Journal of Clinical Studies & Medical Case Reports Category: Medical Type: Case Series

Intraoperative Ultrasound Assistance in Endoscopic and Microsurgical Orbital Surgery: A Feasible, Real-Time Method to Guide Intra-Orbital Dissection

Giuseppe Maria Della Pepa1*, Mario Rigante2, Alberto Benato1, Quintino Giorgio D’Alessandris1, Liverana Lauretti1, Alessandro Olivi1 and Pier Paolo Mattogno1
1 Institute Of Neurosurgery, Fondazione Policlinico Agostino Gemelli IRCCS - Roma, Largo Agostino Gemelli, 8 00168 Rome, Italy
2 Institute Of Otolaryngology, Fondazione Policlinico Agostino Gemelli IRCCS, Rome, Italy

*Corresponding Author(s):
Giuseppe Maria Della Pepa
Institute Of Neurosurgery, Fondazione Policlinico Agostino Gemelli IRCCS - Roma, Largo Agostino Gemelli, 8 00168 Rome, Italy
Tel:0039 0630154408,
Fax:0039 0630154408
Email:giuseppemaria.dellapepa@policlinicogemelli.it

Received Date: Jan 13, 2023
Accepted Date: Jan 19, 2023
Published Date: Jan 23, 2023

Abstract

Background: The treatment of Intraorbital lesions (IOLs) can be difficult due to the numerous delicate salient structures in a small volume and the presence of intraconal adipose tissue that can obstruct the surgical vision and modify the anatomical relationships once herniated, making the precise location of IOLs rather complicated. Intraoperative ultrasound (iUS) is an immediate and simple tool that allows effective "real-time" control of lesions, useful for localization and for verification of total removal. 

Objective: The effectiveness of iUS in the surgical treatment of IOLs. Materials and Methods: This paper reports a case series of 5 patients affected by IOLs, treated with lesion removal surgery, 2 with endonasal endoscopic approach and 3 through craniotomy, according to the position of the lesion, using a trans-orbital ultrasound-assisted technique. 

Results: Of 5 treated patients, 3 were females and 2 males. Mean age at presentation was 60.4. Four cases resulted cavernous hemangiomas, whilst 1 case an optic sheat meningioma (WHO 1). Most common clinical presentation were visual deficits, proptosis, headaches and diplopia. The mean follow up was 20.2 months (6-30 months). Total removal of lesions, confirmed by intraoperative ultrasound and post-operative brain MRI exams, was achieved in all patients. No major complications were registered in perioperative period. Visual outcome resulted improved in 3/5 cases, stable in 2/5 cases. 

Conclusion: The iUS is a useful and effective tool in the surgical treatment of IOLs, both in endoscopic and craniotomy procedures. The technique allows "real-time" intraoperative navigation, which facilitates the surgeon in locating the lesion and verifying the total removal and the absence of perioperative complications.

Keywords

Endoscopic trans-sphenoidal approach; Intraoperative ultrasound; Intraorbital lesions; Real-time neuronavigation; Pterional craniotomy

Introduction

Intraorbital lesions (IOLs) represent a surgical challenge for the complexity of the anatomical area and the proximity of salient neurovascular and muscular structures in a relatively narrow surgical corridor. In particular, both in endoscopic and microsurgical transcranial approaches, orientation into the orbit can be challenging as orbital content dislocates after opening of periorbital membrane. Orientation is further complicated by the expansion of orbital fat after orbital wall decompression [1]. Hence, in fact, neuronavigation tools may result inaccurate and some real-time intraoperative imaging assistance prove useful to guide surgery [2]. Several surgical tools, including intraoperative ultrasonography (iUS), may be useful to potentially reduce surgical morbidity and ease surgical orientation throughout procedure. Orbital ultrasonography is a rapid and noninvasive test that is highly sensitive in displaying an orbital mass [3]; however its role in orbital pathology has been traditionally confined to the diagnostic stage and its use as an intraoperative tool has been investigated only in few seminal studies focused on endoscopic procedures. 

Herein the authors present a surgical series of endoscopic and microsurgical orbital surgeries for expansive lesions in which an innovative intraoperative real-time iUS assessment used to guide intraoperative strategy. Specifically, the technique provided a real-time vision of the intraorbital content throughout the procedure to correctly recognize lesion, identify and preserve anatomical neuro-vascular structures, as well as providing an ongoing evaluation of the extent of resection. Strength and strains of the method, in comparison with other intraoperative tools, are discussed.

