10.1
Introduction
Dysthyroid orbitopathy (or Graves’ ophthal- mopathy) can cause increased orbital pressure, optic neuropathy, palpebral retraction, lagoph- thalmos and corneal exposure. For many pa- tients their appearance is grotesque and esthet- ically unacceptable. Conservative treatment may involve systemic steroids or retrobulbar ra- diation therapy and a slow return to a normal thyroid status with the help of the endocrinolo- gist. However, although effective in the treat- ment of the inflammatory component of the
disease, these methods show little efficacy in the treatment of proptosis. Classical bone removal orbital decompression (BROD) has potential side effects, including infraorbital anesthesia, aggravation of ocular motility, globe displace- ment, and blindness.
In 1988, Olivari [1, 2] demonstrated that sig- nificant reduction of proptosis can be achieved by fat removal orbital decompression (FROD) alone. Thereafter, Trokel [3] published a series of 158 FROD procedures in 81 patients. Various types of surgical decompression combining FROD and BROD have been performed over the years: Hecht [4] described a two-wall de- compression where the orbital medial wall and floor were removed, and resection of orbital fat was added through several incisions of the periorbita. Roncevic [5, 6] described a three- wall decompression (floor, lateral and medial wall) where defatting was added with removal of small lobules of fat. Liu [7] performed FROD alone in two children, with few complications.
Morax [8] recently published 69 BROD proce- dures in which 57 were associated with fat removal. Moreiras [9] described a combined FROD-BROD technique through a small upper eyelid crease incision of 15–20 mm and his ex- perience has extended to more than 1,000 cases.
In the present article we describe the technique of FROD, report our experience and try to evaluate the advantages and drawbacks com- pared with BROD or with combined proce- dures
Therefore the challenge for the orbital sur- geon for orbital decompression in the past was to choose between various techniques remov- ing bone. More recently the choice is more com- plex between BROD, FROD, or both.
Orbital Decompression Using Fat Removal Orbital Decompression
Jean-Paul Adenis, Pierre-Yves Robert
10
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∑Orbital decompression can be achieved successfully by fat removal orbital decom- pression (FROD) or bone removal orbital decompression (BROD) in Graves’ ophthal- mopathy
∑FROD leaves the possibility of concomitant palpebral and/or oculomotor surgery
∑FROD or BROD, or combined surgery, may be performed initially, depending on the severity of clinical presentation, radiologic findings and previous treatments
∑FROD is probably better indicated in pa- tients with large bony orbital volume, large orbital fat volumes and stretched muscles, or cosmetic “grotesque” disability
∑BROD is probably better indicated in pa- tients with small bony orbital volume, small orbital fat volumes and enlarged muscles and/or with compressive optic neuropathy Core Messages
Summary for the Clinician
∑ Graves’ ophthalmopathy may induce proptosis, compressive optic neuropathy, palpebral retraction, lagophthalmos and corneal exposure
∑ Orbital decompression is required after failure of medical treatments (steroids, radiotherapy)
∑ FROD has developed since 1988 as an alternative to BROD. At present the choice and/or the association between both techniques is under discussion
10.2 Description
The operation is performed with the patient under general anesthesia using an operating microscope (a 275-mm lens) and the help of two assistants [9].
10.2.1
The Upper Eyelid (Figs. 10.1–10.7)
After placement of a 4–0 Prolene suture, in the upper tarsus border near the eyelashes down- ward traction is applied to the upper eyelid. The incision is then made along the superior palpe- bral crease (as a blepharoplasty incision).
After dissecting off the orbicularis oculi muscle from the tarsus and the septum with the electric knife, the aponeurosis of the levator palpebrae superioris muscle and then the or- bital septum are identified.
