Anatomic study of the occipital condyle and its surgical implications in transcondylar approach

Anatomy of the craniocervical junction - A review

An in-depth understanding of the anatomy of the craniocervical junction (CCJ) is indispensable in skull base neurosurgery. In this paper, we discuss the osteology of the occipital bone, the atlas (C1) and axis (C2), the ligaments and the muscle anatomy of the CCJ region and their relationships with the vertebral artery. We will also discuss the trajectory of the vertebral artery and review the anatomy of the jugular foramen and lower cranial nerves (IX to XII). The most important surgical approaches to the CCJ, including the far lateral approach, the anterolateral approach of Bernard George and the endoscopic endonasal approach, will be discussed to review the surgical anatomy.

Morphological analysis and morphometry of the occipital condyle and its relationship to the foramen magnum, jugular foramen, and hypoglossal canal: implications for craniovertebral junction surgery

Anatomical knowledge of the occipital condyle (OC) and its relationships to surrounding structures is important for avoiding injury during craniovertebral junction (CVJ) surgeries. This study was conducted to evaluate the morphology and morphometry of OC and its relationship to foramen magnum, jugular foramen (JF), and hypoglossal canal (HC). Morphometric parameters including length, width, height, and distances from the OC to surrounding structures were measured. The oval-like condyle was the most common OC shape, representing for 33.0% of all samples. The mean length, width and height of OC were 21.3±2.4, 10.5±1.4, and 7.4±1.1 mm, respectively. Moreover, OC was classified into three types based on its length. The most common OC length in both sexes was moderate length or type II (62.5%). The mean distance between anterior tips and posterior tips of OC to basion, and opisthion were 11.5±1.4, 39.1±3.3, 25.2±2.2, and 27.4±2.7 mm, respectively. The location of intracranial orifice of HC was commonly found related to middle 1/3 of OC in 45.0%. JF was related to the anterior 2/3 of OC in 81.0%, the anterior 1/3 of OC in 12.5%, and the entire OC length in 6.5%. These morphological analysis and morphometric data should be taken into consideration before performing surgical operation to avoid CVJ instability and neurovascular structure injury.

Anterior occipital condyle screw placement through the endonasal corridor: proof of concept study with cadaveric analysis

PURPOSE

Odontoidectomy for ventral compressive pathology may result in O-C1 and/or C1-2 instability. Same-stage endonasal C1-2 spinal fusion has been advocated to eliminate risks associated with separate-stage posterior approaches. While endonasal methods for C1 instrumentation and C1-2 trans-articular stabilization exist, no hypothetical construct for endonasal occipital instrumentation has been validated. We provide an anatomic description of anterior occipital condyle (AOC) screw endonasal placement as proof-of-concept for endonasal craniocervical stabilization.

METHODS

Eight adult, injected cadaveric heads were studied for placing 16 AOC screws endonasally. Thin-cut CT was used for registration. After turning a standard inferior U-shaped nasopharyngeal flap endonasally, 4 mm × 22 mm AOC screws were placed with a 0° driver using neuronavigation. Post-placement CT scans were obtained to determine: site-of-entry, measured from the endonasal projection of the medial O-C1 joint; screw angulation in sagittal and axial planes, proximity to critical structures.

RESULTS

Average site-of-entry was 6.88 mm lateral and 9.74 mm rostral to the medial O-C1 joint. Average angulation in the sagittal plane was 0.16° inferior to the palatal line. Average angulation in the axial plane was 23.97° lateral to midline. Average minimum screw distances from the jugular bulb and hypoglossal canal were 4.80 mm and 1.55 mm.

CONCLUSION

Endonasal placement of AOC screws is feasible using a 0° driver. Our measurements provide useful parameters to guide optimal placement. Given proximity of hypoglossal canal and jugular bulb, neuronavigation is recommended. Biomechanical studies will ultimately be necessary to evaluate the strength of AOC screws with plate-screw constructs utilizing endonasal C1 lateral mass or C1-2 trans-articular screws as inferior fixation points.

