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ENT Secrets > Chapter 30 - Orbital Surgery > Flashcards

Chapter 30 - Orbital Surgery Flashcards

1
Q

Most common cause of proptosis in adults

A

Thryoid eye disease

Is also most common extra-thyroid manifestation of graves disease

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2
Q

7 bones of orbit

A

lesser wing sphenoid, frontal (roof), maxillary, palatine, zygomatic (floor), ethmoid, maxillary, lacrimal, sphenoid (medial wall), zygomatic, greater sphenoid (lateral)

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3
Q

Orbit dimensions

A

30mL

Entrance height 35mm, width 40mm

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4
Q

Optic foramen

A

through lesser wing of sphenoid from MCF to orbital apex

Contains CN II, ophthalmic a, SNS from carotid plexus

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5
Q

Supraorbital foramen

A

medial third superior margin rim

Supraorbital n/a/v

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6
Q

Anterior ethmoid foramen

A

frontoethmoidal suture
24mm posterior to rim
anterior ethmoid vessels/nerve

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7
Q

Posterior ethmoidal foramen

A

12mm posterior to ant ethm foramen, jxn medial wall/roof

posterior ethmoid vessels/nerve

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8
Q

24/12/16 rule

A 
Anterior ethmoid artery (24mm)
Posterior ethmoid (12mm)
Optic nerve (6mm) in sequential measurements from posterior lacrimal crest
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9
Q

Two foramen in lateral wall of orbit

A

Zygomaticotemporal/facial

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10
Q

Nerves going through Sup and Inf portions of SOF

A

Sup: frontal, lacrimal br V1, IV

Inf: III, nasociliary V1, VI, SOV, SNS

División vía lateral rectus

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11
Q

Nerves through IOF

A

V2 branches

IOV

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12
Q

One EOM not originating at apex

A

Inferior oblique - originates from shallow depression in orbital plate of maxillary bone

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13
Q

Blood supply to EOM

A

Ophthalmic, lacrimal, infraorbital

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14
Q

Blood supply to eye

A

Ophthalmic branches (central retinal, lateral/medial posterior ciliary, lacrimal, muscular, supraorbital, A/P ethmoid, suprateochlear, nasofrontal, dorsonasal aa

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15
Q

Orbital anastomoses between ECA, ICA

A

Lacrimal a, transverse facial/STA

Dorsonasal, angular

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16
Q

Infraorbital a is branch of?

A

Maxillary a

17
Q

Describe venous drainage of orbit

A

IOV … pterygoid plexus…SOV…Cav Sinus

SOV originates sup/med, crosses midorbit below sup rectus, joined by lacrimal v

18
Q

Anatomy of lacrimal gland

A

8-13 ductules into fornix

Accessory lacrimal glands (for basal tearing) in eyelid…papillae medal posterior lid, lead to lacrimal sac

19
Q

Valve of rosenmuller

A

Medial end of common canaliculus (tract from accessory gland upp/low eyelid, prior to entering sac), to prevent tear reflux

20
Q

Advantages of endoscopic DCR

A

Preserve orbic pump mechanism
Better anatomy preservation (medial canthus)
Dec bleed

21
Q

Main Indication for DCR

A

Epiphora

22
Q

Causes of epiphora

A

NLDO

infxn, stone, tumors, other obstruction

23
Q

How to Dx NLDO

A

Dye disappearance test
Lacrimal irrigate/probe
Scintigraphy
Contrast dacryocystography

24
Q

Importance of maxillary line in DCR

A

Corresponds to suture between frontal process maxilla, lacrimal bone

Landmark for lacrimal sac, uncinate, superior attach middle turb

25
Q

How to do DCR

A

Sickle knife for mucosal flap over lacrimal sac

Remove lacrimal bone and frontal process maxilla to expose medial lacrimal sac

Incise and marsupialize sac into nasal cavity, silicone intubation stent

26
Q

Pathogenesis thyroid eye disease

A

TSH receptor autoantigen in eye
Fibroblasts, adipocytes
Cytokine-mediated immunologic Response
Tissue inflammation, hypertrophy

27
Q

Sx of thyroid eye disease

A

Blurry, FB sensation, photophobia, tear, diplopia, dull pain, discomfort

Eyelid retract (90%), periorbital ST swell, lid lag, lagophthalmos, conj inject, exposure keratopathy, restrictive myopathy, exophthalmos, optic neuropathy

28
Q

imaging findings graves opthalmopathy

A

Fusiform enlargement EOM

May see optic nerve compression (MRI)

29
Q

Conservative Tx TED

A

Self-limited 80%

Ocular lubrication, cool compress, sunglasses
Thyroid meds
Steroids if active
Rads, immumod

30
Q

Indications for surgery TED

A

Compressive optic neuropathy, exposure keratopathy, disfigure proptosis
Diplopia common presentation

Orbital Decom Stage 1
Then strabismus surgery
Then eyelid

31
Q

Optic nerve anatomy and segments

A

Covered by dura
Intraocular, orbital, canalicular, cranial

Optic canal formed by lesser wing sphenoid, travels with ophthalmic a

32
Q

When to do surgery: indirect vs direct traumatic optic neuropathy

A

Indirect (neuropathy due to anything but the actual traumatic force), however medical management may suffice (systemic steroids), definitely consider surgery if incomplete vision loss and fail steroids

Direct is from penetrating trauma injuring nerve

33
Q

How to access orbit for decompression

A

Intranasal

Transconj

ENT Secrets (79 decks)

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