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) mass.
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 radiation
therapy (usually Stereotactic Radiosurgery) is warranted.
Figure 1: MRI Scan (Transaxial View)|
Right Optic Nerve Glioma (Arrow) in a 28 year old female known to
have NF2 (Neurofibromatosis).
Compare the size and configuration of the right Optic to Nerve to
the one on the patient's Left side.
Figure 2: MRI Scan (Coronal View)|
Right Optic Nerve Glioma (Curved Arrow) in the same patient.
The Left Optic Nerve (Slender Arrow) is normal.
Meningioma 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 vision.
Figure 3A (Left): CT Scan of Orbits. The Meningioma involving the
Right Optic Nerve (Arrow) was completely removed with preservation
of the patient's vision.|
Figure 3B (Right): Operative Photo of same patient. The majority of
the Meningioma has been removed revealing the Optic Nerve. Part of
the tumor remains to be resected (Arrow).
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
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 surgery.
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.
Figure 4A (Left): Operative Photo of a large Orbital Hemangioma
displacing and stretching the Optic Nerve (surgical exposure is
through a lateral Orbitotomy).|
Figure 4B (Right): Photo of the Orbital Hemangioma immediately
after it was excised. The tumor has been divided to show its
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 recurrence.
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.)
Figure 5A (Left): MRI Scan (Sagittal View). The DERMOID tumor
(Uppermost Arrow) is almost the size of the Globe (Longer Left
Arrow). The two smaller Arrows point to the eye muscles. The
Superior Muscle is directly adjacent to and was found to be
adherent to this tumor.|
Figure 5B (Right): Operative Photo (same patient as Figure 5A).
The Dermoid tumor has been partially "isolated" from the
surrounding orbital contents. The tumor capsule (indicated by the
slender Arrows) has been opened to expose the debris contents. In
order to assure complete removal and reduce the risk to injury of
the Orbital contents, the tumor's internal contents (Broad Arrow)
were removed prior to final dissection of the capsule.
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.
Figure 6A (Left): Lateral oblique photo of patient after having
undergone a Right Lateral Orbitotomy for Orbital Tumor. (The
Arrow indicates the line of the incision.)|
Figure 6B (Right): Front photo of patient after Right Lateral
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
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