1. The dissection begins with the superomedi- an fat pad, while carefully avoiding injury to branches of the frontal nerve. Incision of the septum reveals the intraorbital fat, which bulges through the opening, and the lacrimal gland laterally. Whitnall’s ligament can be vi- sualized after the fat is retracted using a Des- marres’ retractor. The resection begins at this point. The fat lobules are carefully resected after dissection with Vannas’ long scissors, or directly with bipolar diathermy. This dissec- tion can be hampered by bleeding (value of using bipolar diathermy) or especially fibro-
Fig. 10.1. Incision line in the upper eyelid skin crease
Fig. 10.2. Prolapse of the median fat pad behind the septum
10.2 Description 111
Fig. 10.3. Fat removal of the superior median fat pad after incision of the medial orbital septum
Fig. 10.4. Prolapse of the medial fat pad
Fig. 10.5. Fat removal of the superior medial fat with retractors on the superior oblique and on the medial rectus muscle
Fig. 10.6. Large volume of fat removed on a profile view
Fig. 10.7. Indirect portion, trochlea and direct por- tion of the superior oblique after fat removal
sis of the orbital septa, in particular if the pa- tient has previously undergone radiotherapy.
In this case, the fat lobules can tightly adhere to the extraocular muscles fascia and the veins are dilated. The dissection is then con- tinued deeper by exerting gentle traction on the adipose tissue. It is thus possible to resect the extraconical and intraconical orbital fat.
Adequate hemostasis is essential to avoid the complication of retro-orbital hematoma.
2. The second step addresses the superomedial fat pad. During this part of the dissection, it is necessary to avoid injury to the supraor- bital nerve, the superior oblique muscle, and further below, the medial rectus muscle. A second assistant is helpful at this time to re- tract the muscular structures and provide better access to the deep orbital fat.
10.2.2
The Lower Eyelid (Figs. 10.8–10.10)
The lower eyelid is then dissected after per- forming an anterior lamella incision 2 mm be- low the eyelid margin.
The orbicularis oculi muscle is retracted, al- lowing visualization of the septum, which in turn is incised at a distance from the inferior border of the tarsus.
1. The dissection begins with the inferolateral fat pad, which is by far the largest, and does not involve risk to the adjacent anatomical structures.
2. Once inside the inferomedial fat pad, the dis- section must carefully avoid injury to the in- ferior rectus muscle. Lastly, very deep inside, after retracting the orbicularis oculi muscle with a Desmarres’ retractor, the inferior oblique muscle on the outside and the medi- al rectus muscle above, the inferior medial fat pad is removed.
3. The inferior median fat pad surrounds the inferior rectus muscle and is removed by pieces around this muscle. Fat below the muscle is not totally removed to maintain the bumper effect of fat at this level. If necessary FROD can be combined with lower eyelid lengthening with ear cartilage grafting (Figs. 10.11, 10.12). The skin is then sutured
using 6–0 Prolene. Suturing of the upper eye- lid must include several aponeurotic fibers in order to reconstruct the superior palpebral crease.
Fig. 10.8. Inferior oblique muscle after fat removal in the inferomedial and inferomedian fat pad areas
Fig. 10.9. Incision line below the eyelashes in the inferior eyelid
Fig. 10.10. Lower eyelid retractors grasped between two forceps
10.2.3
The Volume of Resection
The inferolateral fat pad contains the most adi- pose tissue and the superomedial fat pad, the least. To satisfactorily reduce the exophthalmos, the total resected volume must be approximate- ly 6–7 cc and is measured in a tube (Fig. 10.13).
Frequently 9 cc is removed. In our experience for an average of 6 cc of fat that is removed, exophthalmos is reduced by 4.7 mm [10].
10.2.4
Treatment Program
The surgical approaches of this procedure make it possible to perform other maneuver that are sometimes necessary, such as resection of skin and the orbicularis oculi muscle, eyelid length- ening using a retroauricular cartilage graft, and
10.2 Description 113
Fig. 10.11. Cartilage harvesting with an incision line behind the ear
Fig. 10.12. Cartilage graft for treatment of the infe- rior eyelid retraction
Fig. 10.13. Measure in a tube of the volume of fat excised
resection of the inferior rectus muscle or the lower lid retractors. Surgery is performed on only one eye at a time. The second eye can be operated on several days later, after verifying there are no visual complications on the first eye.
Summary for the Clinician
∑ FROD is performed with the patient under general anesthesia through a blepharo- plasty approach
∑ Extraconical and intraconical fat is re- moved from the five fat pads, two through the upper eyelid, three from the lower eyelid
∑ The amount of resected fat is measured retrospectively
∑ One eye is operated on at a time
10.3
Our Experience
We report here the results of fat removal orbital decompression in a series of patients operated on in our department between 1992 and 2002 and for which binocular vision was studied before and after FROD [10].
