Hello, my name is Bob Bergman and I'm going to be speaking about principles of intracranial surgery today. We're first gonna start out with a basic overview of considerations for surgery and then we are going to talk about specific approaches. This lecture will be divided into two parts.

Suggested resources, that I feel are really nice to have are the veterinary surgery book by Doctor Tobias and Johnston, as well as Doctor Fossum's small animal surgery book and then I think a couple of good neuroanatomy books are also very helpful and you'll see diagrams from those in, in this presentation. So the presentation overview, we're first gonna discuss the indications for intracranial surgery. We're gonna discuss the diseases that we treat and and potential morbidity and complications that may occur with this and then we're gonna talk a little bit about diagnostic considerations such as imaging and we'll move on to anaesthetic considerations.

And patient preparation and the last part of this talk will be instrumentation, both instruments that we find helpful for intracranial surgery as well as hemostasis, which is obviously a very important part of what we do. The second talk, we'll talk about the basic approaches that we use, certain anatomic considerations, ways that we can identify pathology in surgery. And reasons we might do so reconstruction and other intraoperative considerations and then finally we'll briefly mention aftercare and some of the post operative management that we consider.

So indications for intracranial surgery. So the main indications for intracranial surgery are going to be neoplasia, both scola and in ranal. Trauma is a common reason for surgery, and I'll show you examples of this.

Some patients also an indication maybe infection. In some cases you would like to biopsy something that's unclear on an MRI or CT. And then finally, fairly commonly do surgery for congenital malformations.

So the first indication and probably the most common indication is for intracranial neoplasia. And here we have a boxer with an intracranial mass on that's evident on this MRI. This is a T1 post contrast image that demonstrates an extra axial mass in the occipital lobe and then you can see this dog, this is the postoperative CT that was used for radiation planning and you can see where we've removed this mass.

So indications for tumour removal would be to help with clinical signs and you see this dog having seizures, these focal seizures. We're also that's done through tumour removal or at least debulking the tumour. Sometimes it's a matter of obtaining a tumour biopsy to then make recommendations for treatment.

Also additional therapies, so there's some exciting developments in immunotherapy as far as making vaccines that are targeted against the tumour as well as, planning for radiation therapy. Another common reason for intracranial surgery would be for trauma, and there are some specific goals that we have when we consider surgery, we we want to decompress the skull fragment. We may want to lavage, you know, the bite wound, remove devitalized tissue, and in, most cases we'll also perform a culture.

So this is an example of a patient who had a a bite wound from another dog, which is a, a fairly common type of injury. And so you can see here the CT can be pretty helpful. This is a reconstruction that demonstrates a skull fracture can be pretty helpful in in planning these .

And it's a, it's also a pretty fast way to identify pathology and make treatment decisions. So again, the goals of the surgical treatment for trauma would be removing decompressed skull fragments to relieve brain compression and to remove devitalized and brain tissue and as well as hematomas. And you can see in this CT is transverse view, this dog has a large hematoma.

There on the, the dorsal aspect of the skull. So again, as I mentioned, bite wounds are fairly common source of trauma and particularly the canine of a larger dog will generally penetrate the, the skull, and you'll see this type of indentation from the bite wound. It's important to be able to interpret the CT though in a way that helps you perform the surgery.

For instance, this particular dog has, obviously a displaced fracture. And probably a fragment of bone here, but the dog also has a hyper dense region in the prancuma of the tissue, which is, you know, likely something that does not need to be addressed. We also see that there's mass effect, meaning that this dog has compression of the lateral ventricle, notice the asymmetry, so the the lateral ventricle on this side is, is normal.

The other side is. Compressed likely from swelling of the brain. Infection can be another reason for intracranial surgery.

This is an example of a CT, dorsal planar reconstruction that demonstrates a region of hypo dense, hypo attenuating, tissue that very suggestive of a, of an abscess and indeed with surgery, it was purulent material was identified. So the benefits to surgery would be they allow us to decompress, which can result in fairly immediate response. It also allows us to remove perent material and lavage and finally the culture, which again can be helpful in.

Making treatment decisions. This is an example of the puppy, the CT that I showed you in the previous slide, and this is, relatively soon after surgery and noticed that the dog has responded very well to a simple decompression. Another indication for surgery would be a biopsy.

