1
|
Farooq M, Ashfaq D, Ranjha KU, Ergen A, Atallah O, Badary A, Scalia G. Liliequist membrane: A systematic review of history, anatomy, clinical importance, and surgical challenges. Clin Neurol Neurosurg 2024; 242:108322. [PMID: 38795689 DOI: 10.1016/j.clineuro.2024.108322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Revised: 05/05/2024] [Accepted: 05/06/2024] [Indexed: 05/28/2024]
Abstract
BACKGROUND The Liliequist membrane (LM) represents a crucial yet challenging anatomical structure in neuroanatomy. First observed in 1875 and later elucidated by Bengt Liliequist in 1956, the LM's precise anatomical description and boundaries remain complex. Its significance extends to neurosurgery, impacting various procedures like endoscopic third ventriculocisternostomies, aneurysm and tumor surgeries, treatment of suprasellar arachnoid cysts, and managing perimesencephalic hemorrhages. However, a comprehensive understanding of the LM is hindered by inconsistent anatomical descriptions and limitations in available literature, warranting a systematic review. METHODS A systematic review was conducted by searching PubMed, Science Direct, and Google Scholar for articles pertaining to Liliequist's membrane. The search employed Mesh terms like "Liliequist membrane," "Liliequist's diaphragm," and related variations. Inclusion criteria encompassed studies exploring the historical evolution, anatomical structure, radiological characteristics, and clinical implications of the LM in neurosurgery. RESULTS The search yielded 358 articles, with 276 unique articles screened based on relevance. Following a meticulous screening process, 72 articles underwent full-text assessment, resulting in the inclusion of 5 articles meeting the eligibility criteria. The selected studies varied in methodology, including anatomical dissections, radiological evaluations, and clinical significance in neurosurgical procedures. Insights were derived on LM's anatomical variations, radiological visualization, and its critical role in guiding neurosurgical interventions. CONCLUSIONS Despite advancements in understanding its clinical significance and radiological visualization, challenges persist in precisely delineating its boundaries. Further research, especially on embryological development and histological characterization, is essential. Enhancing comprehension of LM-related pathologies is crucial for accurate preoperative planning and optimizing patient outcomes in neurosurgery.
Collapse
Affiliation(s)
- Minaam Farooq
- Department of Neurosurgery, King Edward Medical University, Mayo Hospital Lahore, Pakistan.
| | | | - Kaleem Ullah Ranjha
- Department of Neurosurgery, King Edward Medical University, Mayo Hospital Lahore, Pakistan
| | | | - Oday Atallah
- Department of Neurosurgery, Hannover Medical School, Carl-Neuberg-Street 1, Hannover 30625, Germany
| | - Amr Badary
- Dessau Clinical Center, Dessau-Rosslau, Brandenburg University, Germany
| | - Gianluca Scalia
- Neurosurgery Unit, Department of Head and Neck Surgery, Garibaldi Hospital, Catania, Italy
| |
Collapse
|
2
|
Pescatori L, Taurone S, Ciccarelli A, Palmieri M, Serraino A, Artico M, Fornai F, Longhitano Y, Zanza C, Tesauro M, Savioli G, Miglietta S, Ciappetta P. Petroclival Clinoidal Folds and Arachnoidal Membranes of the Anteromedial Incisural Space: Clinical Anatomy for Neuro Critical Care. Diagnostics (Basel) 2023; 13:3203. [PMID: 37892024 PMCID: PMC10605941 DOI: 10.3390/diagnostics13203203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/09/2023] [Accepted: 10/12/2023] [Indexed: 10/29/2023] Open
Abstract
A systematic and narrative literature review was performed, focusing attention on the anatomy of the area located at the junction of the sphenoid and the basal portion of the temporal bone (petrous bone, petrous apex, upper petro-clival region) encircled by the free edge of the tentorium, the insertion of the tentorium itself to the petrous apex and the anterior and posterior clinoid processes that give rise to three distinct dural folds or ligaments: the anterior petroclinoid ligament, the posterior petroclinoid ligament and the interclinoid ligament. These dural folds constitute the posterior portion of the roof of the cavernous sinus denominated "the oculomotor triangle". The main purpose of this review study was to describe this anatomical region, particularly in the light of the relationships between the anterior margin of the free edge of the tentorium and the above-mentioned components of the sphenoid and petrous bone.