10.3.1 Patients
This study involved 64 eyes of 39 Graves’ pa- tients, 13 males and 36 females of mean age 52.5 years (27–80 years). Every patient signed an informed consent form and the principles out- lined in the Declaration of Helsinki were fol- lowed. The indication for surgery was proptosis, eyelid disorders or oculomotor disorders. Pa- tients with optic neuropathy were excluded from the study.
Every patient was operated on after thyroid hormonal equilibrium was stable for at least 6 months. Surgery was proposed after previous treatments of Graves’ orbitopathy had failed:
1 month general steroid therapy for every patient and 20 Gy orbital irradiation for eight patients.
10.3.2
Surgical Procedure
Orbital decompression was performed as de- scribed by Olivari, under general anesthesia with two aids and modified by using an operat- ing microscope (300-mm terminal lens).
10.3.3 Clinical Data
Clinical data were collected preoperatively, and at 1 week and 6 months postoperatively. Propto- sis was measured using Hertel’s exophthal- mometer. Visual acuity was evaluated using the ETDRS chart. Patients underwent automated static threshold perimetry using Humphrey’s Sita standard software (Field Analyzer 750, Carl Zeiss Inc., Le Pecq, France). Every patient was skilled in visual field evaluation from at least three previous tests. Intraocular pressure was measured using Goldmann’s applanation tonometer in the primary position of gaze.
10.3.4 Statistics
Clinical data were compared using Pearson’s chi-square test, Student’s t-test, and linear re- gression analysis.
10.4 Results 10.4.1
Proptosis(Figs. 10.14–10.16)
The mean proptosis was 24.3±2.5 mm preopera- tively, and reduced to 19.9±3 mm at 1 week and 19.9±3.1 mm at 6 months. The decrease in propto- sis measurements was clinically significant from preoperatively to 1 week, and from preoperative- ly to 6 months (paired t-test, p<0.001). However, we found no association between proptosis re- duction and the volume of resected fat. Neither was proptosis found as a predictive value for
proptosis reduction after FROD. It appears that some orbits are fairly well decompressed with a small amount of fat resected, and others poorly decompressed despite a large amount of fat re- sected. This finding highlights the non-linear pressure-volume relationship of the orbit.
10.4.2 Visual Field
The average mean defect (MD) was –3.3±5.15 dB preoperatively, –3.3±3.7 dB at 1 week and –1.46±3.25 at 6 months. The improvement was statistically significant between preoperative and 6 months (paired t-test, p<0.001). No signif- icant change of CPSD was shown.
Thirteen eyes were found to have an MD un- der –3 dB preoperatively. Of these patients, five had complete recovery, four partial recovery, and four no change postoperatively. Every pa- tient with preoperative intraocular pressure (IOP) above 21 mmHg had complete VF recov- ery.
The defects persisting after FROD featured glaucoma-like scotomas, whereas defects that disappeared after FROD were rather diffuse or altitudinal.
The visual field MD, measured with Humphrey’s automated perimetry, was statisti- cally improved in the whole group of patients.
On the contrary, no improvement of individual deviation (CPSD) was evidenced. In addition, diffuse or altitudinal defects were significantly lowered in the study, whereas every defect fea- turing glaucoma-like scotoma persisted after FROD.
Recent studies have highlighted the role of retrobulbar vascular changes in the progression of glaucomatous visual field defects. To explain these two different behaviors, we suggest that compressive optic neuropathy may imply two separate mechanisms: on the one hand, me- chanical compression of the optic nerve in the posterior orbit. In this first mechanism, intraor- bital pressure and IOP would be high, and com- pression would induce diffuse or altitudinal scotomas. This kind of optic neuropathy would reduce after FROD. On the other hand, insuffi- ciency of blood supply to the optic nerve during orbital inflammation is implied. This second mechanism would not necessarily be associated with increased intraorbital pressure and IOP, and would rather induce glaucoma-like sco- tomas. This second kind of lesion is more likely to be definitive and to respond poorly to surgi- cal orbital decompression.
