Skull base 360°- Part TWO

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Information about Skull base 360°- Part TWO
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Published on March 9, 2014

Author: muralichandnallamothu

Source: slideshare.net

SKULL BASE 360°-TWO Endoscopic Lateral Skull base (Neuro-otology) Endoscopic Anterior skull base & Microscopic Lateral skull base & Middle cranial fossa skull base & Open skull base approaches [ Dated: 9-3-14 ] I will update continuosly with date tag at the end as I am getting more & more information Art & Presentation by Dr. N. Murali Chand DLO FHM Fellowship in HIV medicine, MAMC, New Delhi My website = www.integratedmedicine.co.in Cell= +91 99496 77605

th 9 nerve

A closer view of the pars nervosa of the jugular foramen. The glossopharyngeal nerve has its own dural porus, which is situated 0-3 mm upwards from the dural porus of the tenth cranial nerve. The vagus and the accessory nerve exit the posterior fossa together in a sleeve of dura through the jugular foramen. Left side. The 30° angled endoscope provides an overview of the inferior part of the CPA. On the right lies the acousticofacial nerve bundle, with the anterior inferior cerebellar artery; the glossopharyngeal nerve and the vagus nerve, as multiple filaments, form three to five major nerve bundles and the accessory nerve.

Note the bone (>, <) left to protect the dura from the drill. AC Supralabyrinthine air cells, CA Cochlear aqueduct, FN Facial nerve, SA Ampulla of the superior canal, V Vestibule Fig. 4.30 The internal auditory canal (IAC) has been identified, but the overlying bone needs to be thinned further. CA Cochlear aqueduct, FN Facial nerve, V Vestibule

Fig. 2.57 After rerouting the facial nerve and drilling away the fallopian canal of a left temporal bone, the cochlear aqueduct (CA) has been opened. The proximity of the glossopharyngeal nerve (IX) can be well appreciated. Since the nerve lies just inferior to the cochlear aqueduct, the latter is used as a landmark to the nerve in the translabyrinthine approach, indicating the lower limit of drilling in order to avoid injury to the glossopharyngeal nerve. ICA Internal carotid artery, JB Jugular bulb, SMF Stylomastoid foramen Retrosigmoid approach – observe 9th nerve near cochlear aqueduct [CA]

Drilling has been carried out more inferiorly to identify the cochlear aqueduct (CA). Note the proximity of the aqueduct to the glossopharyngeal nerve (IX).

The bone overlying the transitional zone from the jugular bulb (JB) to the internal jugular vein (IJV) has been drilled away. The hook can be seen underneath the fibrous band covering the exit of the bulb from the bone. The jugulocarotid spine of bone (<) can be seen lying between the internal carotid artery (ICA) and the jugular bulb. * The fibrous band covering the entrance of the internal carotid artery into the temporal bone.

9th nerve present between internal carotid & jugular bulb at carotid canal area[extra-cranially] View from anterior skull base approach View from Lateral skull base approach

9th nerve – in cadaver

Jugular foramen area [ 9,10,11,12 nerves]

Jugular tubercle [ JT ] , star = foramen lacerum

Note the relationship of clivus & jugular tubercle

Jugular tubercle [ JT ] AICA antero-inferior cerebellar artery, ASC anterior semicircular canal, BA basilar artery, HC hypoglossal canal, IAC internal acoustic canal, ICAh horizontal portion of the internal carotid artery, JT jugular tubercle, LCNs lower cranial nerves, LSC lateral semicircular canal, P pons, PICA postero-inferior cerebellar artery, PSC posterior semicircular canal, VIcn abducens nerve, VIIcn facial nerve, white arrow vestibolocochlear nerve

Jugular tubercle [ JT ]

Exocranial & Endocranial views of Jugular Foramen

The glossopharyngeal nerve has its own dural porus, which is situated 03 mm upwards from the duralporus of the tenth cranial nerve. The vagus and the accessory nerve exit the posterior fossa together in a sleeve of dura through the jugular foramen.

JF= Jugular foramen

th 12 nerve

The pontomedullary junction. 1. The exit zones of the hypoglossal and abducent nerves are at the same level. 2. The abducent nerve exits from the pontomedullary junction, and ascends in a rostral and lateral direction toward the clivus.

