Optic nerve decompression with optic nerve.pdf

optic nerve decompression

1. Orbital & Optic nerve
decompression

2. INTRODUCTION
●walls of each orbit
●lacrimal,
●ethmoid,
●zygomatic,
●palatine,
●frontal,
●sphenoid,
● maxillary bones

4. ●The medial wall is composed of the lacrimal, ethmoid,
maxillary, and lesser wing of sphenoid bones.
●The lateral wall is made of the zygomatic and greater wing
of sphenoid bones.
●The roof is derived from the frontal and lesser wing of the
sphenoid bones.
●The floor comprises the palatine, maxillary, and zygomatic
bones.

5. ●The orbit is surrounded by
●the maxillary sinus inferiorly,
●ethmoid sinus medially,
●brain superiorly,
●temporalis muscle temporally.

6. ●All of the orbital walls have a curvilinear shape that serves as a
cushion against blunt forces.
●Connective tissue and orbital fat that surround the extraocular
muscles provide additional protection to the orbital contents.
●The main lacrimal gland is present near the superior lateral portion
of the orbital roof and the accessory lacrimal gland is found within
the lamina propria of the conjunctiva.
●Their secretory products include tears, which lubricate the eye and
maintain the proper microenvironment for ocular function.

7. Blood Supply

The major artery within the orbit is the ophthalmic
artery, which branches from the internal carotid
artery .

branches include the

central retinal artery (retina),
lacrimal artery (eyelids, lacrimal gland, superior
cheek, conjunctiva),
superior and inferior muscular arteries (superior
rectus, superior oblique, inferior rectus, medial
rectus).

8. The inferior orbital fissure transmits
the infraorbital artery, a branch of the maxillary
artery,
infraorbital vein, which drains into the pterygoid
plexus.
the infraorbital nerve within the orbit before
exiting through the infraorbital foramen.

superior orbital fissure
The superior ophthalmic veins
ophthalmic artery ,

9. Lymphatic drainage of the orbital and periorbital
regions have differing descriptions within the
literature. For many years, the orbit was believed to
have sparse drainage; however, new findings
support greater lymphatics within the area,
particularly in the lacrimal gland.
Lymphatics

11. Nerves supply

Cutaneous innervation to the maxillary region of the face is provided by the infraorbital nerve, a branch
of the maxillary division of the trigeminal nerve.

The superior orbital fissure serves as a channel for cranial nerves (CN) III (oculomotor), IV (trochlear),
V1 (ophthalmic branch of trigeminal), and VI (abducens).
CN III provides innervation to the superior rectus, medial rectus, inferior rectus, and inferior oblique
muscles.
CN IV innervates the superior oblique muscle and
CN VI innervates the lateral rectus muscle.
Sensation to the upper face, mucous membranes, and scalp is supplied by the ophthalmic branch of
the trigeminal nerve.

Slightly medial to the superior orbital fissure lies the optic canal, through which the optic nerve (CN II)
transmits visual input from the retina to the central nervous system.

12. The orbicularis oculi

muscle is a broad, flat muscle that encircles the orbit and serves to
close the eyelids and compress the lacrimal sac.
The muscle may be divided into the orbital, palpebral, and lacrimal
part.
Just beneath the orbicularis oculi is a membranous sheet extending
from the periosteum called the septum orbitale.
This layer attaches to the rim of the orbit and plays a role in reducing
the spread of infection.
Past the septum orbitale lie muscles attaching to the tarsus, which are
thick pads of dense connective tissue within the lid margins.
The aponeurosis of the levator muscle in the upper lid attaches to the
tarsus near the lid margin.
Deep to this aponeurosis lies the inferior tarsal muscle (Mueller’s
muscle) that attaches to the capsulopalpebral fascia and inserts into
the tarsus.
In the lower lid, the inferior rectus fascia connects to the orbicularis
oculi muscle, inferior tarsus, and subcutaneous tissues.

