*4.1.1 Surgical technique*

Patient positioning and head rotation are identical to those for pterional craniotomy and depends on aneurysm location. For all transorbital approaches, a temporary tarsorrhaphy was necessarily performed with preliminary placement

#### **Figure 18.**

*Intraoperative photo. Schematic representation of the main anatomical landmarks of access. Bone borders are marked in black. The skin incision is marked in green. Branches of the superficial temporal artery are marked in red. Arrows: white - supraorbital nerve and artery, blue - frontal branch of the facial nerve.*

**Figure 19.**

*Intraoperative view, A, B – soft tissue incision along the eyebrow, C – subperiosteal dissection of the supraorbital region of the frontal bone, the edge of the orbit and the zygomatic process of the frontal bone.*

of an antiseptic gel subconjunctivally. A skin incision was made directly along the eyebrow, starting from the level of the pupillary line and continuing laterally within the eyebrow, sometimes extending several millimetres laterally. The supraorbital nerve and artery, the frontal branch of the facial nerve, and the superficial temporal artery are always preserved. The initial stage of incision and dissection of the frontalis muscle is identical to that in ESA, however, after transection of the frontalis muscle, careful skeletonization of the upper edge of the orbit was performed from the level of the supraorbital foramen to the fronto-zygomatic suture. Dissection of the contents of the orbit lateral to the fronto-zygomatic suture should be avoided due to the risk of damage to the lateral canthal ligament and impaired movement of the upper eyelid with the formation of a temporary or permanent diastasis when the eyelids is closed. During dissection, special attention was paid to the preservation of the periosteum and periorbital tissue. The temporal muscle was separated from its place of attachment at the level of the superior temporal line and brought down with a retractor towards the temporal fossa (**Figure 19**).

A single burr hole was made downward from the temporal line immediately above the level of the base of the anterior cranial fossa, at the key point. The transorbital approach included the roof of the orbit, a portion of the frontal bone, and approximately 1–1.5 cm of the zygomatic bone. A single bone flap was sawn out using a craniotome and a high-speed burr. The diameter of the bone window is approximately 25–30 mm. The first cut was made from the burr hole upwards in the supraorbital region, describing a C-shaped bend towards the upper wall of the orbit. From the side of the orbit, the contents of which are protected with a spatula, a cut was also made using a craniotome towards the line of the previous cut. In the area of the zygomatic process, sawing towards the key point can be carried out both with a craniotome and with an oscillating saw, using the protection of the contents of the orbit with a spatula. The roof of the orbit was broken using a chisel. After osteotomy, sharp edges were resected in the area of the upper wall of the orbit with a bur and wire cutters (**Figure 20**).

If necessary, extradural resection of the sphenoid bone and anterior clinoid process performed the degree of bony resection depends on the location and size of the aneurysm. All manipulations were performed through minimal craniotomy. Upon completion of the necessary resection of the bone structures, the dura mater was opened with a semi-oval incision with the base towards the orbit. Then, the surgical technique is dictated by the location and size of the aneurysm.

#### **Figure 20.**

*Planning and stages of ETA. A – the sequence of cuts (the arrow indicates the key hole from which the upper wall of the orbit is broken with a chisel), B – the burr hole is placed at the key point and the bone is cut away from the supraorbital hole towards the key point, C – view of the bone flap, D – performed transorbital access, frontal sinus opened.*

#### **Figure 21.**

*Intraoperative view. A - The bone flap is put in place and fixed with miniplates. B – CT craniography after minitransorbital craniotomy.*

Classical microsurgical technique is used. Wound closure is standard and has been described above (**Figure 21**).

## **4.2 Transpalpebral transorbital approach**

The transpalpebral approach, or access through the upper eyelid, is borrowed from ophthalmic and plastic surgery. Transpalpebral approach has been used in neurosurgical practice since 2008 and includes an incision along the natural crease of the upper eyelid followed by a minimal fronto-orbital craniotomy [16–18]. In fact, the TPTA trajectory is identical to the ESA and ETA and provides access to the anterior cranial fossa, the parasellar space.

The indications for TPTA are identical to those for ETA.

### *4.2.1 Anatomical access landmarks*

Knowledge of anatomy is an indispensable condition for ensuring the effectiveness and safety of surgical intervention. Anatomical landmarks are similar to ETA (**Figure 22**).