A closer view of the anterior border of the pontomedullary stem and the vertebral artery junction and origin of the basilar artery. Perforating arteries arise from the vertebral and basilar arteries. The endoscope is focusing on the hypoglossal nerve area. The posterior inferior cerebellar artery arises from the vertebral artery in the background, and runs between the two bundles of the hypoglossal nerve.

Fig. 26a, b Right side. The root fibers of the hypoglossal nerve (12) collect in two bundles, which pierce the dura in two dural pori. The hypoglossal nerve is situated more anteriorly and medially than the root fibers of the lower cranial nerves. The arterial relationship is the vertebral artery, with perforating arteries to the brain stem. The curved vertebral artery displaces and stretches the hypoglossal nerve fibers.

Through lateral skull base - The curved vertebral artery displaces and stretches the hypoglossal nerve fibers. Through anterior skull base

Through lateral skull base - The curved vertebral artery displaces and stretches the hypoglossal nerve fibers. Through lateral skull base - The opposite vertebral artery exits from the dural porus and stretches /raises the hypoglossal nerve.

HC = hypoglossal canal , JT= Jugular Tubercle

SCG = Supracondylar groove

Hypoglossal canals From front – through nose From back

1. The SCG [Supracondylar groove] represents a reliable landmark for hypoglossal canal (HC) identification (red arrow) (Morera et al. 2010 ) . 2. The HC divides the condylar region into the tubercular compartment (superior) and the condylar compartment (inferior). Tubercular compartment contains LPT lateral pharyngeal tubercle, PT pharyngeal tubercle,

12th nerve bissecting internal & external carotid

Vertebral artery

Robbins level II. 1 Sternocleidomastoid muscle, 2 posterior belly of digastric muscle, 3 spinal accessory nerve (common trunk), 4 internal jugular vein, 5 splenius capitis muscle, 6 levator scapulae muscle, 7 anterior scalene muscle, 8 transverse process of atlas, 9 hypoglossal nerve, 10 carotid bifurcation, 11 branches of cervical plexus

Superior view of the atlas and the axis. The atlas consists of two thick lateral masses situated at the anteromedial part of the ring, which are connected in front by a short anterior arch and posteriorly by a longer curved posterior arch. 1, anterior arch of the atlas; 2, superior articular facet is an oval, concave facet that articulates with the occipital condyle; 3, posterior arch of the atlas; 4, vertebral artery (VA); 5, transverse foramina; 6, transverse process; 7, dens of the axis.

The entrance of the vertebral artery is the boundary between the foramen magnum and the spinal part of the accessory nerve. The root fibers of the spinal accessory nerve and the fibres of C1 and C2

Fibrous tissue surrounds the entrance of the vertebral artery into the CPA. Left side. Combined transsigmoid, suboccipital and extreme lateral approaches provide an overview off the craniocervical junction, the foramen magnum area, and the surrounding structures of the medullary stem.

In transcochlear approach

Anterior cranial fossa

Anterior & Posterior perforated substance

Anterior perforated substance & olfactory track relation

Fronto-polar artery

Superior hypophyseal artery = SHA

Cisterns

Oculomotor cistern Cranial nerve III enters the roof included in its own cistern (oculomotor cistern).

Chiasmatic cistern – The chiasmatic cistern is located in front of the optic chiasm and above the sella turcica. In the lateral border of the chiasmatic cistern the first part of the ICAi is visible. lt ICA SEEN ON LT SIDE.. A HOLE IN THE ARACHNOID.. THE STALK JUST BEHIND IT.. THE DIAPHRAGM SEEN IN 5/6 O CLOCK POSITION..

CSF rhinorrhoea case Closed with hadad flap lt ICA SEEN ON LT SIDE.. A HOLE IN THE ARACHNOID.. THE STALK JUST BEHIND IT.. THE DIAPHRAGM SEEN IN 5/6 O CLOCK POSITION..

LT lamina terminalis cistern – The lamina terminalis cistern is situated above the optic chiasm (Martins et al. 2011 ) . Within this cistern, A1 and A2, as well as the anterior communicating artery and the first part of the recurrent artery of Heubner, are evident.

