37 Microscopic Endonasal and Sublabial Approach

37.1 Introduction

The microscopic endonasal and sublabial approach is a midline skull-base approach, which provides direct access to the sellar and parasellar region with a surgical corridor free from major neurovascular structures.

37.2 Indications

•Intraand suprasellar pituitary adenomas.

•Intraand suprasellar craniopharyngiomas.

•Any other intrasellar lesions.

•Suprasellar lesions depending on magnitude of sella enlargement.

37.3 Patient Positioning (Fig. 37.1)

•Position: Patient is positioned supine with the head on a fat headrest.

•Body: The body is positioned straight and fat.

•Head: The head is positioned straight, extended 15°.

•Cushion is placed under patient’s shoulders.

•The upper lip has to be the highest point in the surgical feld.

Fig. 37.1 Patient positioning.

37.4 Mucosal Incision for Endonasal Approach (Fig. 37.2)

•The right nostril is exposed (if surgeon is right-handed).

•The base of right nostril is retracted with Langenbeck retractor.

•A straight unilateral incision is performed.

○Starting point: Incision starts 4 mm below the surface of right cartilage.

○Course: It runs straight above nasal cartilage, parallel to nostril.

○Ending point: It ends at the superior medial margin of the right nostril.

37.5 Mucosal Incision for Sublabial Approach (Figs. 37.3–37.5)

•The upper lip is retracted with 2 Langenbeck retractors.

•A straight unilateral incision is performed (Fig. 37.3).

○Starting point: Incision starts at the level of medial canines.

○Course: It runs parallel to the plica between gingiva and upper lip (4 mm from plica), crossing the phrenulum.

•The anterior margin of nasal cartilage is exposed (Fig. 37.4).

•The mucosa is dissected on a sub-perichondrial plane.

•The self-retaining speculum is inserted (Fig. 37.5).

37.6 Soft Tissue Dissection for Endonasal Approach

(Figs. 37.6–37.9)

•Mucosa is detached unilaterally from the cartilaginous septum and the submucosal tunnel is created (Fig. 37.6).

•Medial nasal mucosa has to be kept intact by careful stepwise dissection.

•A self-retaining speculum is inserted.

•The junction of cartilaginous and bony nasal septum is exposed and dissected (Fig. 37.7).

•The mucosa is detached bilaterally from the bony nasal septum (Figs. 37.7, 37.8).

•The junction of cartilaginous and bony nasal septum is separated.

•The paraseptal mucosa is detached bilaterally from the bony nasal septum.

•Portions of bony nasal septum are resected (Fig. 37.8).

•The self-retaining speculum is inserted (Fig. 37.9).

37.6.1 Critical Structures

•Alveolar branches to the frontal teeth.

•Anterior nasal spine.

•Any irregularities in the osseous nasal spine.

•Beware of subluxation of cartilaginous and bony nasal septum.

37.7 Sphenoid Sinus Dissection for Endonasal Approach

37.7.1 Bone Exposure (Figs. 37.10, 37.11)

•Subperiosteal dissection of the anterior surface of the vomer is performed.

•Bilateral exposure of ostium is carried out.

•Sphenoidotomy must be performed with forceps, rongeur, diamond drill.

37.7.2 Resection of Sphenoid Sinus

Mucosa (Fig. 37.12)

•The mucosa and mucosal polyps are extracted from the sphenoid sinus.

•Hydrogen peroxide cottonoids are inserted for hemostasis and disinfection.

37.7.3 Resection of Sphenoid Sinus

Septa (Fig. 37.13)

•Septa has to be resected, so that a complete view onto the sella foor is provided.

Fig. 37.4 Exposure of anterior margin of nasal cartilage and sub-perichondrial dissection. Abbreviations: G = gingiva; NC = nasal cartilage; SM = septal mucosa; UL = upper lip.

Fig. 37.5 Insertion of the self-retaining speculum.

•Incomplete pneumatization of the sphenoid sinus requires aggressive drilling of clivus so that a sufcient portion of the sellar foor is directly exposed.

•Bleeding from clival bone can be controlled with bone wax.

37.8 Sphenoidotomy Landmarks

Usually, the sphenoidotomy extends from both the anterior ostia until the entire sellar foor can be visualized.

•The entire sellar foor from the planum sphenoidale to the clivus has to be exposed.

•Clival and retro-sellar lesions require more posterior opening.

•Osseous canal of carotid artery is frequently encountered.

•Bone has to be maintained intact around carotid artery.

Fig. 37.6 Sub-perichondrial dissection.

Abbreviations: NC = nasal cartilage;

SM = septal mucosa.

Fig. 37.7 Junction of cartilagenous and bony nasal septum is separated. Abbreviations: BCSJ = bony-cartilage nasal septum junction; BNS = bony nasal septum.

37.8.1 Exposure of the Sellar Floor

•The sellar foor is resected between both cavernous sinus with rongeur or diamond drill (Fig. 37.14).

•Dura has to be kept initially intact (Fig. 37.15).

•Dural opening may be performed in X-shaped fashion or through a straight incision extended to a dural window (Fig. 37.16).

•Edges remain within the course of cavernous sinuses.

37.8.2 Critical Structures

•Cavernous sinuses.

•Internal carotid arteries, particularly in the posterior portion of sphenoid sinus.

•The arachnoid close to the junction with the anterior cranial fossa.

37.9 Intradural Exposure (See

Anatomy in Chapters 36 And 39)

•Parenchymal structures: Anterior and posterior pituitary gland.

•Arachnoidal layer: Optic-chiasmatic cistern.

•Cranial nerves: Second, third, fourth, ffth and sixth cranial nerves (only visible with invasive tumors).

•Arteries: Internal carotid arteries.

•Veins: Cavernous sinuses.

Fig. 37.8 Partial resection of bony nasal septum.

Abbreviations: BNS = bony nasal septum; reBNS = resected bony nasal septum.

Fig. 37.9 Insertion of the self-retaining speculum.

Fig. 37.11 Sphenoidotomy.

Abbreviations: SS = sphenoid sinus; SSep = sphenoid septum.

Fig. 37.10 Exposure of the vomer.

Abbreviations: LSO = left sphenoid ostium;

RSO = right sphenoid ostium; V = vomer.

Fig. 37.12 Dissection and resection of mucosa. Abbreviations: SM = sphenoid mucosa; SS = sphenoid sinus; SSep = sphenoid septum.

Fig. 37.13 Resection of bony septa. Abbreviations: SF = se ; SSep = sphenoid septum.

Fig. 37.15 Se sected and the dura is exposed. Abbreviations: SD = sellar dura.

References

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