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Orbital complications of Endoscopic Sinus Surgery
Dr. T. Balasubramanian M.S. D.L.O.
Functional endoscopic sinus surgery is known to cause various complications involving the orbit due to its proximity to ethmoidal sinus. Orbit is separated from the nasal cavity by a paper thin bone known as lamina papyracea which can be easily breached during endoscopic sinus surgery.
Various orbital complications of FESS include:
Orbital hematoma: This complication is usually caused due to inadvertent breach to lamina papyracea. This complication can occur irrespective of the status of Periorbita. It should be borne in mind that the risk of orbital hematoma quadruples with penetration of Periorbita. Ecchymosis can occur due to breach involving the lamina papyracea. This occurs irrespective of breach of Periorbita.
Differences between ecchymosis and orbital hematoma:
Blindness: This is a disaster following FESS. It should be considered as a surgery grossly gone wrong. Blindness could be temporary or permanent.
Temporary blindness: Is caused by increasing orbital pressure due to orbital hematoma. This increased orbital pressure compromises the vascular supply to the optic nerve which is highly sensitive to ischemia. Studies have shown that increased intraocular pressure gradually returns to normal within a couple of hours. Light perception may not return to normal for several more hours. Pupillary reflexes may take up to 2 days to recover.
Permanent blindness: In blindness caused by retrobulbar and retro orbital hematoma, the retina can tolerate extreme ocular pressures only for a couple of hours. Intervention if any should take place within this time window. This time limit is true only for venous hematoma. If the hematoma is caused due to arterial bleed, this window gets reduced to half an hour. Any damage to the retina and optic nerve becomes irreversible after this window elapses; hence this “light window” should always be borne in mind before embarking on surgical decompression procedures.
Any complication is better prevented than cured. Patients who undergo endoscopic sinus surgery should be carefully examined for evidence of bleeding diathesis, history regarding intake of aspirin should be sought before surgery. Enquiries regarding pre existent eye problems like diabetic retinopathy and glaucoma should be sought prior to surgery.
A right handed surgeon is more prone to cause damage to left orbit because of the anatomical illusion on the left side. The left ethmoidal sinuses are actually more medial than appreciated by the right handed surgeon.
Bulb press test:
Video showing Bulb press test
In arterial hematoma intervention should be immediate. Intravenous mannitol should be started immediately to reduce intraocular pressure. Mannitol is administered in doses of 1-2 g /kg in a 20% infusion. Orbital massage and administration of heavy doses of steroids can be resorted to. Steroids i.e. Dexamethazone should be administered in doses of 1 – 1.5 mg /kg in divided doses in a day. If not successful then endoscopic decompression of orbit / ligation of bleeding vessels / lateral canthotomy may be resorted to.
In cases of venous bleed, the management regimen is pretty same but surgical urgency is not necessary.
Diplopia – (double vision) this is caused by injury to ocular muscles closely related to the paranasal sinuses. These muscles are the medial rectus and the superior oblique. The medial rectus lies lateral to the Periorbita at the centre of lamina papyracea. This muscle is commonly involved during FESS. The superior rectus muscle is placed high in the orbit just lateral to the ethmoidal roof. Anatomically this muscle is difficult to be reached from intranasally.
Unintentional injection of local anesthetics in to the orbit via lamina papyracea may cause transient diplopia due to paralysis of medial rectus.
Nasolacrimal duct injury: