Ventral amygdalofugal pathway as an integrated surgically important network: microsurgical anatomy and segmentation based on fiber dissection.

OBJECTIVE: The ventral amygdalofugal pathway (VAFP) provides afferent and efferent connections to the amygdala and spans along some of the frequently traversed intra-axial surgical corridors as a dominant fiber bundle. This study aimed to reveal the frequently overlooked VAFP fibers by examining their courses and connections to the basal forebrain, septal region, hypothalamus, thalamus, tegmentum, and brainstem. METHODS: Ten postmortem human brains were used to display the characteristics of the VAFP, and fiber dissection results were compared with those of tractography. RESULTS: From anterior to posterior, the VAFP was separated into 5 different portions: 1) amygdala-substantia innominata; 2) amygdaloseptal (diagonal band of Broca); 3) amygdalo-thalamic; 4) amygdalo-hypothalamic, intermingling with the medial forebrain bundle and extending to the bed nucleus of stria terminalis; and 5) amygdalotegmental. The results of fiber dissections were confirmed with findings obtained from diffusion tensor tractography. CONCLUSIONS: This study supports the concept that interconnected forebrain, diencephalic, mesencephalic, and brainstem connections of the VAFP form an integrated surgically important network. The fiber dissection findings also provide the neuroanatomical basis for VAFP segmentation, which may help neurosurgeons better appreciate the complex microsurgical anatomy of the amygdalar connections. Amygdala-substantia innominata and amygdalotegmental connections are demonstrated for the first time and clarified within the structure of the VAFP.

Optimal anatomical angle and distance for drilling in cervical oblique corpectomy: A surgical anatomical study.

Background: One of the difficulties of oblique corpectomy, less discussed in the literature, is the problem of how to achieve an optimum corpectomy. Therefore, this anatomico-radiological study was conducted to shed light on the use of the microscope at an appropriate angle and optimum drill distances in clinical cases undergoing cervical oblique corpectomy surgery. Materials and Methods: We examined the average distance of the diagonal line extending from the medial aspect of the ipsilateral vertebral foramen to the contralateral pedicle in cervical computed tomography -angiography axial scans in four cervical vertebrae, C3, C4, C5, and C6. We also measured the average angle between this diagonal trajectory and the horizontal line, making a total of 712 measurements in 89 patients. Results: We found that horizontal drilling with an average length of 23-26 mm at an acute angle of about 22° -23° is optimal for adequate decompression of the spinal cord in the oblique corpectomy approach. Depending on the patient and the level of the vertebra, the distance and the angle of the horizontal drilling may range from 18 mm to 31 mm and from 15° to 33°, respectively. Conclusions: For an optimum cervical oblique corpectomy that provides adequate spinal cord decompression and maintains spinal stability, it is necessary to operate under a surgical microscope positioned at an acute angle and to know the horizontal drilling distance.

Microsurgical anatomy of the isthmic cingulum: a new white matter crossroad and neurosurgical implications in the posteromedial interhemispheric approaches and the glioma invasion patterns.

