25/06/2010. Scaricato da 1

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1 Approcci chirurgici al Clivus DIPARTIMENTO DI NEUROCHIRURGIA SECONDA UNIVERSITÀ DI NAPOLI Prof. Aldo Moraci Surgical Anatomy of the Clivus Scaricato da 1

2 Midsagittal Section of the Skull Superior View of the Skull Base Scaricato da 2

3 Brain Anatomy Vascular Anatomy Scaricato da 3

4 Neuroradiological Anatomy Surgical Anatomy The clivus is usually divided into the upper, middle and lower clivus. Scaricato da 4

5 Surgical Anatomy The upper clivus is the part above the crossing of the trigeminal and the abducens nerves from the posterior to the middle cranial fossa and includes the dorsum sellae and the posterior clinoid processes. This area is bounded anteriorly by the sella turcica and sphenoid sinus; posteriorly by the basilar artery and the midbrain; laterally by the cavernous sinus, the temporal lobes and (from superior to inferior) cranial nerves III through VI. Surgical Anatomy The middle clivus is the part between the exits of the trigeminal and the glossopharyngeal nerves. It is bounded anteriorly by the upper nasopharinx and retropharyngeal tissues, posteriorly by the basilar artery and by the pons, and laterally by the petrous apices and by the cranial nerves VII and VIII. Scaricato da 5

6 Surgical anatomy The lower clivus is the part from the glossopharyngeal nerve to the foramen magnum. It is bounded anteriorly by the lower nasopharynx and retropharyngeal tissues; posteriorly by the vertebral artery and the medulla; and laterally by the sigmoid sinus, jugular bulb, cranial nerves IX to XII. Surgical approaches The surgical approaches to the clivus are divided into three general groups: 1. Anterior 2. Anterolateral 3. Posterolateral Scaricato da 6

7 Anterior approaches Anterior approaches are mainly used for extradural lesions that t primarily involve the clivus and can extend extracranially, like chordoma and chondrosarcoma. For these tumors, the anterior approaches are usually extradural and include: Anterior approaches transnasal-transsphenoidal transethmoidal transoral-transpalatal transmaxillary transcervical Scaricato da 7

8 Anterior approaches A subfrontal transbasal extraintradural anterior approach can also be indicated for huge tumors with maximal involvement of the clival area and sorrounding structures (e.g. chordoma, pituitary tumors, craniopharyngiomas). Anterolateral approaches Anterolateral approaches are mainly utilized for intradural tumors involving the upper and the middle clivus and extending into the surrounding regions. Scaricato da 8

9 Anterolateral approaches The frontotemporal approach exposes lesions of the upper clivus with extensions in the suprasellar region. Anterolateral approaches The subtemporal transtentorial t t approach exposes lesions of the upper and the tentorial edge (a zygomatic osteotomy and anterior petrosectomy increase the exposure inferiorly and toward the clivus). Scaricato da 9

10 Posterolateral approaches Posterolateral approaches are mainly utilized for tumors involving the medial and the lower part of the clivus with extension to the petrous bone, cerebellopontine angle, foramen magnum or upper cervical region. These approaches include: Posterolateral approaches the combined subtemporal suboccipital presigmoid with posterior petrosectomy (retrolabyrinthine, translabyrinthine, transcochlear and total petrosectomy) Scaricato da 10

11 Posterolateral approaches the retrosigmoid approach Posterolateral approaches the extreme lateral transjugular transcondylar approach Scaricato da 11

12 Surgical Approaches: synthesis CHOICE OF SURGICAL APPROACH IN RELATION TO THE LOCATION OF THE TUMOR Location of Lesion Upper clivus 1. Surgical Approach 1. Frontotemporal approach with orbitozygomatic osteotomy 2. Subtemporal approach with a zygomatic osteotomy and an anterior petrosectomy Upper and middle third of the clivus 1. Subtemporal craniotomy with an anterior petrosectomy 2. Subtemporal-suboccipital craniotomy with a posterior petrosectomy Lower third of the clivus Middle and lower third of the clivus Entire clivus through the level of foramen magnum Extreme lateral transcondylar approach Combined posterior petrosectomy with an extrem lateral approach Far lateral/combined supratentorial and infratentorial approach (including posterior petrosectomy or total petrosectomy) Frequent Meningioma Metastasis t Aneurysm Infrequent Differential diagnosis of juxtasellar masses Chordoma Arachnoid cyst Dermoid Nerve sheath tumor Glioma Cephalocele Tolosa-Hunt syndrome Osteomyelithis Osteosarcoma Paget s disease Fibrous dysplasia Mucocele Scaricato da 12

13 Chordomas Others CNS neoplams/local Extensions from Regional Tumors Chordomas are slow-growing and uncommon tumor arising i from nothocordal remnants. The clivus is the second most common lacation, following the sacrococcygeal region. Intracranial chordomas account for fewer than 1% of all intracranial tumors. M:F is equal. Peak incidence of intracranial chordomas is yrs of age (rare < 30 yrs). Typical presenting symptoms are diplopia and headache. These tumors are managed with surgery and post-operative operative radiotherapy. Chordomas: imaging findings 75%of chordomas are isointense to gray matter on T1-weighted images. They are almost always hyperintense on T2- weighted images. Chordomas enhance intensely. Scaricato da 13

14 Meningiomas Other CNS neoplasms/tumors of the Meninges Meningiomas of the clivus and apical petrous bone are the most common intradural neoplasm in this region. They are slow but progressive growing lesions that eventually enables these tumors to achieve an enormous size before manifesting neurologic symptoms related to distortion of the brain stem or cranial nerves III to XII. Meningiomas: imaging findings Scaricato da 14

15 Presigmoid approach: historical background 1904 Fraenkel & Hunt sub-occipitaltranslabyrinthine 1939 Bailey combined supratentorial-infratentorial 1973 Morrison & King subtemporal and translabyrinitine 1977 Hakuba petrosal approach with labyrintine preservation Patient positioning Supine with heavy roll Supine with heavy roll under ipsilateral shoulder and the head turned approximately 70 to the contralateral side Scaricato da 15

16 Skin Incision C-Shaped extending along the superior temporal line into the retroauricolar region into the upper neck. Preparation to the craniotomy The skin, subcutaneous tissues, galea are elevated. The temporalis muscle and fascia are reflected forward The sternocleidomastoid and fascia are reflected forward along the skin incision The semispinalis capitis and splenius capitis are detached and reflected postero-inferiorly Scaricato da 16

17 Craniotomy Combined temporal and retrosygmoid with four burr holes at each side of the transverse sinus Mastoidectomy Partial (unroofing the sigmoid sinus) Completed (visualisation of the labirynth, the facial nerve and sigmoid sinus) Scaricato da 17

18 Retrolabyrintine approach The silk sutures mark the dural incision Partial labyrinthectomy petrous apicectomy Points of fenestration into posterior and superior semicircular canals have been marked Scaricato da 18

19 Partial labyrinthectomy petrous apicectomy Superior posterior and lateral canals have been removed (the triangular space represents the petrous apex) Dural opening The temporal dura is incised along the floor of the temporal fossa The posterior fossa dura is incised anterior to the sigmoid sinus toward the superior petrosal sinus dissection of the Labbè vein Scaricato da 19

20 Tentorial division Attention to the IV nerve Attention to the SCA Attention to the V nerve Surgical view Scaricato da 20

21 Presigmoid approach variants Caricature of neurosurgeon of today (top)) and of tomorrow (bottom) Scaricato da 21