So this is an example and you can see the fungal hyphae in this H&E stain, but it also helps us to identify, you know, potential pathology such as autoimmune disease, neoplasia, or infections, particularly fungal infections. And so again, the, a biopsy would be the, the goal for diagnosis of the patient, such as this. And then the last area that we talk about is the need for surgery for congenital malformations and here we have a puppy that's just had ventricular perineal shunt placed and you can see the puppy is, is gradually acclimating to a change in the pressure, intracranial pressure.

So you notice from the MRI you can see this pretty marked, increase in, . The volume of the, the spinal fluid in the lateral ventricles. Another form of congenital malformation that is somewhat controversial as far as treatment would be decompression and and potential cranioplasty for dogs with caudal occipital malformation.

So here we see an MRI, a sagittal T2, that demonstrates both compression and herniation of the cerebellum, as well as a dorsal compression at C12 and the resulting syrinx that's. Likely all contributing to the signs of this dog, as you know from scratching. So when considering intracranial surgery, preoperative considerations to Think about and also discuss with the owner or it's very important to address, you know, what to expect with the owner because these these can be very involved cases you want to discuss with the owner, you know what to expect with this type of surgery and what potential complications such as behaviour changes or seizures or changes on one side as far as weakness, that type of thing.

I wanna talk about, you know, expectations for recovery, how long that might take, and. The unfortunate part of surgery, the, the potential for postoperative complications, morbidity such as, as pneumonia. So when considering surgery, we wanna talk about with the owner, you know, where is the lesion in the brain and so this is a diagram that demonstrates some of the regions of the brain that you might expect to see some deficits if surgery is performed in those areas.

For instance, the somatosensory cortex is important for changes in behaviour that you might see if if surgery is done in that particular location. So diagnostic considerations. So it's important to evaluate the animal's entire health or general health, so that we can avoid, you know, potentially doing surgery and then finding out that the dog had some other major medical problem, as a lot of these animals are, are relatively advanced in age.

Some basic diagnostic testing that's generally recommended would be complete blood chemistry and a complete blood count. In addition to thoracic radiographs and, and potentially abdominal ultrasound. Other diagnostics would depend on clinical suspicion.

So abdominal ultrasound can be helpful as mentioned a blood pressure, sometimes in serum insulin or glucose ratio, certain endocrine diseases, evidence of liver dysfunction, cerebrospinal fluid analysis can be helpful. This top frame demonstrates a dog with lymphoma. And that particular patient would not have responded well to surgery and then clotting times if there's any concern for the possibility that we could have An increased risk for bleeding.

So the key to diagnosis of intracranial lesions as, as you know, it is gonna be CT or MRI both of these diagnostic. Tools have limitations as well as advantages in the CT reconstruction you can see the skull fracture, one of the benefits to a CT. So again, I consider imaging really the most important diagnostic test whether that be CT or MRI and we perform diagnostic imaging again generally with, with the anaesthesia and it does allow us to make some educated guesses as to the type of lesion we may.

Have, this is an example of a T1 transverse image in a boxer and you notice that there's a contrast enhancing region in the area of the cerebellum. This dog has what we call a dural tail which is suggestive of a meningioma. So we have an idea prior to surgery, you know, that we may have a meningioma, and be able to give the, the owner a little bit more in the, the, way of prognosis prior to surgery.

And the CT characteristics, MR characteristics have been fairly well described for most types of common intracranial tumours, and again, as I mentioned, that dural tail is evident on the fox cerebra of this particular dog's MRI. So this dural tail sign again would be potential indication of a meningioma. CT is a more economical form of imaging and maybe more available .

It is used, it's it's a good screening tool for most intracranial masses. It identifies an estimate about 90% of brain tumours. You do have to be careful because you can miss small brain tumours, you can miss small tumours that are adjacent to bone.

Or in areas where there, there's artefact, particularly in the brain stem. You also miss tumours that don't contrast enhance, particular glial tumours. So CT again is, is helpful in, in many cases it's just.

Remember its limitations. It's very helpful in, in trauma and, and identifying bone pathology. MRI is really considered to be the best form of imaging for intracranial disease and in humans for tumour sensitivity, it's considered to have about a 99% sensitivity which makes it unlikely that you would miss pathology.

When interpreting these masses, we want to try to identify the tumour location. Is it an intraaxial mass, meaning is it in the prancuma of the brain? Which would indicate the potential for a glial type tumour for instance.

