Proptosis

1. Balasubramanian Thiagarajan Proptosis Otolaryngology online

2. Otolaryngology online Definition • Proptosis is defined as abnormal protrusion of eye ball • If protrusion of globe is 18 mm / less it is known as proptosis • If protrusion of globe is more than 18 mm it is known as exophthalmos • Proptosis + lid lag = exopthalmos

3. Otolaryngology online Exorbitism • This is caused due to decrease in the volume of orbit causing the orbital contents to protrude forwards • Usually bilateral • Should be differentiated from proptosis / exophthalmos

4. Otolaryngology online Difference between proptosis / exophthalmos

5. Otolaryngology online Anatomy of orbit • Volume of orbit is fixed • 30 ml • Increase in soft tissue volume of 5 ml will cause 5 mm of proptosis

6. Otolaryngology online Anatomy of orbit - 2 • Resembles a four sided pyramid • Rim is 40 mm horizontally and 35 mm in an adult male • Medial walls are parallel and 25 mm apart in adults • Lateral orbital walls angle about 90 degrees from each other

7. Otolaryngology online Orbital rim • Superior orbital rim is formed by frontal bone • Inferior rim is formed by maxillary bone medially and zygomatic bone laterally • Lateral orbital rim is formed by zygoma • Superior rim contains a notch at the junction of medial and lateral thirds (supraorbital notch) • Medial portion of the rim is formed by frontal process of maxilla

8. Otolaryngology online Lacrimal fossa • Lodges the lacrimal sac • This fossa is formed by maxillary and lacrimal bones • Bounded by anterior and posterior lacrimal crests • Anterior crest is formed by maxillary bone • Posterior lacrimal crest is formed by lacrimal bone

9. Otolaryngology online Weber's suture • Lies anterior to lacrimal fossa • Also known as sutura longitudinalis imperfecta • This suture runs parallel to anterior lacrimal crest • Infraorbital nerve artery branches pass through it to supply nasal mucosa • Bleeding occurs from these vessels during lacrimal sac surgeries

10. Otolaryngology online Embryology • 7 bones involved in the formation of orbit are derived from neural crest cells • Ossification of orbit is complete at birth excepting its apex • Lesser wing of sphenoid is cartilagenous • Other bones undergo membranous ossification

11. Otolaryngology online Orbital roof • Formed by frontal bone • Posterior 1.5 cms of the roof is formed by lesser wing of sphenoid • Optic foramen contains optic nerve • Optic nerve enters orbit at an angulation of 44 degrees • Lacrimal gland is located at the lateral end of orbital roof

12. Otolaryngology online Medial orbital wall • Formed by frontal process of maxilla, lacrimal bone, ethmoidal bone and lesser wing of sphenoid • Thinest portion of medial wall is the lamina papyracea • It separates orbit from the nasal cavity • Infections from ethmoidal sinuses can breach this bone and spread into the orbit.

13. Otolaryngology online Medial wall of orbit applied anatomy • Lacrimal bone at the level of lacrimal fossa is very thin • This bone can easily be penetrated during endoscopic DCR • If the maxillary component is predominant then it is really difficult to breach this bone during endoscopic DCR since this bone is rather thick.

14. Otolaryngology online Fronto ethmoidal suture line • Very important surgical landmark • Marks the approximate level of ethmoidal roof • Dissection above this line will expose the cranial cavity • Anterior and posterior ethmoidal foramina are present in this suture line • Anterior and posterior ethmodial arteries pass throught these foramina

15. Otolaryngology online Orbital roof • Roof of orbit is formed by frontal bone • Posterior 1.5 cm of roof is formed by lesser wing of sphenoid • Optic foramen is located in the lesser wing of sphenoid

16. Otolaryngology online Floor of orbit • It is the shortest of all the walls • Bounded laterally by infraorbital fissure • Medially bounded by maxilloethmoidal strut of bone • Almost entirely formed by orbital plate of maxilla with minor contribution from orbital plate of palatine bone posteriorly • Floor is thin medial to infra orbital groove • Infraorbital groove becomes infraorbital foramen anteriorly

17. Otolaryngology online Lateral wall • Formed by greater wing of sphenoid • Zygoma & zygomatic process of frontal bone – minor contribution • Recurrent meningeal branch of middle meningeal artery is seen in this wall • 4-5 mm behind the lateral orbital rim and 1 cm inferior to the fronto zygomatic suture line lie the whitnall's tubercle.

18. Otolaryngology online Whitnall's tubercle (structures attached) • Lateral canthal tendon • Lateral rectus check ligament • Suspensory ligament of lower eyelid (Lockwood's ligament) • Orbital septum • Lacrimal gland fascia

19. Otolaryngology online Anatomical relationship of orbit with paranasal sinuses • By its location – it is closely related to all paranasal sinuses • By venous drainage – Both these areas share a common venous drainage

20. Otolaryngology online Peculiarities of orbital venous drainage • Entire venous system is devoid of valves – hence two way communication between orbit and sinuses is a reality • Superior opthalmic vein connects facial vein to cavernous sinus – causing spread of infections from face to cavernous sinus • Inferior ophthalmic vein communicates with pterygoid venous plexus and cavernous sinus by its two branches

21. Otolaryngology online Pseudoproptosis • High myopia • Enophthalmos of one eye may cause apparant proptosis of the other one

22. Otolaryngology online Exophthalmometer • Hertel's mirror exophthalmometer is used for this purpose • The distance between the lateral orbital rim and the corneal apex is used as a measure for proptosis • This distance is normally 18 mm

23. Otolaryngology online ENT - Causes • Mnemonic – VEIN V – Vascular causes E – Endocrine causes I – Inflammatory causes N – Neoplastic causes

24. Otolaryngology online Imaging • CT / MRI may help in identifying the cause • Fat in the orbit serves as a contrast medium • 3 mm cuts is ideal • Ultrasound – A mode / B mode can be done to identify the cause

25. Otolaryngology online Role of MRI • MRI is sensitive in identifying extraocular muscle oedema • Increased T2 relaxation time indicates extraocular muscle oedema, these pts respond well to steroid therapy • Patients with normal T2 relaxation levels need orbital decompression

26. Otolaryngology online Vascular causes • Classified into arterial and venous • Venous causes are due to dilated veins – Positional proptosis is the classical feature in these patients. It can also be induced by valsalva maneuver • Initially there may be atrophy of fat in these pts causing enophthalmos • CT scan after jugular vein compression is diagnostic • Surgery is disastrous in these patients. Conservative management is the best modality

27. Otolaryngology online Proptosis due to dural venous sinus fistula • Shunt is low flow type • Proptosis is insidiuous and often goes unnoticed • A high index of suspicion is necessary to diagnose these cases

28. Otolaryngology online Carotid cavernous fistula • High flow shunts • Can occur spontaneously / trauma • Subjective bruit / proptosis / chemosis / vision loss • Arterolization of conjunctival vessels causing corkscrew pattern • Intractable cases – shunt must be closed using balloon / carotid artery ligation

29. Otolaryngology online Endocrine proptosis - features • Presence of lid lag / retraction • Presence of temporal flare in upper eyelid • Presence of orbital congestion • Imaging shows enlarged extraocular muscles, bulging of orbital septum due to fat protrusion

30. Otolaryngology online Inflammatory causes • Idiopathic inflammation – Pseudotumor of orbit • Due to specific causes of orbital inflammation • These pts have pain during ocular movement • Associated dacryo adenitis + • Perioptic neuritis can cause blindness • Steroids may be helpful

31. Otolaryngology online Neoplastic lesions involving nose and sinuses • Inverted papilloma • Fungal infections • Mucoceles of paranasal sinuses • Fibrous dysplasia of maxilla • Osteomas involving frontal / ethmoidal sinuses • JNA

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33. Otolaryngology online Management • Low dose irradiation (rarely used) • Surgery

34. Otolaryngology online Indications for orbital decompression • Visual disturbance due to proptosis • Failure of steroids to improve vision • If steroids are necessary on a long term basis for maintaining vision • To preven exposure keratitis • Diplopia • Cosmesis

35. Otolaryngology online Risks of orbital decompression • Diplopia • Intractable strabismus • Hypoglobus • Injury to optic nerve due to prolonged globe retraction • Retrobular hematoma – this can cause blindness • Injury to infraorbital nerve • Epistaxis

36. Otolaryngology online Orbital decompression (Goals) • To enlarge the confining space of orbit by removing 1-4 of its walls • 15 mm of decompression can be achieved by removing all 4 walls of the orbit • Usually successful surgery causes 3-7 mm decompression of orbit

