scholarly journals Microsurgical Anatomy of Safe Entry Zones on the Ventrolateral Brainstem: A Morphometric Study

2021 ◽  
Author(s):  
Ilke Bayzıt Kocer ◽  
Mine Oner Demiralin ◽  
Mete Erturk ◽  
Dilek Arslan ◽  
Gulgun Sengul
Keyword(s):  
Trigeminal Nerve ◽  
Inferior Olive ◽  
Careful Analysis ◽  
Anatomical Landmark ◽  
Oculomotor Nerve ◽  
Preoperative Imaging ◽  
Morphometric Study ◽  
Lateral Side ◽  
Microsurgical Anatomy ◽  
Descending Fibers

Abstract Surgery of the brainstem is challenging due to the complexity of the area with cranial nerve nuclei, reticular formation and ascending and descending fibers. Safe entry zones are required to reach the intrinsic lesions of the brainstem. The aim of this study was to provide detailed measurements for anatomical landmark zones of the ventrolateral surface of the human brainstem related to previously described safe entry zones. In this study, 53 complete and 34 midsagittal brainstems were measured using a stainless caliper with an accuracy of 0.01 mm. The distance between the pontomesencephalic and bulbopontine sulci was measured as 26.94 mm. Basilar sulcus-lateral side of pons (origin of the fibers of the trigeminal nerve) distance was 17.23 mm, transverse length of the pyramid 5.42 mm and vertical length of the pyramid 21.36 mm. Lateral mesencephalic sulcus was 12.73 mm, distance of the lateral mesencephalic sulcus to the oculomotor nerve 13.85 mm and distance of trigeminal nerve to the upper tip of pyramid 17.58 mm. The transverse length for the inferior olive at midpoint and vertical length were measured as 5.21 mm and 14.77 mm, consequently. The thickness of the superior colliculus was 4.36 mm, the inferior colliculus 5.06 mm; length of the tectum was 14.5 mm and interpeduncular fossa 11.26 mm. Profound anatomical knowledge and careful analysis of preoperative imaging are mandatory before surgery of the brainstem lesions. The results presented in this study will serve neurosurgeons operating in the brainstem region.

Comprehensive anatomy of the foramen ovale critical to percutaneous stereotactic radiofrequency rhizotomy: cadaveric study of dry skulls

2020 ◽  
Vol 132 (5) ◽  
pp. 1414-1422
Author(s):  
Adel Elnashar ◽  
Smruti K. Patel ◽  
Almaz Kurbanov ◽  
Kseniya Zvereva ◽  
Jeffrey T. Keller ◽  
...  
Keyword(s):  
Trigeminal Neuralgia ◽  
Facial Pain ◽  
Preoperative Imaging ◽  
Morphometric Study ◽  
Microsurgical Anatomy ◽  
Foramen Ovale ◽  
Percutaneous Approach ◽  
Head Ct ◽  
Adjacent Structures ◽  
Shape And Size

OBJECTIVEPercutaneous stereotactic radiofrequency rhizotomy (PSR) is often used to treat trigeminal neuralgia, a serious condition that results in lancinating, episodic facial pain. Thorough understanding of the microsurgical anatomy of the foramen ovale (FO) and its surrounding structures is required for efficient, effective, and safe use of this technique. This morphometric study compares anatomical and surgical orientations to identify the variations of the FO and assess cannulation difficulty.METHODSBilateral foramina from 174 adult human dry skulls (348 foramina) were analyzed using anatomical and surgical orientations in photographs from standardized projections. Measurements were obtained for shape, size, adjacent structures, and morphometric variability effect on cannulation. The risk of potential injury to surrounding structures was also assessed.RESULTSThe authors identified 6 distinctive shapes of the FO and 5 anomalous variants from the anatomical view, and 6 shapes from the surgical view. In measurements of surface area of this foramen obtained using the surgical view, loss (average 18.5% ± 5.7%) was significant compared with the anatomical view. Morphometrically, foramen size varied significantly and obstruction from a calcified pterygoalar ligament occurred in 7.8% of specimens. Importantly, 8% of foramina were difficult to cannulate, thus posing a 12% risk of inadvertent cannulation of the foramen lacerum.CONCLUSIONSSignificant variability in the FO’s shape and size probably affected its safe and effective cannulation. Preoperative imaging by 3D head CT may be helpful in predicting ease of cannulation and in guiding treatment decisions, such as a percutaneous approach over microvascular decompression or radiosurgery.