Collapse
Affiliation(s)
- Lorenzo Pescatori
- Department of Neurosurgery, S. Eugenio Hospital of Rome, 00144 Rome, Italy
| | - Samanta Taurone
- Department of Movement, Human and Health Sciences, Division of Health Sciences, University of Rome “Foro Italico”, 00135 Rome, Italy
| | - Antonello Ciccarelli
- Department of Movement, Human and Health Sciences, Division of Health Sciences, University of Rome “Foro Italico”, 00135 Rome, Italy
| | - Mauro Palmieri
- Human Neurosciences Department, A.U.O. “Policlinico Umberto I” Neurosurgery Division, Sapienza University, 00185 Rome, Italy (A.S.)
| | - Alessandra Serraino
- Human Neurosciences Department, A.U.O. “Policlinico Umberto I” Neurosurgery Division, Sapienza University, 00185 Rome, Italy (A.S.)
| | - Marco Artico
- Department of Sensory Organs, “Sapienza” University of Rome, 00185 Rome, Italy;
| | - Francesco Fornai
- IRCCS Neuromed, 86077 Pozzilli, Italy;
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Yaroslava Longhitano
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Department of Emergency Medicine, Humanitas University Hospital, 20089 Rozzano, Italy
| | - Christian Zanza
- Italian Society of Prehospital Emergency Medicine (SIS 118), 74121 Taranto, Italy
- Post Graduate School of Geriatric Medicine, University of Rome “Tor Vergata”, 00133 Rome, Italy
| | - Manfredi Tesauro
- Post Graduate School of Geriatric Medicine, University of Rome “Tor Vergata”, 00133 Rome, Italy
- Department of Systems Medicine, University of Rome “Tor Vergata”, 00133 Rome, Italy
| | - Gabriele Savioli
- Emergency Department, IRCCS Fondazione Policlinico San Matteo, 27100 Pavia, Italy;
| | - Selenia Miglietta
- Department of Anatomical, Histological, Forensic Medicine and Orthopedics Sciences, “Sapienza” University of Rome, 00185 Rome, Italy;
| | | |
Collapse
|
3
|
Theologou M, Kouskouras K, Natsis K, Varoutis P, Zaggelidou E, Tsonidis C. Microanatomic Morphometric Characteristics of the Third Ventricle Floor. Brain Sci 2023; 13:brainsci13040580. [PMID: 37190545 DOI: 10.3390/brainsci13040580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 03/27/2023] [Accepted: 03/27/2023] [Indexed: 04/01/2023] Open
Abstract
Background: Endoscopic third ventriculostomy (ETV) is an effective treatment for hydrocephalus. The in-depth understanding of microanatomy is essential for accurate diagnosis, treatment and complications prevention. The aim of this study is to supplement the knowledge gap regarding the microanatomical metrics and correlations for which the literature includes only scarce mentions at best. Methods: This is a descriptive microanatomical study including 25 cadaver brains. Specimens from donors with neurological, psychiatric disorders or alcohol abuse were excluded. Surgical loops were used for harvesting. High-precision tools were employed to dissect and measure the anatomical landmarks under a surgical microscope. Each measurement was performed in three consecutive attempts and outliers were rejected. RStudio was used for statistical analysis. Distribution was evaluated employing the Shapiro–Wilk test. Normally distributed values were presented as mean and standard deviation, and others as median and interquartile range. Results: The age of the donors was 61.72 (±10.08) years. The distance from the anterior aspect of the foramen of Monro to the anterior margin of the mamillary body was 16.83 (±1.04) mm, and to the posterior margin was 16.76 (±1.9) mm. The distance from the anterior mamillary body margin to the infundibulum was 6.39 (±1.9) mm, to the optic recess was 8.25 (±1.84) mm, and to the apex of the vertebral artery was 5.05 (±1.62) mm. The distance from the anterior commissure to the brain aqueduct was 22.46 (±2.29) mm, and to the infundibulum was 13.93 (±2.54) mm. The mamillary body diameter was 4.91 (±0.34) mm in the anteroposterior and 4.21 (±0.48) mm in the cranio-caudal plane. The intraventricular segment was protruding by 1.63 (±0.46) mm. The diameter of the hypothalamus on the anterior margin of mamillary bodies was 1.37 (±0.75) mm, of the Liliequist membrane was 0.19 (±0.07) mm and of the lamina terminalis was 0.35 (±0.32) mm. Conclusion: The presented microanatomical measurements and correlations are expected to contribute to the improvement of ETV safety.
