Neurosurgical Approach – Pterygopoint Approach Explanation 1. Scope of application: (1) ipsilateral and contralateral anterior cranial fossa; (2) ipsilateral orbital region; (3) saddle region, paracranial, cavernous sinus, slope and posterior slope region; (4) ipsilateral middle cranial fossa and medial base of temporal region; (5) entire Willis ring, including ipsilateral MCA region, ICA, PcoA, AcoA, AchoA, A1, A2 proximal, basal distal, P1 , SCA, P2 proximal and contralateral ICA, A1, ICA bifurcation, M1 proximal, and the ophthalmic artery portion of the sheath. 2.Position: The patient is positioned supine with the head tilted 30 degrees to the contralateral side with the neck extended downward so that the zygomatic arch is located at the highest point. 3, Skin incision: The soft tissue anatomy at the pterygoid point is more complex than at other cranial caps due to the temporalis muscle and fascia. The capitellar tendon membrane covers the entire area and has the superficial temporal artery located in its outer layer of subcutaneous tissue. The capitellar tendon membrane first separates between the connective tissue of the vegetative pine, the deep periosteum and the superficial fascia of the temporalis muscle to within 4 cm of the orbital rim, until the rest of the connective tissue attachment forms a plane covering the anterior quarter of the temporalis muscle. Deep in the capitellum is a layer of loose connective tissue covering the periosteum and superficial temporalis fascia, which is approximately 1 mm thick on the surface of the periosteum and only 0.5 mm on the surface of the superficial temporalis fascia. The skin and capitellum form the outer flap, and the periosteum and superficial temporalis fascia and temporalis muscle serve as the inner flap, and this layer can be used as a graft source when closing the dura mater. 4, muscle stripping: It is now recognized that free bone flap is the best, according to which the retraction method of the temporalis muscle has been studied, the ideal is to retract the temporalis muscle to open the cranial site without damaging the temporal branch of the facial nerve (innervated frontalis), separating from under the capitellar tendon membrane and reflexing the temporalis muscle and fascia at intervals has a 30% chance of damaging the temporal branch of the facial nerve. The first quarter of the superficial temporalis fascia separates to form two overlapping fascial layers, the superficial layer (upper layer) containing only fat, temporal branches of the facial nerve, and large temporal veins, and the deep layer (lower layer) covering the temporalis muscle containing the deep temporal artery and veins, the deep and superficial layers of the superficial temporalis fascia are connected in an arch at the front of the temporal line, and a thinner layer under the superficial temporalis fascia covers the entire temporalis muscle, maintaining the shape of the temporalis muscle regardless of where it is cut. The deep temporalis fascia lies beneath the temporalis muscle and is thin, separating the temporalis muscle from the skull below. The planes separating the two layers of the superficial temporalis fascia can be identified by the presence of a small amount of fat exposure. The upper layer is incised at its arch, from where it joins the infratemporal line to where it joins the zygomatic arch and separates from the lower layer, reflexed along the skin and connective tissue gap, which protects the frontal branch of the facial nerve in the superficial layer. The separation is made to the point of attachment of the superficial temporal fascia on the lateral surface of the zygomatic arch and frontal zygomatic process. At the end of the separation, the sickle-shaped anterior quarter of the temporalis muscle can be seen to be covered by the inferior layer of fascia and varying amounts of fat. The inferior layer of the temporalis fascia is incised at its attachment point on the medial aspect of the zygomatic arch and frontal zygomatic process, and the adjacent periosteum and deep temporalis fascia are also incised beginning close to the medial aspect of the frontal zygomatic process, before being incised along the semicircular temporal line, a few centimeters past the coronal suture and close to the edge of the flap. The frontal periosteum is incised, forming a triangular flap turned toward the orbit, and the periosteal-temporalis flap is turned toward the temporal fossa. The temporalis muscle and its attached fascia are stripped first from the temporal line and then downward from most of the temporal fossa, terminating at the level of the zygomatic arch parallel to the base of the middle cranial fossa. The temporalis muscle and its fascia are turned in a posterior-inferior direction along its tendon attachment point, and most of the temporal fossa is removed to expose the pterygoid point and most of the temporal scales, pterygoid crest, and zygomatic bone, plus some of the frontal and parietal bones that extend into this fossa. 