Electromyographic assessment of condylar screw placement during occipitocervical fusion

OBJECTIVE

This is a retrospective study of a series of occipitocervical fusion procedures with condylar screw fixation in which the authors investigated the utility of electromyography (EMG, free-running and triggered) as a reliable tool in assessing the positioning of condylar screws. This series consisted of 197 patients between 15 and 60 years of age who presented with craniocervical instability, and who were treated between October 2014 and December 2017.

METHODS

Intraoperative free-running EMG was observed at the placement of condylar screws, as well as at realigning of the spine. After placement the condylar screws were stimulated electrically, and the thresholds were recorded. CT scans were obtained intraoperatively soon after screw stimulation, and the results were analyzed by the surgeon in real time. Free-running EMG results and triggered EMG thresholds were tabulated, and the minimum acceptable threshold was established.

RESULTS

Intraoperative free-running EMG and triggered EMG were able to correlate alerts with condylar screw placement accurately. A triggered EMG threshold of 2.7 mA was found to be a minimum acceptable threshold. A combination criterion of free-running EMG and triggered EMG alerts was found to enable accurate assessment of condylar screw positioning and placement.

CONCLUSIONS

Intraoperative free-running EMG and triggered EMG were both found to be invaluable utilities in assessing the placement and positioning of condylar screws. Stimulation thresholds below 2.7 mA correlated with a superior or anterior condylar breach. Thresholds in the 2.7-mA to 9.0-mA range were generally acceptable but warranted additional inspection by the surgeon. Threshold values above 9.0 mA corresponded with solid condylar screw placement.

C1-C2 Dorsal Epidural Hematoma on Cervical Spine CT: A Novel Imaging Sign of Posterior Atlanto-Occipital Membrane Stripping Injury

Background and Purpose: Identify patients with a dorsal epidural hematoma at C1-C2 and examine the major craniocervical junction ligaments for injury on follow-up magnetic resonance imaging.

Materials and Methods: Adult and pediatric trauma patients who suffered a dorsal epidural hematoma at C1-C2 were identified using Nuance mPower software (Nuance Communications, United States). The cervical computed tomography and magnetic resonance imaging exams for these patients were reviewed for craniocervical junction osteoligamentous injuries. An age-matched control group was obtained.

Results: Eight trauma patients were identified with a dorsal epidural fluid collection at C1-C2. All patients with a dorsal epidural hematoma, who underwent follow-up cervical magnetic resonance imaging demonstrated a stripping injury of the posterior atlanto-occipital membrane from the C1 posterior arch with increased short tau inversion recovery signal in the posterior atlanto-occipital membrane complex. Disruption of additional major craniocervcial ligaments on magnetic resonance imaging was relatively common with the most frequently associated ligamentous injuries involving the tectorial membrane (five patients) followed by the alar ligaments and anterior altanto-occiptial membrane (four patients each). 

Conclusions: A C1-C2 dorsal epidural hematoma is a rare injury that may be identified on cervical spine computed tomography but may be easily overlooked by the radiologist. We propose that a C1-C2 dorsal epidural hematoma is a direct result of a significant hyperflexion-hyperextension force with subsequent stripping of the posterior atlanto-occipital membrane from the posterior C1 arch. Trauma patients with a C1-C2 dorsal epidural hematoma on cervical spine computed tomography should undergo a cervical magnetic resonance imaging examination to evaluate the integrity of the posterior atlanto-occipital membrane complex and remaining craniocervical junction ligaments for injury.

Morphometric analysis of posterior cranial fossa and surgical implications

Background

Posterior cranial fossa (PCF) is an important area in terms of anatomy and surgery. It is a common site of many neoplastic, vascular, and degenerative lesions. Craniovertebral surgeries require special attention regarding detailed information about the morphology and morphometry of this region. The aim of this study was to analyze the morphometric characteristics of PCF and distances between the inner base of the skull.

