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World Neurosurgery Oct 2023Lesions of the foramen magnum (FM) and craniocervical junction area are traditionally managed surgically through anterior, anterolateral, and posterolateral skull-base...
Approaching Intradural Lesions of the Anterior Foramen Magnum and Craniocervical Junction: Anatomical Comparison of the Open Posterolateral and Anterior Extended Endonasal Endoscopic Approaches.
BACKGROUND
Lesions of the foramen magnum (FM) and craniocervical junction area are traditionally managed surgically through anterior, anterolateral, and posterolateral skull-base approaches. This anatomical study aimed to compare the usefulness of a modified extended endoscopic approach, the so-called far-medial endonasal approach (FMEA), versus the traditional posterolateral far-lateral approach (FLA).
METHODS
Ten fixed silicon-injected heads specimens were used in the Skull Base ENT-Neurosurgery Laboratory of the University Hospital of Strasbourg, France. A total of 20 FLAs and 10 FMEAs were realized. A high-resolution computed tomography scan was performed for quantitative analysis of the different approaches. The analysis aimed to estimate the extent of surgical exposure and freedom of movement (maneuverability) through the operating channel using a polygonal surface model to obtain a morphometric estimation of the area of interest (surface and volume) on postdissection computed tomography scans using Slicer 3D software.
RESULTS
FMEA allows for a more direct route to the anterior FM, with wider brainstem exposure compared with the FLA and an excellent visualization of all anterior midline structures. The limitations of the FMEA include the deep and narrow surgical corridor and difficulty in reaching lesions located laterally over the jugular foramen and hypoglossal canal.
CONCLUSIONS
The FMEA and FLA are both effective surgical routes to reach FM and craniocervical junction lesions. Modern skull base surgeons should have a good command of both because they appear complementary. This anatomical study provides the tools for comprehensive preoperative evaluations and selection of the most appropriate surgical approach.
PubMed: 37482086
DOI: 10.1016/j.wneu.2023.07.080 -
Operative Neurosurgery (Hagerstown, Md.) Oct 2023The extreme lateral approach is useful for both extradural and intradural anterior and anterolateral lesions at the lower clivus down to the level of C2.
INDICATIONS CORRIDOR AND LIMITS OF EXPOSURE
The extreme lateral approach is useful for both extradural and intradural anterior and anterolateral lesions at the lower clivus down to the level of C2.
ANATOMIC ESSENTIALS NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT
The patient is evaluated with MRI, computed tomography (CT), and an angiogram. Special attention is given to vascular (vertebral artery course, dominance, tumor feeders) and bony (occipital condyle, jugular tubercle, foramen magnum and extent of bony involvement) anatomy.
ESSENTIALS STEPS OF THE PROCEDURE
The patient is positioned lateral with the head flexed and tilted down without axial rotation. A hockey-stick incision is performed, and the myocutaneous flap is raised. A retrocondylar craniectomy is performed. The extradural vertebral artery is exposed for proximal control. A C1 hemilaminectomy is performed. Cephalad/caudal exposure and drilling of the occipital condyle are determined per case. The dura is opened, and the vertebral artery is released at the dural entry point to facilitate the tumor removal. The tumor is debulked and delivered inferoventrally away from the neuroaxis and cranial nerves. After removing the tumor, the dura is closed using an allograft.The patients consented to the procedure and to the publication of their images.
PITFALLS/AVOIDANCE OF COMPLICATIONS
• Cranial nerve deficits• Craniocervical instability• Postoperative hydrocephalus• Postoperative pseudomeningocele.
VARIANTS AND INDICATIONS FOR THEIR USE
A transmastoid extension of the craniectomy allows access further rostrally in the clivus. For C1-2 chordomas, the approach is extended inferiorly, and the vertebral artery is mobilized out of the C1-2 transverse foramina. For tumors involving the joints, an occipitocervical stabilization is required.Images in video reused with permission as follows: image at 00:16 from Revuelta Barbero et al, Endoscopic endonasal transclival-medial condylectomy approach for resection of a foramen magnum meningioma: 2-dimensional operative video, Oper Neurosurg , 16(2), 2018, by permission from the Congress of Neurological Surgery; images at 00:30, and top image at 00:52 reused from Wen et al, Microsurgical anatomy of the transcondylar, supracondylar, and paracondylar extensions of the far-lateral approach, J Neurosurg , 87(4), 1997, with permission from JNSPG; bottom images at 00:52 from Muthukumar et al, A morphometric analysis of the foramen magnum region as it relates to the transcondylar approach, Acta Neurochir , 147(8), 2005, by permission from Springer Nature.