37. Otolaryngology online Superior orbital decompression • Naffzeiger technique • Superior wall decompression • Complete unroofing of orbit – frontal craniotomy • Large amounts of bone can be removed creating more space • Craniotomy may be needed • Used in pts with orbital trauma

38. Otolaryngology online Naffzeiger --- Contd • In collaboration with neurosurgeon • Optic nerve should be visualized to begin with • The roof of the orbit is removed starting from the optic foramen to the anterosuperior orbital rim • Periosteum should be left intact to prevent injury to levator muscle • H shaped incision is made over superior periosteum allowing orbital fat to prolapse through it • Titanium mesh can be used to cover orbital roof

39. Otolaryngology online Medial orbital decompression • Also known as Sewell procedure • Coronal incision / external ethmoidectomy incision • Medial canthal tendon is identified and divided • Anterior and posterior ethmoidal arteries identified and clipped • Complete ethmoidectomy is performed starting from lacrimal fossa

40. Otolaryngology online Bicoronal incision for medial orbital decompression • Medial canthal tendon can be left intact • Ethmoidectomy is performed from above • Lacrimal sac and trochlea should not be damaged • Medial periosteum is incised and orbital fat is allowed to prolapse into the nasal cavity

41. Otolaryngology online Inferior decompression • Hisch and Urbanek procedure • Artificial creation of blow out fracture of orbital floor sparing infra orbital nerve • Trans conjunctival / subciliary incision plus Caldwell Luc procedure • Laterally floor can be removed up to zygoma and medially up to lacrimal fossa • Posteriorly bone is thick – 3 cms of bone can be removed from this area

42. Otolaryngology online Inferior decompression -- Contd • Periosteum is incised to allow orbital fat to prolapse into the maxillary antrum • Forced duction test should be performed to ensure orbital muscles are not entrapped.

43. Otolaryngology online Lateral decompression • Kronlein procedure • Coronal incision, and lateral extension of subciliary incision • Extended lateral canthotomy • Lateral orbital rim periosteum is exposed from zygomatic arch to zygomatico frontal suture • Periosteum incised along lateral orbital rim and orbital fat is teased out

44. Otolaryngology online Combination of approaches • Any of the above said approaches can be combined for optimal benefit • Combination of apporaches reduces the surgical risk and provides more increase of space than one procedure alone

45. Otolaryngology online Endoscopic decompression • Inferior and medial orbital walls can be accessed easily using nasal endoscope • A large middle meatal antrostomy is performed – 30 degree endoscope is used to identify the position of inferior orbital nerve in the roof of maxillary sinus • Total ethmoidectomy is performed • Sphenoid osteum is identified and enlarged

46. Otolaryngology online Endoscopic decompression ---Contd • Lamina papyracea is exposed • Position of anterior & posterior ethmoid arteries noted • If middle turbinate is resected it helps in post op cleaning. If left behind it prevents excessive collapse of orbital fat • Lamina papyacea is remove bit by bit using Freer's elevator. It should be cracked in the middle portion first

47. Otolaryngology online Endocopic decompression --- Contd • Initially periorbita is left intact to prevent orbital fat prolapse which could obstruct vision • Bone is to be removed up to the roof of the ethmoid superiorly, face of the sphenoid posteriorly, the nasolacrimal duct anteriorly. • Inferiorly it can be removed up to maxillary antrostomy • Small piece of bone is retained over frontal recess area to prevent orbital fat obstruction frontal sinus drainage

48. Otolaryngology online contd • Starting posteriorly periorbita is incised • Sickle knife is kept superficial to avoid injury to extraocular muscles • Mutliple cuts are made in the periorbita allowing orbital fat to prolapse into the nasal cavity • Exophthalmos of up to 3.5 mm can be corrected by endoscopic decompression • Nasal packing is to be avoided to prevent optic nerve compression

49. Otolaryngology online Tips • Nose blowing is to be avoided for 2 weeks following surgery • Bilateral decompression should be done within an interval of a week • For mild exophthalmos 2-3 mm any of the approaches would suffice • For moderate – 3-5mm inferior decompression is sufficient • For severe ones – 5-7 mm three wall decompression is preferred

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