Collapse
|
4
|
Arachnoid and dural reflections. HANDBOOK OF CLINICAL NEUROLOGY 2021; 169:17-54. [PMID: 32553288 DOI: 10.1016/b978-0-12-804280-9.00002-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The dura mater is the major gateway for accessing most extra-axial lesions and all intra-axial lesions of the central nervous system. It provides a protective barrier against external trauma, infections, and the spread of malignant cells. Knowledge of the anatomical details of dural reflections around various corners of the skull bases provides the neurosurgeon with confidence during transdural approaches. Such knowledge is indispensable for protection of neurovascular structures in the vicinity of these dural reflections. The same concept is applicable to arachnoid folds and reflections during intradural excursions to expose intra- and extra-axial lesions of the brain. Without a detailed understanding of arachnoid membranes and cisterns, the neurosurgeon cannot confidently navigate the deep corridors of the skull base while safely protecting neurovascular structures. This chapter covers the surgical anatomy of dural and arachnoid reflections applicable to microneurosurgical approaches to various regions of the skull base.
Collapse
|
5
|
The role of the Liliequist membrane in the third ventriculostomy. Neurosurg Rev 2021; 44:3375-3385. [PMID: 33624133 DOI: 10.1007/s10143-021-01508-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/27/2021] [Accepted: 02/16/2021] [Indexed: 10/22/2022]
Abstract
Endoscopic third ventriculostomy (ETV) is a hydrocephalus treatment procedure that involves opening the Liliequist membrane (LM). However, LM anatomy has not been well-studied neuroendoscopically, because approach angles differ between descriptive and microsurgical anatomical explorations. Discrepancies in ETV efficacy, especially among children age 2 and younger, may be due to incomplete LM opening. The objective of this study was to characterize the LM anatomically from a neuroendoscopic perspective to better understand the impact of anatomical features during LM ostomy and the ETV success rate. Additionally, the ETV success score was tested to predict patient outcome after the intraoperatively difficult opening of LM. Fifty-four patients who underwent ETV were prospectively analyzed with a mean follow-up of 53.1 months (1-90 months). The ETV technical parameters of difficulty were validated by seven expert neurosurgeons. The pediatric population (44) of this study represents the majority of patients (81.4%). The overall ETV success rate was 68.5%. Anomalies on the IIIVT floor resulted in an increased rate of ETV failure. The IIIVT was anomalous, and LM was thick in 33.3% of cases. Fenestration of LM was difficult in 39% of cases, and the LM and TC were opened separately in 55.6% of cases. The endoscopic third ventriculostomy success score (ETVSS) accurately predicted the level of difficulty opening the LM (p = 0.012), and the group with easy opening presented greater durability in ETV success. Neurosurgeons should be aware of the difficulty level of the overture of LM during ETV and its impact on long-term ETV effectiveness.
Collapse
|
6
|
The membrane of Liliequist-a safe haven in the middle of the brain. A narrative review. Acta Neurochir (Wien) 2020; 162:2235-2244. [PMID: 32193727 PMCID: PMC7415027 DOI: 10.1007/s00701-020-04290-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/11/2020] [Indexed: 10/27/2022]
Abstract
BACKGROUND The membrane of Liliequist is one of the best-known inner arachnoid membranes and an essential intraoperative landmark when approaching the interpeduncular cistern but also an obstacle in the growth of lesions in the sellar and parasellar regions. The limits and exact anatomical description of this membrane are still unclear, as it blends into surrounding structures and joins other arachnoid membranes. METHODS We performed a systematic narrative review by searching for articles describing the anatomy and the relationship of the membrane of Liliequist with surrounding structures in MEDLINE, Embase and Google Scholar. Included articles were cross-checked for missing references. Both preclinical and clinical studies were included, if they detailed the clinical relevance of the membrane of Liliequist. RESULTS Despite a common definition of the localisation of the membrane of Liliequist, important differences exist with respect to its anatomical borders. The membrane appears to be continuous with the pontomesencephalic and pontomedullary membranes, leading to an arachnoid membrane complex around the brainstem. Furthermore, Liliequist's membrane most likely continues along the oculomotor nerve sheath in the cavernous sinus, blending into and giving rise to the carotid-oculomotor membrane. CONCLUSION Further standardized anatomical studies are needed to clarify the relation of the membrane of Liliequist with surrounding structures but also the anatomy of the arachnoid membranes in general. Our study supports this endeavour by identifying the knowledge hiatuses and reviewing the current knowledge base.
