Ali Karadag

Transcortical selective amygdalohippocampectomy technique through the middle temporal gyrus revisited: An anatomical study laboratory investigation

The anterior temporal lobectomy (ATL) and selective amygdalohippocampectomy (SelAH) have been used for surgical treatment of mesial temporal lobe epilepsy. We examined the comprehensive white matter tract anatomy of the temporal lobe to gain an insight into the trans-middle temporal gyrus, a lateral approach which has been commonly used. The transmiddle temporal gyrus approach was performed in a stepwise manner on cadaveric human heads to examine the traversing white matter pathways through it and the structures located in the temporal horn. We reviewed the literature to compare the trans-middle temporal gyrus approach with other SelAH techniques based on surgical outcomes. There does not appear to be a significant difference in seizure outcome between SelAH and ATL. However, the SelAH provides a better neuropsychological outcomes than the ATL in selected patients. Each SelAH approach has individual advantages and disadvantages. Based on our anatomical study, in the transcortical amygdalohippocampectomy technique through the middle temporal gyrus the white matter pathways to be encountered. In the temporal horn, the collateral eminence, hippocampus, lateral ventricular sulcus, choroidal fissure, inferior choroidal point, choroid plexus, fimbria of the fornix, and amygdala are exposed. The subpial dissection is performed along the lateral ventricular sulcus from the collateral eminence on lateral side and from the choroidal fissure on medial side by microdissector for en bloc resection of the hippocampus proper. The trans-middle temporal gyrus approach is commonly used in treatment of mesial temporal lobe epilepsy patients. A better anatomical and functional understanding of the structures of the temporal lobe is crucial for safer and more accurate surgery.

C1 lateral mass screw insertion from the caudal–dorsal to the cranial–ventral direction as an alternate method for C1 fixation: A quantitative anatomical and morphometric evaluation

OBJECT C1 lateral mass screw has been widely used for fixation of the upper cervical spine. However, traditional fixation methods are not without complication. Morphometric measurement of an alternative approach is conducted. METHODS Three-dimensional CT scans of the cervical spine obtained in 100 adults were evaluated, and key measurements were determined for screw entry points, trajectories, and screw lengths for placement of a C1 screw via this alternate approach. Additional measures were included to account for relevant anatomic variation, including the size of the dangerous lateral zone of the C1 entry point and depth of the atlantooccipital joint surface. Twenty dried atlantal specimens were evaluated to determine corresponding ex vivo measurements. RESULTS The mean maximum angle of medialization was 20.8°±2.8° (right) and 21.1°±2.8° (left), as measured in the axial CT images. Sagittal CT images show the mean maximum superior angulation was 24.7°±4.3° (right) and 24°±4.0° (left), and the mean minimum superior angulation was 13.6°±4.4° (right) and 13.6°±3.9° (left). The mean screw length within the lateral mass was 21.2±1.9mm (right) and 21.3±2.0mm (left). Given an additional 10-15mm needed for rod adaptation, an ideal screw length of 30-35mm was determined. CONCLUSION The C1 insertion caudally from the C2 nerve root may become an alternate method. Preoperative consideration of the ideal screw insertion point, trajectory, and length are vital for safe and effective surgical intervention.

Mammillothalamic and Mammillotegmental Tracts as New Targets for Dementia and Epilepsy Treatment

BACKGROUND Recently, neuromodulation through deep brain stimulation (DBS) has appeared as a new surgical procedure in the treatment of some types of dementia and epilepsy. The mammillothalamic and mammillotegmental tracts are involved among the new targets. To our knowledge, a review article focused specifically on these mammillary body efferents is lacking in the medical literature. Their contribution to memory is, regrettably, often overlooked. METHODS A review of the relevant literature was conducted. RESULTS There is evidence that mammillary bodies can contribute to memory independently from hippocampal formation, but the mechanism is not yet known. Recent studies in animals have provided evidence for the specific roles of these mammillary body efferents in regulating memory independently. In animal studies, it has been shown that the disruption of the mammillothalamic tract inhibits seizures and that electrical stimulation of the mammillary body or mammillothalamic tract raises the seizure threshold. In humans, DBS targeting the mammillary body through the mammillothalamic tract or the stimulation of the anterior thalamic nucleus, especially in the areas closely related to the mammillothalamic tract, has been found effective in patients with medically refractory epilepsy. Nonetheless, little knowledge exists on the functional anatomy of the mammillary body efferents, and their role in the exact mechanism of epileptogenic activity and in the memory function of the human brain. CONCLUSIONS A comprehensive knowledge of the white matter anatomy of the mammillothalamic and mammillotegmental tracts is crucial since they have emerged as new DBS targets in the treatment of various disorders including dementia and epilepsy.

