Proptosis

Balasubramanian Thiagarajan 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 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 Otolaryngology online

Difference between proptosis / exophthalmos

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Anatomy of orbit

 Volume of orbit is fixed  30 ml  Increase in soft tissue volume of 5 ml will cause 5 mm of proptosis 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 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 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 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 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 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 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.

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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.

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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 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 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 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.

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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 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 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 Otolaryngology online

Pseudoproptosis

 High myopia  Enophthalmos of one eye may cause apparant proptosis of the other one 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 Otolaryngology online

ENT - Causes

 Mnemonic – VEIN V – Vascular causes E – Endocrine causes I – Inflammatory causes N – Neoplastic causes 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 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 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 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 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 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 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 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 Otolaryngology online

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Management

 Low dose irradiation (rarely used)  Surgery 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 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 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 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 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 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 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 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 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.

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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 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 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 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 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 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 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 Otolaryngology online

Thank You

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