5.Craniotomy: A total of four holes are made to form a diamond-shaped free bone flap. First hole: directly above the frontal zygomatic suture in the temporal line. The second hole (frontal hole): 2 cm above the orbital rim, outside the frontal sinus. Third foramen (parietal foramen): directly behind the coronal suture on the temporal line. The fourth foramen (temporal foramen): the squamous part of the temporal bone, behind the pterygoid suture. When the bone flap is well positioned, the outermost part of the pterygoid crest should be seen on its inner surface, separating the pterygoid crest from the dural adhesions and biting the pterygoid crest to the level of the flat skull base. 6.Dural cut: semicircle around the lateral fissure vein is cut and bowed toward the pterygoid crest and orbit, the temporal end of the dural cut is protected with suture suspension to prevent the dura from peeling off in the middle cranial fossa under the bone edge, the dural flap is suspended toward the pterygoid crest and orbit, at this time, it should be possible to view the brain base structure from the skull base along the pterygoid crest. Once the brain tissue is relaxed, the frontal lobe can be retracted to gain access to the carotid, optic cross and endplate pools to release cerebrospinal fluid to expand the surgical space. In a small number of patients, these operations do not release more cerebrospinal fluid, and the contralateral and interpeduncular pools need to be opened to obtain appropriate decompression, and the endplate pool can be opened to release cerebrospinal fluid from the three ventricles. However, it is only used when the above operation fails or when the basal pool is obstructed by the tumor. The arachnoid membrane is sometimes thin and transparent, sometimes thickened, and no matter how it is separated, avoiding damage to the lateral fissure vein is the basic principle. The arachnoid of the lateral fissure should be opened on the frontal side of the vein so that it does not cross the vein when the frontal lobe is retracted. Occasionally, two or three branches of the orbitofrontal vein cross the lateral fissure into the middle cerebral vein and need to be sacrificed during complete separation. Once the arachnoid is separated, the frontal lobe can be retracted. There is a 2-3 mm space between the frontal and temporal lobe surfaces, which allows easy access to the lateral fissure and identification of the middle cerebral artery. Sometimes there may be adhesions between the arachnoid and soft meninges on the frontal and temporal lobe surfaces, but they can be easily separated after entering the lateral fissure by a few millimeters. The arachnoid plane over the lateral fissure opens at a convenient point about 8 to 10 mm, usually at the level of the triangle of the inferior frontal gyrus. Once the lateral fissure is entered, the separation should continue to the arterial trunk consisting of the middle cerebral artery branches, while the rest of the proximal lateral fissure opens inward toward the surface, following the arterial plane forward and back to the point of entry, and continues to the superficial level until the arachnoid and the lateral fissure vein are separated on the frontal side of the lateral fissure vein and the proximal lateral fissure to the middle cerebral artery bifurcation is revealed. Occasionally, the frontal and temporal lobes are tightly linked up to the level of the middle cerebral artery, in which case opening the lateral fissure is very difficult and may cause damage to the frontal or temporal lobe surface, in which case the proximal end is located along the cortical artery as far as the M1 segment. The next step in widening the space is to incise the arachnoid cords and bands that anchor the frontal lobe to the anterior cranial fossa, temporal pole, and optic cross dura. These structures can be identified and incised by gently pulling upward on the lateral orbitofrontal gyrus. However, care must be taken when performing this procedure, as occasionally the dural artery will originate directly from the ICA or A1 segment and may be inappropriately cut or pulled at its origin. The optic cross pools on both sides of the optic nerve are opened, then the endplate pool on the optic cross and the olfactory pool below, and finally, the contralateral carotid pool and into the contralateral lateral fissure, where the displaced and elongated olfactory nerve can be separated forward along the olfactory sulcus to avoid pulling off. After the above separation is completed, the frontal and temporal lobes separate and leave the pterygoid crest and orbital roof, expanding the apex of the conical space. In conjunction with the aforementioned opening of the carotid and endplate pools bilaterally, the interpeduncular pool, smoothing of the pterygoid crest and orbital apex to expand the base, and the