Fat Herniation and Violation of the Orbit

The orthodox anterior approach to an uncinectomy is potentially one of the most dangerous procedures in endoscopic sinus surgery and we now recommend a retrograde removal of the uncinate process for those who are just starting ESS. Not infrequently there are no ethmoid air cells to act as a cushion between the unci-nate process and the lamina papyracea and an incision

Fig. 12.6 A line diagram to show the plane of the medial walls of the orbits.
Periorbital Ecchymoses
Fig. 12.7 Ecchymosis caused by traversing the orbital periosteum.

as little as 2 mm through the unciate process can also go through the lamina papyracea and into the orbit. Even if the uncinate process is ballotted to define its extent and the sickle knife is kept as near as possible to the sagittal plane to avoid traversing the lamina papyracea, it is easy to inadvertently enter the orbit. We have seen this happen with experienced surgeons and therefore advise a retrograde approach for beginners. When operating on the lateral nasal wall, it is best to have the eyes exposed and kept moist with simple eye ointment and to ask an assistant to look for any eye movement. We offer a bottle of the best champagne we can buy to an assistant who reports any orbital movement and is correct. This has certainly saved several patients a complication, as well as and our reputation! If the assistant says that they think there has been some movement when there has not, we do not ignore them or chastise as we want their threshold for alerting us to remain low.

Both at the start of a procedure and during it, it is worth asking the assistant to palpate the closed eye to see whether there is any dehiscence of the lamina papyracea, as in this case the lateral wall will be seen to balloon medially (Fig. 12.5a, b). Occasionally, you will be surprised and find that the orbital contents prolapse into the nasal cavity when the eye is bal-lotted. This can occur even in a patient who has not had any previous surgery, particularly if they have marked nasal polyposis.

Another danger area is the "armpit" where the lateral nasal wall joins the middle turbinate. Frequently, agger nasi air cells cushion the operator from the lamina papyracea, but sometimes the lamina papyracea and the uncinate process have already merged and it is possible to go straight into the orbit here. Remember that the orbits are not "carrot shaped" cylindrical structures whose long axis is sagittal (Fig. 12.6). The orbit's medial walls are sagittal and as long as you stay medial to the medial wall of the maxillary sinus you are likely to be safe. It is true that there are often cells lateral to the sagittal plane of the medial wall of the maxillary sinus that need opening, but these are best identified on CT and they are readily found and opened after the more medial cells have been exposed. Gentle palpation with a blunt-ended probe behind the remaining lamella will safely disclose most of these cells.

If the lamina papyracea is cracked or a segment is removed during the procedure, this may cause a minor ecchymosis (Fig. 12.7); this will settle spontaneously in 3-4 days. If the orbital periosteum is traversed, then orbital fat prolapses into the nasal airway. Although fat has a yellow hue, it can look remarkably like nasal polyps. Palpation of the closed eye by the assistant, or you, will tell whether it is orbital fat as it will move abruptly with this maneuver. If it is fat, do not panic; there is a temptation to push it back into the orbit (this will fail), to pull it out (this will make the damage to the orbit worse), or to cauterize it. None of these is necessary and they may cause more harm.

If powered instrumentation is being used, this should be stopped because the suction can easily remove the fat, which is then sheared off, and this makes matters worse. If the surgeon has the experience to carry on, placing a moist neurosurgical patte over the fat can protect this area while the rest of the procedure is completed. As long as the only damage done is opening the periosteum, the only problem will be some periorbital ecchymosis. The surgeon who has performed an extensive orbital decompression and widely decompressed and incised the periosteum, allowing the fat to prolapse medially without creating a problem, will realize that this is not a major complication/difficulty as long as it is recognized and the orbit is not entered further.

The patient should be advised to avoid blowing their nose and or stifling any sneezes for 4 days in order to avoid surgical emphysema and it is best to give prophylactic antibiotics to avoid the theoretical risk of orbital cellulitis (Fig. 12.8). The tension within the orbit should be monitored by gently comparing it with the other eye to ensure there is no bleeding or pressure building up in the posterior compartment. If the globe is tense and proptosed then decompression may be required. The axis of the pupils should be checked. If it is altered, this may indicate that a considerable amount of the orbital contents have been removed or proptosed into the airway, or that the medial rectus has been damaged. Under these circumstances, an urgent ophthalmological opinion should be sought.

The pupils' light reflexes should be checked with the "swinging flashlight test" (Mason et al., 1998 a) (Fig. 12.9 a-c). This will show whether there is an afferent pupil defect. As an example, if there is concern

Periorbital Cellulitis
Fig. 12.8 Postoperative periorbital cellulitis.

Left pupil diluted during endoscopic sinus surgery hur has a NORMAL swinging flashlight test Therefore no optic nerve damage - pharmacological dilatation

+ lull reujveiy likely.

"iiJi:

StepT: Shine light In left eye & right pupil constricts briskly. Therefore afferent pathway iiHdLLun left.

Swinging Light Test Pathway

Step 3; Swing light rapidly back to left and the pupils luuk the same ┬┐gain.

In nrher words, nn matter which eye the llghr shines In, rhe pi ipll of the right eye remains responsive to light. (The left pupil is sluqqish or non-responsive because of pharmacological dildtdUuMor damage loLlie oculomotor nerve an this side (rare).)

Fig. 12.9a The swinging flashlight test to check for an afferent optic nerve defect.

Assistant nulitei Lugging movement of ML eye during endoscopic sinus surgery. Swinging flash light

(.ebt hiliowi leftdlfeienL pupil defect. Therefore uptk neive ddmdge.

Surgery Flashlight

Fig. 12.9b, c Eye signs in various clinical situations.

Eye Signs Legionella

Fig. 12.10 A line diagram of the optic and oculomotor pathways.

Optic Nerve Diagram

Transection of left optic nerve would causc loss of the direct response In the left pupil and consensual responses in the right pupil.

about left optic nerve damage then the light is shone in the left eye. If there has been damage to that optic nerve, then if light is shone in that eye both pupils will show poor or absent constriction (the pupils may be normal size initially because of a normal afferent pathway on the right). The light is then swung rapidly over to the right eye, and both pupils should show good constriction. The light is then swung rapidly back to the left eye, and if both pupils dilate then this indicates that the afferent pathway on the left is defective. This is the best way of checking to see whether there is an afferent pupil defect if the patient is anaesthetized. The appearance of the pulsation of the retinal vessels is not a reliable sign. The ultimate test is to wake the patient up and check their vision (Fig. 12.10).

The surgeon should not ignore any complication or potential complications (Fig. 12.11a, b). The authors have sometimes been asked to comment as expert witnesses on events where the surgeons have realized that they have damaged the orbital contents and then failed to take the appropriate action.

If there is an orbital complication, the light reflexes, the pressure of the orbit, and, most importantly, the visual acuity should be checked. No harm comes from checking these, in particular the vision. If there is any concern about the integrity of the afferent pathway or the orbit, we recommend that the vision be checked every 15 minutes for the first hour, then every 30 minutes for 2 hours, and then hourly for a further 2 hours. If the pressure is raised within the orbit, requiring decompression, this should be done within one hour. To ignore this puts the patient's sight at risk.

Be sure to close the other eye when checking the vision of the eye in question. It is best to gently remove any excess eye ointment by wiping the eye while it is closed, otherwise acuity will be affected and this can alarm both the patient and the surgeon (Fig. 12.12 a-e).

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