Interpeduncular cistern

Interpeduncular cistern IR = infundibulum

Optic chiasma – infundibulum – Mamillary bodies

Craniopharyngioma https://www.facebook.com/groups/4 05175366256295/permalink/552393 251534505/?stream_ref=2

CRANIOPHARYNGIOMAS-Removal corridors.

Optic pathway

Interpeduncular cistern 3rd ventricle is visualised ..through the tuber cinereum

Recurrent artery of Heubner

Recurrent artery of Anterior cerebral artery = Recurrent artery of Heubner

The recurrent artery of Heubner usually origins from the post-communicating segment of the anterior cerebral artery (ACA). It doubles back the ACA to reach the medial part of the Sylvian fi ssure, below the anterior perforated substance. Sometimes its path is so long that the artery loops below the basal surface of the frontal lobes. Not frequently more than one recurrent arteries can be present (Rhoton 2003 ). According to Lang the artery is double in about 30% of cases (Lang 1995 ) .

rd 3 ventricle

Intradural Anatomy

Different positions of the anterior inferior cerebellar artery (AICA) in relation to the internal auditory meatus.

st 1 & nd 2 cervical vertebrae

Don’t use cutting bur while drilling “Frontal T” in Draf 3 – Use only diamond bur – we may injure the dura .

HADAD FLAP ---1, area of origin of the nasoseptal flap (dotted line); 1b, area of origin of the extended nasoseptal flap, including the floor of the nasal fossa, and if necessary, the mucosa of the inferior meatus; 2, position of the nasoseptal flap used for repair of the anterior and posterior ethmoid roof and cribriform plate; when bilateral flaps are taken, the anterior skull base can be repaired from orbit to orbit; 3, position of the nasoseptal flap used for repair of the sellar and parasellar regions; 4, position of the nasoseptal flap used for repair of the region of the clivus; the arrows indicate the different ways in which the nasoseptal flap (HBF) can be rotated from the nasal septum for repair of different zones of the cranial base.

anterolateral endonasal flap.

Pituitary surgery

pituitary tumors schematic diagram.

Fig. 13.17 Classification of Knosp et al.10 grading the cavernous sinus extension when compared with lines drawn medial through the middle and on the lateral aspect of the carotid arteries—grades 0 to 3. Grade 4 encases the carotid.

Cavernous Sinus MRI anatomy

Liliequist membrane

Craniopharyngioma removal - Sylvian fissure & Lamina terminalis view

Craniopharyngioma removal - Sylvian fissure & Lamina terminalis view

APPROACHES

DRAF III

1st olfactory neuron seen in draft 3

Outside-in approach of draf III – similar like outside-in mastoid Inside-out approach of draf III – similar like Inside-out mastoid

Trans-ptyregoid approach

The wedge bone between V2 & Vidian nerve decreases as we go posteriorly towards petrous carotid

The wedge bone between V2 & Vidian nerve decreases as we go posteriorly towards petrous carotid

Accessories

anterior ethmoidal artery ( AEA) and nerve (AEN) , anterior falcine artery (AFA)

Deep temporal artery

Trigeminal area at Cerebello Pontine Angle – along with my voice Click http://www.youtube .com/watch?v=YBqk 4Jdnxic

CAROTID COURSE Click http://www.youtube.c om/watch?v=JlNmSI3t S8Q

PETROCLIVAL MENINGIOMA DECISION MAKING •Click http://www.youtube.com /watch?v=kUa9fQ4_aQY

Frontal sinus surgery concepts – must for to do DRAF-III – Don’t use cutting burr while drilling the Frontal-T , high chances of injuring the dura -- use only dimond drill Click http://www.youtube.com /watch?v=2rhafq3Ur0s

Hemifacial spasm Video-1 http://www.youtube.com/watc h?v=-zlymD2LYsM Video-2 http://www.youtube.com/watc h?v=gGyQFh3PqPg

Subfrontal craniotomy.

Subfrontal craniotomy.

Mandibulotomy [ Mental nerve bilaterally ]

AFB area

Fig. 74a, b The reference level is the acousticofacial nerve bundle. The anterior inferior cerebellar artery, lying between the auditory and facial nerves, is found in 38% of cases.

CBI- Cochlear nerve- Inferior

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