#### **Figure 22.**

*Intraoperative view. Schematic representation of the main anatomical landmarks of access. Bone borders are marked in black. Arrows: white - supraorbital nerve and artery, grey - circular muscle of the eye, black - lateral cantal ligament, red - temporalis muscle with branches of the frontal branch of the facial nerve.*

#### *4.2.2 Surgical technique*

The eyebrow and eyelid area are prepped with antiseptic solutions, an ophthalmic gel was applied subconjunctivally. Next, a temporary tarsorrhaphy was performed with a 5–0 thread. The planned incision area was infiltrated with an anaesthetic solution and a vasoconstrictor. The incision was made along the natural fold of the upper eyelid from the level of the supraorbital opening 3.5–4 cm long. If necessary, the incision can be extended laterally by several millimetres exclusively within the fold. The incision should start at least 10 mm above the upper edge of the eyelid and at least 5–6 mm above the projection of the lateral canthal ligament. Thus, the incision is planned below the supraorbital and frontotemporal branches of the facial nerve, which makes it possible to exclude negative cosmetic consequences associated with nerve damage. Initially, the incision was made through the skin and the orbicular muscle of the eye while maintaining the orbital septum. Damage to the orbicularis muscle must be minimized as the blood supply to the eyelid passes through the orbicularis muscle. A single musculoskeletal flap was formed, which ensures adequate healing. Dissection by the sharp way was carried out mainly in the upper and lateral direction. At this stage, the upper and lateral edges of the orbit were palpated for control. Next, a subperiosteal dissection of the supraorbital region, the upper lateral edge of the orbit, and the zygomatic process of the frontal bone was performed with visualization of the fronto-zygomatic suture. During dissection, special attention was paid to the preservation of the periosteum and periorbital tissue. The temporalis muscle was dissected by monopolar coagulation from the place of its attachment at the level of the superior temporal line. Limitation of muscle dissection, its dissection and devascularization eliminates the formation of a depression in this area.

A minimal orbitofrontal craniotomy included the roof of the orbit, a portion of the frontal bone, and approximately 1–1.5 cm of the frontal process of the zygomatic bone. A single bone flap was sawn out using a craniotome and a highspeed burr. The diameter of the bone defect was no more than 25–30 mm. After

*Keyhole Microsurgery for Cerebral Aneurysms DOI: http://dx.doi.org/10.5772/intechopen.110396*

#### **Figure 23.**

*Intraoperative view, A – soft tissue incision along the natural crease of the upper eyelid, B – mobilization of the upper wall of the orbit, C – dissection of a part of the temporal muscle over the area of application of the burr hole, D – burr hole is applied at a key point, E – propyl in the area of the frontal process of the zygomatic bones, above the fronto-zygomatic suture. E – cut in the region of the upper wall of the orbit, medial to the supraorbital notch, G – using a chisel, the upper wall of the orbit is broken, H – view after craniotomy, I – the dura mater is opened with the base to the orbit.*

craniotomy, the roof of the orbit was broken using a chisel. If necessary, extradural resection of the anterior clinoid process and decompression of the optic nerve canal were performed from this access. When opening the frontal sinus, the defect was closed according to the previously described principles. The dura mater was opened with a semi-oval incision with the base towards the orbit. Additionally, tension sutures were placed on the edges of the dura mater to increase the viewing angle and epidural hemostasis (**Figure 23**).

At the end of the intervention, the bone flap was fixed with miniplates. The wound was sutured in three layers: muscle, subcutaneous tissue and skin. The temporalis muscle can be fixed to miniplates or to holes formed in the area of the upper lateral wall of the orbit. The orbicular muscle of the eye was sutured with a 4–0 absorbable suture. An intradermal suture was applied using a 5–0 or 6–0 suture. Postoperative drainage was not used.

Clinical example of ophthalmic aneurysm clipping through ETA (**Figure 24**).

#### **Figure 24.**

*Clinical example of clipping of multiple ETA aneurysms. A –CT angiography, B- intraoperative view, position of the patient on the table, incision marking; C – view after opening the dura mater; D – intraoperative view after dissection and clipping of the ICA bifurcation aneurysm; ICA, E – dissection of the aneurysm (An) of the MCA bifurcation with visualization of the M1 and M2 branches of the MCA, G – view after clipping of the aneurysm, H – view of the patient 1 month after surgery, I, J – postoperative CT craniography with reconstruction, CT angiography.*

#### **Figure 25.**

*Clinical example. A – CT angiography, basilar artery aneurysm, B – Intraoperative view of planning a skin incision along the natural fold of the upper eyelid on the right, C – intraoperative view through the retrocarotid space: 1 – ICA, 2 – aneurysm, 3 – PCA P1 segment, D – view through the retrocarotid space: 1 – optic nerve, 2 - ICA, 3 - Aneurysm, 4 – posterior cerebral artery (PCA), P1 segment on the left, E - view through the endoscope 0°: 1 - PCA, 2 - Pecheron artery, C - clivus, 3n - oculomotor nerve, A - aneurysm, E – view through the 0° endoscope. After clipping: 1 - PCA, 2 – superior cerebellar artery, 3 - Pecheron artery, P - pons, G - control of CT angiography - a clip is visualized. H - during bone reconstruction, the volume of the craniotomy is visualized, I - is the view of the patient after 2 months.*

A 58-year-old woman with multiple unruptured aneurysm: ICA terminus and MCA artery aneurysms.

Clinical example of basilar bifurcation aneurysm clipping through TPTA (**Figure 25**). A 53-year-old woman unruptured basilar bifurcation artery aneurysm.
