Approaches and planning inApproaches and planning inskull base surgeryg y

Alexis Bozorg Grayeli, Michel Kalamarides,g y , ,Didier Bouccara, Françoise Cyna-Gorse &

Olivier SterkersOlivier SterkersOtoneurosurgery and Radiology DepartmentsHôpital Beaujon Université Paris 7 FranceHôpital Beaujon, Université Paris 7, France

1960 19801960-1980:Rationalizing the skull base approaches

Willi H Middl i l f d• William House : Middle cranial fossa andtranslabyrinthine approaches

Re introduction of already described approaches– Re introduction of already described approaches– Microdrill

Surgical anatomy– Surgical anatomy– Mortality reduction from 20% to less than 5%

House WF, Laryngoscope, 1961, 71:1363House WF, Archives Otolaryngol, 1964, 80:752

House WF Luetje CM In: Acoustic tumors 1979House WF, Luetje CM, In: Acoustic tumors, 1979

1960-1980:1960 1980:Rationalizing the skull base approaches

Ugo Fisch : Infratemporal aproachesUgo Fisch : Infratemporal aproachesExtradural aproaches of the lateral cranial baseFisch U, In: Microsurgery. Applied to Neurosurgery, 1969

Fisch U, Mattox D, In: Microsurgery of the skull base, 1988

A B CA B C

1960-1980:1960 1980:Rationalizing the skull base approaches

• Retrosigmoid approach : – Otogical principals added to aOtogical principals added to a

« neurosurgical approach »– Hearing preservation especially in NF2Brémond G, Garcin M, Magnan J. Cahiers d’ORL, 1974Sterkers JM, Corlieu P, Hamann FK, Sterkers O. Ann Oto

Laryng, 1980

• Transotic and transcochlear approaches :approaches :– Particular situationsHouse WF, Hitselberger W. Archives Otolaryngol, 1976Jenkins HA, Fisch U. Am J Otol, 1980

Surgical objectives

Zero mortality and morbidity Total tumor removalFacial and caudal nerve preservationHearing preservationHearing preservation

Planning and pre operativePlanning and pre operativework-upwork up

Evaluating the pre opertive deficitsAssessing the size, the location and the agressiveness of the lesiong

Preop symptomes and tumor locationPreop symptomes and tumor location

A H d hPetroclival : SNHL, VII, V

Apex : Headaches

Estachian tube: Serous Otitis media

Labyrinthe and middle ear:

CPA: Retrococh SNHL, vertigo

Labyrinthe and middle ear:vertigo, mixed HL

Endolymphatic sac: Fluctuating

Foramen lacerum: aspiration

y p gSNHL, vertigos

Foramen lacerum: aspiration,hoarsness, SNHL

Clinical preop deficits

• Interrogation• Otoscopy• Otoneurological examination:Otoneurological examination:

– VII : Facial motricity, ShirmerV : Blink reflex– V : Blink reflex

– Cerebellar syndrome C d l l l l d– Caudal nerves: velar palsy, vocal cordeand pharyngeal mobility, stroboscopy

Audiovestibular examinationAudiovestibular examination

ImagingImaging

CT• CT scan:– Overlaping slices or spiral acquisition

B i d ith t t t i j ti– Bone window without contrast injection– Axial and coronal views

Study of Bony structures– Study of Bony structures• MRI:

T1 without (lipomes) and with gadolinium injection– T1 without (lipomes) and with gadolinium injection– T2 (acousticofacial bundle in CPA)

Diffusion (B1000 cholesteatoma)– Diffusion (B1000, cholesteatoma)– Angio MRI

I iImagingAngiography:Angiography:

Hypervascularized lesions (paragangliomas, some meningiomas)g )Tumor pedicules (embolisation ?)Willis polygoneygCarotid occlusion testEmbolisation 24-48 h before surgery

Octreoscan® (indium In-111 pentetreotide) : paragangliomasBone scan and et thoraco abdominal CT scanBone scan and et thoraco-abdominal CT scan:metastases and malignant lesions