Microsurgical Anatomy of the Oculomotor Nerve

2016 ◽  
Vol 30 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Hae Kwan Park ◽  
Hyung Keun Rha ◽  
Kyung Jin Lee ◽  
Chung Kee Chough ◽  
Wonil Joo
Keyword(s):  
Oculomotor Nerve ◽  
Microsurgical Anatomy

Bilateral Extensive Ossification of the Posterior Petroclinoid Ligament: An Anatomical Case Report and Literature Review

2018 ◽  
Vol 80 (02) ◽  
pp. 122-126 ◽  
Author(s):  
Robert Haładaj ◽  
Michał Polguj ◽  
Andrzej Żytkowski ◽  
Mirosław Topol ◽  
Grzegorz Wysiadecki
Keyword(s):  
Case Report ◽  
Literature Review ◽  
Surgical Procedures ◽  
Oculomotor Nerve ◽  
Microsurgical Anatomy ◽  
Case Description ◽  
Detailed Data ◽  
Dorello’S Canal ◽  
Research Material ◽  
Close Proximity

Background The posterior petroclinoid dural fold (commonly referred to as a ligament) forms the roof of the trigeminal porus and the roof of the petroclival venous confluence. It lies in close proximity to the oculomotor nerve that crosses it. Due to the low availability of research material, only a few cadaveric studies have been conducted on the microsurgical anatomy of the petroclinoid ligament in cases of its ossification. Thus our report complements earlier studies and provides detailed data on the spatial relationships between the ossified posterior petroclinoid ligament and the trigeminal, oculomotor, and abducens nerves, with special attention to the topographical relationships within the petroclival venous confluence and Dorello's canal. Case Description Bilateral massive ossification of the posterior petroclinoid ligament was observed during the dissection of a 76-year-old female cadaver. The presence of an osseous bridge over the trigeminal notch was also detected on the left side. No narrowing of the space occupied by the petroclival venous confluence was observed. However, the dural sheath of the oculomotor nerve was fixed much more than usual. Conclusions Because the ossification of the posterior petroclinoid ligament may be considered a factor influencing diagnostic and surgical procedures, neurosurgeons and neuroradiologists should be aware of this variation. Ossification of the posterior petroclinoid ligament may also potentially result in greater susceptibility of the oculomotor nerve to injury.

scholarly journals Microsurgical anatomy and approaches around the lateral recess with special reference to entry into the pons

2018 ◽  
Vol 129 (3) ◽  
pp. 740-751 ◽  
Author(s):  
Osamu Akiyama ◽  
Ken Matsushima ◽  
Maximiliano Nunez ◽  
Satoshi Matsuo ◽  
Akihide Kondo ◽  
...  
Keyword(s):  
Surgical Approaches ◽  
Morphometric Study ◽  
Microsurgical Anatomy ◽  
Entry Zone ◽  
Lateral Recess ◽  
Fiber Tracts ◽  
Adjacent Structures ◽  
Microsurgical Techniques ◽  
Safe Entry Zone ◽  
Wide Exposure

OBJECTIVEThe lateral recess is a unique structure communicating between the ventricle and cistern, which is exposed when treating lesions involving the fourth ventricle and the brainstem with surgical approaches such as the transcerebellomedullary fissure approach. In this study, the authors examined the microsurgical anatomy around the lateral recess, including the fiber tracts, and analyzed their findings with respect to surgical exposure of the lateral recess and entry into the lower pons.METHODSTen cadaveric heads were examined with microsurgical techniques, and 2 heads were examined with fiber dissection to clarify the anatomy between the lateral recess and adjacent structures. The lateral and medial routes directed to the lateral recess in the transcerebellomedullary fissure approach were demonstrated. A morphometric study was conducted in the 10 cadaveric heads (20 sides).RESULTSThe lateral recess was classified into medullary and cisternal segments. The medial and lateral routes in the transcerebellomedullary fissure approach provided access to approximately 140º–150º of the posteroinferior circumference of the lateral recess. The floccular peduncle ran rostral to the lateral recess, and this region was considered to be a potential safe entry zone to the lower pons. By appropriately selecting either route, medial-to-lateral or lateral-to-medial entry axis is possible, and combining both routes provided wide exposure of the lower pons around the lateral recess.CONCLUSIONSThe medial and lateral routes of the transcerebellomedullary fissure approach provided wide exposure of the lateral recess, and incision around the floccular peduncle is a potential new safe entry zone to the lower pons.

Microsurgical Anatomy of the Cisternal Course of the Perforating Branches of the Posterior Communicating Artery

Neurosurgery ◽  
1990 ◽  
Vol 26 (5) ◽  
pp. 824-831 ◽  
Author(s):  
F. Vincentelli ◽  
G. Caruso ◽  
F. Grisoli ◽  
P. Rabehanta ◽  
C. Andriamamonjy ◽  
...  
Keyword(s):  
Close Relationships ◽  
Oculomotor Nerve ◽  
Posterior Communicating Artery ◽  
Microsurgical Anatomy ◽  
Embryological Development ◽  
Interpeduncular Cistern ◽  
Anatomical Arrangement ◽  
Human Brains