Methods

Operative setting 

Patients undergoing surgical excision of intraorbital intraconal expansive lesions were evaluated with iUS in a real-time fashion while surgical resection progresses. 

The surgical field was examined with MyLabTwice, Esaote, Italy, a linear-array multifrequency 3-11 MHz device, using standard B-mode modality. The probe was covered with sterile ultrasound coupling gel and a sterile plastic sheet. In both transcranial and transnasal procedures the surgical field was prepared with the eye-bulb protected by the eyelid covered with sterile drape and easily accessible by the surgeons (Figures 1 and 2). The probe is gently placed on the eyelid and oriented with different angulations in order to explore the orbital cavity through a trans-ocular window.

Figure 1: Example of transorbital iUS in a transcranial microsurgical setting; (A) Preparation and draping of the surgical field. Fronto-temporal skin incision for pterional approach (double arrow) is sterilely draped as usual, along with the ipsilateral eye (protected by ocular gel, covered by eyelid firmed with standard paper-tape, single arrow) that is sterilely draped as well. (B-C) Surgery in preformed without diverging from standard procedure. Once orbital space and periorbita is opened second operator holds the US probe on the eye while the operator reaches the lesion. Surgeon instruments approaching the lesion can be controlled under US guidance. (D) Surgical microscope and retractors can be used as usual US check can be repeated throughout the procedure in order to evaluate anatomy and completeness of resection.

Figure 2: Example of transorbital iUS in a transnasal endoscopic setting; (A) Preparation and draping of the surgical field. Patient is positioned as usual and nostrils (double arrow) along with the eye ipsilateral to the lesion (the eye is protected by ocular gel, covered by eyelid firmed with standard paper-tape, single arrow) that is sterilely draped as well. (B-C-D) Transnasal endoscopic surgery in preformed without diverging from standard procedure. Once orbital space and periorbita is opened second operator holds the US probe on the eye while instruments approaching the lesion can be controlled under US guidance.

All transcranial surgeries were performed though a pterional approach under Leica M720 OH5 (Leica Microsystems, Wetzlar, Germany) microscope. Transnasal endoscopic procedures were performed with 4-hand surgical technique, in collaboration with the ENT surgeons, using the UHD endoscopy system (Visera 4K UHD, Olympus, Tokyo, Japan) equipped with a 4-mm 0-degree and 30-degree endoscopes (Carl Zeiss, Oberkochen, Germany). 

Choice of surgical approach was established according lesion position within the orbital cavity, and considering the dislocation of neurovascular orbital content. If lesion was extending in the supero-lateral orbital compartment, a transcranial approach with pterional craniotomy and opening of the roof of the orbit was chosen, whilst for lesions extending to the infero-medial orbital compartment. An endoscopic transnasal approach was the preferred option, performing an ipsilateral middle turbinectomy and ethmoidectomy including uncinated process and bulla ethmoidalis, exposing and opening the lamina papyracea and periorbital membrane between rectus medialis and inferior rectus muscles. 

Our iUS protocol included multiple B-mode scans prior to, during, and after orbital dissection. 

The surgical protocol can be schematically summarized as follows: 

Preliminary Evaluation (Figure 3). 

The surgical field is examined with ultrasound before orbital cavity is accessed. Pre-dissection information provides the baseline characteristics to be used as reference to further evaluations at different stages. In addition, at this stage the best insonation parameters are established.

Figure 3: Example of a pictorial case of an intraorbital cavernoma; the MRI (left) is sided to the iUS images (right) for reference. The iUS allows to clearly depicting intraorbital anatomy in relationship with the lesion (*). Extraocular muscles (single arrow) as well as dislocated optic nerve (double arrow) can be easily identified.

This preliminary evaluation allows assessing: 

Echogenic characteristics of the lesion. 

Anatomical relationship of with surrounding structures such as optic nerve, eyeball, extraocular muscles. 

Eventual integration with Color Doppler information about tumor vascularization.

Intraoperative Evaluation (Figure 4). 

During the dissection, the orbital cavity is scanned in order to: 

Evaluate anatomical modification of orbital contents during the surgical manipulation. 

Identify the surgical instruments that can be used as a ‘guide’ to the lesion: their metallic components can be easily identified and led to the lesion edge. A slight pressure on the lesion under iUS control confirms that instrument is effectively touching the lesion (this is especially useful for deeply located lesions when orbital fat completely fulfils vision). 

During this stage, the scan can be continuous (with 2nd operator holding the probe) or repeated intermittently as many times as needed.

Figure 4: frame line showing the metallic tip of surgical instrument (arrow) approaching the lesion (*). The iUS guidance provider real-time imaging to guide surgeon.

