Key-words:
Carotid endarterectomy - microscope - neurosurgery - ORBEYE
Introduction
The neurosurgery under an operating microscope was introduced in the 1960 by Yaşargil.[[1]] Moreover, vascular neurosurgery under operative microscope was first reported by
Spetzler et al. in 1986.[[2]] After the publication, microneurosurgery has become a gold standard procedure for
vascular neurosurgeons.[[3]] The microscope provides clear three-dimensional (3D) stereoscopic vision with high
magnification of the operative field which enables neurosurgeons a precise procedure
during dissection of vessels, neural structures, tumors, and brain tissue. However,
a state-of-art operative microscope has two major shortcomings: (1) The shallow depth
of field needs frequent repositioning of the microscope to the operative field.[[4]] (2) Operator's eyes are enforced to fix to the eyepieces of the microscope, leading
to their fatigue. For such reasons, longer depth of field and neurosurgeon-friendly
monitor system would be welcome to the operative microscope.
Carotid endarterectomy (CEA) is an established treatment for carotid stenosis. The
surgery can contribute better clinical outcome than optimal medical treatment for
not only symptomatic patients but also asymptomatic patients.[[5]],[[6]] One of the most crucial steps of this surgery is a manipulation of a distal end
of carotid plaque. After removal of the carotid plaque, a precise fixation of the
intima of the distal internal carotid artery (ICA) is required for the prevention
of postoperative acute occlusion or restenosis.[[3]] Microsurgical repair of the diseased artery allows the neurosurgeon to manipulate
elaborately. On the other hand, the shallow depth-of-field and narrow field-of-view
of the operative microscope compels neurosurgeons to reposition the microscope frequently
during the surgery, leading to the surgeon's fatigue. Thus, the microsurgical CEA
is sometimes hesitated.
An Exoscope, high-definition video telescope operating monitor system to perform microsurgery
has recently been proposed an alternative to the operating microscope.[[4]] This system enables the neurosurgeon to execute the operation by its high magnified
images on a high-definition display. The major advantages of the scope compared with
the operative microscope are the deep depth-of-field and wide field of view.[[4]],[[7]],[[8]] However, the system provides 2D views. Thus, the operators are required to develop
eye-hand coordination for microsurgical procedures with the usage of the system. This
is the major shortcoming of the Exoscope.
To overcome the weak points of the operative microscope and Exoscope listed above,
we innovated ultra-high definition 3D-surgical microscope system, ORBEYE™ Surgical
Microscope (OLYMPUS, Tokyo, Japan) for CEA. We report here our initial experience
of the system and its usefulness and future perspective in vascular neurosurgery.
Materials and Methods
Case presentation
A 66-year-old male with asymptomatic progressive left ICA stenosis was referred to
our hospital. His 3D-computed tomography angiography (3D-CTA) revealed left ICA severe
stenosis (NASCET 87%) [[Figure 1]]a. Neck magnetic resonance imaging study (MRI) revealed left ICA severe stenosis
due to high volume plaque, which was high intensity on T1-weighted and time of flight
images [[Figure 1]]b. His initial clinical diagnosis was asymptomatic progressive left ICA severe stenosis
with vulnerable plaque, and he was decided to undergo CEA. Written informed consent
for the surgery was obtained from him and his family, though separate consent for
using the ORBEYE™ Surgical Microscope was considered unnecessary because the microscope
was approved medical device in ordinary medical care.
Figure 1: Preoperative three-dimensional computed tomography angiography (a) and neck magnetic
resonance imaging study (b) revealed left internal carotid artery severe stenosis
due to high volume plaque. Postoperative three-dimensional computed tomography angiography
showed disappearance of left internal carotid artery stenosis (c)
Operative procedures
The ORBEYE™ surgical microscope was used in this surgery, with initial onsite support
by the manufacturer. Briefly, this system consists of two of the Sony's 4K (4096 ×
2160 pixels) Exmor R™ CMOS image sensors, providing a high-sensitivity, low noise,
and a wide color range image, which is displayed on a 55-inch monitor [[Figure 2]]a. The observers are allowed for active 3D vision with passive light 3D glasses
[[Figure 2]]b. The OPMI PENTERO operative microscope (Carl Zeiss AG, Jena, Germany) was prepared
as backup.
Figure 2: Operating room setup with the ORBEYE™ Surgical Microscope (a) and intraoperative
finding (b). The microscope coming from the surgeon's left-frontal side is held over
the surgical field resulting in no obstacle between the surgeon and the monitor. The
operator, the assistant and the entire operating staff using three-dimensional glasses
have the same view as the operator
The CEA was performed in the ordinal way as we described elsewhere.[[9]] The ORBEYE™ Surgical Microscope provided surgeons with an excellent surgical view
with good clarity, contrast, and color in 3D images. During the surgery, the operator
should adjust the position of the ORBEYE™ Surgical Microscope far less than the ordinal
binocular microscope due to its deeper depth-of-field. Moreover, the operator and
the assistant could perform the surgery in an agreeable posture throughout the surgery
which was provided by its ergonomic design.
The surgery was successfully completed in a skin-to-skin manner using the ORBEYE™
surgical microscope without switching to the OPMI PENTERO. The operation time was
3 hours and 4 minutes, and total intraoperative bleeding was 28 ml.