Materials and Methods

An observational, retrospective cross-sectional study was made. Fifty-five dry human skulls of unknown sex were measured ascertained using digital Vernier caliper with 0.01 mm precision.

Results

The morphometric analysis of the mean length and width of the FM was 34.51 mm and 29.85 mm, respectively. We found a significant difference (P < 0.05) among the distance between the posterior tip of occipital condyle and basion of the right and left sides.

Conclusion

According to our observations, the present study yielded detailed morphometry of the PCF and neurovascular relationship. It can facilitate successful instrumentation and minimize neurovascular injuries. Furthermore, it provides safe and suitable data for guiding neurosurgical procedures. The major limitation of this study was the lack of knowledge regarding the age and gender of the participants whose skull base was studied.

Tectorial Membrane Injury, Frequently Identified in Adult Trauma Patients Who Undergo Occipital-Cervical Fusion for Craniocervical Instability

Background In the absence of frank craniocervical dissociation, there is a lack of consensus regarding what patterns of craniocervical junction ligamentous injuries require occipital-cervical fusion. This study was undertaken to examine the integrity of the craniocervical junction ligaments and analyze clinical outcomes in patients who underwent occipital-cervical fusion for craniocervical junction injury. Methods Adult patients requiring occipital-cervical fusion were identified retrospectively utilizing keyword searches in cervical computed tomography and magnetic resonance imaging reports between 2012 and 2020 using Nuance mPower software (Nuance, Burlington, MA). The cervical magnetic resonance imaging examinations for these patients were reviewed for craniocervical ligamentous injury by two neuroradiologists. Descriptions of craniocervical junction injuries, demographic information, clinical history, surgical management, and global outcomes were recorded. Results Nine adult patients were identified with an acute, post-traumatic craniocervical junction injury requiring occipital-cervical fusion. All nine patients demonstrated a ligamentous tear in at least one of the four major craniocervical junction ligaments - the occipital condylar-C1 capsular ligaments, alar ligaments, tectorial membrane, and posterior atlantooccipital membrane. The tectorial membrane was the most commonly torn ligament followed by the alar ligament(s), posterior atlantooccipital membrane, and capsular ligament(s). There was wide variability in the number of major craniocervical junction ligaments torn, ranging from one ligament to all four ligaments. Four patients suffered persistent neurologic deficits following surgery. Conclusion Craniocervical injury is best evaluated by cervical magnetic resonance imaging. In the absence of overt craniocervical dissociation, we propose that an injury of the tectorial membrane in the adult population may indicate patients with significant craniocervical instability, possibly necessitating occipital-cervical fusion.

Anatomical study of a surgical approach through the neck to the jugular foramen under endoscopy

OBJECTIVES

To investigate the feasibility of an endoscopic surgical approach through the neck to the jugular foramen, to determine the relevant techniques and extent of exposure, and to provide a new surgical approach with minimal trauma.

METHODS

Nine cadaveric head specimens with attached necks were fixed with 10% formalin solution. Two of the heads were fixed and injected with colored silicone rubber. Through the dissection of these cadaver head and neck specimens, we designed a surgical approach from the neck to the jugular foramen area with the use of a neuroendoscope and performed simulated surgery to determine which anatomical structures were encountered in the approach.

RESULTS

The posterior aspect of the internal jugular vein is adjacent to the rectus capitis lateralis. The internal carotid artery is anteromedial to the internal jugular vein, with the glossopharyngeal nerve, accessory nerve, vagus nerve and hypoglossal nerve in between. Removal of the rectus capitis lateralis can reveal the jugular process, and exposing the space between the superior oblique muscle and the jugular process can reveal the atlanto-occipital joint. Drilling through the occipital condyle can facilitate entrance into the skull, expose the flank of the medulla oblongata, and reveal the medullary olive and accessory nerve, vagus nerve, hypoglossal nerve, vertebral artery and posterior inferior cerebellar artery. Removing the jugular vein and completely opening the posterior wall of the jugular foramen can expose the inferior wall of the jugular bulb and the inferior wall of the sigmoid sinus. Drilling through the styloid process, which is lateral to the internal jugular vein, can expose the lateral area and upper wall of the jugular bulb and cranial nerves (CN) IX-XII; and near the top of the jugular bulb, the tympanic cavity and the external auditory canal can be easily opened.