ABTRACT: The dichotomy of the cingulum bundle into the dorsal supracallosal and ventral parahippocampal parts is widely accepted; however, the retrosplenial component with its multiple alternative connections has not been revealed. The aim of this study was to delineate the microsurgical anatomy of a connectionally transition zone, the isthmic cingulum, in relation to the posteromedial interhemispheric access to the atrium and discuss the relevant patterns of glioma invasion on the basis of its fiber connections. White matter (WM) fibers were dissected layer by layer in a medial-to-lateral, lateral-to-medial, and posterior-to-anterior fashion. All related tracts and their connections were generated using deterministic tractography. The magnetic resonance imaging (MRI) tractography findings were correlated with those of fiber dissection. A medial parieto-occipital approach to reach the atrium was performed with special emphasis on the cingulate isthmus and underlying WM connections. The isthmic cingulum, introduced as a retrosplenial connectional crossroad for the first time, displayed multiple connections to the splenium and the superior thalamic radiations. Another new finding was the demonstration of lateral hemispheric extension of the isthmic cingulum fibers through the base of the posterior part of the precuneus at the base of the parieto-occipital sulcus. The laterally crossing cingulum fibers were interconnected with three distinct association tracts: the middle longitudinal (MdLF), the inferior frontooccipital fasciculi (IFOF), and the claustro-cortical fibers (CCF). In the process of entry to the atrium during posterior interhemispheric approaches, the splenial and thalamic connections, as well as the laterally crossing fibers of the isthmic cingulum, were all in jeopardy. The connectional anatomy of the retrosplenial area is much more complicated than previously known. The isthmic cingulum connections may explain the concept of interhemispheric and medial to lateral cerebral hemisphere invasion patterns in medial parieto-occipital and posteromesial temporal gliomas. The isthmic cingulum is of key importance in posteromedial interhemispheric approaches to both: the atrium and the posterior mesial temporal lobe.

Comparison of Clinical and Radiologic Outcomes between Dural Splitting and Duraplasty for Adult Patients with Chiari Type I Malformation.

BACKGROUND: The most used surgical procedure in the treatment of patients with Chiari type I malformation (CIM) is posterior fossa decompression. However, no consensus has been reached regarding the superiority of either dural splitting or duraplasty. Thus, the aim of this study was to compare clinical and radiologic outcomes between the two techniques used in consecutive patients. METHODS: We retrospectively reviewed 74 adult patients with CIM who were diagnosed and treated surgically between 2015 and 2020 at our neurosurgery department. The patients were divided into two groups: dural splitting in group 1 and duraplasty in group 2. Clinical outcomes based on Chicago Chiari Outcome Scale (CCOS) scores at the last control visits were compared between the groups. Radiologic outcomes were compared in terms of tonsillar regression rate based on 12-postoperative-month magnetic resonance images. RESULTS: Overall improved, unchanged, and worsened neurologic statuses were observed in 75.6% (n = 56), 17.5% (n = 13), and 6.7% (n = 5) of our patients, respectively. The mean last visit CCOS scores in groups 1 and 2 were 12.3 ± 2.1 and 13.5 ± 1.7, respectively. The difference between the groups was statistically significant (p < 0.01). The mean tonsillar regression rates were 34.7 ± 17.0% and 52.1 ± 15.3% in groups 1 and 2, respectively, with a statistically significant difference (p < 0.001). CONCLUSION: Adult patients undergoing duraplasty had better clinical and radiologic outcomes than those treated with dural splitting. Therefore, we recommend decompression with duraplasty for adult CIM patients.

Efficacy of Middle Meningeal Artery Embolization in Treatment Resistant Spontaneous Intracranial Hypotension Caused Subdural Hematoma : Report of Two Cases and Review of the Literature.

Spontaneous intracranial hypotension (SIH) most commonly manifests as bilateral subdural hematoma (SH). SIH cases mostly resolve spontaneously but further treatment would be needed via blind epidural blood patch (EBP). Cerebrospinal fluid (CSF) leakage in EBP-refractory cases can be treated surgically only if the localization of CSF leakage is detectable but it cannot be possible in most of the cases. Also surgical evacuation of SH secondary to SIH (SH-SIH) is not favorable without blocking the CSF leakage. Thus the management of these patients is a challenge and alternative treatment options are needed. Although middle meningeal artery embolization (MMAE) is an effective treatment option in non-SIH SH, there is no report about its application in the treatment of SH-SIH. We present two cases of SH-SIH which their clinical and radiological findings were completely resolved by bilateral MMAE treatment.

Contralateral vs. Ipsilateral Approach to Superior Hypophyseal Artery Aneurysms: An Anatomical Study and Morphometric Analysis.