10.4 Results 115
Fig. 10.14. Patient with proptosis and eyelid retrac- tion before fat removal orbital decompression
Fig. 10.15. Patient after fat removal orbital decom- pression
Fig. 10.16. Final aspect of the patient after lower eyelid retraction treatment
10.4.3
Intraocular Pressure
Mean preoperative IOP was 19.3±4.4 mmHg (12–29 mmHg), and reduced to 17.0±2.9 (10–25) at 1 week and 15.9±3.7 (10–26) at 6 months. The reduction of IOP was significant from preoper- atively to 1 week, and from preoperatively to 6 months (paired t-test, p<0.001).
10.4.4
Volume of Excised Fat
The volume of excised fat was not found to in- fluence any postoperative change, especially proptosis reduction, IOP reduction or MD im- provement, even when separately studying pa- tients with and without preoperative elevated IOP. Also, the reduction of IOP was not statisti- cally related to the reduction of proptosis.
10.4.5 Diplopia
Seven patients had preoperative diplopia. Two of them underwent unilateral decompression, and five bilateral decompression with a 6.3-ml resected volume of fat. Every patient main- tained a diplopia after surgery, which was suc- cessfully corrected by secondary oculomotor surgery.
In the group of 28 patients without pre- operative diplopia, 9 presented postoperative diplopia. Two of them had unilateral FROD, and seven bilateral FROD with a 7.4-ml volume of resected fat. In this group, four patients were treated successfully by prisms only, four were operated on, seven patients had no diplopia, one patient persistent diplopia and one was lost to follow-up. Finally 19 patients had no diplopia after surgery, including 8 with unilateral FROD and 11 bilateral FROD with an average of 7.5 ml of resected fat.
These data show no correlation between sur- gical volume, uni- or bilateral FROD, and the occurrence of postoperative diplopia.
Summary for the Clinician
∑ In 64 eyes operated on in 39 patients, FROD allowed significant proptosis reduction, visual field improvement, and IOP decrease
∑ Proptosis reduction was not correlated with the volume of resected fat, showing that the pressure/volume relationship is not linear in the orbit
10.5 Discussion 10.5.1
Types of Bone Removal Orbital Decompression (BROD) Performed
Various types of surgical bone removal orbital decompression have been performed over the years, but the most commonly used types of modern decompression are:
1. Lateral orbital decompression [12]
2. The two-wall decompression [13] and eth- moidal or antral ethmoidal decompression by various routes:
– The anterior translid approach – The outer canthus and fornix approach – The transantral approach [14]
– The endonasal approach is another possi- bility for removal of the medial orbital wall and varying amounts of the floor.
This approach is best performed by ENT surgeons.
In MacCord’s [15] survey of orbital decompres- sion, the two-wall decompression, antral-eth- moidal route was the most frequently per- formed procedure. Of the antral-ethmoidal decompressions, the transantral route was more effective than the translid route in the manage- ment of optic neuropathy because of its ability to decompress the posterior ethmoid.
In terms of dealing with optic neuropathy the equivalence of a transantral and a trans- frontal decompression (also a two-wall decom- pression) was shown by Gorman et al. [16]. Un- der experimental conditions these two same procedures were compared in terms of their ability to lower intraorbital pressure and were
found to be equally effective. Interestingly, bone removal was associated with pressure reduc- tion, whereas incision of the periorbita was as- sociated with proptosis reduction [17].
In three-wall decompression, lateral wall de- compression is added to antral-ethmoidal de- compression. This procedure is widely used in Europe in two different ways:
1. Using a small horizontal skin incision in the lateral canthus and a larger incision along the whole length of the inferior fornix, allow- ing the removal of the lateral wall, the floor medially to the infraorbital nerve, and the ethmoidal cells under the origin of the two ethmoidal arteries.
2. Using the coronal approach with a long skin incision from one tragus to the other behind the first rows of hair follicules. This approach allows a good view of the lateral and medial wall but sometimes needs an inferior fornix incision for the floor.
Described by Kennerdell [18], in the “four-wall decompression” the lateral wall portion of the three-wall decompression technique is extend- ed. In the Kennerdell decompression, a large portion of the sphenoid bone in the apex of the orbit and the lateral half of the orbital roof are removed, a process which invariably exposes dura.
The three- and four-wall decompressions have their greatest utility in the management of excessive proptosis.
10.5.2
FROD or BROD?