Topics: Humans; Occipital Bone; Foramen Magnum; Neurosurgical Procedures; Meningioma; Meningeal Neoplasms
PubMed: 37387583
DOI: 10.1227/ons.0000000000000739 -
The Neuroradiology Journal Dec 2023Intra-osseous vessels are normal anatomic structures in the calvarium and skull base. On imaging, these structures-particularly venous lakes-can mimic pathologic...
BACKGROUND
Intra-osseous vessels are normal anatomic structures in the calvarium and skull base. On imaging, these structures-particularly venous lakes-can mimic pathologic abnormalities. This study sought to assess the prevalence of veins and lakes in the skull base on MRI.
MATERIALS AND METHODS
A retrospective review was completed of consecutive patients that underwent contrast-enhanced MRI imaging of the internal auditory canals. The clivus, jugular tubercles, and basio-occiput were assessed for the presence of both intra-osseous veins (serpentine and/or branching vessels) and venous lakes (well-circumscribed round or oval enhancing structures). Vessels in the adjacent synchondroses major foramina were excluded. Three board-certified neuroradiologists performed independent blinded reviews, with discrepancies agreed upon by consensus.
RESULTS
96 patients were included in this cohort (58.3% female). Mean age was 58.4 years (range = 19-85). At least one intra-osseous vessel was identified in 71 (74.0%) patients. 67 (70.0%) had at least one skull base vein, and 14 (14.6%) had at least one venous lake. Both vessel subtypes were observed in 8.3% of patients. Vessels were more commonly observed in women, though this did not reach statistical threshold ( = 0.56). Age was not associated with the presence of vessels (0.59) or vessel location ( values ranged from 0.44-0.84).
CONCLUSIONS
Intra-osseous skull base veins and venous lakes are relatively common findings on MRI. Both vascular structures should be considered normal anatomy, and care should be taken to not confuse these for pathologic entities.
Topics: Humans; Female; Young Adult; Adult; Middle Aged; Aged; Aged, 80 and over; Male; Prevalence; Veins; Skull Base; Skull; Magnetic Resonance Imaging; Cranial Fossa, Posterior
PubMed: 37382936
DOI: 10.1177/19714009231187350 -
Operative Neurosurgery (Hagerstown, Md.) Nov 2023The endoscopic endonasal transpterygoid approach (EETPA) provides direct access to the petrous apex, lateral clivus, inferior cavernous sinus compartment, jugular...
INDICATIONS CORRIDOR AND LIMITS OF EXPOSURE
The endoscopic endonasal transpterygoid approach (EETPA) provides direct access to the petrous apex, lateral clivus, inferior cavernous sinus compartment, jugular foramen, and infratemporal fossa. 1,2 In the coronal plane, it provides exposure far beyond a traditional sphenoidotomy.
ANATOMIC ESSENTIALS NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT
The pterygoid process of the sphenoid bone forms the junction between the body and greater sphenoid wing before bifurcating because it descends into medial and lateral plates. The key to this exposure lies in the region's bony foramina: the palatovaginal canal, vidian canal, and foramen rotundum. 3.
ESSENTIALS STEPS OF THE PROCEDURE
After performing a maxillary antrostomy, stepwise exposure of these foramina leads to the pterygopalatine fossa. The sphenopalatine artery is cauterized as it becomes the posterior septal artery at the sphenopalatine foramen, and the maxillary sinus' posterior wall is opened to expose the pterygopalatine fossa. After mobilizing and retracting the contents of the pterygopalatine fossa, the pterygoid process is removed, improving access in the coronal plane. 4.