13. ●superior rectus,
●inferior rectus,
●lateral rectus,
●medial rectus,
●superior oblique,
●inferior oblique,
●levator palpebrae superioris
●
● Except for the inferior oblique, all other extraocular muscles
originate at the annulus of Zinn.
●
extraocular muscles

14. ENDOSCOPIC ORBITAL DECOMPRESSION
●Orbital decompression is a surgical procedure that is used
to treat exophthalmos.
● Orbital decompression involves careful removal or thinning
of the orbital walls (and orbital fat)
●Decompression can be customized according to the
severity of proptosis, along with considerations for
functional and cosmetic requirements.
●In some cases, the increase in orbital contents places
pressure on the optic nerve and surrounding vasculature,
leading to exposure keratopathy, optic neuropathy, and
other visual disturbances.

15. INDICATIONS

Orbital cellulitis
Developmental anomalies
Primary or metastatic neoplasm
Metabolic disease
Thyroid eye disease
Cavernous sinus thrombosis
Orbital myositis
Metastatic neuroblastoma
Obesity-related increase in orbital fat
Cushing’s syndrome
Idiopathic orbital inflammation (Orbital Pseudotumor)
Vascular structural abnormalities (such as aneurysm, fistula (Carotid Cavernous Fistula), thrombosis)
Infiltrative/Autoimmune disorders (such as IgG4 Disease)
Physiologic Asymmetry of the orbits
Asymmetric axial orbital length
Contralateral enophthalmos (due to blow out fractures, scirrhous tumors)
compressive optic neuropathy,
exposure keratitis,
diplopia,
cosmesis.
Both external and intra-nasal decompression

16. Pre-operative evaluation
ophthalmology examination
●evaluation of the degree of proptosis,
●assessment of eye movements and
●diplopia, measurement of visual acuity, and
●colour vision.
●Preoperative consent must include discussion of risks
including permanent double vision and need for
strabismus surgery.

17. Surgical procedure
●Perform a maxillary antrostomy, complete ethmoidectomy
and sphenoidotomy
●During sinus surgery, it is important to completely resect
the uncinate process.
●In addition, we advocate resection of the middle turbinate
for improved exposure and decreased risk of adhesions.
●During dissection, special attention should be made to
identify all ethmoid cells have been removed along the
lamina papyracea.
●The maxillary antrostomy should be as large as possible
to allow for ideal exposure during decompression.

18. Resection of medial orbital wall bone
●The orbital wall should be penetrated in a controlled fashion.
Typically a j-curette or Freer elevator can be used.
●The fragments can be freed from the periorbita with the j-curette or
Freer elevator and subsequently removed with Blakesley forceps.
●All bone should be resected
●superiorly up to the ethmoid roof,
●inferiorly to the orbital f loor,
●anteriorly to the maxillary line
●posteriorly to the face of the sphenoid sinus

19. Down fracture of the orbital floor
● Start by elevating the periorbita off the medial orbital f loor.
● Use a spoon curette to down fracture the medial aspect of the
orbital floor.
●The bone of the orbital floor is significantly thicker than the
medial orbital wall and requires increased force.
●The bone often fractures in one large piece at the infraorbital
canal junction.

20. Incision of periorbita
●The incision should begin at the posterior limit of the decompression
and follow a posterior to anterior direction to prevent prolapsing orbital
fat from obstructing visualization.
●A series of parallel incisions should be made in this fashion. In patients
without optic neuropathy, a fascial sling can be left in place overlying
the medial rectus to prevent diplopia.
●17 A curved seeker can be used to gently dissect the remaining fibrous
bands between fat lobules.

21. Prolapse of orbital fat into maxillary and ethmoid sinuses
●If done completely, a significant amount of fat will prolapse in the
sinuses.
●The eye may be balloted to confirm fat herniation and allow further
prolapse

22. 1.Hemorrhage, infection, surgical failure


Complications
2. Periorbital ecchymosis

Though rarely caused by surgical interventions, capillaries may be
stretched during orbital procedures, leading to blue or purple
discoloration of the eyelids.
3. Edema

Postoperative orbital swelling is typically considered inflammatory
in origin, but other diagnoses should be considered as failure to
treat may lead to loss of vision or life.

23. 4. Vision loss

Some common causes:

excessive traction on the globe and
optic nerve,
contusion of the optic nerve,
infection,
hemorrhage
5.Sinusitis

Orbital fat may herniate and block the
maxillary sinus ostium.
The frontal sinus is less commonly
involved in postoperative sinusitis.