superior and inferior margins to divide the frontal and temporal insula, a larger space is created, revealing the entire MCA branch, M1 segment and branch and Willis ring. These exposures demonstrate the value of the pterygoid approach, as there is minimal or no cerebral traction through this approach. The trans-lateral fissure approach provides a tapered entrance to the dorsal and medial basal aspects of the temporal lobe, the frontal floor area, the paracavalculo-cavernous sinus, and the paracentral region of the optic chiasm, and sometimes the anterior bed processes are removed or smoothed to reveal tumors in the posterior saddle, slope, and anterior pontine pools. How to protect the supraorbital nerve and facial nerve? The temporal branch of the facial nerve and the zygomatic branch of the facial nerve, after the parotid gland, both cross the surface of the zygomatic arch subcutaneously and anteriorly, and travel within the thin layer of fat between the capillary tendon membrane and the superficial layer of the temporalis fascia, and the branches of the temporal branch can travel between the superficial and deep layers of the temporalis fascia. The temporal branch is 10-15 mm from the ear screen in front of the upper edge of the parotid gland, crosses the superficial surface of the posterior part of the zygomatic arch under the skin, and distributes upward to the ear, frontal muscles and the upper part of the orbicularis oculi. The superior zygomatic branch is thin and crosses the surface of the zygomatic bone to the orbicularis oculi of the upper and lower lids through the middle 1/3 of the line between the foot of the ear and the external canthus; the posterior branch is thicker and runs along the average 1.3 mm below the zygomatic arch and forward to the deep surface of the zygomaticus muscle and the superior labial square muscle. The supraorbital vessels and nerves, the terminal branch of the frontal nerve, are located in the orbit with the supraorbital artery and exit the orbit through the supraorbital foramen or supraorbital notch, and are responsible for the sensation of the frontal skin. The long frontotemporal scalp incision starts from the lower edge of the earlobe under the ipsilateral zygomatic arch, after the temporal branch of the facial nerve and the zygomatic expenditures of the parotid gland, crosses the middle and anterior l/3 of the zygomatic arch subcutaneously, and proceeds in the subcutaneous tissue on the superficial surface of the temporalis fascia. Therefore, the temporal flap incision should be as close to the ear screen as possible to avoid damaging the nerve and leaving a postoperative wrinkled forehead that cannot be. If the flap is removed from between the capitellum and the superficial layer of the temporalis fascia, it can be complicated by frontal muscle paralysis. We found that: it is also possible to separate between the superficial and deep layers of the temporalis fascia from the temporal incision. If the superficial layer of the temporalis fascia is cut here as early as possible and separated along between the deep and superficial 2 layers, it is relatively safe to protect the facial nerve, but the degree of freeing is small and operationally difficult to a certain extent. When the supraorbital rim needs to be removed, care should be taken to protect the supraorbital nerve and vessels entering and leaving the orbit via the supraorbital foramen or supraorbital notch to avoid damage that may cause sensory disturbance of the frontal skin. This foramen or incision is 24.59 mm from the midline. Careful separation and identification of the supraorbital foramen or supraorbital notch is required during surgery. In the case of the supraorbital foramen, the inferior border bone can be abraded and the supraorbital nerve and vessels can be freed and protected, whereas in the case of the supraorbital notch, the nerve and vessels can be freed directly and protected. Pterygopoint approach craniotomy technique Classical pterygopoint approach craniotomy steps and requirements: 1. Position: supine with the shoulder on the sick side elevated 15 degrees, head turned 15-20 degrees to the healthy side and tilted back 10-15 degrees so that the frontal zygomatic process is at the highest point of the surgical center and the operator’s line of sight can look directly at the saddle side. The head is fixed with a Mayfield-Kess head frame. 2. Skin incision: cut the skin 1 cm before the ear screen on the zygomatic arch, the incision reaches upward to the temporal line, then turns forward in an arc, and continues the incision about 1 cm inside the hairline to the midline. The temporal incision pays attention to the superficial temporal fascia in two layers, containing a small amount of adipose tissue between the superficial and deep layers to protect the superficial temporal artery trunk. The skin incision and flap design can be situationally modified by turning the skin and capitellar fascia forward in its entirety. 