Microsurgical Anatomy of the Hypoglossal Nerve in the Lateral Approaches to the Craniovertebral Junction: A Study on Fresh Non-Formalin-Fixed Human Specimens

The aim of this anatomical study is to describe the anatomy of the hypoglossal nerve (HN) from its origin to the extracranial portion as it appears by performing a combined posterolateral and anterolateral approach to the craniovertebral junction (CVJ). Twelve fresh, non-formalin-fixed adult cadaveric heads (24 sides) were analyzed for the simulation of the combined lateral approach to the CVJ. The HN is divided into three main parts: cisternal, intracanalicular, and extracranial The anatomical relationships between the HN and other nerves, muscles, arteries and veins were carefully recorded, and some measurements were made between the HN and related structures. Thus, various landmarks were determined for the easy identification of the HN. Understanding the detailed anatomy of the HN and its relationships with the surrounding structures is crucial to prevent some complications during CVJ surgery.

SIMULTANEOUS PERFORMANCE OF ENDOSCOPIC VENTRICULOCISTERNOSTOMY OF THE THIRD VENTRICLE FLOOR, AQUEDUCTOPLASTY, FENESTRATION OF THE SUPRACEREBELLAR CYST IN OCCLUSIVE HYDROCEPHALUS IN A CHILD IN THE FIRST MONTH OF LIFE

The article presents a clinical case of the simultaneous execution of endoscopic ventriculocisternostomy of the third ventricle floor (ETV), aqueductoplasty, fenestration of the supracerebellar cyst in occlusive hydrocephalus using a semi-rigid needle neuroendoscope. The authors describe a child who, at the age of 1 month, was admitted to Neurosurgical Department No. 1 of the Federal Center for Neurosurgery of the Ministry of Health of the Russian Federation in Tyumen with a diagnosis of congenital internal occlusive hydrocephalus, subcompensated course. MRI scan of the brain: triventricular occlusive asymmetric hydrocephalus is visualized, adhesions in the upper parts of the aqueduct, supracerebellar arachnoid cyst were visualised. ETV, aqueductoplasty, fenestration of the supracerebellar cyst were performed. There were no postoperative neurological, endocrine and infectious complications. The observation period after surgery is 7 years from today. Conclusion: preoperative MRI analysis of the structures of the third ventricular floor, interventricular and prepontine cisterns is important for understanding endoscopic, microsurgical anatomy and surgical planning. The use of modern improved endoscopic instruments, low-traumatic performance of all stages of the operation allow to restore cerebrospinal fluid circulation and achieve high efficiency in the treatment of occlusive hydrocephalus in the long-term period. This, in turn, relieves patients of the shunt-dependent state, constant correction of the dysfunctions of the shunt system and long-term, and often ineffective, treatment performed by neurologists and pediatricians.

A study of the anatomical variations in branching pattern of middle cerebral artery

Middle cerebral artery (MCA) is the largest and most complex arterial system of the brain. Variations of the aortic arch branches are due to alteration in the development of specific branchial arch arteries during the embryonic period. Knowledge of these variations is important during aortic instrumentation, thoracic, and neck surgeries. The anatomy of the anterior cerebral artery branches and the anterior communicating artery complex needs to be investigated individually to minimise neurovascular morbidity before iatrogenic procedures. The study aimed to study the variations in the microsurgical anatomy of the MCA in our population and compare the variables and discuss their importance with anatomic and surgical considerations. Specimens were collected from the embalmed cadavers and the post-mortem bodies in the department of forensic medicine of Thanjavur Medical College. The different variables regarding the MCA in our population were analysed and compared with the studies in the Western population and other Indian studies. The mean length of the MCA in this study was 12.8 mm with a standard error of 3.79 mm. The outer diameter of the M1 segment was with a mean length of 3.75mm. In 69.2% middle, Cerebral Artery shows bifurcation and in 20%, it shows trifurcation and in 10.8%, it shows ramification types of branching patterns. The 39.1% cases show Temporo polar, 21.7% orbitofrontal, 9.1% anterior temporal, 6.6% prefrontal, and 4.1% middle temporal branches. Our results also reveal that the origin of the lenticulostriate branch in the middle cerebral artery was 85.85% from the trunk and 14.2% from division, respectively. MCA branching pattern is slightly higher in trifurcation pattern as compared to bifurcation and ramification. Thorough knowledge of the microvascular anatomy and the myriads of variations is essential for the operating surgeon to choose the ideal technique to avoid any catastrophe during and after surgery and give the best possible functional outcome.

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

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.