Or is it extra axial meaning originating from the. Covering of the brain or outside of the brain and pushing on the brain. So this is a CT example of a dog with a meningioma.

We also want to characterise the shape of the mass as well as, you know, is there contrast enhancement and the type of contrast enhancement. This particular dog and on this MRI has a ring enhancement that again is very suggestive of a glial type tumour. But be careful with imaging, here we have a dog that on transverse T1 and and sagittal T1 post contrast images has really homogeneously contrast enhancing mass.

In the frontal lobe, prefrontal and frontal lobes, and in most patients, this type of lesion is, is gonna be a meningioma. However, at the time of surgery and after evaluation of this tissue, it was determined this was actually a granulominous lesion and so this actually turned out to not be neoplastic, but rather, an immune-mediated type of disease. So again, be very careful in making assumptions.

Again, fairly common presentation in a large breed dog, I think a golden retriever. This dog had an exam forebrain mass that looked extra axial, meningioma being the most common, and so removal with potential radiation has a fairly long survival time with relatively low morbidity. Unfortunately, this dog's lesion.

Was histocytic sarcoma. And the histocytic sarcoma has a very poor prognosis, even despite Surgical removal and radiation. This is a CT that demonstrates recurrence of this particular mass in this dog a matter of a few months later.

So it's, it's important to again remember that imaging is not a a. A a definitive diagnosis. So another important concept that I use when.

Evaluating scans is I used them to help me identify, before surgery where a lesion is located. So for instance, the CT, you can see the temporal muscle in this particular dog begins, a little bit more laterally on on this particular skull and so that helps me to, to know that that's gonna be the area where I'm gonna wanna make my craniectomy. That helps to minimise your, your types of your trauma, and the, the size of the, the craniectomy you have to make.

So anaesthetic considerations are gonna be the next topic that we discussed. We're gonna talk a little bit about the drugs that are helpful for intracranial surgery as well as, intracranial pressure, the effect of both craniectomy and, and neurotomy on this, and what all of this means. So it's just in a very brief overview.

Remember, the Monroe Kelly doctrine states that the skull is rigid, that it doesn't expand, and so that's just important because normally we have 3 basic components that live within the skull, and those are the brain tissue, the brain pranum itself, the cerebrospinal fluid, and then the blood. And so when there are alterations in one of these contents, something will have to change. And so in a normal dog, the intracranial pressure is measured at about 5 to 12 millimetres of mercury.

And this is considered this is the pressure exerted by those tissues within the skull. So alterations in say a hematoma would cause an increase in intracranial pressure or tumour and this is an example of a dog who has a large mass in the thalamus, and you'll notice on this sagittal T2 weighted image, this dog actually has fairly marked herniation. Predominantly it's the trans foraminal herniation, so you notice the cerebellum is exiting the foramen and this is a result of that.

Rigid skull that doesn't allow for expansion and as you can see with the signal in the cord, this is a very devastating change in the, in the animal. Another thing to consider when when when performing anaesthesia. Is the cushing response.

And so the response to brain ischemia and increased intracranial pressure will be a systemic hypertension and generally and a bradycardia. So this is, an ECG taken from an actual patient and you notice that but the . Noticed that the heart rate's about 44, which is very unnerving for your nurse, during anaesthesia.

And so the, the temptation would be to use. And an anticholinergic such as glycopyrolate or atropine. However, we have to remember that this is a protective mechanism and so as long as your blood pressure is adequate, it's probably better to forgo giving those drugs until we've actually reduced intracranial pressure, which would, would be through the craniectomy and the neurotomy.

The derotomy in particular has been shown to be have the most impact on its cranial pressure. Ventilation for these patients is also essential, you really wanna have control over the ventilation during the entire process, so for that reason I would recommend a ventilator. The title volume would be set to somewhere around 10 to 7 to 10 millilitres per kilo.

Your respiratory rate's gonna be about 10 to 20. Peak airway pressures should always be less than 20 millimetres of mercury. We want to have moderate inspiratory times and we really don't wanna have positive and expiratory pressure.

Or excessive, I should say. Monitoring is essential in these patients. We want to maintain a a pulse oximetry, a pulse oxygen saturation of over 95%.