3.Treatment of temporalis muscle: incise the temporalis muscle attachment along the frontal zygomatic process, separate 3-4 cm toward the distal end, incise the periosteum along the outer edge of the temporalis muscle attachment (0.5 cm ), and additionally incise the periosteum parallel along the base of the flap about 1 cm, with the two incisions of the frontal periosteum intersecting in a triangular shape and gradually separating to the orbital rim. The first hole of the bone flap and dural flap is above the zygomatic-frontal suture of the frontal bone, after the zygomatic prominence, the midpoint of the supraorbital margin of the second hole, and these two holes should be as close as possible to the skull base, after the coronal suture in the temporal line of the third hole, and the squamous part of the temporal bone of the fourth hole, as close as possible to the bottom of the middle cranial fossa, saw the skull, and remove the bone flap. The dura of the pterygoid crest is separated, and the pterygoid crest is occluded to reach the anterior bed prominence, and the decision to remove the anterior bed prominence is made depending on the situation. Drill 4-6 holes in the bone margin and suspend the dura with a thin wire. The dura is cut and turned toward the pterygoid crest. 5. Dissect the arachnoid pool to lift the frontal lobe, dissect the lateral fissure pool, open the internal carotid artery pool, endplate pool, optic cross pool, pedicle pool, interpedicle pool and other skull base arachnoid pools, release cerebrospinal fluid and gradually reveal the lesion. Advantages of pterygopoint approach for cerebral hemorrhage Using pterygopoint craniotomy or frontotemporal craniotomy with the lateral fissure as the midpoint, the lateral fissure is separated on the frontal lobe side to reveal the insula, and the avascular area between the branches of the middle cerebral artery on the surface of the insula is first punctured with a cerebral needle to confirm the hematoma, and then the insular cortex is incised with an incision of 0.5~1.0M, and the insula is separated with a narrow cerebral pressure plate to enter the hematoma cavity, and the hematoma is removed with a suction device. Compared with the traditional approach, there are obvious advantages: (1) The natural channel is used, which has little pull on the cortex and avoids damaging the normal cortex of the frontotemporal lobe. (2) The damage to the insula cortex is small, the insula can be exposed directly, the cortical incision is small, the bleeding site is easy to reach, and the operative field is well revealed. (3) Intraoperatively, the lateral fissure pool is opened first to release cerebrospinal fluid and release bleeding from the lateral fissure pool, which can improve brain swelling. (4) For cerebral hemorrhage caused by aneurysm, this approach is easy to reveal the aneurysm neck and clip the aneurysm. (5) The incidence of postoperative epilepsy is low. Pterygopoint craniotomy or frontotemporal craniotomy with the lateral fissure as the midpoint is used. The surgical incision and the size of the bone window should be selected according to the patient’s condition. If the patient is clear preoperatively or is old, a small straight incision with a small bone window can be chosen. If the preoperative midline shift is obvious or the onset of the disease is long from the surgery, and the cerebral edema is heavy, you can choose the pterygoid human incision and decompression by debridement; separate the lateral fissure on the frontal lobe side, and separate the lateral fissure vessels by longitudinal division and transverse division, that is, the vessels parallel to the longitudinal lateral fissure should be divided, and the vessels perpendicular to the lateral fissure should be cut after electrocoagulation, preferably with microscopic instruments, and the vessels should be separated near the frontal lobe side, and the vessels on the temporal lobe side should be preserved, from shallow to deep. It is recommended to use an automatic retractor until the insula is exposed. Sometimes, when the vein is bleeding from rupture, a small piece of gelatin sponge with cerebral cotton can be used to stop the bleeding, which is effective. After confirming the hematoma, the cortex of the insula is incised and the incision is 0.5-1.0 M. The insula is separated from the hematoma cavity with a narrow cerebral pressure plate and the hematoma is removed with a suction device. During the operation, special attention should be paid to protect the lateral fissure vein and the branches of the middle cerebral artery, and the operation should be performed under the microscope as much as possible. The hemostasis should be careful and thorough. For active bleeding branches of the middle artery, bipolar electrocoagulation can be used to stop the hemorrhage, and a small amount of bleeding in the deep part near the internal