Collapse
|
7
|
Kurucz P, Ganslandt O, Buchfelder M, Barany L. Arachnoid Membranes Around the Cisternal Segment of the Trigeminal Nerve: A Cadaveric Anatomic Study and Intraoperative Observations During Minimally Invasive Microvascular Decompression Surgery. World Neurosurg 2019; 125:e262-e272. [DOI: 10.1016/j.wneu.2019.01.060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 01/03/2019] [Accepted: 01/05/2019] [Indexed: 10/27/2022]
|
8
|
Kurucz P, Barany L, Buchfelder M, Ganslandt O. The Clival Line as an Important Arachnoid Landmark During Endoscopic Third Ventriculostomy: An Anatomic Study. World Neurosurg 2018; 120:e877-e888. [DOI: 10.1016/j.wneu.2018.08.180] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Revised: 08/22/2018] [Accepted: 08/23/2018] [Indexed: 11/24/2022]
|
9
|
Kurucz P, Ganslandt O. Letter to the Editor Regarding "Anatomic Dissection of Arachnoid Membranes Encircling the Pituitary Stalk on Fresh Non-Formalin-Fixed Specimens: Anatomoradiologic Correlations and Clinical Applications in Craniopharyngioma Surgery". World Neurosurg 2017; 109:505-506. [PMID: 29232813 DOI: 10.1016/j.wneu.2017.09.036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 09/07/2017] [Indexed: 12/01/2022]
Affiliation(s)
- Peter Kurucz
- Department of Neurosurery, Klinikum Stuttgart, Stuttgart, Germany.
| | - Oliver Ganslandt
- Department of Neurosurery, Klinikum Stuttgart, Stuttgart, Germany
| |
Collapse
|
10
|
Park HK, Rha HK, Lee KJ, Chough CK, Joo W. Microsurgical Anatomy of the Oculomotor Nerve. Clin Anat 2016; 30:21-31. [DOI: 10.1002/ca.22811] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 11/16/2016] [Indexed: 02/02/2023]
Affiliation(s)
- Hae Kwan Park
- Department of Neurosurgery; Yeouido St. Mary's Hospital, The Catholic University of Korea College of Medicine; Seoul South Korea
| | - Hyung Keun Rha
- Department of Neurosurgery; Yeouido St. Mary's Hospital, The Catholic University of Korea College of Medicine; Seoul South Korea
| | - Kyung Jin Lee
- Department of Neurosurgery; Yeouido St. Mary's Hospital, The Catholic University of Korea College of Medicine; Seoul South Korea
| | - Chung Kee Chough
- Department of Neurosurgery; Yeouido St. Mary's Hospital, The Catholic University of Korea College of Medicine; Seoul South Korea
| | - Wonil Joo
- Department of Neurosurgery; Yeouido St. Mary's Hospital, The Catholic University of Korea College of Medicine; Seoul South Korea
| |
Collapse
|
11
|
Visualization of Liliequist's membrane prior to endoscopic third ventriculostomy. Radiol Med 2015; 121:200-5. [PMID: 26474584 DOI: 10.1007/s11547-015-0588-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 09/25/2015] [Indexed: 10/22/2022]
Abstract
PURPOSE Endoscopic third ventriculostomy (ETV) is an effective treatment in patients with obstructive hydrocephalus caused by aqueductal stenosis. Operative failure may occur if an unnoticed membrane below the floor of the third ventricle is present, such as Liliequist's membrane (LM). To analyze how often LM can be visualized by high-resolution heavily T2-weighted 3D-MRI prior to ETV, and to find out potential reasons for diagnostic failure. MATERIALS AND METHODS Preoperative 3D-MR images of 37 consecutive patients (19 female, median 42 years) were retrospectively analyzed. Visualization of three LM segments (sellar, diencephalic, mesencephalic), dimensions of the space below the third ventricle, and extent of hydrocephalus were measured. Image quality was scored (score 1[poor] to 3[excellent]). Preoperative imaging findings were compared with intraoperative findings. RESULTS Patients were subdivided into group 1 (no segment of LM identified, n = 18), and group 2 (at least one segment of LM was identified, n = 19). The sellar segment of LM was most often positively identified (10 out of 19 cases). The mean distance between the pons and the sella/clivus was significantly shorter in group 1 than in group 2 (3.7 vs. 6.2 mm; p < 0.01). Other variables, such as the distance between tip of the pons and the mamillary bodies as well as the image quality, were not significantly different between both groups. Intraoperatively, LM was present in 78 % of group 2 patients, and in 28 % of group 1 patients, respectively (p < 0.03). CONCLUSIONS LM can be detected in about half of patients prior to ETV. Reduced PSD influences visualization of LM.