PITFALLS/AVOIDANCE OF COMPLICATIONS
Vidian neurectomy causes decreased or absent lacrimation. Injury to the maxillary nerve or its branches results in facial, palatal, or odontogenic anesthesia or neuralgia. In addition, the EEPTA precludes the ability to raise an ipsilateral nasal septal flap, making it crucial to plan reconstruction preoperatively. 4,5.
VARIANTS AND INDICATIONS FOR THEIR USE
There are 5 variants of the EEPTA: extended pterygopalatine fossa, lateral recess of the sphenoid sinus, petrous apex, infratemporal fossa and petrous carotid artery, and middle and posterior skull base. 5The patient consented to the procedure.Images in the video used with permission as follows: images at 0:33 and 1:15 reused from Bozkurt et al, 3 © Georg Thieme Verlag KG; image at 0:39 from Prosser et al, 5 © John Wiley and Sons; images at 0:54, 9:03, and 9:38 from Kasemsiri et al, 1 © John Wiley and Sons; images at 1:07 and 9:44 from Falcon et al, 2 © John Wiley and Sons; image at 1:15 from Sandu et al, 4 © Springer Nature.
Topics: Humans; Skull Base; Nose; Endoscopy; Sphenoid Bone; Petrous Bone
PubMed: 37350591
DOI: 10.1227/ons.0000000000000738 -
Operative Neurosurgery (Hagerstown, Md.) Dec 2023This approach is intended for tumors centered in the jugular foramen with extensions between intracranial and extracranial spaces, possible spread to the middle ear, and...
INDICATIONS CORRIDOR AND LIMITS OF EXPOSURE
This approach is intended for tumors centered in the jugular foramen with extensions between intracranial and extracranial spaces, possible spread to the middle ear, and variable bony destruction. 1,2.
ANATOMIC ESSENTIALS NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT
Jugular foramen paragangliomas are complex lesions that usually invade and fill related venous structures. They present complex relationships with skull base neurovascular structures as internal carotid artery, lower cranial nerves (CNs), middle ear, and mastoid segment of facial nerve. In this way, it is essential to perform an adequate preoperative vascular study to evaluate sinus patency and the tumor blood supply, besides a computed tomography scan to depict bone erosion.
ESSENTIAL STEPS OF THE PROCEDURE
Mastoidectomy through an infralabyrinthine route up to open the lateral border of jugular foramen, allowing exposure from the sigmoid sinus to internal jugular vein. Skeletonization of facial canal without exposure of facial nerve is performed and opening of facial recess to give access to the middle ear in way of a fallopian bridge technique. 2-10.
PITFALLS/AVOIDANCE OF COMPLICATIONS
If there is preoperative preservation of lower CN function, it is important to not remove the anteromedial wall of the internal jugular vein and jugular bulb. In addition, facial nerve should be exposed just in case of preoperative facial palsy to decompress or reconstruct the nerve.
VARIANTS AND INDICATIONS FOR THEIR USE
Variations are related mainly with temporal bone drilling depending on the extensions of the lesion, its source of blood supply, and preoperative preservation of CN function.Informed consent was obtained from the patient for the procedure and publication of his image.Anatomy images were used with permission from:• Ceccato GHW, Candido DNC, and Borba LAB. Infratemporal fossa approach to the jugular foramen. In: Borba LAB and de Oliveira JG. Microsurgical and Endoscopic Approaches to the Skull Base. Thieme Medical Publishers. 2021.• Ceccato GHW, Candido DNC, de Oliveira JG, and Borba LAB. Microsurgical Anatomy of the Jugular Foramen. In: Borba LAB and de Oliveira JG. Microsurgical and Endoscopic Approaches to the Skull Base. Thieme Medical Publishers. 2021.
Topics: Humans; Jugular Foramina; Skull Base; Glomus Jugulare Tumor; Temporal Bone; Cranial Nerves
PubMed: 37350587
DOI: 10.1227/ons.0000000000000775 -
Operative Neurosurgery (Hagerstown, Md.) Oct 2023
Topics: Humans; Jugular Foramina; Neurilemmoma; Craniotomy; Endoscopy; Endoscopes
PubMed: 37345947
DOI: 10.1227/ons.0000000000000800 -
Journal of Cerebral Blood Flow and... Oct 2023Brain fluid dynamics remains poorly understood with central issues unresolved. In this study, we first review the literature regarding points of controversy, then pilot...
