Key-words:
Intraoperative aneurysm rupture - surgical training - three-dimensional artificial
model
Introduction
Intraoperative aneurysm rupture (IAR) is one of the most dreaded complications of
microsurgical cerebral aneurysm clipping. If the surgeon cannot control the bleeding
appropriately, IAR is more likely to cause undesirable results.[[1]],[[2]],[[3]],[[4]],[[5]],[[6]],[[7]],[[8]],[[9]],[[10]] However, the development of endovascular treatment has decreased the exposure of
neurosurgical residents to this situation. Therefore, neurosurgical residents must
develop the skills and mental attitude through off-the-job training, without conducting
actual operations. Several models with three-dimensional (3D) modeling have been developed,
and they are useful for improving the surgical techniques of neurosurgeons.[[11]],[[12]],[[13]],[[14]],[[15]] However, there are a limited number of reports of models for training for the management
of IAR. Aboud et al.[[16]] reported the use of a cadaver model, which is remarkably similar to the real situation
and was very available. However, it requires a human cadaver, specific materials and
facilities, and incurs considerable costs. Hence, we have developed a tabletop training
system for the management of IAR using 3D modeling and materials used in daily clinical
practice. Our low-cost model is useful for off-the-job training and is both reusable
and easy to prepare and practice.
Materials and Methods
Initially, we prepared the following: the cerebral hemispheric brain retractable soft
model with the bone model (Kezlex ®; Ono and Co., Ltd., Tokyo, Japan), the cerebral
aneurysm model (Kezlex ®; Ono and Co., Ltd., Tokyo, Japan), a suction unit, a large
syringe, aneurysm clips and applier, red ink, and an operating microscope [[Figure 1]].
Figure 1: The preparations and the whole system. (a) The cerebral aneurysm model. (b) The whole
system containing the right cerebral hemispheric brain model with the bone model,
the cerebral aneurysm model, and a syringe. (c) The enlargement view. (d) The inferior
oblique view
Subsequently, a pinhole was made using an 18-G needle at the aneurysmal wall by an
assistant so that a trainee could not recognize the location of the hole. The aneurysm
model was set in the cerebral hemispheric brain retractable soft model with bone model
through a hole at the bottom. The flush system was made using the large syringe containing
red ink in tap water [[Figure 1]]. The total cost of this system was approximately 1000 dollars.
Following the setup, training was conducted with the use of an operating microscope.
When the trainee was peeling around the aneurysm, he or she encountered the scene
of aneurysm rupture once the assistant flushed the artificial blood [[Figure 2]]. First, point suction was performed calmly. The larger suction tubes were used
for trying to clean the operative field. Next, a tentative clipping of the aneurysm
or temporary clipping of M1 was performed to stop the bleed temporarily. Because this
model was a closed model, the assistant had to control the flush. Once the aneurysm
could be viewed as much as possible, a permanent clip was applied across the neck
of the aneurysm. If needed, another permanent clip was applied additionally to the
aneurysm. Finally, the training was completed once the surroundings of the aneurysm
were checked [[[Figure 3]], Video 1].
Figure 2: The training scene. (a) Before the training. (b) During the training
Figure 3: A series of the training session. (a) Peeling around the aneurysm. (b) Encountering
the aneurysm rupture. (c) Performing the point suction. (d) Performing temporary clipping.
(e) Identifying the full view of the aneurysm after achieving hemostasis. (f) Performing
the neck clipping. (g) Adding another permanent clip to the aneurysm. (h) Checking
the surroundings of the aneurysm
Discussion
Microsurgical cerebral aneurysm clipping is a standard surgical treatment performed
by neurosurgeons. IAR is the most serious and stressful complication encountered during
clipping surgery. A recent study demonstrated that IAR occurs in a wide range of all
cranial aneurysm surgeries (7%–40%).[[1]],[[2]],[[3]],[[4]],[[5]],[[6]],[[7]],[[8]],[[9]],[[10]] Because the inappropriate management of this critical situation may lead to the
most dreaded complications, the surgeon's abundant experience, technical skills, and
mental attitude are needed to handle this situation.[[1]],[[2]],[[3]],[[4]],[[5]],[[6]],[[7]],[[8]],[[9]],[[10]]
There are three important steps in the management of IAR.[[17]],[[18]] The first step is to ensure the operative field. The rupture point should be identified
using one or two large and strong suctions. It is important not to use the suctions
blindly but instead perform the point suction calmly, despite the visual field being
restricted with overflowing blood. Because this model simulates the IAR using artificial
blood and a pressurized bag, the trainee can experience the first step. The second
step is to achieve hemostasis. Tentative or temporary clipping is the typical way
to achieve hemostasis. Tentative clipping has a lower tendency to cause brain ischemia
than a temporary clipping, which temporarily interrupts the parent artery. Depending
on the situation, tentative clipping, if possible, is preferable over temporary clipping.
In addition to an aneurysm, this model includes a trunk of the middle cerebral artery
made from silicon so that the trainee can experience both a temporary clipping and
a tentative clipping. The third step is to aim for the final form. The aneurysm is
carefully separated from the surrounding tissue after achieving hemostasis using tentative
or temporary clipping. Once the aneurysm is identified to the maximum extent, a permanent
clip should be applied across the neck of the aneurysm. The trainee can experience
this final step of neck clipping.
Advantages of our model include that it is reusable, low cost, and no need for large-scale
preparations or special facilities. These advantages ensure this model is suitable
for off-the-job training. In addition, the trainee can practice in a simulated situation,
resembling the real situation, because he or she is unaware of the rupture point and
the artificial blood is pooled in the Sylvian fissure.
Disadvantages of this model include that it is a closed circuit system rather than
a perfusion system. A different point of the model may be destroyed if the assistant
creates too much flush of the artificial blood once the clipping has been performed.
Therefore, the assistant must control the flush while assessing the situation. Moreover,
it is better to put the aneurysm model in a cerebral hemispheric brain model directly,
not in a silicone cup, as this is more practical.
Conclusions
We have developed a tabletop training system for the management of IAR using 3D modeling.
Our model is useful for the training of neurosurgical residents because of its low
cost, reusability, and ease of preparation and practice. However, this model could
be improved to ensure it is closer to the real situation.
