Capsule Granulation Tissue Harvested from Abdominal Region Used as Dural Autologous Graft
Abstract
I
n neurosurgery neural defects are a common prob-
lem, many etiologies compromise dura mater in-
tegrity. These scenarios had demonstrated the need
for a dural substitute. Multiple substitutes had been
proposed: autografts, allografts, xenografts and syn-
thetic materials. None of them fulfill all the “ideal
substitute” enquiries. The hypothesis of this paper
is supported by previous work of Tomohisa et al. And
Campbell et al. Tomohisa et al presented 12 cases
were synthetic substitutes had infected tissue and
the need of removal was inevitable. Fortunately, the
capsule was protecting brain parenchyma, and the
absence of CSFL give them the option of closing with
no further duroplasty. They suggest that in these sce-
narios where infection prevents the option any graft,
the preexisting capsule works as an appropriate sub-
stitute. In the other paper, a new vascular graft was
presented, where sylastic tube were placed in rab-
bits and mice, then harvested after two weeks and
used the capsule of granulation tissue as an autolo-
gous vascular graft. This autologous substitute could
work as an adequate scaffold for graft integration in
dura mater.
Introduction: In neurosurgery neural defects are
a common problem, many etiologies compromise
dura mater integrity. These scenarios had demon-
strated the need for a dural substitute. Etiologies
affecting dura mater are tumor invasion, congenital
meninges defects, traumatism other pathologies [1].
Many experimental studies had been realized. Still,
no ideal dural substitute is available [2]. Dural decent
substitute is necessary to avoid complications. For
example, Cerebrospinal Fluid Leakage (CSFL) result-
ing in fistula, cerebral herniation, pneumoenceph-
alus, pseudomeningocele, adhesions among others
can be present [3]. Multiple substitutes had been
proposed: Autografts, allografts, xenografts and
synthetic materials [4]. None of them fulfill all the
“ideal substitute” enquiries, which are: inexpensive,
available, strong, malleable, easily managed, inert,
nontoxic, watertight barrier, don’t create adhesions
to brain parenchyma or cranium, safe of infectious
diseases [5]. Most of the research is in xenografts
and synthetic materials. Many advantages had been
extensively described in the literature. In the other
hand, these substitutes have the specific disadvan-
tage of creating complications such as infection or
allergic reactions [6,7].
For fortune these complications are uncommon,
but once they appear surgeon options are narrowed
nearly to zero. The hypothesis of this paper is sup-
ported by previous work of Nagasao et al. [6] and
Campbell et al. [8]. Nagasao et al. [6] presented 12
cases were synthetic substitutes had infected tissue,
and the need of removal was inevitable. Fortunate-
ly, the capsule was protecting brain parenchyma and
the absence of CSFL gives them the option of clos-
ing with no further duroplasty. They suggest that in
these scenarios where infection prevents the option
any graft, the preexisting capsule works as an appro-
priate substitute [6]. In the other paper, Campbell et
al. [8] present a new vascular graft, they put sylastic
tube in rabbits and mice, then harvested after two
weeks and used the capsule of granulation tissue as
an autologous vascular graft [8]. This autologous sub-
stitute could work as an adequate scaffold for graft
integration in dura mater. The search for the ideal
substitute after nearly 100 years still is on, and as
we had described every graft has its pros and cons.
We want to add a tool, into the tool box for develop-
ment countries or well when a synthetic substitute
presents infection. In this paper, the objective is to
describe a new alternative. We will introduce the hy-
pothesis of autologous fibrous tissue harvested from
the subcutaneous tissue, as a dural graft. This is just
a theoretical paper; we want to encourage other re-
searchers to conduct this experiment.
Should be implanted in the peritoneal cavity or well
in the subcutaneous tissue
Measurements of mechanical strength
The mechanical strength of the fibrous capsule
should be performed under 37°C. Measuring tensile
strength and elongation breakage. Multiple methods
to do it had been described in the literature [1-4,9].
Water retention also is strongly advised to document
[3,9]. It can be measured with the formula:
In vivo stage 1: Implantation surgical technique
This experiment can be conducted in New Zealand
Rabbits, Wistar rats or canine model. We suggest
conducting the investigation in New Zaeland Rabbit
model. Be sure to respect all the local authorities’
regulations. In Mexico are NOM ZOO099 and Inter-
national Council for Laboratory Animals ICLAS. In this
experiment design, would need a two staged surgery.
The first when the sylastic material are implanted in
the subcutaneous tissue or in the peritoneal cavi-
ty. So either dermis dissection or well laparotomy
should be performed.
In vivo stage 2: Harvesting the implants and conduc-
tion craniectomy
After two weeks, the implants should be ready for
harvesting [9]. Wang et al. [9] collected the implants
and everted the borders for implantation. We sug-
gest that the inner part of the capsule (the one that
has in contact with the sylastic) is on the brain side
of the implant. Standardized Craniectomy should be
addressed measuring 2 × 1 cm in the right parietal re-
gion (Figure 2). Opening the dura under microscopic
observation then remove 5 × 5 mm of dura mater.
Later harvest 6x6 mm fibrous capsule and suturing
it with Nylon 7-0 monofilament USP in interrupted
knots [3,4]. The cranial bone defect can be left open
or can be closed with the bone autograft, but it has
to be standardized in every craniectomy [2]. At this
stage, a local antibiotic such as Penicillin powder
can be used [1]. The skin can be sutured with Nylon
monofilament 4-0 USP.
neurosurgery-craniectomy
Figure 2: A&B) A craniectomy with dimensions 2 × 1
cm should be performed.
A 5 × 5 mm of dura mater should be excised to create
de gap, for later reparation with the capsule grano-
lous tissue
Postoperative observation
Postsurgical outcomes must be documented, such as
eating or drinking abnormally, animal activity, infec-
tion or CFSL.
Staged standardized leakage documentation
We recommend conducting fluid leakage pressure as
Fillipi et al. [10] described. Standardized dates have
to be defined for example days 10, 21 and 30 days
and subsequently performed.
General anesthesia should be given, then reopen the
cranial wound (optional: Removing skull), making an
incision in the native dura (respecting the autologous
graft). Then the insertion of a catheter of 22 G into
the cisterna magna fixing with an adhesive sealant,
attaching the catheter to a pressure monitor and a
continuous infusion device. Then a Fluorescein solu-
tion (0.9% saline with 0.05% sodium fluorescein) is
perfused to the cisterna magna. With the assistance
of ultraviolet illumination, any fluorescein leakage
should be evident. The infusion should continue un-
til the pressure reaches 100 mm Hg [5]. Alternatively
Sandoval-Sánchez et al. method can be conducted
[3].