CONCLUSION

Endoscopic surgical access from the neck to the jugular foramen is feasible. This surgical approach can simultaneously remove intracranial and extracranial tumors and can also be used to remove tumors in the ventral region of the occipital foramen and the hypoglossal canal. Furthermore, this approach is advantageous in that minimal trauma is inflicted. With judicious patient selection, this approach may have significant advantages and may be used as a primary or secondary surgical approach in the future. Nonetheless, this approach is still in development in a laboratory setting, and further research and improvements are needed before facing more complicated situations in clinical practice.

Morphometric Trajectory Analysis for Occipital Condyle Screws

Objectives

Occipitocervical fusion (OCF) is an effective treatment for instability of occipitocervical junction (OCJ). The occipital condyle screw serves as a novel surgical technique for occipitocervical fixation. However, the intraoperative procedures for the occipital condyle screw technique have relied on surgeons’ experience, so the pool of surgeons who are able to perform this surgery safely is limited. The present study aims to evaluate the feasibility and safety of the occipital condyle screw technique using human cadavers and to provide image anatomy for clinical application basis.

Methods

The scientific study comprised 10 fresh‐frozen cadaveric specimens from the anatomy department of Qingdao University. Placement of the occipital condyle screws (3.5 mm diameter and 20.0 mm length) was performed in the 10 fresh‐frozen cadaveric specimens with intact occipitocervical junctions, respectively. Occipitocervical CT was performed for all specimens and the DICOM data was obtained. Occipitocervical CT three‐dimensional (3D) reconstruction was performed for the cadavers. Morphometric analysis was performed on the bilateral occipitocervical junction of 10 cadaveric specimens based on the 3D reconstruction CT images. Detailed morphometric measurements of the 20 occipital condyles screws were conducted including the average length of the screw trajectory, inside and upper tilting angles of screws, distance to the hypoglossal canal, and to the medial wall of occipital condyle.

Results

Placement of the occipital condyle screws into the 20 occipital condyles of the 10 cadaveric specimens was performed successfully and the trajectory of implantation was satisfactory according to 3D CT reconstruction images, respectively. There was no obvious injury to the spinal cord, nerve root, and vertebral artery. The length of the bilateral screw trajectory was, respectively, 20.96 ± 0.91 mm (left) and 20.59 ± 0.77 mm (right) (t = 1.306, P > 0.05). The upper tilting angle of bilateral screws was, respectively, 11.24° ± 0.74° (left) and 11.11° ± 0.64° (right) (t = 0.681, P > 0.05). The inside tilting angle of bilateral screws was, respectively, 31.00° ± 1.32° (left) and 30.85° ± 1.27° (right) (t = 0.307, P > 0.05). The screw's distance to the bilateral hypoglossal canal was, respectively, 4.84 ± 0.54 mm (left) and 4.70 ± 0.54 mm (right) (t = 0.685, P > 0.05). The screw's distance to the medial wall of the bilateral occipital condyle was, respectively, 5.13 ± 0.77 mm (left) and 5.04 ± 0.71 mm (right) (t = 0.384, P > 0.05).

Conclusion

The occipital condyle screw technique can serve as a feasible and safe treatment for instability of the occipitocervical junction with meticulous preoperative planning of the screw entry point and direction based on individual differences. Morphometric trajectory analysis is also an effective way to evaluate the surgical procedure.

