Optic Nerve Tumors are quite uncommon. The
usual reasons for these patients to be sent for consultation
include diminished or complete loss of vision on one side, proptosis
(protrusion of the optic globe (eyeball) and a change in facial
appearance. Diagnosis is made once an MRI or CT scan
has demonstrated an intraorbital (the "orbit" is the eye socket)
OPTIC NERVE GLIOMA is a tumor of the "Glial cells" that make up
part of this vitally important nerve. These tumors are more common in
childhood, and usually, are slow growing. It can reduce
vision. Tumor excision is generally not undertaken, since it
will lead to permanent loss of vision in that eye. Surgery
is indicated, if the tumor type is in question and the tumor
is extending intracranially to involve the Optic Chiasm (the
extension of the Optic Nerve inside the skull). In this case,
Chemotherapy and/or Stereotactic Radiosurgery (Radiation
Therapy) is warranted.
of the Optic Nerve within the Orbit, although uncommon,
represents one of the most difficult challenges that
Neurosurgeons and Neuro-ophthalmologists are called upon to treat.
Most Optic Nerve Meningiomas arise form a meningeal layer that shares
its blood supply with the Optic Nerve. If surgery is done to
remove this tumor, then it usually requires the removal of the
blood supply to both the tumor and the Optic Nerve. This results in
complete visual loss in that eye.
There are very few instances of complete removal of an Optic
Nerve Meningioma with PRESERVATION OF VISION. One case was
reported by Drs. Joseph C. Maroon and John S. Kennerdell in the
American J Ophthalmology 86: 704-709, 1978. In our series of
over 150 Orbital Tumor Operations, we have had one similar case of
complete removal of an Optic Nerve Meningioma with preservation of
Although we have made other attempts to preserve vision in Optic Nerve
Meningioma patients, these efforts failed to preserve vision in the
affected eye. Among the challenges, is the reasonable certainty
that the tumor will progress. If it begins at the apex of the orbit
near the Optic Canal (the channel through which the Optic Nerve enters
the skull, to travel backwards to the Occipital Lobe of the Brain),
then early definitive surgery is required, even if it means
sacrificing the Optic Nerve and thus the vision in that eye. Failure
to do so may well lead to progression of the tumor to cause bilateral
(both sides) blindness.
Radiosurgery has a place in the treatment, to attempt to
control these tumors, particularly in patients who refuse to
permit exenteration (removal of all the contents) of the
Orbit. There are no easy decisions in the management of this
difficult clinical problem.
The most common tumor, in our large experience of Orbital
Tumors, is a
Hemangiomas are tumors of blood vessels. They can
occur anywhere inside the Orbit and usually result in some
displacement of the globe. The direction of
displacement (up/down or to one side or the other as well as
forward) is entirely dependent on the location of the tumor
within the orbit. Most of these tumors have an intimate
relationship with the Optic Nerve, as well as the muscles in the Orbit
that control the motion of the eye. In addition, these tumors
almost always have one, or more, Ciliary Nerves intimately
involved in the tumor's capsular surface. Sacrifice of these
nerves leads, to problems with the function of the pupil on the
affected side. The treatment of Hemangiomas of the Orbit is
Dermoid Tumors (which
represent 0.3% of brain tumors) tend to be located near the midline.
These benign tumors are considered to be "developmental", since
they result from retained ectodermal implants that as a consequence of
some failure of migration of cells during embryonic development
are trapped within the growing skull and orbit and are present at
birth. These generally slow growing tumors also tend to
be associated with other congenital abnormalities.
Orbital Dermoids usually become apparent as a localized
orbital "mass" and may produce diplopia (double vision) as it
displaces the globe and/or pain.
The diagnosis is usually made with MRI scanning (See Figure
Surgical excision is the only treatment option and is usually
curative. In this instance, care must be taken not to spill
the contents of the cyst (See Figures 5B and 7 A-C) as the fluid can
incite a severe inflammatory response. It is important to avoid
leaving remnants of the capsule behind in order to avoid the risk of
Radiation is not appropriate for these tumors, since
the tumor is benign, and will not respond, nor does it prevent
There are some other very rare conditions that require attention such
as Varices (large dilated veins), the discussion of
which is beyond the scope of this paper.
In most cases, we prefer to use a Lateral Orbitotomy
(opening of the eye socket) approach, since this minimizes that
risks to vision and generally offers the extent of
exposure required to manage these tumors. (Figures 3B and 4A represent
examples of Lateral Orbitotomies.)
Some tumors are situated within the Orbit in such a manner that makes
an Anterior Orbitotomy Approach more appropriate. An
example is presented below in Figures 7 A-C. In this case, an
Orbital Dermoid was
located in the superior medial Orbit making an Anterior Orbitotomy the
most favorable avenue for complete removal of the tumor.
The Orbit can be, and is frequently, entered from the
intracranial side to remove intraorbital tumors, particularly those at
the Orbital Apex, or where the tumor involves intracranial structures,
as well as, those of the Orbit such as in some cases of
Anterior Skull Base Meningiomas.
Skull Base Tumors
and Nasopharyngeal Carcinomas
often invade the Skull Base as well as the Orbit. We often
simultaneously perform a Craniotomy together with
Anterior or Lateral Orbitotomies in conjunction with our
Craniofacial Plastic Surgeons.
These are generally quite extensive operations undertaken by our
Skull Base Tumor Group.
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This page last edited on 2/19