Microsurgical anatomy of the anterior cerebral artery and the arterial supply of the cingulate gyrus

PURPOSE

The cingulate gyrus is a potential surgical area to treat tumours, psychiatric diseases, intractable pain and vascular malformations. The aim of the study was to define the topographic anatomy and arterial supply of the cingulate gyrus located on the medial surface of the cerebral hemisphere.

METHODS

We studied thirty-six hemispheres, each hemisected in the midsagittal plane. The vertical thickness of the cingulate gyrus was measured at the anterior commissure (AC), posterior commissure (PC), and genu levels of the corpus callosum. The branches of the anterior and posterior cerebral arteries supplying each zone were noted separately. The arterial pathways were transformed to digital data in AutoCAD to identify the condensation and reduction areas.

RESULTS

The mean AC-PC distance was 27.17 ± 1.63 mm. The thinnest region was the genu level of the corpus callosum (10.29 mm). The superior internal parietal artery (SIPA), inferior internal parietal artery (IIPA) and pericallosal artery (PrCA) supplied all zones of the cingulate gyrus. The anterior zone received the greatest supply. The arterial condensation and reduction areas on both sides of cingulate gyrus and its x, y, and z coordinates specified.

CONCLUSIONS

The target cingulotomy (TC) area was determined for anterior cingulotomy. The properties of the TC area are that the thinnest region of the cingulate gyrus is supplied relatively less than other areas and is close to the anterior cingulotomy areas in the literature. The arterial reduction area (ARA) was found to be suitable for corpus callosotomy in terms of avoiding haemorrhage.

Effectiveness of multiple endoscopic fenestrations for the treatment of Sylvian fissure arachnoid cysts: a multicenter study

PURPOSE

Arachnoid cysts are usually asymptomatic lesions. However, they can sometimes cause intracranial hypertension, headache, seizures, focal neurological deficits, and bleeding. The most commonly used surgical techniques are microsurgical cyst fenestration/excision/drainage, cyst shunting, and endoscopic procedures. We aimed to investigate the success of different surgical techniques.

METHODS

Between 2000 and 2021, patients with Sylvan fissure arachnoid cysts who received treatment via an endoscopic approach chosen as the first-line treatment in three centers were enrolled. All case notes and radiological studies were evaluated retrospectively.

RESULTS

The study included 131 (female, n = 28; male, n = 103) patients with a mean age of 87.04 ± 66.76 (range, 0-216) months. Of the patients, 25 had Galassi type II left-sided arachnoid cysts, 33 had Galassi type II right-sided arachnoid cysts, 40 had Galassi type III left-sided arachnoid cysts, and 32 had Galassi type III right-sided arachnoid cysts. No difference was found between patients who underwent single and multiple fenestrations in terms of Galassi type, side, clinical outcome, and cyst size (p > 0.05). On the contrary, the rate of additional surgical intervention was lower in patients with multiple fenestrations than in those with single fenestration (36.10% vs. 5.30%; p < 0.001).

CONCLUSION

Endoscopic fenestration of Sylvian fissure arachnoid cysts is a good alternative to open surgery or cystoperitoneal shunting, and the number of fenestrations made during this surgery decreases the need for a second surgical procedure.

Topographical Anatomy of the Superficial Temporal Artery

AIM

This study was conducted to describe in detail the gross anatomy of the superficial temporal artery (STA), its course and branches, its relationships with the branches of the facial nerve, and certain anatomical and surgical landmarks to preserve these structures in daily neurosurgical practice and use the STA during revascularization surgery.

MATERIAL AND METHODS

This cadaveric study was conducted on 16 cadaver heads bilaterally, in which 32 silicon/latex-injected STAs were dissected using a microdissection technique in a neuroanatomy laboratory. The distances between the facial nerve, tragus, STA, superficial temporal vein (STV), and imaginary lines created between important anatomical landmarks were measured. The curvilinear lengths of STA and STV were also measured.

RESULTS

The average distances of the most posteriorly located branch of the facial nerve to the frontal region and the tragus at the midpoint of zygoma in the horizontal plane, at the superior border of the zygoma and at the level of the superior border of the parotid gland, were measured as 25.39, 29.84, and 15.56 mm, respectively. The average distance directly measured between the tragus and STA was 39.29 mm, and that between the tragus and STV was 20.26 mm. The average curvilinear lengths of the frontal and parietal branches of STA were 97.63 and 96.45 mm, respectively.

CONCLUSION

Understanding the clinical anatomy of the STA and its branches and its relationships with other structures is of critical importance for a successful and noncomplicated surgery. Our findings will be useful not only for surgical approaches such as pterional craniotomy and orbitozygomatic approaches but also for cerebral revascularization.