capsule can be stopped by hemostatic gauze; for small blood clots that have been tightly adhered to the hematoma wall, it is not advisable to remove them reluctantly to prevent greater damage to the surrounding brain tissue, and sometimes the pursuit of complete hematoma removal is often more than worth the loss. The white matter of the edema layer should be protected, and only the clot should be aspirated under direct vision rather than the white matter around the hematoma, especially for those with onset more than 24 h before surgery; when crossing this thin edema zone, extremely difficult to control bleeding will be encountered, resulting in rebleeding after surgery. As it is via the natural fissure human pathway, the brain tissue tension around the incision is often low during surgery, and generally no assistant is needed to help pull the brain tissue, so that one person can operate as much as possible, one holding the brain pressure plate to expose the hematoma cavity in order, and one holding the suction device to aspirate the hematoma, which can reduce the traction damage to the brain tissue, and the postoperative cerebral edema is mild. Notes: 1. Choose the right patient, the outer capsule in the basal ganglia hemorrhage, the shell nucleus site is best to do, the hematoma leans back as the inner capsule hind limb reveals some difficulties. 2. Separate at the root of the lateral fissure, separate the lateral fissure with a sense of direction, enter vertically, brain cotton protects the blood vessels on both sides. 3. Before entering the hematoma, it is best to puncture it first to determine where the hematoma is. 4. Lighting is most important after entering the hematoma. 5. Clear the hematoma It is better to turn off the suction device when clearing the hematoma, and it is much faster to clear it slowly than by strong suction.6. There are obvious advantages compared with the traditional approach; (1) the natural channel is used, the cortical traction is small, and the normal frontotemporal cortex is avoided. neck and clamping the aneurysm. (5) The incidence of postoperative epilepsy is low. The temporalis muscle is fan-shaped and located in the temporal fossa, starting from the temporal fossa of the skull, gradually concentrating downward and migrating into a strong muscle bond on the deep side of the zygomatic arch, ending at the rostral process and the anterior edge of the mandibular branch, whose superficial layers are skin, subcutaneous tissue, superficial temporal fascia, superficial deep temporal fascia, deep deep temporal fascia, and deep temporal fat pad in order, and whose deep layer is the cranial periosteum. The blood supply of the temporal muscle comes from the anterior deep temporal artery, the posterior deep temporal artery, the middle temporal artery emanating from the superficial temporal artery and the anastomosis between them, in which the posterior deep temporal artery is the main source of blood supply to the temporal muscle, emanating from the middle of the pterygoid segment of the maxillary artery or from the occlusal artery, entering the deep central surface of the temporal muscle, passing between the temporal scales and the deep temporal muscle to the middle and posterior parts of the temporal muscle, mainly supplying the middle of the temporal muscle; the superficial temporal artery crossing the zygomatic arch often emanates Middle temporal artery. It crosses the fascia and enters the temporalis muscle from below posteriorly, supplying the posterior part of the temporalis muscle. The integrity of temporalis muscle morphology depends on its blood supply, innervation, intact muscle fibers and moderate muscle tone, so the common causes of temporalis muscle atrophy are: (1) injury to temporalis muscle fibers: direct injury to the temporalis muscle mouth due to improper separation, excessive pulling, etc.1; (2) impaired blood supply to the temporalis muscle: blockage of the blood vessels supplying the temporalis muscle, resulting in muscle ischemia; (3) injury to the nerves innervating temporalis muscle movement; (4) failure to maintain moderate muscle tone during temporalis muscle repositioning. Adequate muscle tone was not maintained during temporal muscle repositioning. Retrograde separation of the temporalis muscle, i.e., peeling the temporalis muscle upward at an acute angle from the muscle attachment, is aimed at protecting the integrity of the temporalis muscle by preserving the integrity of the periosteum, avoiding damage to blood vessels and nerves, and making the peeling of the temporalis muscle easy. Since the deep temporal vessels and nerves travel in the deep layer of the temporal muscle and are closer to the periosteum, the separation of the temporal muscle should always be kept under the periosteum, which can ensure that the deep middle and anterior temporal nerves and arteries are not damaged and prevent the loss of innervation of the muscle.