Introduction: Surgical clipping of superior hypophyseal artery (SHA) aneurysms is a challenging task for neurosurgeons due to their close anatomical relationships. The development of endovascular techniques and the difficulty in surgery have led to a decrease in the number of surgical procedures and thus the experience of neurosurgeons in this region. In this study, we aimed to reveal the microsurgical anatomy of the ipsilateral and contralateral approaches to SHA aneurysms and define their limitations via morphometric analyses of radiological anatomy, three-dimensional (3D) modeling, and surgical illustrations. Method: Five fixed and injected cadaver heads underwent dissections. In order to make morphometric measurements, 75 cranial MRI scans were reviewed. Cranial scans were rendered with a module and used to produce 3D models of different anatomical structures. In addition, a medical illustration was drawn that shows different sizes of aneurysms and surgical clipping approaches. Results: For the contralateral approach, pterional craniotomy and sylvian dissection were performed. The contralateral SHA was reached from the prechiasmatic area. The dissected SHA was approached with an aneurysm clip, and maneuverability was evaluated. For the ipsilateral approach, pterional craniotomy and sylvian dissection were performed. The ipsilateral SHA was reached by mobilizing the left optic nerve with left optic nerve unroofing and left anterior clinoidectomy. MRI measurements showed that the area of the prechiasm was 90.4 ± 36.6 mm2 (prefixed: 46.9 ± 10.4 mm2, normofixed: 84.8 ± 15.7 mm2, postfixed: 137.2 ± 19.5 mm2, p < 0.001), the distance between the anterior aspect of the optic chiasm and the limbus sphenoidale was 10.0 ± 3.5 mm (prefixed: 5.7 ± 0.8 mm, normofixed: 9.6 ± 1.6 mm, postfixed:14.4 ± 1.6 mm, p < 0.001), and optic nerves' interneural angle was 65.2° ± 10.0° (prefixed: 77.1° ± 7.3, normofixed: 63.6° ± 7.7°, postfixed: 57.7° ± 5.7°, p: 0.010). Conclusion: Anatomic dissections along with 3D virtual model simulations and illustrations demonstrated that the contralateral approach would potentially allow for proximal control and neck control/clipping in smaller SHA aneurysm with relatively minimal retraction of the contralateral optic nerve in the setting of pre- or normofixed chiasm, and ipsilateral approach requires anterior clinodectomy and optic unroofing with considerable optic nerve mobilization to control proximal ICA and clip the aneurysm neck effectively.

A comparative study for glioma classification using deep convolutional neural networks.

Gliomas are a type of central nervous system (CNS) tumor that accounts for the most of malignant brain tumors. The World Health Organization (WHO) divides gliomas into four grades based on the degree of malignancy. Gliomas of grades I-II are considered low-grade gliomas (LGGs), whereas gliomas of grades III-IV are termed high-grade gliomas (HGGs). Accurate classification of HGGs and LGGs prior to malignant transformation plays a crucial role in treatment planning. Magnetic resonance imaging (MRI) is the cornerstone for glioma diagnosis. However, examination of MRI data is a time-consuming process and error prone due to human intervention. In this study we introduced a custom convolutional neural network (CNN) based deep learning model trained from scratch and compared the performance with pretrained AlexNet, GoogLeNet and SqueezeNet through transfer learning for an effective glioma grade prediction. We trained and tested the models based on pathology-proven 104 clinical cases with glioma (50 LGGs, 54 HGGs). A combination of data augmentation techniques was used to expand the training data. Five-fold cross-validation was applied to evaluate the performance of each model. We compared the models in terms of averaged values of sensitivity, specificity, F1 score, accuracy, and area under the receiver operating characteristic curve (AUC). According to the experimental results, our custom-design deep CNN model achieved comparable or even better performance than the pretrained models. Sensitivity, specificity, F1 score, accuracy and AUC values of the custom model were 0.980, 0.963, 0.970, 0.971 and 0.989, respectively. GoogLeNet showed better performance than AlexNet and SqueezeNet in terms of accuracy and AUC with a sensitivity, specificity, F1 score, accuracy, and AUC values of 0.980, 0.889, 0.933, 0.933, and 0.987, respectively. AlexNet yielded a sensitivity, specificity, F1 score, accuracy, and AUC values of 0.940, 0.907, 0.922, 0.923 and 0.970, respectively. As for SqueezeNet, the sensitivity, specificity, F1 score, accuracy, and AUC values were 0.920, 0.870, 0.893, 0.894, and 0.975, respectively. The results have shown the effectiveness and robustness of the proposed custom model in classifying gliomas into LGG and HGG. The findings suggest that the deep CNNs and transfer learning approaches can be very useful to solve classification problems in the medical domain.