Quantification of anatomical variation at the atlanto-occipital articulation: morphometric resolution of commingled human remains within the repatriation documentation process

Within many institutional collections are skeletal and mummified human remains representing a part of our species' adaptation and evolution to various biocultural environments. Archaeologically recovered individuals come from deep into our past, and possess information that provides insight into population history, genetics, diet, health and other questions relevant to all living peoples. Academic concerns have been raised regarding the reinterment of these collections due to the rise of the international repatriation movement, the passage of various laws and implementation of institutional policies. While all potential research questions cannot be anticipated, the proactive documentation of collections is one way to ensure primary data are maintained for future study. This paper explores developments in digitization technology that allow the archive of virtual copies of human remains, and an example of how anatomical and archaeological collections can be digitized towards pragmatic research goals. The anatomical variability of the human atlanto-occipital (AO) articular surfaces was studied using non-metric categorical shape, 2D measurement and 3D morphometric analyses to provide reference standards for the reassociation of individuals from commingled skeletal remains, such as found in some archaeological sites or forensic investigations including mass grave or mass disaster recovery scenes. Results suggest that qualitative shape observations and caliper-derived measurements of the articulating AO condyles tend to display significant sexual dimorphism and biological ancestry-related size and shape differences. Variables derived from a scanned 3D mesh, such as condylar angle and articular surface curvature, quantify biomechanical variation and display a stronger congruency within individuals. It is recommended that a two-stage approach involving initial screening and identification of possible reassociation candidates is accomplished with a linear osteometric approach, followed by 3D laser scanning of the candidate joint surfaces for morphometric analyses to confirm reassociations when destructive DNA typing is not allowed or otherwise impractical due to cost or other resource restrictions.

Morphometric Evaluation of Occipital Condyles: Defining Optimal Trajectories and Safe Screw Lengths for Occipital Condyle-Based Occipitocervical Fixation in Indian Population

Study Design

Computed tomographic (CT) morphometric analysis.

Purpose

To assess the feasibility and safety of occipital condyle (OC)-based occipitocervical fixation (OCF) in Indians and to define anatomical zones and screw lengths for safe screw placement.

Overview of Literature

Limitations of occipital squama-based OCF has led to development of two novel OC-based OCF techniques.

Methods

Morphometric analysis was performed on the OCs of 70 Indian adults. The feasibility of placing a 3.5-mm-diameter screw into OCs was investigated. Safe trajectories and screw lengths for OC screws and C0–C1 transarticular screws without hypoglossal canal or atlantooccipital joint compromise were estimated.

Results

The average screw length and safe sagittal and medial angulations for OC screws were 19.9±2.3 mm, ≤6.4°±2.4° cranially, and 31.1°±3° medially, respectively. An OC screw could not be accommodated by 27% of the population. The safe sagittal angles and screw lengths for C0–C1 transarticular screw insertion (48.9°±5.7° cranial, 26.7±2.9 mm for junctional entry technique; 36.7°±4.6° cranial, 31.6±2.7 mm for caudal C1 arch entry technique, respectively) were significantly different than those in other populations. The risk of vertebral artery injury was high for the caudal C1 arch entry technique. Screw placement was uncertain in 48% of Indians due to the presence of aberrant anatomy.

Conclusions

There were significant differences in the metrics of OC-based OCF between Indian and other populations. Because of the smaller occipital squama dimensions in Indians, OC-based OCF techniques may have a higher application rate and could be a viable alternative/salvage option in selected cases. Preoperative CT, including three-dimensional-CT-angiography (to delineate vertebral artery course), is imperative to avoid complications resulting from aberrant bony and vascular anatomy. Our data can serve as a valuable reference guide in placing these screws safely under fluoroscopic guidance.

Morphological and Morphometric Analysis of Hypoglossal Canal in North Indian Dry Skulls and It's Significance in Cranial Base Surgeries

INTRODUCTION

Hypoglossal Canal (HC) is a paired bony passage which is situated above the Occipital Condyle (OC) and transmits hypoglossal nerve and blood vessels. Studies on the osteotic variations of HC has been a field of considerable interest to research workers especially because of its clinical, radiological and surgical significance.

AIM

The aim of the present study was to analyze the morphological and morphometric features of HC and its topographical relationship with OC.