Final Evaluation (Figure 5). 

After lesion removal, the orbital content is scanned in order to assess: 

Extent of resection and absence of lesion’s residuals eventually hidden by orbital fat. 

Anatomical integrity of relevant anatomical structures and absence of intraobital complications such as bleeding.

Figure 5: iUS control after resection; the MRI (left) is sided to the iUS images (right) for reference. The iUS shows completeness of resection of the lesion, along with decompression and re-alignment of the optic nerve (double arrow). Extraocular muscles can be identified (single arrow).

Data Collection 

Demographical characteristics of the patients, histopathology, preoperative lesion features and localization, clinical onset outcome and complications were registered.

Results

Between June 2019 and February 2020, 5 patients with IOLs came to our Institution and they were treated with the abovementioned intraoperative US protocol. Main characteristics of the clinical series are summarized in (Table 1). 3 patients were Female and 2 male. Mean age at presentation was 60.4 (46-72). 

Four cases were histologically confirmed as cavernous hemangiomas, whilst one case resulted optic sheat meningioma (WHO grade 1). Most common clinical presentation were visual deficits (3/5), proptosis (3/5), headaches (2/5) and diplopia (1/5). Three cases (60%) were approached with a transcranial microsurgical procedure and two (40%) through an endoscopic transnasal approach. 

In all treated cases, a post-operative brain MRI with gadolinium confirmed the complete resection of the intraorbital lesion. No major complications were reported. The follow up varies from 6 to 30 months (20.2 months, mean range) in the most recent case. No adverse events related to the iUS exploration was recorded in the series. 

Pts

Age/sex

Disease

Clinical symptoms

Treatment

Lesion Removal

Visual Outcome

Follow up

1

51/m

Intraconal cavernous haemangioma

diplopia, visual field/acuity deficit

ETA

Total

improved

6

2

56/f

Intraconal cavernous haemangioma

Proptosis, Headaches

ETA

Total

stable

17

3

68/m

Optic sheat meningioma

Proptosis, visual acuity deficit

TCA

Total

improved

26

4

46/f

Intraconal cavernous haemangioma

visual field/acuity deficit

TCA

Total

improved

30

5

72/f

Intraconal cavernous haemangioma

Headaches, Proptosis

TCA

Total

stable

22

Table 1: Characteristics of patients treated for IOLs with endoscopic trans-sphenoidal approach (ETA) and transcranial approach (TCA) with the assistance of intraoperatory ultrasound (iUS).

Discussion

Orbital lesions necessitating surgical intervention can be challenging in view of the restricted space available to the surgeon and because of the the intraorbital content, especially intraorbital fat, tends to expand when surgeon accesses the orbital cavity, obstructing surgical vision [4]. Various specialists have been traditionally involved in the surgery of the orbit - ophthalmologists, maxillofacial surgeons, plastic surgeons, otorhinolaryngologists and neurosurgeons. The neurosurgeon generally deals with lesions of the posterior orbit or skull base pathologies that secondarily involve the orbit. However, many orbital lesions, irrespective of their situation in the orbit, are being increasingly referred to the neurosurgeons for surgical management. It is paramount that the surgeon is intimately familiar with the microsurgical anatomy of the area before venturing into this rather complex region, and actually orbital surgery represents a challenge in experienced hands [5]. 

Many routes have been described for the excision of intraorbital expansive lesions, and include both different microsurgical transcranial and transorbital approaches and, more recently, with the introduction of the expanded endonasal corridors, the endoscopic technique has also gradually gained high acceptance among the neurosurgeons [5-7]. 

Besides the surgical technique, orientation can be complex [8]. In fact, once the orbital content has been exposed, its relatively packed adipose content tends to expand thus displacing the orbital content itself [4-6]. Given the complex anatomy of the orbit, correct orientation and precise identification of relevant anatomy is of outmost importance to mimize risk of inadvertent damages and neuro-ophthalmological sequelae. 

Furthermore, in some cases orbital fat hinders anatomical and pathological structures fulfilling the working channel, making 'blind' maneuvers often necessary to identify the relevant pathological or normal neural, muscular and vascular structures. Moreover, given the abovementioned strains, the correct evaluation of the extent of resection can be difficult. 

Because of these peculiar characteristic of orbital anatomy, classic neuro-navigation techniques may often prove imprecise and inadequate in guiding the surgeon's action, as these rely on preoperatively acquired parameters. In this perspective, intraoperative imaging techniques are often helpful in minimizing these problems thus facilitating orientation, evaluate surgery progress and correctly establish the extent of resection. Besides their undisputed value, intraoperative CT scan or MRI have several limitations, including costs, temporary stop of surgical procedure and time waste. These important strains make these hardly repeatable during surgery [9]. 

