Combined Exoscopic and Endoscopic Two-Step Keyhole Approach for Intracranial Meningiomas

Abstract

The advantages of neuroendoscopic surgery are the wide viewing angle and the freedom of an axis of view with minimal surgical trauma. With the advent of the exoscope, which has similar advantages to endoscopy, such as a small body and ergonomically superior heads-up surgery, it has become possible to add a field of view that is similar to that of microsurgery to endoscopic surgery. By taking advantage of the features of these scopes, we report the usefulness of the minimally invasive combined exoscopic and endoscopic two-step keyhole approach (EEKA) for various types of meningiomas. We reviewed data from 34 consecutive cases of EEKA for various types of intracranial meningiomas compared with that of conventional microsurgery. All of the tumors were resected as planned without severe complications. Significantly better outcome data were obtained in terms of the blood loss and the surgical time in the EEKA group, in addition to the craniotomy size. The well-illuminated fine vision in the deep corners by the endoscope enabled radical resection of the tumors with minimum burden on the patients. This technique has the potential for minimally invasive surgery in intracranial meningioma patients, including the older population.

Keywords: endoscope; exoscope; keyhole approach; meningioma.

Figure 1

(a) Intraoperative photo of the lateral suboccipital approach. The exoscope is being used in this moment, while the endoscope is placed on the scope table. (b) The scopist repositions the exoscope as appropriate to maintain the best field of view. Regardless of the movement of the scope, the surgeon can operate with a certain comfortable posture. The four additional processed exoscope photographs were created to represent its movement. (c) The layout of operation room. Sc: scopist, Su: surgeon, As: assistant.

Figure 1

(a) Intraoperative photo of the lateral suboccipital approach. The exoscope is being used in this moment, while the endoscope is placed on the scope table. (b) The scopist repositions the exoscope as appropriate to maintain the best field of view. Regardless of the movement of the scope, the surgeon can operate with a certain comfortable posture. The four additional processed exoscope photographs were created to represent its movement. (c) The layout of operation room. Sc: scopist, Su: surgeon, As: assistant.

Figure 2

Scheme of observation by exoscope as the first step (a), and by endoscope as the second step (b).

Figure 3

Photographs of the endoscopic keyhole approach and schemas showing the position relationship of the endoscope (E), suction (S), and tool (T). The craniotomy is represented by the blue line and the yellow circle indicates the field of view of the endoscope. The shaft of the endoscope is placed on the craniotomy edge, and delicate control is possible by touching it with a finger, similar to supporting a billiard cue.

Figure 4

Our surgical tools for EEKA. (a) Conventional microsurgical instruments and dissectors with a curved tip. (b) Thin and long malleable bipolar forceps (FUJITA Medical Instruments Co., Ltd., Tokyo, Japan). (c) Malleable dissectors (Mizuho Medical Co., Ltd., Tokyo, Japan).

Figure 5

An 83-year-old male patient complaining of left lower-limb weakness underwent endoscopic intratumoral decompression and detachment of the tumor from the falx 1 year prior, after which the symptoms improved; however, because of its rapid growth, total resection of the tumor was planned. (a,b) Preoperative contrast-enhanced T1-weighted images (CET1WI sagittal and coronal). (c) A 3D reconstructed image of enhanced MRI showing diploic veins and bridging veins. Since the diploic vein may be involved in cerebral perfusion, and there was also a large bridging vein just above the tumor, it was planned to remove the tumor of the parasagittal sinus from the frontal side under endoscopic observation. The craniotomy was designed to be 6 cm in length and 4 cm in width anterior to the bridging vein, with his head rotated 80° to the ipsilateral side and fixed as shown in (d). Dissection of strong adhesions to the brain and internal decompression were performed using an exoscope (g). The observation and dissection at the posterior site and parasagittal attachment were performed using an endoscope (h). (e,f) Postoperative CET1WI sagittal and coronal view showing gross total resection of the tumor.

Figure 6

A 60-year-old male patient who complained of gait disturbance due to compression of the brain stem. (a) Axial T2-weighted images showing a right petro-clival meningioma. (b,c) Postoperative 3D CT images presenting a curved skin incision and retro-mastoid craniotomy fixed by a titanium plate. In this case, where the combined petrosal approach or staged surgery would have been selected in conventional microsurgery to achieve maximum resection, the tumor was partially removed by a lateral suboccipital approach using an exoscope (e), and the tumor in the ambient cistern that compressed the midbrain was removed by endoscopic observation (f). (d) Postoperative axial T2-weighted images showing the tumor removed, except the part in the cavernous sinus, while the compression of the brain stem was released.