Endoscopic skull base surgery
a brief
Dr.Mohammed Tariq
FRCS
Associate professor ENt Unit II SIMS
Services hospital,Lahore.
History
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The earliest approaches to brain surgery
were at the skull base.
1870 .. Francesco Durante was the first to
remove an olfactory groove meningioma
from the skull base in a 35-year-old woman
who presented with proptosis, loss of smell,
and memory impairment
1879 ..William Macewen contributed further
Subsequent innovations
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Sir Victor Horsley (1857–1916) sectioned the
posterior root of the trigeminal nerve for pain relief,
Sir Charles Ballance (1856–1936) reported one of
the earliest cases of acoustic tumor removal,
Fedor Krause (1857–1937) from Germany, Thierry
de Martel (1875–1940) from France, and others
made major contributions to skull base surgery
feasibility
With this approach it is possible to expose the intradural cranial
base, from the olfactory groove to the odontoid process of C2.
The most common surgery related problems are related to the
prevention of postoperative CSF leakage and, in cases
involving the lower skull base, the usual issues of stability of the
craniovertebral junction.
Nevertheless, the potential benefits of such an approach, which
allows exposure of the surgical area with no skin incision or
neurovascular retraction, cannot be overestimated.
The midline skull base
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is an anatomical area that extends from the anterior
limit of the cranial fossa down to the anterior border
of the foramen magnum.
Resection of lesions involving this area requires a
variety of innovative skull base approaches.
These include anterior, anterolateral, and
posterolateral routes, performed either alone or in
combination, and resection via these routes often
requires extensive neurovascular manipulation.
The major potential advantage
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it provides a direct anatomical route to the
lesion without traversing any major
neurovascular structures, obviating brain
retraction.
Many tumors grow in a medialtolateral
direction, displacing structures laterally as
they expand, creating natural corridors for
their resection via an anteromedial approach.
Potential disadvantages
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the relatively restricted working space
the danger of an inadequate dural repair with
cerebrospinal fluid (CSF) leakage .These
approaches often require a large opening of the dura
mater over the tuberculum sellae and posterior
planum sphenoidale, or retroclival space. In addition,
they typically involve large intraoperative CSF leaks,
which necessitate precise and effective dural closure
potential for meningitis
accuracy and safety
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the constant improvements in diagnostic
imaging techniques and the increasing use of
image guidance systems during endoscopic
endonasal procedures has provided
increasing accuracy and safety for this
approach, allowing improved, constant
surgical orientation in an anatomically
complex area.
Endoscopic trajectories
different areas of the midline skull base exposed through the
endoscopic endonasal approach.
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to the olfactory groove;
to the sella turcica and planum sphenoidale;
to the clivus
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to the craniovertebral junction and foramen magnum.
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Currently approach provides
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the definitive treatment of choice for most
pituitary adenomas,
craniopharyngiomas and meningiomas of the
sellar region.
The elegant minimally invasive transnasal
endoscopic approach to the sella turcica and
the anterior skull base has added a new
dimension of versatility to pituitary surgery
and can be adapted to many lesions in the
region.
removal of pituitary tumors
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The refinement of minimally invasive
endoscopic techniques has resulted in 'pure'
endoscopic endonasal trans-sphenoidal
surgery, which is a relatively new approach
for the removal of pituitary tumors.
removal of pituitary tumors
The technique
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wide anterior sphenoidotomy
detachment of the septum from the sphenoid
face avoiding the use of a trans-sphenoidal
retractor and any intraoral or nasal incisions.
Straight and angled endoscopes are used
throughout the procedure to provide a wide
view of the sella and are manipulated by a
co-surgeon.
an improvement over pituitary
microsurgery
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decreased post-operative morbidities
a shortened postoperative stay
it eliminates the need for packing
providing an opportunity to monitor the sella after
surgery.
It incorporates image-guided surgery, with the fusion
of computer tomography and magnetic resonance
imaging
employs new and dedicated instrumentation.
Future advancements
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in intraoperative imaging,
cranial base reconstruction, and
robotics will make this technique even more
successful
unique reconstructive challenges
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The creation of large defects of the bone and dura
endoscopically presents unique reconstructive challenges.
A layered reconstruction of the dura with inlay and onlay fascial
grafts covered with fat grafts is an effective technique for repair.
An intranasal balloon catheter is used to provide
counterpressure in the early phase of healing and
a lumbar spinal drain is a useful adjunct in patients at increased
risk of a cerebrospinal fluid leak.
Vascularized flaps may be necessary in some patients
receiving radiation therapy.
Continued advances in surgical technology and the introduction
of new biomaterials will facilitate the reconstruction of skull
base defects following surgery.
Endoscopic experience
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with the repair of small cranial base defects following
trauma,
sinus surgery, and
spontaneous CSF leaks (meningoencephaloceles)
has demonstrated a high rate of successful repair
using a variety of techniques.
Endoscopic experience
1 Success does not appear to be dependent on the type of
reconstructive material, repair technique, or use of lumbar
spinal drainage.
2 A special population of patients that appear to be at increased
risk of recurrent CSF leak are those presenting with
spontaneous CSF leaks.
3 These patients are characteristically obese, middle-aged
females and measurement of CSF pressures following repair
often confirms occult hydrocephalus. Despite initial success,
such patients remain at risk for recurrent CSF leaks months to
years following repair
vascularized tissue flaps
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Some populations of patients may require
reconstruction with vascularized tissue flaps
due to the volume of the defect or the lack of
vascularized tissue (prior irradiation).
Options include a pedicled pericranial scalp
flap, temporoparietal fascial flap, or
microvascular free flap
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Dural defect following
endoscopic craniofacial
resection of a
neuroendocrine
carcinoma of the
anterior cranial base.
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A synthetic dural substitute (DuraGen) is placed
intradurally over the surface of the exposed brain so
that the dural edges overlap the inlay graft.
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The first fascial graft (Alloderm) is sutured to
the dural margins.
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Nitinol U-clips are used
to anchor the fascial
graft to prevent
migration or
displacement by CSF.
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Fat grafts cover the
fascia and are in
contact with the
surrounding bone.
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A Foley balloon catheter crosses the
nasopharynx posterior to the nasal septum,
prior to inflation with saline. The surface of
the fat graft is covered with Surgicel to form
an adherent crust.
thanks