Conversely, as demonstrated by several experiences in other neurosurgical settings, iUS is a feasible intraoperative imaging technique, as it is readily repeatable, dynamic, and inexpensive and provides a truly real-time dynamic visualization of anatomical characteristics and vascular patterns [10-13]. The study of IOLs can be effectively carried out using ultrasonography, which is a rapid and noninvasive method, which has a high sensitivity (>90%) in the identification and localization of orbital masses as shown by some experiences in a diagnostic setting [3]. 

Intraoperatively US assessment is immediate, feasible, and reliable and can be performed any time during surgery. As mentioned before, it is not dependent from brain/orbital shift as US exploration is a truly real-time technique. Above all, it does not significantly modify or interrupt the normal surgical workflow. 

On the heels of several experiencers in both oncological and vascular neurosurgery [10-16] in our series we applied the iUS guidance to assist surgery for expansive intraconal lesions both microsurgical and endoscopic procedures. 

In the herein presented series, the US probe was placed directly on the eyeball and images were recorded throughout the procedure exploiting the transocular window. This allowed a relatively straightforward: 

Identification of relevant anatomical structures, such as optic nerve and extraocular muscles, and how their position varies during surgical manipulation. 

Real-time guidance of surgeon instrument position, allowing the correct identification of the pathology. 

Verify the completeness of resection and presence of eventual residuals hidden by the orbital content. 

Compared to standard navigation devices, iUS is independent from brain shift and this grants useful information to surgeons throughout the procedure also in advanced phases of resection, as iUS does not rely on preoperatively acquired images. Moreover, iUS is capable of showing unexposed, hidden, anatomical characteristics: this is particularly effective in orbital surgery where, despite the approach chosen, orbital fat fulfills the working channel. This is especially true in advanced phases of resection, when orbital content is dislocated and orbital fat exits the orbital cavity, hindering the relevant anatomy or when non-orthogonal working corridors further complicate orientation and surgical exposition. This relate-time assessment, in our limited series, definitely proved useful in minimizing unnecessary ‘blind’ surgical exposition and manipulation. 

Even if limited, our experience confirmed the general applicability of iUS guidance also to orbital neurosurgery: it is a reliable instrument in experienced hands, as it provided a good definition of tumoral margins and its relationship with the delicate intraorbital structures. Surgical metallic instrument tip is easily seen on iUS images and guided to the lesion under US guide. This surely minimizes unnecessary manipulation and exposition that can definitely lead to morbidity. Above all, compared to more evolved intraoperative images techniques, such as intraperatory CT or MRI, it is a truly real-time technique as it can be repeated as many times as necessary, without interrupting or modifying the normal surgical flow. In addition, it is relatively unexpansive, as iUS devices are relatively diffused also in low-income neurosurgical operating rooms and, above all safe. The only shrewdness to be mentioned is a different draping of the surgical field: in both transcranial and endoscopic Tran’s nasal procedures, the eye protected by the eyelid has to be sterilely draped and kept easily reachable by the surgeon. Once the surgical field is prepared, the US probe is gently rested on the eyelid. From the ocular bulb window, orienting the probe with different angles, the orbital cavity can be easily explored. 

However, it should be mentioned that iUS imaging could be unfamiliar to neurosurgeons; hence, the interpretation of the dynamic modifications throughout surgery is not always straightforward. The procedure is operator dependent and the scanning visualizes only a portional plan of the lesion at a time. Imaging interpretation and correct machine setting requires a learning curve.

Conclusion

Surgical treatment of IOLs can be complex and requires a mandatory knowledge of the salient surgical anatomy for orientation, in order to perform safe procedures, both for craniotomic and endoscopic approaches. iUS fills the limits of conventional navigation in this district, providing a feasible and rapid intraoperative imaging useful for the localization and removal of orbital masses, allowing to real-time identify relevant anatomy, predict complications and detect inadvertent residuals.

Declarations of interest

None

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Citation: Della Pepa GM, Rigante M, Benato A, D’Alessandris QG, Lauretti L, et al. (2023) Intraoperative Ultrasound Assistance in Endoscopic and Microsurgical Orbital Surgery: A Feasible, Real-Time Method to Guide Intra-Orbital Dissection. J Clin Stud Med Case Rep 10: 0148.

Copyright: © 2023  Giuseppe Maria Della Pepa, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


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