Orbital surgery for sphenoid wing meningioma: When, why, and how

Orbital surgery for sphenoid wing meningioma- when, why and how?
Presenter: Geoffrey E. Rose

I don’t have any disclosure.

Looking at the orbital effects of sphenoid wing meningioma, basically one can consider the simple mass effects within the orbit and they can lead to the globe displacement problems, namely proptosis and inferomedial globe displacement. Further, you get the bulk effects of reduced eye movements, which may lead to squint and/or diplopia. Some of the patients may have distortion with refractive changes due to large mass. Lastly, if they get significant prominence of the globe, the blink cycle may be incomplete and they’ll get the problems due to an uncomfortable eye.

The second group of the problems are those due to vascular congestion and this is often the first way that these patients will present.  They will say, ‘For the last two or three years, I’ve woken up in the mornings and my lower lid is swollen’ and, in some cases, the swelling will extend out onto the cheek, and then progressively becomes more troublesome. They may get conjunctival chemosis as well, it being a congestive component due to episcleral congestion with leakage from dilated episcleral vessels, and that is a real problem with these orbital meningiomas.

Then last of all visual impairment, which is either due to the ocular surface problems with keratopathy, or it can be due to globe distortion. In addition, intraorbital compressive neuropathy can occur, where the canal is normal but the nerve is being so squeezed by the orbital soft-tissue mass, that they actually get a compressive optic neuropathy. It also may be retro-orbital optic neuropathy – an ischaemic optic neuropathy within the optic nerve canal, secondary to hyperostosis.

This case is not an unusual type of presentation, whereby the patient has a little bit of temporal redness, a little bit of chemosis (‘I’ve had this for months on end’), and somebody notices that the upper lid is slightly asymmetric. That may be all in the way of signs or it may be more obvious — as in this lady’s right eye, where she clearly has hypoglobus, and a full upper lid sulcus. In other cases, the congestive component can be a real problem and they get gross and widespread periocular oedema. The oedema will continue even after resection of the meningioma, for reasons that I’ll bring out later. Patients may also get calvarial hyperostosis, as in this lady where there is quite marked hyperostoses, or they may present with choroidal folds and/or atrophy due to years of pressure on the optic nerve and globe.

Regarding orbital treatments for sphenoid wing meningioma: The first thing to make clear to the patient is that no treatment is going to cure this disease. It’s not curable.  We are trying to contain the disease and limits its effects. Orbital decompression is useful either if it is optic neuropathy due to excessive tissue in the orbit, and where the canal is not involved, or where there is significant proptosis. Subtotal resection may be either through an orbital or cranial route, the latter being for those with a significant bulk problem inside the head.  Radiotherapy may slow or delay the recurrence of disease. About pharmacological treatments: remember progestogen antagonists. There was interest in them for some years, but they had too many side effects and therefore have not been widely adopted; however, these patients should be warned to avoid progesterone HRT supplements, because they are significant drivers to meningioma.

The problems arising from treatment are largely attributable to the fact that one can only achieve partial resection — which means you’ve left something behind: therefore, ‘how do we deal with this residual disease?’.  Another question is, ‘’Does tumour disturbance make recurrence more pervasive?’   Certainly, I have seen that you can get patches of meningioma recurring in the orbit, away from the main site tumour, and I think that tumour resection might make it more pervasive by “tumour seeding”.  The other issue that we have is scarring: we know most fluid drainage from the orbit is posteriorly and, with scarring at the orbital apex, the patient will get quite marked oedema – this commonly being an insidious presenting sign.  Following surgery they have even more fibrosis, which increases the congestive component and it can take months, even more than a year, before the oedema settles.  Patients can lose vision due to optic nerve injury during surgery, particularly if you are operating near the canal or at the apex.  Lastly, patients may have problems due to secondary tumours or pituitary insufficiency following radiotherapy.  Radiological colleagues will give us some guidance as to whether the optic neuropathy is due to a canal problem or a problem in front of the canal.

One of the first steps in the assessment is to perform a scan and decide whether the optic nerve compression is due to lateral wall bulk in the orbit, or hyperostosis of the optic nerve canal.  If the canal is clearly very hyperostotic (as on the right slide), this is unlikely to benefit from orbital surgery, but if it is orbital bulk causing neuropathy, one can go for a medial wall decompression — and that can lead to significant improvement without disturbing the tumour itself, or you can do a lateral decompression and/or medial if proptosis is a major problem.

How do we do medial orbital decompression?   Well, effectively we use a retrocaruncular approach and it gives us excellent access to the whole of the ethmoid complex and the medial half of the floor. You can remove the whole of the ethmoid complex, the maxillo-ethmoidal interface and part of the floor of the orbit. We go in behind the caruncle, between the plica and the caruncle, to reach the posterior lacrimal crest outlined on the right-hand slide.  You then go down past the lacrimal sac to reach the posterior lacrimal crest, then jump into the extraperiosteal plane at the crest and, using a 16 millimetre malleable retractor, you can go all the way down right back to the annulus.

Medial orbital decompression is a straightforward procedure when you’ve done it a few times.  It is a very clean access to the whole of the ethmoidectomy area without disturbing the lateral wall of the nose at all. You can perform a complete ethmoidectomy, get back into the posterior ethmoidal cells and, indeed, into the sphenoid (where the sphenoid is anteriorly-placed). The “Mercedes sign” is useful when approaching these sinuses for medial orbital decompression.  ‘What is the Mercedes sign?’: It is the junction between the orbital floor (the orbito-maxillary interface), the orbito-ethmoidal interface (the lamina papyracea) and the maxillo-ethmoidal interface (the infero-medial strut) — so you’ve got your three arms of a Mercedes sign.  After removing the medial wall right back to the posterior ethmoids and part of the floor, we can remove the periosteum (if it is significant) and conjunctival closure is two 7/0 Vicryl sutures just to stop fat prolapse forwards.

Medial orbital decompression can be considered as a useful approach: very clean, and the patient really doesn’t know how you’ve got in there — all the way to their sphenoid!  It gives you excellent expansion medially and inferomedially, and it will generally relieve the optic neuropathy by allowing the optic nerve to gain more space.  It is an almost atraumatic surgery, as it heals incredibly quickly — at 10 days the patient really has no idea how you got there.  It gives excellent relief of optic neuropathy if this is due to compression within the orbit.  It can also markedly reduce 3-6mm proptosis, where the patient does not want craniotomy.  It doesn’t disturb the tumour at all, and so does not impair cranio-facial surgery if needed at a later date for progressive major disease — so you don’t get in the way of your friendly neurosurgeon!!

However, medial orbital decompression also increases infero-medial globe displacement, which of course is already a feature of meningioma. It may increase the esophoria and so the patient might get a convergent squint – but, again, there’s ophthalmologists who deal with that quite regularly – and medial decompression is very good at relieving optic neuropathy when caused by optic nerve compression within the orbit.  Here for example is a field in a patient on presentation and a couple years later, clearly getting increasing neuropathy; after medial decompression there is a marked improvement in the field and a slow change thereafter (due to changes in the meningioma).

Regarding lateral decompression, we tend to use this more for those cases where there’s clear orbital hyperostosis, but the patient doesn’t want to craniotomy — where it is predominantly a proptosis problem. Here for example, a patient with 13 millimetres of exophthalmos wants something done: You can see the eye “closed” in the lower picture and, in these cases, I have tended to either use a horizontal incision through the skin, extended into the upper lid skin crease, and also into the lower lid. It gives very good access to the whole of that lateral wall with the incisions that heal very well.  One can see the mass, the hyperostotic rim, the actual lateral rectus over there, and the soft tissue mass between them — and you can resect all of the tumour. Here is the same patient at the end, with over a centimetre reduction in the exophthalmos, by removing that hyperostotic bone and the soft tissue component, and they heal extremely well. Here before and after, as you see much improvement in the exophthalmos, although it doesn’t cure the disease.

Likewise a second case, you can see this patient has already had somebody attack them through the brow incision — which I never use because they get a marked scar – and they clearly have  significant proptosis (in the upper picture).  Using an upper lid skin crease incision (I don’t use the canthotomy now), it gives beautiful access to the lateral rim and heals brilliantly, and one can see the soft-tissue component after raising the periosteum.  One can remove as much bone as you like and then deal with the soft-tissue component, which is this hyperostotic periosteum. There is a complete reduction in proptosis and there is the periosteal tissue component and various bone blocks; you may need to take it out piecemeal, which I tend to do with something like the Ellman monopolar loop electrode you can resect it right back to the apex.

Our real problem is, of course, that it isn’t just an orbital disease: In this case, our patient started getting optic neuropathy, so we did a medial decompression that held her vision for many years. However, she carried on developing ever more proptosis and more of this dependent periocular oedema — which is one of the difficult problems that they get.  We did a lateral debulking and, although there is a marked reduction in proptosis, the periocular oedema remains a big problem due to congestion around the superior orbital fissure.  But the oedema very slowly settles — six months after surgery, two years after surgery — but it never goes; it’s a congestive problem that you see with meningiomas in particular.  She has had radiotherapy to try and stop this progression of the soft tissue disease but, clearly, if the tumour becomes more of a problem she might want something done about the neurosurgical component.

In summary: No treatment is curative in these patients.  With optic neuropathy due to orbital tissue, think medial orbital decompression, whereas lateral decompression is more for trying to control the hyperostotic component.  Subtotal resections can be either orbital and/or cranial. Radiotherapy does slow the progression of the disease and so is very useful adjunct.  Remember to avoid the hormones -the progestogens- which are known to drive these tumours and are often given at the age when most common.  And the second area is the problems with the treatment: ‘What do we do with residual disease?  Are we actually making the tumours more pervasive by disturbing them, and how can we overcome this problem of residual oedema?’

Q & As section

Question 1
How often do you get quite a lot of bleeding when you’re resecting all this tumour soft tissue or bone? Because they are quite “vascular tumours”

Answer
We’re dealing with fairly small stuff and the Ellman monopolar loop -I have no financial interests in it- is actually quite useful with the coagulation-cut mode — you’re taking it out like pieces of cheese.  Every so often you’ll hit a rather more spectacular vessel — for which we use bipolar cautery at the time — and so you work your way through the tumour, but bleeding isn’t too much of a problem. The hyperostotic component is typically rather avascular, as it is real “ivory” bone.

Question 2
It’s a good opportunity in this forum to hear from the endoscopic advocates in the room about the alternative technique to yours of medial decompression by an ENT approach. Can we hear it from both sides please?

Answer
The retrocaruncular route is a lovely approach and, for thyroid eye disease, I’ve done something over 200 medial decompressions for optic neuropathy. The lovely thing about it is the clear and open approach to the ethmoidectomy and removal of the medial part of the floor. It takes about 20-25 minutes and, in addition, it doesn’t disturb the nose at all — so there are no restrictions: we tell the patient not to blow their nose, in case they blow air back through the natural ostea, but you don’t disturb the lateral wall of the nose, so you’re not affecting nasal airflow. Further, the patient doesn’t have to use nasal douches or medications: it is a lovely approach and so, for very obvious reasons, I tend to favour going through retrocaruncular approach — but that’s a bias!

Question 3
Don’t you think there are some potential advantages with an endonasal approach? When you’ve got a great big lateral wall and roof mass pushing the globe and the optic nerve, you’ve got a compressive optic neuropathy. For an endonasal approach one does not have to retract the globe against that great big mass, and this must be potentially safer?

Answer
You bring out a good point, and that is the fact that the optic nerve is already impaired – but, of course, it is in thyroid optic neuropathy and you don’t have to displace it laterally. We have had a couple of cases where the pupil is enlarged after surgery and we think it may be because of the orbital congestion — but it’s never really been a problem getting to the apex.  As you’re only there for a few seconds as you take out that last piece of the medial wall – and it is therefore a very quick procedure.

Question 4
Those cases with periocular congestion, where you are contemplating lateral wall decompression, it is useful to deal with the intracranial components, the bony component, and the compression around the superior orbital fissure.  In those patients, do you not think it might be justifiable to do a combined approach with your neurosurgical colleagues?

Answer
I have seen very persistent periocular congestion after neurosurgical resection of sphenoid wing meningiomas, this probably being due to marked apical fibrosis in the area of all that surgery – having had craniotomy as well as the orbital surgery.  Certainly, neurosurgery is very important where there is a marked calvarial or intracranial component to the tumour, and I think it is fair enough if the patient wants a craniotomy.