Multi-Level Anterior Cervical Decompression in Multi-Level Cervical Spondylotic Myelopathy without Extending the Corpus Resection: A Cadaveric Study of a Novel Surgical Technique.

AIM: To perform three-level decompression with a single-level corpectomy by modifying the fusion with anterior cervical corpectomy (ACC-F) method on a cadaver. MATERIAL AND METHODS: The anterior cervical region of four whole-head cadavers was dissected. The corpectomy was performed under a surgical microscope with a MT4-20+ ultrasonic bone dissector (UBD) tip. Superior and inferior decompression were conducted and viewed with a 70° neuroendoscope using two types (vertically and horizontally oriented) of specially designed 23 mm-long, 90°-angled UBD tips. RESULTS: After neck dissection and the removal of the thyroid and cricoid cartilages, C5 corpectomy and adjacent-level discectomies were performed. Following discectomy and corpectomy, superior and inferior decompression were conducted with specially designed UBD tips and viewed with a 70° neuroendoscope. A three-level anterior cervical decompression was provided with a single-level corpectomy. CONCLUSION: This study demonstrated that two more level decompression is possible with a single-level corpectomy in the cervical region using the new technique.

The Synergistic Effect of Combined Transforaminal and Caudal Epidural Steroid Injection in Recurrent Lumbar Disc Herniations.

Background Recurrent lumbar disc herniation (RLDH) is one of the most common causes of chronic low back and leg pain. Although surgical treatment has high success rates in primary lumbar disc herniations, recurrence is not an uncommon clinic condition after the surgery. Considering the recurrent surgeries have lower success rates and higher risks, such as dural tear and nerve injury, alternative treatment modalities are needed for RLDH patients. Epidural steroid injections (ESI), particularly transforaminal steroid injection (TFESI) and caudal steroid injection (CESI), which are the alternative treatments to surgery, have not shown reasonable results in RLDH separately. In this study, we aimed to investigate the effects of combined TFESI and CESI (TFESI + CESI) treatment, which has been found successful in primary lumbar disc herniation (PLDH) and on pain control and quality of life in RLDH patients for the first time. Materials and methods A total of 71 patients, who had ESI treatment as only TFESI or TFESI + CESI because of RLDH in our clinic between March 2017 and February 2020, were investigated retrospectively. The visual analog scale (VAS) leg, VAS back, and Oswestry disability index (ODI) were used to assess leg pain, low back pain, and limitation of daily routine activities. Each assessment was done before the intervention and repeated at the third week, the third month, and the sixth month of injection, and the results were noted. Results Out of 71 patients, 38 were female and 33 male. Patients were divided into two subgroups according to the applied ESI methods as only TFESI (n = 32) and TFESI + CESI (n = 39). In the only TFESI group, the mean VAS leg score was 7.84, 4.63, 5.40, and 6.19 before, at the third week, the third month, and the sixth month of the injection, respectively. Also, in this group, the mean VAS back score was 8.06, 4.16, 4.88, and 5.97; the mean ODI score was 55.81, 34.31, 37.5, and 49.04 in the same respect. In the TFESI + CESI group, the mean VAS leg score was 8.20, 2.87, 3.64, 4.23; mean VAS back score 8.03, 3.05, 3.90, 4.08; mean ODI score 56.56, 28.05, 30.21, 33.64 before, at the third week, third month, and sixth month of the injection, respectively. The mean of the initial VAS leg, VAS back, and ODI scores was not found to be statistically significantly different between the two groups. The mean of all VAS leg, VAS back, and ODI scores was found to be lower in the TFESI + CESI group than the only TFESI group at each third-week, third-month, and sixth-month controls, and these differences were statistically significant. (p<0.0001 at each controls for VAS leg; p = 0.001 at third week, p = 0.002 at third month and p <0.0001 at sixth month for VAS back; p= 0.0003 at third week, p<0.0001 at third month, p<0.0001 at sixth month for ODI) Conclusion Our study demonstrates that TFESI + CESI treatment is an effective non-surgical treatment for RLDH. Considering the higher risks and lower success rates of recurrent surgeries, TFESI + CESI can be a potential treatment option for RLDH patients.