Evaluating the tumor locationEvaluating the tumor location

SupralabyrinthineApical Infralabyrinthine

R t l b i thiTranslabyrinthine RetrolabyrinthineTranslabyrinthine

Supralabyrinthine ApexInfralabyrinthineSupralabyrinthine pInfralabyrinthine

Translabyrinthine Retrolabyrinthine Cervicomastoid

Paragangliomas:g gFisch classification

Intracranial:

• De (extradural):- De1 < 2 cmDe1 < 2 cm- De2 > 2 cm

C2C3

• Di (intradural):- Di1 < 2 cm

Di2 > 2BC1C2C3C4- Di2 > 2 cm

Tumor extension following cell tracts

Post. supra-labyrinthine

Translabyrinthine

Post. supra labyrinthine

Ant supra-labyrinthine

Precochlear

Anterior infra-labyrinthine

Posterior infra-labyrinthine

Evaluating the tumor type and aggressiveness

TOP FIVECholesteatomaCholesterin granulomaP liParagangliomaSchwannomaMeningioma

Imaging of cholesteatomaImaging of cholesteatoma

CT scan:Lytic and convex edgesIn density similar to CSF

MRI:Hyposignal on T1Hyposignal on T1Variable signal on T2Not enhaced after godoliniumNot enhaced after godoliniumHypersignal on diffusion

B 1000

Imaging of cholestrin granuloma

Benign cyctic lesionsCT scan:

Round and regular marginsRound and regular marginsIn density similar to brain

MRI:Hypersignal on T1 and T2ype s g a o a dVariable homogeneity

Imaging of paraganglioma

CT-scan:F b iFuzzy bone erosion

IRM:H i l T1Hyposignal on T1Hypersignal on T2 (variable)Pepper and salt image: vessel voids andPepper and salt image: vessel voids andhemorrhage hypersignal Intense enhancementIntense enhancement

Angiography: highly vascularised OctreoscanOctreoscan

Imaging of the temporal bone Swartz JD Harnsberger HR Thieme

Imaging of schwannomas

• CT-scan:L t d– Located on a nerve

– Regular enlargement of nerve foramenBone erosion with regular margins– Bone erosion with regular margins

• MRI:Hyposignal on T1– Hyposignal on T1

– Isosignal on T2– Cystic components in large lesions– Cystic components in large lesions– Enhancement after contrast– « Bell clapper » forme« Bell clapper » forme

Imaging of meningiomes

CT-scan:HyperostosisBone erosionBone erosion

MRI:Intermediate signal on T1variable signal on T2Thinckening and enhancement of dura

Location can indicate pathologyp gy

CholesteatomaCholesteatoma,Cholesterin granuloma Meningioma

F i l h

SchwannomaMeningioma

Facial schwannomaCholesteatomaCholestrin granuloma

Endolymphatic sac tumorMeningiomaHistiocytosis X

Foramen lacerum: ParagangiomaCaudal nerve schwannomaCaudal nerve schwannoma

Evaluating nerve location andEvaluating nerve location andinvolvement

MRI 3D reconstructionMRI T2 with multiplanar reconstruction MRI 3D reconstructionSuperior view

p

P ti t fPreoperative assessment ofvascularisationvascularisation

Tumor vesselsArteriesVenous drainage: sigmoid sinus hypoplasia, Labbé vein

Computer assisted navigation

More user-friendlyM iMore precise

Useful in retrosigmoid: locatin of the posterior semicircular canal

Useful in MCF approachpp

L t l k ll b hLateral skull base approaches

Enlarged middle cranial fossa

Transotic

Transcochlear

Translabyrinthine

Transotic

Retrolabyrinthine

Translabyrinthine

Retrosigmoid

I t ll tiInstallation

Intra operative monitoring

Facial :Improves the quality and the

reliability of dissectionAccelerates learning curveAccelerates learning curve

Hraring:No impact on hearingNo impact on hearing

preservation

C d lCaudal nerves: :In large VS and paragangliomas

Translabyrinthine approachTranslabyrinthine approach

Lateral cranial base approach trough the posterior labyrinth

Indications:Indications:

Translabyrinthine and large CPA lesions

Lesions invading the fundus of IAMo

Class C or D hearing

Transotic approachTransotic approach

Anterior extension of the translabyrinthine approachtranslabyrinthine approach

Indications:

Translabyrinthine and largeTranslabyrinthine and largeCPA lesions extending anteriorly

Lesions invading theLesions invading thefundus of IAM and cochlea

Class C or D hearing

Transotic approachTransotic approach

E L t l R t d lE. Lescanne et al., Rapport de laSociété Française d’ORL, 2001

T hl hTranscochlear approach

Posterior rerouting of the facial nervefacial nerve

Indications:

Apical lesions with class C or D hearingor D hearing

Lesions located anterior to the IAM

Retrosigmoid approachRetrosigmoid approachIndications:

Mid-size CPA lesionsClass A or B hearingClass A or B hearingFundus free of tumorCan be combined to mastoid-retrolabyrinthine

Drilling the posteriorIncisionaspect of IAM

3 cm23 cmcraniotomy

Retrosigmoid approach

Middle cranial fossa approachMiddle cranial fossa approachIndications:d cat o s

Supralabyrinthine lesionsIAM or small CPA lesions notIAM or small CPA lesions not

involving the fundusClass A or B hearing

Vertical incision � from tragus upward� from tragus upward� < 1 cm from helix insertion

Bone flap: 3 x 3 cm

Middle Cranial fossa approachMiddle Cranial fossa approach

Dural retraction:�Dural opening and CSF aspiration�Hyperventilation and Mannitol� C l ti f th iddl� Coagulation of the middlemeningeal artery� Caution: geniculate gangion may� Caution: geniculate gangion maybe adherent to the dura with no bony cover (15% of cases)

Middle Cranial fossa approachMiddle Cranial fossa approach

Front

Middle cranial fossaMiddle cranial fossa

� Identification of MAI:

E i i tEminancia arcuata

Greater petrosal nerveGreater petrosal nerve

� MAI on the bisecting line

�Measuring the depth from the24 mm 27 mm

�Measuring the depth from theinternal diploe

Infratemporal approachesIndications:

Paragangliomas other aggressive tumors:

A: Foramen lacerum and C1

A B C

A: Foramen lacerum and C1segment of carotid

B: Petrous apex and C2 tsegment

C: Rhinopharynx, petroclival junction, cavernous sinus

Can be combined translabyrinthine approach

Type A Type B anterior rerouting of facial nerve

ypTrijeminal sacrifice

Type C Condylar section and trijeminal sacrificeCondylar section and trijeminal sacrifice

Preoperative deficits and signsGeneral status

Imaging

Apical Infralabyrinthine Supralabyrinthine Retrolabyrinthine Translabyrinthine

Hearing

+ - + - + -+ -

SP TO STP SP TOTORLTO SP ou TOSP TO STPor ITA

SP TOTORLTO SP ou TO

ComplicationsComplications

• Keratitis• Keratitis• CSF leak

I f ti i t i i iti• Infectious: respiratory, urinary, meningitis• Pulmonary embolism• CPA hematoma• Stroke, lateral sinus thrombophlebitisp• Carotid artery dissection and hemorrage

(paragangliomas)(p g g )

Immeiate postoperative careImmeiate postoperative care• ICU for 24 – 48 h• No systematic antibiotics• Prevention of phlebitis• Prevention of phlebitis• Eye care• Prevention of cough and constipation (CSF hypertension)

• Early facial and vestibular rehabilitationy• In case of caudal nerve deficit:

– Speech therapistSpeech therapist– Nasogastric tube or gastrostomy– Tracheotomy– Tracheotomy

Late postoperative careLate postoperative care

• Ophtalmological follow-up and facial h i thphysiotherapy

• Facial nerve rehabilitation: eyelid surgery,y g y,muscular transposition, 7-12 anastomosisVestibular rehabilitation• Vestibular rehabilitation

• Hearing rehabilitation (BAHA)g ( )

C l iConclusions

Imaging and otoneurological explorations are essential in the preoperative work-up.p p p

Transpetrous approaches are the safest approaches to lateral skull base lesions and can be t il d t i di id ltailored to individual cases.

Facial and caudal nerve are mandatory. Auditory monitoring remains difficultmonitoring remains difficult.

Computer assisted surgery improves the quality of tumor resection in selected cases.