Postoperative course
The patient's postoperative course was uneventful. His postoperative imaging studies
demonstrated no ischemic lesion of diffusion-weighted image on MRI and good patency
and disappearance of the stenosis of right ICA on 3D-CTA [[Figure 1]]c. He discharged home on the 8th postoperative day.
Discussion
In our experience, the ORBEYE™ Surgical Microscope is a progressive optical tool with
clear advantages over the surgical microscope or 2D Exoscopes in terms of its high-resolution
3D surgical images and ergonomics.
CEA under operative microsurgery was first reported by Spetzler et al. in 1986[[2]] and microneurosurgery has become a gold standard procedure for vascular neurosurgeons
thereafter.[[3]] The microscope produces highly-magnified stereoscopic images while providing highly-detailed
surgical views. On the other hand, a state-of-art operative microscope has two major
shortcomings: (1) The shallow depth of field needs frequent repositioning of the microscope
to the operative field.[[4]] (2) Operators' eyes are enforced to fix to the eyepieces of the scope, leading
to their fatigue. The less ergonomics may become an inconvenience for surgeons when
they perform relatively look-up surgery in awkward arm-extension posture, i.e., manipulation
of the distal end of the atheromatous plaque in CEA [[Figure 3]]a.[[9]] Thus, longer depth of field and more neurosurgeon-friendly operating monitor system
would be welcome.
Figure 3: Schematic representations of operator's posture in awkward scope angle under the
binocular surgical microscope (a) and the ORBEYE Surgical Microscope (b). Note the
difference in the arm angle
An Exoscope, high-definition video telescope operating monitor system to perform microneurosurgery
has been proposed an alternative to the operating microscope.[[4]],[[10]],[[11]] It provides surgeons with high-quality surgical image with adequate magnification.
The major advantages of the Exoscope are its wide field-of-view and long depth-of-field
in comparison with the operative microscope.[[4]] Moreover, the Exoscope provides ergonomic advantage by separating the surgeons
from the eye pieces of the microscope and displaying the operative image ahead of
the surgeons on a high-definition monitor.[[10]] The separating prevents the surgeons to be enforced keeping discomfortable positions
at awkward angles. On the other hand, early Exoscope provides only 2D views, becoming
the major shortcoming of the Exoscope, lack of stereoscopy of depth perception. Thus,
stereopsis was required to improve hand-eye coordination for microsurgical procedures
with the usage of the Exoscope, such as taking hold the needle and stitch up when
suturing arteriotomy in case of CEA.[[4]]
A newly developed the ORBEYE™ surgical microscope, which is a kind of Exoscope, was
launched in the united states and Japan on October 5, 2017.[[12]],[[13]] This microscope offers 4K ultra-high-definition, 3D imaging for surgeons. They
can operate while observing surgical field images on a 55-inch 4K monitor with special
3D light glasses. The system allows the operator and assistant to perform procedures
in their comfortable position without fixing their gaze to eyepieces, leading a reduction
in their fatigue [[Figure 3]]b.[[12]],[[13]] In our experience, the surgeon was able to operate the CEA under the ORBEYE™ surgical
microscope without any discomfort about his posture, even in an awkward scope angle
as removal of distal end of the high-positioned carotid plaque or making stitches
on distal arteriotomy. After the completion of the surgery under the ORBEYE™ Surgical
Microscope, he felt less stiff back than the ordinary CEA under surgical microscope.
Thus, the unsurpassed ergonomics is one of the major advantages of the ORBEYE™ surgical
microscope. Moreover the layout of operating room equipment and surgeons could be
more flexibly arranged, allowing surgeons to observe vital signs or regional oxygen
saturation of the patient with a glance during the surgery [[Figure 2]]b. Moreover, as the large 55-inch monitor enables the entire operating team to view
the same 3D image with the glasses, it improves efficiency and education by allowing
information to be shared with the anesthesiologist, nurses, and medical students.
On the other hand, there was a difficulty for the assistant to manipulate from his
position. Under the ordinal operating microscope, the surgical field could be arranged
as required for an operating surgeon and an assistant. On the contrary, the ORBEYE™
surgical microscope provides only one direction of the surgical field on the monitor
which is the most suitable for an operator. Hence, the assistant is enforced to perform
surgical manipulation after compensating for the view on the monitor by suitably rotating
the surgical field in his head, making manipulation from the position of an assistant
uncomfortable.[[12]] One of the possible solutions for this problem may be a virtual reality system
for each operating surgeon that presents the surgical field in the real-world direction.[[12]] Moreover, the other possible solution may be dual the ORBEYE™ surgical microscope-monitor
systems or head-mounted monitor system for each operating surgeon.
The major limitation of this report is the technical report of one surgical case without
learning curve. More experience with the ORBEYE™ surgical microscope would contribute
a real improvement of surgical results, especially operation time, and subjective
sensations of operators.
Conclusion
This is the first report of a vascular surgery under the ORBEYE™ surgical microscope.
Its highly ergonomic technology and high-resolution 3D optical system allow surgeons
to perform safe and precise surgery.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms.
In the form the patient(s) has/have given his/her/their consent for his/her/their
images and other clinical information to be reported in the journal. The patients
understand that their names and initials will not be published and due efforts will
be made to conceal their identity, but anonymity cannot be guaranteed.