Generally we'll monitor entitle CO2 and the goal is to have slight hyperventilation, that number is gonna be somewhere around 35 is is ideal remember that entitled CO2 can underestimate the true PA CO2, . But again, it's a good, good indicator of, of where you wanna be with your ventilator. It's also important to keep in mind the blood pressure is, we want to maintain blood pressure to maintain cerebral perfusion pressure.

And we really don't want that pressure to drop below 70 or we run, we risk causing ischemia and additional damage to the patient. So, the main arterial blood blood pressure should really try to be maintained above 80 millimetres mercury. We have both direct and indirect methods of of monitoring blood pressure.

Direct methods with an arterial line are are gonna be most accurate. Sometimes that's not always practical in our indirect methods such as the Doppler are, would be the method that we use. So medications that we, we use, the resources I mentioned at the beginning of this discussion have very specific doses of these medications.

When I first think about treatment of a patient, I'm going to use drugs that are not something you might consider right away for anaesthesia, but very important considering the morbidity that we can experience with. This type of surgery and this type of disease. Cerenia or ripotent, is a drug that a substance pee inhibitor that would help with the nausea that, that can be associated with the medications that we use.

Ideally, it should be given at least an hour before induction or premedication to help prevent vomiting. Remember, aspiration is one of our largest or biggest complications of intracranial surgery and so anything we can do to protect that. I tend to use pantoprazole or a proton pump inhibitor, because of the, the potential to lessen the chance for gastric and GI alteration, both because the animals in the hospital, it's stressed, and we're generally using corticosteroids.

So again, the pre-medications I mentioned previously, the, the first two discussed, ideally, we wanna give a drug that would help with anxiety to minimise the stress on the patient and then . Benzodiazepine drug like midazolam really is a good drug for that. And then drugs such as fentanyl are gonna be helpful to help calm the patient and also drugs such as dexedatomidine have also been shown to have some helpful properties when used at low doses pre-medication.

Perioperative drugs or drugs that I'll use generally at the time of induction when we're starting the proceed or prepping the patient for the procedure. Generally if it's a tumour, I'm gonna use sodium or dexamethasone SP at a fairly low dose because again, the perittumoral edoema is gonna be impacted by the dexamethasone. And as much as we can do to reduce that pressure is the goal behind using that drug.

Cefazolin or, or some form of an antibiotic are generally recommended prior to induction and then generally bring 90 minutes to 2 hours during the procedure. And then Manitol, some people would use hypertonic saline, but Manitol is used, as an osmotic diuretic to help reduce intracranial. Pressure.

Induction agents, ideally either propofol or alfa alfaxolone can be used, I would probably avoid drugs such as ketamine in this particular instance as it may, increase in cranial pressure. At the time of induction. And then an inhalant anaesthesia would be used generally in combination with other drugs, typically either isofluorine or acevoflurane.

So drugs that are also used at intraoperative period would include fentanyl and and dexamedatomidine. These drugs would allow for a lower setting on the the inhalant. And maintain a more balanced anaesthesia.

So instrumentation. To consider, there are certain instruments we use that are very helpful in, particular for intracranial surgery that you may not use for other forms of neurosurgery or other forms of surgery. So probably the first thing to consider as a light source is very important to be able to identify pathology.

So a headlamp is is very helpful. Magnification is also important whether those are loops, as seen in this picture or an operating microscope. This will help us to maintain really good visualisation for these patients.

Retraction of tissues is also another very important consideration here, in these first two pictures, you notice this is what's called a Lone Star retractor. It's used in, in other soft tissue type surgeries but can be very helpful for certain types of intracranial surgery to remove or to, to retract the, the muscles that overlie the potential lesion. And then generally Gelpi retractors are are a mainstay of of.

Intracranial surgery and, and generally in, in dogs. So bone removal, couple options for bone removal, a high speed drill as you can see in these pictures is the. Instrument of choice for me.

I, I tend to use a haul air drill, but a cranioone would also be an option. So the the high speed burr you can make a burr hole and then generally use a smaller burr to complete the. The craniectomy.

Cranioome can be used. The problem with craniotomes is that you can see in this particular picture this is a dog that had head trauma. This is the underside of the skull.

And so you notice the undulations in the skull. And so the problem with the cranioome is that this hook can sometimes pierce the dura if the duras attached to the skull and so sometimes it's, it's. It's not necessarily the most efficient way to perform a craniectomy in dogs.

