Endoscopic anatomy of lateral wall of sphenoid sinus
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Endoscopic anatomy of lateral wall of sphenoid sinus
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Endoscopic anatomy of lateral wall of sphenoid sinus
- 1. ENDOSCOPIC ANATOMY OF LATERAL WALL OF SPHENOID SINUS & TNESSS Dr. Ankit Choudhary PGT M.S. (ENT) IPGME & R & SSKM Hospital
- 12. ENDOSCOPIC ANATOMY & TNESS • Sphenoid ostium is visualised in 2nd pass. • Endoscope is passed upwards medial to middle turbinate. • Spheno-ethmoidal recess is visualised between superior turbinate laterally and septum medially. • Sphenoid ostium opens into the spheno-ethmoidal recess 1-1.5cm above the roof of choana. • Ostium may be round, oval, slit like or even pin-point. • Below the ostium, at the roof of the choana lies the Woodruff’s plexus. • Septal branch of Sphenopalatine artery runs across anteroir wall of sphenoid in this region.
- 14. APPROACH TO SPHENOID SINUS • Paraseptal approach • Intermediate approach • Lateral approach • Endoscopic Transnasal with Posterior Septectomy
- 19. REVISION CASES • Superior Turbinate is most reliable when middle turbinate is excised (2 cm behind it) • 1-1.5 cm above Roof of Choana • Ostia lies below the Imaginary line drawn along Medial Orbital floor • Bow Sign/ Bird Beak sign after posterior Septectomy (Bowing of Anterior Sphenoid wall along with Rostrum is seen)
- 20. INDICATIONS • Reccurent Sphenoidal sinusitis not responding to maximal medical management • Fungal Sinusitis • Polyp • Mucocele • Skull Base Procedures
- 21. PRECAUTIONS • Ostium is always dilated Inferiomedially first and then on other sides under proper visualisation • Care must be take for dehiscent Optic or ICA • No sharp instruments should be used which may cause inadverent trauma to lateral or posterosuperior wall • Septations to be trimmed with precision with tru cut to prevent any injury to surrounding structures • Proper Radiological Evaluation for pattern of Septation, Extent of Pneumatization, Presence of Onodi cells and Dehiscence of Structures to be done
- 32. Thank You
Editor's Notes
- Seen from front sphenoid looks bat with outstreched wings. Central portion is the body which is pneumatised by 2 sphenoid sinuses.extending laterally from central body are a pair of greater wings and lesser wings. A stout process extends downwards on either side at junction of body and greater wing-pterygoid process which split into medial and lateral pterygoid Body consist of Superior ,anterior,posterior,inferior and 2 lateral surface Superior surface from anterior to posterior-Ridge, sulcus chiasmiticus,tubercullum sellae,sella tursica, dorsum sellae, clivus Lateral surface has carotid sulcus like a letter “f” deep in posterior part Inferior surface forms roof of nasal cavity and have rostrum of sphenoid Anterior surface has a median sphenoidal crest and lateral to it opening for sphenoid air sinus
- Optoc canal formed between the two roots of Lesser wings Superior orbital fissure – Lateral- Superior opthalmic vein , Frontal and lacrimal nerve, trochlear nerve Annulus of zinn - Occulomotor nerve, Abducent nerve, nasociliary nerve Medial- inferior opthalmic vein Inferior orbital fissure- by inferior border of greater wing which forms posterolateral boundary, passes zygomatic nerve, maxillary nerve as infraorbital nerve,infraorbital vessels and inferior opthalmic vein.