10.5.2.1
Proptosis Reduction
The average reduction in proptosis is similar in our study and in Olivari’s study [2], demonstrat- ing that FROD alone is efficacious in correcting proptosis. We did not find any correlation be- tween proptosis reduction and the volume of excised fat. In the three FROD series [2, 3, 11], the effect on proptosis was quite variable, despite a similar mean volume of excised fat; further
studies are necessary to determine other pre- dictive factors.
More interesting will be the study of the in- fluence on proptosis reduction of the volumes of the orbital bony compartment, the volume of the increased muscles, the volume of orbital fat and its relative proportion with the two previ- ous volumes.
10.5.2.2
Optic Neuropathy
Until recently, BROD was considered to be the only available surgical technique with which to address proptosis and optic neuropathy. In 1993, Garrity [18] reported results of 491 BROD in 428 patients. His study comprised 50 % of patients with optic neuropathy. Our study addressed the efficacy of FROD in reducing proptosis and im- proving the eyelid position. The size of the se- ries is too small to draw any conclusions regard- ing improvement of the visual function.
The visual field is impaired differently dur- ing optic neuropathy depending on the size of the muscles.
If the muscles are stretched and fat volume increased (Fig. 10.17), the visual field is impaired in its superior portion. If the muscles are en- larged at the apex (Fig. 10.18) with compressive neuropathy in this area, the visual field is im- paired centrally.
For patients with optic neuropathy, Rootman [19] and ourselves recommend steroids and retrobulbar irradiation before performing or- bital surgery when possible.
FROD reduces the IOP in patients with pre- operative IOP above 21 mmHg, even after un- successful prior treatment with b-blockers.As a hypothetical explanation of this finding, we postulate that FROD might reduce the down- stream venous pressure of the eye, which in turn might reduce the IOP.
Considering that FROD effectively reduces IOP in patients with a preoperative IOP above 21 mmHg, it might be indicated in Graves’ pa- tients with an elevated IOP threatening the op- tic nerve if the orbital volume is large and fat pad compartments enlarged.
10.5 Discussion 117
10.5.2.3
Palpebral Retraction
The results of FROD alone on palpebral retrac- tion are poor. Successful palpebral lengthening may be obtained with combined levator apo- neurosis weakening of the upper eyelid, and a cartilage graft on the lower eyelid.
10.5.2.4
Oculomotor Disorders
Oculomotor disorders subsequent to FROD were as follows: Three out of 23 patients (13 %) experienced a new diplopia, for which two (9 %) required orthoptic therapy. In Garrity’s study [20], 74 patients (17 %) had new diplopia and 300 (70 %) ultimately had surgery for strabis-
mus after BROD. As opposed to BROD, in which it is mostly the inferior and internal walls that are removed, FROD achieves fat removal all around the eye, in a circumferential fashion.
This might explain why FROD induces fewer ocular motility disturbances than BROD.
Summary for the Clinician
∑ Among BROD techniques, the three-wall and four-wall techniques are probably the most useful in the management of excessive proptosis
∑ FROD is probably best indicated in patients with large orbital volume and fat enlarge- ment
∑ BROD is probably best indicated in patients with small orbital volume and muscle enlargement
Fig. 10.17. MRI aspect of proptosis with stretched muscles and large fat volume compartment
Fig. 10.18. CT scan aspect of proptosis with small bony orbit enlarged muscles at the apex and small fat volume compartments
∑ Oculomotor and eyelid disorders can be treated together with FROD in a single procedure
10.6 Conclusion
FROD is efficacious in reducing proptosis in Graves’ ophthalmopathy. Although FROD alone fails to reduce palpebral retraction, significant palpebral lengthening can be achieved with combined section of the levator aponeurosis horns in the upper eyelid and/or a cartilage graft in the lower eyelid. FROD leaves the possi- bility of concomitant palpebral and/or oculo- motor surgery.
Further studies are necessary to determine which procedure, FROD or BROD, or combined surgery, should be performed initially, depend- ing on the clinical presentation, radiologic find- ings, and previous treatments.
However, our impression is that FROD is better indicated in patients:
∑ With large bony orbital content, large orbital fat volumes and stretched muscles.
∑ With cosmetic “grotesque” disability On the contrary BROD is better indicated in patients:
∑ With small bony orbital volume, small orbital fat volumes and enlarged muscles
∑ With compressive optic neuropathy
Finally combined FROD and BROD techniques can address nearly all the indications of orbital decompression as a first choice.
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