Other helpful instruments that you may not have used previously are both specific neurosurgery instruments which in this region you see these are penfield detectors that are used to dissect tumour tissue from normal brain forranoma. And then we also have our ophthalmic instruments, so Bishop Harman . Forceps which are in this particular case don't have teeth then we also have these Castroviejo scissors that both straight and angled are very helpful for cutting dura and small pieces of tissue.

This is an example of an intraoperative photo that demonstrates the use of a castro VA scissor, cutting a piece of dura in a craniectomy. Another instrument that's type of instrument that's particularly helpful is a lens loop, which are generally an ophthalmic instruments. Both the Lewis and the Wilder serrated lens loop I find very helpful for both dissecting tumour tissue from normal tissue and then following along a bone in order to remove, you know, tissue related tumour tissue.

So these are, these are particular instruments that I use very frequently with this surgery. So when the next step is to incise the dura as most tumours are intradural, we want to, we have a couple options with this, some people recommend a number 11 blade, some people recommend a number 12 blade, it just, I think somewhat surgeon preference. Some people use a bent needle and lift the dura and then incise it with scissors, .

Any of these are viable options that the picture of surgery here shows you a 12 blade that's being used to incise this particular dura. It's also important to note that prior to the dural incision we really want to make sure we've made. An adequate craniectomy.

It's not ideal to try to extend the neurotomy underneath the craniectomy and so always be sure to try to make your craniectomy as large as possible. Hemostasis is also really essential, adequate hemostasis for surgery in order to visualise tissues. Bipolar cautery is really a must if you're doing intracranial surgery.

Remember that the electric current passes through the tips of these of this hand piece and anything between there will be cauterised, . It spares the other tissues in the region and so it's, it's, it's a very safe way to cauterise tissues that are very close to her in neuralyma. Minimises the thermal damage that occurs.

Again, remember that the tips can't be together. They need to be at least 1 millimetre apart to actually be effective. I also want to remember that it's important to control bleeding prior to closure so that we don't develop a, a hematoma.

After surgery, there are various forms of other types of . Hemostasis that are available, you know, gelatin, denatured gelatin, patties made out of cotton, bone wax, depending on where the bleeding is originating are all useful tools and, and should be considered, available during these surgeries. So this is an example of bleeding of the deploic vessels, and so you'll notice that there is pretty substantial bleeding in this deployed vessel on this inner table of bone, and this is an example of using bone wax, and that's a very effective way to control that bleeding.

Prior to continuing the surgery. So, bone wax in this particular case is very helpful. This is an example of bleeding from a dural vessel that we're using bipolar cautery and I noticed the combination of the bipolar cautery with the suction is is a very useful tool.

For for that type of bleeding. So the best way to avoid. Bleeding is to anticipate bleeding.

This is an example of a neurotomy that was performed at the level of the middle meningeal artery and so as you can see the. Bleeding is excessive and so anticipation is, is your best tool however, if that, if you happen to damage that vessel, you you really need to not be afraid to use bipolar cautery and here you can see where. Cauterising that vessel, sometimes using some saline is also a nice way to identify the particular part of the bleeding.

So here again we're controlling this. And eventually we're able to get it to stop. And continue with the surgery.

There are also some other anatomical considerations for hemostasis which goes back to the idea of avoiding the problem before it occurs, the dorsal sagittal sinus is located. As it stated dorsally on top of the skull. And is something that we must keep in mind when when working on midline the transfer sinuses are located at the level of the tintorium therealley.

And it's important to know what can be occluded and what can't be occluded. So this is an example of a craniectomy that was done to remove an MLO multilobular osteochondroma, and the blue arrow is actually pointing to the dorsal sagittal sinus. The this is the actual brain.

Covered by the dura. So it's important to understand we really can't ligate the dorsal sagittal sinus after about a third from the cranial aspect or rotor aspect. This is at the level of the dorsal cerebral vein, so it's really important not to ligate or disrupt that caddle 2/3.

As this can lead to intractable intracranial swelling and unfortunately, death of the patient. Now there are times when this is disrupted over a slow period of time and that's not a problem, but again, be mindful that this is, this can be dangerous. It's also possible to ligate or disrupt a transverse sinus, but it's important to understand you can't ligate both transverse sinuses.

Again, this can lead to intractable intracranial pressure. So patient preparation. So once the patient has been induced, we want to make sure we have our adequate monitoring and then a liberal preparation of the surgical site is important.