- Foramen lacerum- anterior margin by posterior margin of greater wing of sphenoid and post by petrous apex. Passes- Meningeal branch of ascending pharyngeal artery emissary vein and greater superficial petrosal nerve which joins with deep petrosal nerve to form nerve of pterygoid canal Foramen rotundum-maxillary nerve Foramen ovale- Male Foramen spinosum-
- Based on Pneumatization it is classified in 3 types Conchal-small pit like depression Presellar-Extending upto the anterior wall of pitutary fossa Sellar-Extending upto the clivus. Pitutary forms a distinct bulge in roof of sinus Relationship of surrounding structures best identified in sellar type
- Relations are best understood in sellar type Posterosuperiorly- in the midline of the roof lies the pitutary bulge Laterally and superiorly the optic canal can be visualised which at times is dehiscent in 6 % cases Posteriorly and inferiorly the internal carotid artery bulge produces a prominence which is dehicent in 25% of cases
- Part of lateral wall is removed here to show the siphon of internal carotid artery which has following part in relation to sphenoid sinus 2nd genu-horizontal petrous carotid turns to vertical cavernous carotid Para clival Parasellar-where it bends anteriorly IntraCavernous portion Intracranial portion Between the carotid and Optic bulge lies the Caratico-optic recess which may be deep if anterior clinoid process is pneumatised
- Extensively Pneumatized sphenoid sinus show a lateral recess due to pneumatization of greater wing of sphenoid between the foramen rotundum and vidian canal…in such a case 2 additional bulges can be seen- the maxillary nerve inferolaterally and vidian nerve inferomedially which forms 2 boundary of the lateral recess The Sphenoid sinus may contain septae within it. These septae are usually attached to important structures on the lateral wall like optic nerve , ICA so care must be taken while breaking these septae. Often these Septae are assymetrical so sphenoid dominance is noted radiologically beforehand to avoid any trauma. Like in this case there is Left dominance
- Cavernous sinus lies in major part of lateral wall and roof sphenoid sinus..Pitutary gland lies between the cavernous sinus of two sides which are connected anteriorly and posteriorly by inter cavernous connections. Various nerves which lies in relation to lateral wall and cavernous sinun can be seen from above downwards as 3rd, 4th ,v1, v2 and 6th just inferior to cavernous carotid
- In 10 percent cases a posterior ethmoidal cell extend posterolaterally over the sphenoid sinus.called onodi cell , when present it insinuates itself between sphenoid sinus and optic nerve. Thus optic nerve presents a bulge in onodi cell and not in sphenoid sinus.
- Paraseptal- Access to sphenoid Sinus cab be gained directly by lateralising the middle and superior turbinates and identifying sphenoid os 1-1.5 cm above roof of coana..lower one third or half of Superior turbinate is removed to facilitate dilation of sphenoid os
- Intermediate-After opening the ant ethmoidal cell superior meatal window is made in ground lamella just below the imaginary line drawn along medial orbital floor and bony ridge of middle meatus antrostomy to identify the superior turbinate. Posteroinferior part of this turbinate is removed and sphenoid os is accessed.
- Lateral approach- Prior clearance of Anterior and posterior ethmoidal cells which will then expore the anterior wall of sphenoid sinus
- Endoscopic transnasal approach with posterior septectomy for approach to lateral recess or skull base surgeries. 4 hand techinique can be done..also helpful in revision surgery where all the landmarks are lost
- . An endoscopic picture showing both the sphenoid sinus cavities. CP, carotid protuberance; CR, clival recess; IS, intersphenoid septum; mOCR, medial opticocarotid recess; OCR, lateral opticocarotid recess; OP, optic protuberance; PS, planum sphenoidale; SF, sellar floor.
- An endoscopic picture showing both the sphenoid sinus cavities. CP, carotid protuberance; DPS, dura of planum sphenoidale; DTS, dura of tuberculum sellae; OCR, lateral opticocarotid recess; OP, optic protuberance; PG, dura covering the pituitary gland
- An endoscopic picture after opening the chiasmatic cistern. A2, A2 segment of the internal carotid artery; OC, optic chiasma; ON, optic nerve; PS, pituitary stalk; SHA, superior hypophyseal artery.
- An endoscopic picture after passing the endoscope in the corridor below the optic chiasma. BA, basilar artery; MB, mammillary body; PS, pituitary stalk; SCA, superior cerebellar artery; SHA, superior hypophyseal artery
- An endoscopic picture after passing the endoscope in the corridor below the optic chiasma. BA, basilar artery; MB, mamillary body; OMN, oculomotor nerve; PCA, posterior cerebral artery; SCA, superior cerebellar artery; V3, floor of the third ventricle
- An endoscopic picture of the transclival approach. DC, dura behind the clivus; ICA, paraclival part of the internal carotid artery; PG, pituitary gland.
- An endoscopic picture of the transclival approach after opening the dura (D). AICA, anterior inferior cerebellar artery; BA, basilar artery; P, pons; VA, vertebral artery; VI, abducent nerve.
- An endoscopic picture of the transclival transcraniovertebral approach after opening the dura (D). AICA, anterior inferior cerebellar artery; ASA, anterior spinal artery; BA, basilar artery; PICA, posterior inferior cerebellar artery; VA, vertebral artery; VI, abducent nerve.
- An endoscopic picture of the transclival approach after opening the dura (D). AICA, anterior inferior cerebellar artery; BA, basilar artery; P, pons; VA, vertebral artery; VII, facial nerve; VIII, vestibulocochlear nerve; IX, X, XI, glossopharyngeal, vagus, and accessory nerves