MATERIALS AND METHODS

The present study was done on 50 human dry skulls. The HC was looked for presence of spur and septa along with its location in the canal and were classified into different types accordingly. The distance of extracranial and intracranial openings of HC from the posterior end of OC was measured by Sliding Vernier caliper. Angle of inclination of HC with the midsagittal plane was measured with the help of goniometer.

RESULTS

In the present study, we observed osteotic variations in the HC in 52% skulls. The spur (Type 2) was seen in 28% and incomplete septa (Type 3) was noted in 26% skulls. In some cases, spur and septa were seen in different locations of same HC. However, complete septa (Type 4) were not observed in our study. Spur and septa, both were present more frequently on the left side. The external and internal distance of HC from posterior end of OC was more on the left side in comparison to the right side. The anterior angle of HC to the midsagittal plane is less in comparison to posterior angle in case of double internal opening of HC.

CONCLUSION

The present study regarding morphologic and morphometric analysis of HC and its relation to the OC will provide important information in North Indian population. It will enable effective and reliable surgical intervention in the area of HC and craniovertebral junction leading to better postoperative outcome.

Morphometric Analysis of the Occipital Condyle and Its Surgical Importance

INTRODUCTION

The Occipital Condyle (OC) is an integral component of craniovertebral region which is predisposed to a wide array of traumatic, degenerative and neoplastic diseases. Frequent surgical interventions of OC are required for successful management of these conditions. Hence a meticulous anatomical knowledge of the OC is vital but variability in morphometric dimensions exist amongst different races and hinder the standardization of measurements.

AIM

The aim of this study was to present a morphometric reference database for OC of the Indian population and enable comparisons with other populations.

MATERIALS AND METHODS

The study was performed on 228 OC of 114 adult human skulls. Linear measurements of the OC were taken with the help of digital Vernier's Calliper and angular measurements were determined with software Image J.

STATISTICAL ANALYSIS

Mean and standard deviation of the morphometric parameters taken into account were analysed. The comparison of morphometric dimensions of the right and left sides was carried out using Student's t-test and p-value was calculated.

RESULTS

The morphometric analysis of the OC established that mean width was larger (12.97 mm) in Indians population when compared to other races. The anterior and posterior intercondylar distances as well as the distances between the tips of OC and opisthion and basion were observed to be shorter in Indians. We found a significant difference (p=0.01) among the distance between Posterior tip of Occipital Condyle (POC) and basion of the right and left sides. The sagittal condylar angle and sagittal intercondylar angle were found to be greater in our study when compared to other researchers. There existed a highly significant difference (p=0.001) between the sagittal condylar angles of the right and left sides.

CONCLUSION

The present morphometric study would be valuable for the successful instrumentation of the OC as wider and ventrally oriented OC as well as smaller intercondylar distances may pose challenge to the surgeons during condylectomy. The data of present study offer anatomical reference to the surgeons and would be helpful in designing implants for the OC.

Imaging of Atlanto-Occipital and Atlantoaxial Traumatic Injuries: What the Radiologist Needs to Know

Approximately one-third of all cervical spine injuries involve the craniocervical junction (CCJ). Composed of the occiput and the first two cervical vertebrae, this important anatomic landmark, in conjunction with an intricate ligamentous complex, is essential to maintaining the stability of the cervical spine. The atlantoaxial joint is the most mobile portion of the spine, predominantly relying on the ligamentous framework for stability at that level. As acute onsite management of trauma patients continues to improve, CCJ injuries, which often lead to death onsite where the injury occurred, are increasingly being encountered in the emergency department. Understanding the anatomy of the CCJ is crucial in properly evaluating the cervical spine, allowing the radiologist to assess its stability in the trauma setting. The imaging findings of important CCJ injuries, such as atlanto-occipital dissociation, occipital condyle fractures, atlas fractures with transverse ligament rupture, atlantoaxial distraction, and traumatic rotatory subluxation, are important to recognize in the acute setting, often dictating patient management. Thin-section multidetector computed tomography with sagittal and coronal reformats is the study of choice in evaluating the extent of injury, allowing the radiologist to thoroughly evaluate the stability of the cervical spine. Furthermore, magnetic resonance (MR) imaging is increasingly being used to evaluate the spinal soft tissues and ligaments, and to identify associated spinal cord injury, if present. MR imaging is also indicated in patients whose neurologic status cannot be evaluated within 48 hours of injury. .