Abstract Both the perforating branches-especially the extracerebral segments-and the arachnoidal anatomy at the level of the posterior communicating artery were studied in 60 human brains previously fixed in formalin. The close relationships between this artery and the oculomotor nerve are described, and it is noted that each of them is enclosed in its own arachnoidal compartment, which in the case of the posterior communicating artery is to be distinguished from the interpeduncular cistern. The latter cistern was found to contain only the terminal segments of the posterior communicating artery. The hypothalamic branches were within the inner wall of the arachnoidal cistern surrounding the posterior communicating artery. The variations in diameter of this artery are explained by its embryological development and are not related to the number and the diameter of the perforators. The posterior communicating artery was absent at times. The surgical implications of such a variable anatomical arrangement are discussed in the light of the literature.

scholarly journals Microsurgical anatomy of safe entry zones on the ventrolateral brainstem: a morphometric study

2021 ◽  
Author(s):  
Ilke Bayzıt Kocer ◽  
Mine Oner Demiralin ◽  
Mete Erturk ◽  
Dilek Arslan ◽  
Gulgun Sengul
Keyword(s):  
Morphometric Study ◽  
Microsurgical Anatomy

scholarly journals Morphometric Study of Pterion in Dry Human Skull at Medical College of Eastern Nepal

2019 ◽  
Vol 2 (3) ◽  
pp. 214-219
Author(s):  
Umesh Kumar Mehta ◽  
Arun Dhakal ◽  
Surya Bahadur Parajuli ◽  
Sanjib Kumar Sah
Keyword(s):  
Cross Sectional Study ◽  
Surgical Approaches ◽  
Morphometric Study ◽  
Lateral Side ◽  
Lateral Aspect ◽  
Cross Sectional ◽  
Medical College ◽  
Bony Landmarks ◽  
Human Skulls ◽  
The Right

Background: The pterion is defined as an H shaped sutural confluence present on the lateral side of the skull. This pterion junction has been used as a common extra-cranial landmark for surgeons in microsurgical and surgical approaches towards important pathologies of this region. Methods:This is ananalytical cross sectional study conducted at Department of Anatomy, Birat Medical College & Teaching Hospital, Tankisinuwari, Morang, Nepal. Total enumeration technique was used to collect samples where 31 dry human skulls of unknown age and sex were taken. The sutural pattern and location of the pterion was determined and measured on both sides of each skull using digitalvernier caliper. Results: Three types of sutural patterns of pterion were observed. Among them, Sphenoparietal type was higher in frequency.The frequency was 26 (83.8%) on the right side and 24 (77.4%) on the left side. The distance between the centre of pterion to the midpoint of upper border of zygomatic arch was 3.82±0.3 cm on the right side and 3.8±0.29 cm on the left side. The distance between the centre of pterion to the postero-lateral aspect of fronto-zygomatic suture was 3.02±0.23 cmon the right side and 3.0±0.23 cm on the left side. Conclusions: The information of thesutural pattern and the location of the pterion from the different bony landmarks of our study may be useful for anthropologists and neurosurgeons.

Functional anatomy of headache: circle of Willis aneurysms, third cranial nerve and pain

2011 ◽  
pp. 82-88
Author(s):  
Marcelo Moraes Valença ◽  
Luciana P. A. Andrade-Valença ◽  
Carolina Martins
Keyword(s):  
Cranial Nerve ◽  
Nerve Palsy ◽  
Functional Anatomy ◽  
Circle Of Willis ◽  
Oculomotor Nerve ◽  
Oculomotor Nerve Palsy ◽  
Microsurgical Anatomy ◽  
Third Nerve Palsy ◽  
The Right ◽  
Third Nerve

Patients with intracranial aneurysm located at the internal carotid artery-posterior communicating artery (ICA-PComA) often present pain on the orbit or fronto-temporal region ipsilateral to the aneurysm, as a warning sign a few days before rupture. Given the close proximity between ICA-PComA aneurysm and the oculomotor nerve, palsy of this cranial nerve may occurduring aneurysmal expansion (or rupture), resulting in progressive eyelid ptosis, dilatation of the pupil and double vision. In addition, aneurysm expansion may cause compression not only of the oculomotor nerve, but of other skull base pain-sensitive structures (e.g. dura-mater and vessels), and pain ipsilateral to the aneurysm formation is predictable. We reviewed the functional anatomy of circle of Willis, oculomotor nerve and its topographical relationships in order to better understand the pathophysiology linked to pain and third-nerve palsy caused by an expanding ICAPComA aneurysm. Silicone-injected, formalin fixed cadaveric heads were dissected to present the microsurgical anatomy of the oculomotor nerve and its topographical relationships. In addition, the relationship between the right ICA-PComA aneurysm and the right third-nerve is also shown using intraoperative images, obtained during surgical microdissection and clipping of an unruptured aneurysm. We also discuss about when and how to investigate patients with headache associated with an isolated third-nerve palsy.

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