Brain fluid dynamics remains poorly understood with central issues unresolved. In this study, we first review the literature regarding points of controversy, then pilot study if conventional MRI techniques can assess brain fluid outflow pathways and explore potential associations with small vessel disease (SVD). We assessed 19 subjects participating in the Mild Stroke Study 3 who had FLAIR imaging before and 20-30 minutes after intravenous Gadolinium (Gd)-based contrast. Signal intensity (SI) change was assessed semi-quantitatively by placing regions of interest, and qualitatively by a visual scoring system, along dorsal and basal fluid outflow routes. Following i.v. Gd, SI increased substantially along the anterior, middle, and posterior superior sagittal sinus (SSS) (82%, 104%, and 119%, respectively), at basal areas (cribriform plate, 67%; jugular foramina, 72%), and in narrow channels surrounding superficial cortical veins separated from surrounding cerebrospinal fluid (CSF) (96%) (all p < 0.001). The SI increase was associated with higher intraparenchymal perivascular spaces (PVS) scores (Std. Beta 0.71, p = 0.01). Our findings suggests that interstitial fluid drainage is visible on conventional MRI and drains from brain parenchyma via cortical perivenous spaces to dural meningeal lymphatics along the SSS remaining separate from the CSF. An association with parenchymal PVS requires further research, now feasible in humans.
Topics: Humans; Pilot Projects; Brain; Magnetic Resonance Imaging; Stroke
PubMed: 37254892
DOI: 10.1177/0271678X231179555 -
Operative Neurosurgery (Hagerstown, Md.) Sep 2023The anterolateral approach (ALA) enables access to the mid and lower clivus, jugular foramen (JF), craniocervical junction, and cervical spine with added anterior and...
BACKGROUND AND OBJECTIVES
The anterolateral approach (ALA) enables access to the mid and lower clivus, jugular foramen (JF), craniocervical junction, and cervical spine with added anterior and lateral exposure than the extreme lateral and endoscopic endonasal approach, respectively. We describe the microsurgical anatomy of ALA with cadaveric specimens and report our clinical experience for benign JF tumors with predominant extracranial extension.
METHODS
A stepwise and detailed microsurgical neurovascular anatomy of ALA was explored with cadaveric specimens. Then, the clinical results of 7 consecutive patients who underwent ALA for benign JF tumors with predominant extracranial extension were analyzed.
RESULTS
A hockey stick skin incision is made along the superior nuchal line to the anterior edge of the sternocleidomastoid muscle (SCM). ALA involves layer-by-layer muscle dissection of SCM, splenius capitis, digastric, longissimus capitis, and superior oblique muscles. The accessory nerve runs beneath SCM and is found at the posterior edge of the digastric muscle. The internal jugular vein (IJV) is lateral to and at the level of the accessory nerve. The occipital artery passes over the longissimus capitis muscle and IJV and into the external carotid artery, which is lateral and superficial to IJV. The internal carotid artery (ICA) is more medial and deeper than external carotid artery and is in the carotid sheath with the vagus nerve and IJV. The hypoglossal and vagus nerves run along the lateral and medial side of ICA, respectively. Prehigh cervical carotid, prejugular, and retrojugular surgical corridors allow deep and extracranial access around JF. In the case series, gross and near-total resections were achieved in 6 (85.7%) patients without newly developed cranial nerve deficits.
CONCLUSION
ALA is a traditional and invaluable neurosurgical approach for benign JF tumors with predominant extracranial extension. The anatomic knowledge of ALA increases competency in adding anterior and lateral exposure of extracranial JF.
Topics: Humans; Jugular Foramina; Cranial Fossa, Posterior; Accessory Nerve; Head and Neck Neoplasms; Cadaver
PubMed: 37195061
DOI: 10.1227/ons.0000000000000763