24. 6.Cerebrospinal fluid leak

Reports of CSF leakage are rare.
Beta-2-transferrin presence is the gold standard in CSF leakage
diagnosis.
7. Trigeminal nerve hypoesthesia

Most, if not all patients report temporary injury to the peripheral
branches of the trigeminal nerve, particularly the V1 and V2
divisions.
For some, hypoesthesia remains a permanent complication

25. 8. Diplopia

Postoperative onset of diplopia ranges, but is typically reported in
the range of 15%-25% Visual Field Defects
9.Supraorbital anesthesia

Fat decompression can has been shown to produce supraorbital
anesthesia in 1.5-6%.
This complication can be reduced by minimizing dissection in the
superomedial orbit or avoiding extraconal fat resection
Temporal Wasting

26. Outcome and Prognosis

●Orbital decompression surgery is a viable treatment modality for some
patients with proptosis.
●However, the aggregate consensus is a favorable outcome with a marked
potential for reducing proptosis.
●Postoperative resolution of diplopia associated with proptosis ranged in
some studies from moderate (20-30%) to as high as 90%.

27. Optic Nerve Decompression
●Optic nerve sheath decompression, more commonly known as
optic nerve sheath fenestration (ONSF).

●surgical procedure performed to decompress the optic nerves
by creating a window in the optic nerve sheath to release CSF
from the subarachnoid space around the optic nerve.

28. indication
●Traumatic optic neuropathy
●Benign or malignant tumours of the skull base
●Meningiomas
●Benign fibro-osseous lesions or sinonasal tumours
●PTC syndrome, cerebral venous sinus thrombosis, and intracranial
tumors
●papilledema

29. PRE-OPERATIVE CONSIDERATIONS
●ophthalmologic history and physical
examination
●CT scan
●MRI

30. PROCEDURE
●Perform a posterior
ethmoidectomy with a
wide antrostomy; for less
experienced surgeons it
is best to perform a
complete ethmoidectomy
and expose the lamina
papyracea

31. Perform a wide sphenoidotomy
with the anterior sphenoid wall
resected to the skull base and to
the lamina papyracea; this helps
one to identify the orbital axis
and orbital apex

32. ●The easiest and safest way to achieve this is to
resect the lamina papyracea posteriorly,
starting 10-15mm anterior to the face of the
sphenoid
●One can sometimes remove the lamina
papyracea with a Freer elevator, but if it is too
thick, then a high-speed drill is first used to thin it
to an egg-shell thickness
●Take care not to injure the periorbita and the
underlying extraocular muscles; if the periorbita
are injured, fat protrudes into the field of view; it
is safe to carefully bipolar small pieces of fat
Identify the orbital apex and optic canal

33. After the posterior lamina papyracea has
been removed, follow the periorbita
posteriorly to where they converge at the
orbital apex; the thick bone between
posterior ethmoid and sphenoid is known as
the optic tubercle
The Annulus of Zinn is attached to the
superior, inferior and medial margins of the
orbital junction with the optic canal and can
be identified after complete resection of the
lamina papyracea at the level of the optic
tubercle

34. Identify the bony protrusion of the
optic canal in the sphenoid sinus; it is
a continuation of the optic tubercle
Use a diamond burr attached to a
highspeed drill or a powered
endonasal handpiece to thin the
bone down to an egg-shell
thickness

35. Incise the optic nerve sheath along the
optic nerve and through the Annulus of
Zinn. Place the incision(s) at the
superomedial quadrant, as the
ophthalmic artery is located in the
inferomedial quadrant of the optic
canal

36. Postoperative care: Instruct the patient to
irrigate the nose with saline and corticosteroid
drops. The authors advocate systemic
antibiotics while the packing is in place (in the
absence of a CSF leak)
Pack the nose and surgical cavity with
haemostatic material; in case of bleeding,
lightly pack the nose with sponges. Remove
the packing on Day 1 or 2 .

37. POST-OPERATIVE CONSIDERATIONS

●Close communication with the ophthalmologic team is critical.
●They will aid in serial eye examination and help guide the
generally required high dose oral steroids.
●Additionally, antibiotics and gentle saline rinses are
recommended.
●To minimize intra-conal pressures, nasal packing is not utilized
following the procedure, and the patient should be instructed on
avoiding nose blowing and straining post-operatively.