Proptosis Causes and Diagnosis

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


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 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.


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 online cover orbital roof
Otolaryngology
to

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 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

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


Proptosis Causes and Diagnosis

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