Morphology of the trigeminal ganglion: anatomical structures related to trigeminal radiofrequency rhizotomy

BACKGROUND

Trigeminal neuralgia is the most common example of craniofacial neuralgia. Its etiology is unknown and is characterized by severe episodes of paroxysmal pain. The trigeminal ganglion and its adjacent anatomical structures have a complex anatomy. The foramen ovale is of great importance during surgical procedures such as percutaneous trigeminal rhizotomy for trigeminal neuralgia.

OBJECTIVE

We aimed to identify the anatomical structures associated with the trigeminal ganglion and radiofrequency rhizotomy on cadavers and investigate their relationship with the electrodes used during rhizotomy to determine the contribution of the electrode diameter and length to the effectiveness of the lesion formation on the ganglion.

METHODS

Five fresh-frozen cadaver heads injected with red silicone/latex were used. A percutaneous puncture was made by inserting of a cannula through the foramen ovale to create a pathway for electrodes. The relationships between the electrodes, Meckel's cave, trigeminal ganglion, and neurovascular structures were observed and morphometric measurements were obtained using a digital caliper.

RESULTS

Trigeminal ganglion, therefore the electrode in its final position, shows proximity with important anatomical structures. The electrode was inserted posteriorly into the foramen ovale in all of the specimens and was located on the retrogasserian fibers. This study revealed that the electrodes targeting the ganglion and passing through the foramen ovale may cause a radiofrequency lesion due to the contact effect of the dura itself pressing on the electrode. Pushing the cannula beyond the petroclival angle may result in puncturing of the dura propria and moving further away from the target area.

CONCLUSION

The success of radiofrequency rhizotomy is directly related to the area affected by the lesion. Understanding the mechanism of action underlying this procedure will ensure the effectiveness, success, and sustainability of the treatment.

Repeat endoscopic third ventriculostomy success rate according to ventriculostoma closure patterns in children

PURPOSE

This study aimed to examine the success rate of repeat endoscopic third ventriculostomy (redo-ETV) according to pattern of ventriculostoma closure based on observations in 97 paediatric redo-ETV patients.

METHODS

Clinical data and intraoperative video recordings of 97 paediatric hydrocephalus patients who underwent redo-ETV due to ventriculostoma closure at two institutions were retrospectively analysed. We excluded patients with a history of intraventricular haemorrhage, cerebrospinal fluid (CSF) infection or CSF shunt surgery and those with incompletely penetrated membranes during the initial ETV.

RESULTS

Verification of ventriculostoma closure was confirmed with cine phase-contrast magnetic resonance imaging and classified into 3 types: type 1, total closure of the ventriculostoma by gliosis or scar tissue that results in a non-translucent/opaque third ventricle floor; type 2, narrowing/closure of the ventriculostoma by newly formed translucent/semi-transparent membranes; and type 3, presence of a patent ventriculostoma orifice with CSF flow blockage by newly formed reactive membranes or arachnoidal webs in the basal cisterns. The overall success rate of redo-ETV was 37.1%. The success rates of redo-ETV according to closure type were 25% for type 1, 43.6% for type 2 and 38.2% for type 3. The frequency of type 1 ventriculostoma closure was significantly higher in patients with myelomeningocele-related hydrocephalus.

CONCLUSION

For patients with ventriculostoma closure after ETV, reopening of the stoma can be performed. Our findings regarding the frequencies of ventriculostoma closure types and the success rate of redo-ETV in paediatric patients according to ventriculostoma closure type are preliminary and should be verified by future studies.

Endoscopic Anatomy and a Safe Surgical Corridor to the Anterior Skull Base

OBJECTIVE

We describe the possibility to create precise preoperative planning for endonasal endoscopic approaches to the anterior skull base by overlapping endoscopic and radiologic anatomy. The important anatomic structures were marked. Morphometric measurements between these anatomic landmarks were performed endoscopically and compared with radiologic measurements of the same areas to ensure result compatibility.

METHODS

Seven cadaver heads injected intravascularly with colored silicone were used for this study. Thin-section brain and paranasal sinus computed tomography scans were obtained on all cadavers. Using 0-degree rigid endoscopes and endonasal endoscopic surgical instruments, the anterior skull base was examined binostrally in all cadavers. Bilateral middle turbinates were identified and preserved. Next, an inferior uncinectomy and middle meatal antrostomy were performed. After performing a frontal antrostomy, bilateral anterior and posterior ethmoidal cells were opened and the skull base was identified and followed to the posterior wall of the frontal sinus. A transnasal transethmoidal sphenoidotomy was done with full exposure to the entire anterior skull base.

RESULTS

The anatomic landmarks for endonasal endoscopic skull base approaches were distinguished and measurements were made. The anterior skull base was divided into 3 compartments: anterior (area between the posterior inferior border of the frontal sinus and the course of anterior ethmoidal artery), middle (area between the course of the anterior ethmoidal artery and that of the posterior ethmoidal artery [PEA]), and posterior (area between the course of the PEA and the attachment point of the anterior border of the sphenoid sinus to the skull base) compartments. The distances between important anatomic markers and endoscopic depth measurements of this area were measured.