Collapse
|
12
|
Anatomical variations and neurosurgical significance of Liliequist's membrane. Childs Nerv Syst 2015; 31:15-28. [PMID: 25395307 DOI: 10.1007/s00381-014-2590-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 11/03/2014] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Liliequist's membrane is an arachnoid membrane that forms a barrier within the basilar cisternal complex. This structure is an important landmark in approaches to the sellar and parasellar regions. The importance of this membrane was largely recognized after the advance of neuroendoscopic techniques. Many studies were, thereafter, published reporting different anatomic findings. METHOD A detailed search for studies reporting anatomic and surgical findings of Liliequist's membrane was performed using "PubMed," and included all the available literature. Manual search for manuscripts was also conducted on references of papers reporting reviews. RESULTS Liliequist's membrane has received more attention recently. The studies have reported widely variable results, which were systematically organized in this paper to address the controversy. CONCLUSION Regardless of its clinical and surgical significance, the anatomy of Liliequist's membrane is still a matter of debate.
Collapse
|
13
|
Arachnoid membrane: the first and probably the last piece of the roadmap. Surg Radiol Anat 2014; 37:127-38. [DOI: 10.1007/s00276-014-1361-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 08/12/2014] [Indexed: 10/24/2022]
|
14
|
The intracranial arachnoid mater : a comprehensive review of its history, anatomy, imaging, and pathology. Childs Nerv Syst 2013; 29:17-33. [PMID: 22961357 DOI: 10.1007/s00381-012-1910-x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 08/27/2012] [Indexed: 10/27/2022]
Abstract
INTRODUCTION The arachnoid mater is a delicate and avascular layer that lies in direct contact with the dura and is separated from the pia mater by the cerebrospinal fluid-filled subarachnoid space. The subarachnoid space is divided into cisterns named according to surrounding brain structures. METHODS The medical literature on this meningeal layer was reviewed in regard to historical aspects, etymology, embryology, histology, and anatomy with special emphasis on the arachnoid cisterns. Cerebrospinal fluid dynamics are discussed along with a section devoted to arachnoid cysts. CONCLUSION Knowledge on the arachnoid mater and cerebrospinal fluid dynamics has evolved over time and is of great significance to the neurosurgeon in clinical practice.
Collapse
|
15
|
Anik I, Ceylan S, Koc K, Tugasaygi M, Sirin G, Gazioglu N, Sam B. Microsurgical and endoscopic anatomy of Liliequist's membrane and the prepontine membranes: cadaveric study and clinical implications. Acta Neurochir (Wien) 2011; 153:1701-11. [PMID: 21380853 DOI: 10.1007/s00701-011-0978-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 02/15/2011] [Indexed: 11/28/2022]
Abstract
BACKGROUND Liliequist's membrane is mostly described as having a diencephalic leaf, mesencephalic leaf, and diencephalic-mesencephalic leaves in the literature. Also different descriptions of the prepontine membranes were reported. In this study, we visualized the regular structural forms of membranes without disturbing any attachments and defined infrachiasmatic and prepontine safety zones. We discussed the clinical significance of these structures. MATERIALS AND METHODS The study was carried out on 24 adult human cadavers at the Morgue Specialization Department of the Forensic Medicine Institution following the initial autopsy examination. Liliequist's membrane and the prepontine membranes were explored after retraction of the frontal lobes. Dissections were performed under the operative microscope. A 0- and 30-degree, 2.7-mm angled rigid endoscope (Aesculap, Tuttlingen, Germany) was advanced through the prepontine cistern from the natural holes of membranes, or small holes were opened without damaging the surrounding structures. RESULTS The basal arachnoid membrane (BAM) continued as Liliequist's membrane (LM) without any distinct separation in all specimens. The LM coursed over the posterior clinoids and split into two leaves as the diencephalic leaf (DL) and mesencephalic leaf (ML) in 18 specimens; the medial pontomesencephalic membrane (MPMM) coursed anterolaterally as a continuation of the ML and attached to the medial surfaces of the fifth and sixth nerves, joining with the lateral pontomesencephalic membrane (LPMM), which was also a posterolateral continuation of the ML in all specimens. The medial pontomedullar membrane (MPMdM) and lateral pontomedullar membrane (LPMdM) were observed in 21 specimens. The MPMdM membrane was a continuation of the MPMM, and the LPMdM was a continuation of the LPMM in all 21 specimens. CONCLUSION We observed that the LM is a borderless continuation of the BAM. The MPMM and LPMM split from the ML without any interruptions. The MPMdM and LPMdM were a single membrane continuing from the MPMM and LPMM. We determined infrachiasmatic and prepontine areas that can be important for inferior surgical approaches.
Collapse
Affiliation(s)
- Ihsan Anik
- Department of Neurosurgery, Kocaeli University, School of Medicine, 41380, Umuttepe, Kocaeli, Turkey
| | | | | | | | | | | | | |
Collapse
|