Otolaryngology online Proptosis Balasubramanian Thiagarajan

Otolaryngology online

Proptosis

Balasubramanian Thiagarajan


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


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


Difference between proptosis / exophthalmos


Anatomy of orbit

Volume of orbit is fixed 30 ml Increase in soft tissue

volume of 5 ml will cause 5 mm of proptosis


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


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


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


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


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


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


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.


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.


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


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


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


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.


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


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


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


Pseudoproptosis

High myopia Enophthalmos of one eye may cause apparant

proptosis of the other one


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


ENT - Causes

Mnemonic – VEIN

V – Vascular causes

E – Endocrine causes

I – Inflammatory causes

N – Neoplastic causes


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


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


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


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


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


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


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


Neoplastic lesions involving nose and sinuses

Inverted papilloma Fungal infections Mucoceles of paranasal sinuses Fibrous dysplasia of maxilla Osteomas involving frontal / ethmoidal sinuses JNA



Management

Low dose irradiation (rarely used) Surgery


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


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


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


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


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


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


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


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


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.


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


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


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


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


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


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


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


Thank You

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Otolaryngology online Proptosis Balasubramanian Thiagarajan