Patient positioning is important. We want to maintain a position that's gonna lessen our chances for, increased intracranial pressure. We can use either towels as in these pictures or headstand, it's really surgeon preference and what you have available.

Ideally the head should be at a 30 degree elevation and we also wanna have our patients. On the table so that we limit any compression of either the jugular veins or the abdomen. Adequate lubrication of the eyes is really important to protect the corneas as we're working very close to the eyes.

It also keeps, it helps to keep some of the hair from the preparation as well as the cleaning agents out of the away from the corneas. And then finally we also generally we'll use a betaine or an iodine based scrub rather than a chlorhexidine type scrub for these patients and that's because it's, it's potentially less irritating to the corneas again again trying to avoid that as a as a potential complication. So on to surgery.

Some interoperative considerations that we wanna, consider. We wanna talk about, you know, how can we actually identify the pathology once we're in surgery and we have our, our, tissue exposed. What are we gonna do about the dura?

Do we need to close the dura or suture the dura? And then is this patient gonna require replacement of the skull or reconstruction of the skull? And these can all be planned prior to surgery.

So some general concepts that I find important or that the dura in dogs and cats is generally not replaced. We don't worry or seem to . Find that there's any type of leakage from or leakage that results in serious problems from the brain tissue.

At least it's not appreciated. So therefore we don't try to suture the dura in most patients, in cases where you're worried about, the potential for adhesions, gel foam or a biological type of dressing, could be placed over the. The brain tissue, this brain tissue will eventually develop op proliferation and within a few months, it, what's called a neodura will form and replace the dura.

This is a postoperative CT that demonstrates immediately after surgery, the, the air that that is in place after removal of the tumour. And then you'll notice that a few months later we have nice expansion of that underlying normal brain tissue and this is the goal. Post operative or what we would find after surgery.

So skull reconstruction, when do we reconstruct the skull? This is an example of a patient who had a, a fairly large ML. Molobular.

Sarcoma chondrosarcoma. And this is a dog in order to get complete margins that. We essentially had to remove the entire top of the skull.

And so by moving the of a dog to be and this was accomplished by in this particular dog placing a titanium mesh and this titanium mesh can be moulded to fit the craniotomy defect, and you'll notice in this lower image that we're using small screws to anchor to the skull. Another, probably more economical option is this is a CT. Reconstruction that demonstrates the use of methacrylate or acrylic, anchored with screws to again reconstruct the skull after a fairly radical removal.

Screws aren't always necessary as the the tissue itself can tend to hold the, the plate in place. It's, it's a matter of surgeon preference. So yeah.

Masses in surgery can be . Challenging. So when you bur it actually shows you the opening of the brain or that is placed directly in the opening of the brain, and you notice on this ultrasound image, this is the actual tumour and we can see some edoema surrounding that tumour.

So this can be a very nice tool to evaluate both where the tumour is located as well as the amount of resection and edoema that's developing from manipulation. Another recently described method for identifying abnormal tissue is the use of a contrast agent such as fluorescene. So fluoresine is injected IV, and it allows you to identify tissue based on the colour.

So this is prior to. Injection of the the fluoresce and then you'll notice this tissue in the region of the tumour has turned a fairly bright yellow. And that helps us to identify abnormal tissue.

For removal, the protocol that was described recently in veterinary surgery, is listed in, in this slide. And again, it's a similar concept to how contrast agents work for CT and MRI. The agent leaks out of abnormal blood vessels and stains the abnormal tissue.

This is a technique that's been used for quite some time in humans for retinal surgery, but it's also, useful for brain tumour resection. So there are protocols again that are listed and and described in these in this particular study but it's basically a protocol for an extra axial image and then an axial image as to when maximum staining occurs so the procedure, you know, is as listed below. A test dose ideally is given and then, the full dose is given at the time of surgery.

So this is the, the first part this is the conclusion of the first part of this discussion of intracranial surgery, some of both, you know, the indications as well as our diagnostic considerations prior to surgery as well as the planning that we might need. We wanna, we also discuss some of the anaesthetics that we may use, how we prepare our patient for the surgery, and then some of the more basic instruments that are used during the surgery. The second part of this discussion will discuss the the various approaches that are used as well as some of the aftercare that we consider for our patients.

Thank you for your attention.