CONCLUSION

During endonasal endoscopic anterior skull base surgery, the area between the anterior border of the sphenoid sinus and PEA artery was safe as the first dissection zone. Preoperative radiologic width and depth measurements facilitate orientation to the endoscopic anatomy during surgery and help predict the endonasal surgical corridor anatomy preoperatively.

Transcranial endoscopic treatment of thalamic neuroepithelial cyst: case report and review of the literature

Thalamic neuroepithelial cysts are rare, benign lesions. Thirteen cases have been published in eight articles. The most frequent symptoms are headache, hemiparesis, tremor and related signs of hydrocephalus such as gait disturbance, confusion, and Paranaud's syndrome. Surgical interventions include endoscopic fenestration, open surgery and stereotaxic biopsy or aspiration. We report a case of a 63-year-old woman who had headache and right hemiparesis for 1 week, but no hydrocephalus. We treated her with transcranial neuronavigation-guided endoscopic complete resection. The patient recovered completely after cyst removal.

Third Ventricle Floor Variations and Abnormalities in Myelomeningocele-Associated Hydrocephalus: Our Experience with 455 Endoscopic Third Ventriculostomy Procedures

AIM

To evaluate the incidence of anatomical variations and abnormalities of the third ventricle floor encountered during the endoscopic third ventriculostomy (ETV) procedure in myelomeningocele-associated hydrocephalus (MAH) cases.

MATERIAL AND METHODS

A retrospective analysis was performed on 455 pediatric MAH cases that had been treated with ETV. This case series consisted of the patients who were initially treated with ETV and also those who were treated with ETV for the management of cerebrospinal fluid shunt dysfunction. Variations and anomalies of the third ventricle floor were determined by reviewing the video records of the ETV procedures.

RESULTS

The analysis of the data revealed that the rate of the MAH cases with variations and abnormalities of the third ventricle floor was 41.1%. The most common anatomical features were "thick and prominent massa intermedia" (37.1%) and "narrow tuber cinereum" (33.1%).

CONCLUSION

This study documents the most common anatomical variations and abnormalities of the third ventricle floor in cases with MAH. Various anatomical situations and specific ventricular configuration of MAH cases may add an operative factor of difficulty which should be well recognized by the neurosurgeon who plans and executes an ETV procedure in this patient population.

Does Shunt Selection Affect the Rate of Early Shunt Complications in Neonatal Myelomeningocele-Associated Hydrocephalus? A Multi-Center Study

AIM

To evaluate the effect of shunt selection on the rate of shunt revision due to early shunt complications in neonatal myelomeningocele-associated hydrocephalus.

MATERIAL AND METHODS

The data of 157 neonatal myelomeningocele cases in three pediatric neurosurgery centers (Ankara University, Kocaeli University, Selcuk University) who underwent shunt surgery at the time of myelomeningocele repair between 2000 and 2014 were retrospectively analyzed. Clinical features of the patients, shunt types, and early shunt complications within the first three months were recorded. The patients were classified according to several features of the shunt systems, such as the valve type, valve size/contour and catheter type.

RESULTS

Of all patients, 71 (45.2%) underwent early shunt revision surgery due to various complications. Mechanical complications were the most frequent cause of shunt failure, followed by infection. There was no significant difference among the valve types. Also, no significant difference was observed among the catheter types. Only valve contour/size (contoured regular/ultra-small/burr-hole/ cylindrical/neonatal) seemed to significantly affect the rate of early complications. The patients with neonatal-design valves or ultrasmall valves had significantly less complications, such as poor wound-healing, wound-dehiscence, cerebrospinal fluid leak or shunt exposure. The infection rate secondary to these complications was found to be lower.

CONCLUSION

Myelomeningocele patients with prominent hydrocephalus frequently have a friable skin, due to reduced macrocrania-related subcutaneous tissues. Small-sized (neonatal-design or ultra-small) valves may significantly reduce the early shunt complication rate among this population.

Effect of Pre/Postconditioning at Temporary Clipping

Intracranial aneurysms and their treatment is one of the leading problems of neurosurgery that create high mortality and morbidity. The technique of safe clipping is as generally used depends on the temporary occlusion of the cerebral vasculature during surgery. However, there is no exact data about temporary clipping or timing of this procedure. Preconditioning by exposure to sublethal hypoxic stress, hours or days before severe hypoxia, decreases cell death, and this resistance of the brain to injury is known as ischemic tolerance. Brief alternating periods of reperfusion-reocclusion at the beginning of reperfusion is defined as postconditioning. Cerebral ischemic pre/postconditioning protects against stroke, but is clinically feasible only when the occurrence of stroke is predictable. Brief, repetitive occlusion and release of the main trunk of a vessel during early aneurysm surgery or before long-lasting temporary artery occlusion may protect the brain against later possible vasospasm/ischemia.