The anatomical perspective of human occipital condyle in relation to the hypoglossal canal, condylar canal, and jugular foramen and its surgical significance

Background:

The transcondylar approach (TCA) has gained importance in recent era which enables shorter and direct route to access the lesions ventral to the brainstem. The important step in this approach is resection of the occipital condyle (OC). The detailed knowledge of bony anatomy of OC and its relation to the hypoglossal canal (HC), condylar canal (CC), and jugular foramen (JF) is very important to avoid any iatrogenic injury during craniovertebral surgeries. The aim of the present study is to conduct a morphometric and morphological study and note the variations of the OC and the structures surrounding it in North Indian population.

Materials and Methods:

The study was carried out on 100 OC. Morphometric measurements of OC and the distances of HC and JF from the posterior end of OC were noted. In addition, the extent of the HC and JF in relation to OC, presence or absence of CC, shape of the OC, and its articular facet were also noted.

Results:

The incidence of short OC was seen in 13% skulls. The most common shape of OC was oval or rhomboid. Even though the articular facet was convex in majority of skulls but flat (10%) and concave (1%) were also observed. The external and internal distance of HC from the posterior end of OC was13.83 mm and 10.66 mm on the right side and 15.02 mm and 11.89 mm on the left side. The OC was related in its middle 1/3 to the HC in 15% skulls and to the whole extent of JF in 3% skulls. Thirty-four percent skulls displayed the septa in the HC. The CC was present bilaterally in 38% skulls and unilaterally in 40% skulls.

Conclusion:

The OC and related structures such as HC, CC, and JF are likely to have variations in respect to morphometry and morphology. This study may prove helpful to neurosurgeons operating in this field, especially during TCA where neurovascular structures emerging from these canals and foramen are more vulnerable to injury.

Elevated serum monocyte chemoattractant protein-1 levels and its genetic polymorphism is associated with diabetic retinopathy in Chinese patients with Type 2 diabetes

AIM

Previous studies have reported that monocyte chemoattractant protein-1 (MCP-1) is involved in inflammatory and metabolic diseases. The purpose of this study is to investigate the role of MCP-1 in the pathogenesis of diabetic retinopathy (DR) in Han Chinese patients with Type 2 diabetes.

METHODS

Serum levels of MCP-1 protein in patients classified as diabetic without retinopathy (DWR) and DR, including NPDR and PDR, were assayed by enzyme-linked immunosorbent assay. Genomic DNA from 198 DWR patients, 176 NPDR patients and 143 PDR patients were genotyped by using a PCR restriction fragment length polymorphism (PCR-RFLP) assay.

RESULTS

MCP-1 serum levels were significantly higher in NPDR and PDR patients than in the DWR patients. The frequencies of the GG genotype and G allele of the single nucleotide polymorphism (SNP) were significantly increased in DR patients compared with DWR patients. Further subgroup analysis was performed to test whether there was an association between the PDR or NPDR and DWR groups. Significantly higher frequencies of the GG genotype and G allele were observed in PDR and NPDR patients compared with DWR patients. Furthermore, the 25 patients with PDR were divided into three groups according to the genotype of the tested SNP. The expression of the MCP-1 gene was higher in the GG genotype group compared with the other two groups.

CONCLUSIONS

The results suggested that the -2518 GG genotype and G allele of MCP-1 are associated with an increased risk of PDR in the Chinese Han population. This polymorphism may influence the expression of the MCP-1 gene, which may play an important role in the pathogenesis of DR.