Surgical Approaches to the Thalamus in Relation to the White Matter Tracts of the Cerebrum.

BACKGROUND: Approaching the thalamus from any angle remains a challenge because of its deep-seated location and intimate relations with adjacent important neurovascular structures and functions such as relaying sensory and motor signals and cognition. Our aim was to explore the relationship of the white matter tracts of the cerebrum to the thalamus using a fiber dissection technique, to delineate anatomic principles of approaches to the thalamus, and to discuss the tracts at risk in relation to each approach. METHODS: The thalamus was subdivided into 6 different regions and 13 approaches were examined in an attempt to describe a surgical road map. RESULTS: To reach the anteroinferior, medial, and lateral parts of the thalamus, the anterior and middle group approaches were used, and to reach the posterosuperior and posteroinferior thalamus, posterior and middle group approaches were used. The anteroinferior zone was the most difficult site to be accessed and the posterosuperior thalamus had the maximum number of alternative approaches. The distal transsylvian approach to the posterosuperior thalamus and the supracarotid infrafrontal approach to the anteroinferior thalamus had the highest number of neural structures severed within the surgical corridor. The infratentorial approaches and the suboccipital transtentorial approach preserve most of the white matter tracts en route to the posterosuperior and medial posteroinferior parts of the thalamus. CONCLUSIONS: When the surgical approaches for thalamic lesions are defined, white matter tracts along the surgical route should be taken into consideration.

Intraventricular Gadoteric Acid Intoxication: First Report.

BACKGROUND: Gadolinium-based contrast agents are relatively safe for use in magnetic resonance imaging (MRI) of nervous system pathology. Few reports have been reported regarding the severe adverse effects. These are mostly mild anaphylactoid reactions, especially in the vulnerable group. CASE DESCRIPTION: We report a case of an adverse effect of gadoteric acid concerning the misuse as intraventricular administration. To our knowledge, this is the first report related to intraventricular spillage and its results. A 38-year-old male patient with a complaint of headache and drowsiness was admitted to the hospital, after which cranial MRI revealed that he had a posterior fossa mass. An operation was performed with the catheterization of the lateral ventricule as a safety device at the beginning, and later mass was evacuated gross totally. Frozen pathology result showed the tumor was medulloblastoma. On the first postoperative day a control contrasted cranial and total spinal MRI was planned. He was observed to have a tonic-clonic generalized seizure soon after returning to the ward. After giving the acute management with antiepileptics, the patient was stabilized and it was recognized that the patient was administered contrast media by the intraventricular route. Symptomatic treatment and cerebrospinal fluid irrigation by external ventricular drainage helped the patient's improvement. After a week his symptoms were relieved and he had no complications during outpatient controls. CONCLUSIONS: In addition to formal basic supportive treatment, cerebrospinal fluid irrigation of the toxic contrast material is the best management method in case of such an unexpected misadministration of gadoteric acid.