior orbital fissure. After reaching the inferior orbital fissure the craniotome is turned ninety degrees and the cut is made across the zygoma. The third cut is made from the burr hole above the zygomatic arch to all the way to the orbit, lateral to the supraorbital notch. This cut is deepened with a chisel or a reciprocating sagittal saw into the orbital roof and then extended laterally towards keyhole. The single piece limited FTOZ flap can be mobilized in this fashion. Bone is bitten up to the Superior orbital fissure and the meningo orbital band is cut. This allows the basal dura to be retracted maximally downwards after the dural opening. There is no need to peel off the dura propria of the cavernous sinus or for anterior clinoidectomy as for standard skull base approaches. Dural opening The dural opening should be as basal as possible in a line about 2.5 cm long parallel to the supraorbital bow. The brain is usually tight and after the subdural hematoma which is usually present at the base, the surgeon usually gets a "2 millimeter window" to go to the interoptic cistern. The trajectory is important and I feel, going from slightly lateral subfrontal is the best approach...and there should be no delay in this step since the brain swelling can be very severe at times if the surgeon waits. Interoptic cistern The interoptic cistern may not contain much CSF, but opening this wide with the suction first and then with sharp dissection into the interhemispheric cistern and along the opposite A1 is important. After this step, one visualises both the A1s and the Acom. Optico carotid and Carotico-oculomotor cistern After the above said dissection one can open the arachnoid medial to the carotid and then lateral to the carotid. The optico carotid window will show the perforators from IC, Pcom and the pituitary stalk. It will also show the membrane of Lilliquist and posteriorly the posterior clinoid process will be seen. Membrane of Lilliquist The membrane of Lilliquist may be opened by sharp dissection and the "basilar quad" comprising of the 2 posterior cerebral arteries, superior cerebellar arteries and the third nerve in between is visualised. All the cisterns are irrigated with normal saline and the blood is washed out in a thorough fashion. Any bleeding into the cisterns will usually stop with irrigation. The brain which was tight to begin with will be seen as lax and pulsatile, if there was already no gross ischemia. A drain can be put into the prepontine cistern through the opticocarotid cistern and the dura can be left open, but approximated. The bone is replaced and the wound is closed in layers. The drain is kept at a height of 15 cm and allowed to drain for 5 days [1][2]