Surgical Management in Cervical Spondylotic Myelopathy Due to Alkaptonuria

BACKGROUND Ochronotic arthropathy related to alkaptonuria is a rare condition. Cervical spine involvement with myelopathic features has been even more rarely described, particularly related to atlantoaxial instability. As such, little is known about the optimal surgical management in these patients. CASE DESCRIPTION We described the first case, to our knowledge, of a patient with alkaptonuria and related cervical spondylotic myelopathy from pannus formation at the atlantoaxial joint. We describe our choices in surgical management of this rare condition in a patient with an excellent outcome. CONCLUSION Ochronotic cervical spondylotic myelopathy is a rare condition and may require additional considerations in surgical treatment compared to more common causes of cervical spondylotic myelopathy. In our case, we elected for decompression with posterior occipitocervical screw fixation and were able to achieve neurologic recovery with no complications, currently at 2-year follow-up.

Cortical Bone Trajectory Screw for Lumbar Fixation: A Quantitative Anatomic and Morphometric Evaluation

BACKGROUND Lumbar cortical bone trajectory (CBT) screw constructs provide an alternative method of pedicle screw fixation in minimally invasive spine surgery. In this study, we explored the CBT technique in further anatomic detail. The primary aims were to evaluate variations in anatomy relevant to CBT screw placement and to determine optimal screw location, trajectory, and length using measures obtained from computed tomography (CT) scans. METHODS One hundred CT scans of the lumbar spine were reviewed, and 14 total measurements of entry points, trajectories, and lengths for placement of CBT screws were evaluated. RESULTS Across all lumbar levels, the mean right pedicle-pars interarticularis junction length ranged from 7.58 ± 1.18 mm to 8.37 ± 1.42 mm, and the mean left pedicle-pars interarticularis junction length ranged from 7.95 ± 1.42 mm to 8.6 ± 1.74 mm. The pedicle-pars interarticularis junction from L1 to L5 was deemed too small for a 5-mm-diameter CBT screw in 35%, 24%, 17%, 17%, and 19%, respectively, on the right, and in 30%, 17%, 17%, 17%, and 20%, respectively, on the left. The average length of a screw placed along the cranial cortical bone of the pedicle ranged from 27 ± 2.5 mm to 30.5 ± 3.4 mm, and the angle of the screw with respect to the vertebral body endplate ranged from 44 ± 4.1° to 48 ± 6.2°. CONCLUSIONS Improved anatomic knowledge relevant to CBT screw placement for lumbar fixation offers the potential for improving outcomes and reducing complications. Moreover, detailed analysis of the anatomy of the pedicle-pars interarticularis junction via preoperative CT can aid in determining the ideal fixation method.

Fiber Connections of the Supplementary Motor Area Revisited: Methodology of Fiber Dissection, DTI, and Three Dimensional Documentation

The purpose of this study is to show the methodology for the examination of the white matter connections of the supplementary motor area (SMA) complex (pre-SMA and SMA proper) using a combination of fiber dissection techniques on cadaveric specimens and magnetic resonance (MR) tractography. The protocol will also describe the procedure for a white matter dissection of a human brain, diffusion tensor tractography imaging, and three-dimensional documentation. The fiber dissections on human brains and the 3D documentation were performed at the University of Minnesota, Microsurgery and Neuroanatomy Laboratory, Department of Neurosurgery. Five postmortem human brain specimens and two whole heads were prepared in accordance with Klinglers method. Brain hemispheres were dissected step by step from lateral to medial and medial to lateral under an operating microscope, and 3D images were captured at every stage. All dissection results were supported by diffusion tensor imaging. Investigations on the connections in line with Meynerts fiber tract classification, including association fibers (short, superior longitudinal fasciculus I and frontal aslant tracts), projection fibers (corticospinal, claustrocortical, cingulum, and frontostriatal tracts), and commissural fibers (callosal fibers) were also conducted.

A Rare History: an Intracranial Nail Present for Over a Half-Century

We present a rare case of a patient with a persistent headache for many years found to have an intracranial nail present for nearly 65 years. The nail was found entering approximately 1 cm from the midline on the left side, passing below the superior sagittal sinus, with the tip 1.5 mm right of the frontal horn of the lateral ventricle. Treatment strategies designed to optimize outcome for intracranial foreign bodies and possible complications are discussed in this report. We also discuss the decision for surgical intervention for foreign bodies and the relevance of position of the foreign body.

A Case of Pseudoaneurysm of the Internal Carotid Artery Following Endoscopic Endonasal Pituitary Surgery: Endovascular Treatment with Flow-Diverting Stent Implantation

Internal carotid artery (ICA) pseudoaneurysm is a rare complication of endoscopic endonasal surgery occurring in 0.4-1.1% of cases. Pseudoaneurysms can subsequently result in other complications, such as subarachnoid hemorrhage, epistaxis, and caroticocavernous fistula with resultant death or permanent neurologic deficit. In this case, we illustrate endovascular treatment with a flow-diverting stent for an ICA pseudoaneurysm after endoscopic endonasal surgery for a pituitary adenoma in a 56-year-old male. Surgery was complicated by excessive intraoperative bleeding and emergent CT angiography confirmed an iatrogenic pseudoaneurysm on the anteromedial surface of the ICA. The pseudoaneurysm was treated endovascularly with flow-diverting stent implantation only. Follow-up CT angiography after three months demonstrated occlusion of the pseudoaneurysm.