Acute Myocardial Infarction in a Patient with Twin Pregnancy: A Case Report

INTRODUCTION

Acute myocardial infarction (AMI) rarely occurs during pregnancy and presents unique challenges in diagnosis and management. Traditionally, pregnancy has not readily been considered a risk factor for AMI in the emergency department despite the potential for adverse impacts on maternal and fetal health. As cardiovascular risk factors and advanced maternal age become more prevalent in society over time, the incidence will continue to increase. Prior cases with singular gestation have been reported; however, only one previous case during a twin pregnancy was identified in the medical literature.

CASE REPORT

We describe a rare case of acute ST-segment elevation myocardial infarction in a 37-year-old woman at 24 weeks gestation with a dichorionic diamniotic twin pregnancy.

CONCLUSION

It is important for the emergency physician to recognize acute coronary syndrome as a part of the differential diagnosis of chest pain in pregnant patients and be familiar with the diagnostic and management options available for this special population.

A Suspected Case of Acute Embolic Myocardial Infarction Following Direct-Current Cardioversion of Atrial Fibrillation

Patient: Male, 66

Final Diagnosis: A suspected case of acute embolic myocardial infarction following direct current cardioversion of atrial fibrillation

Symptoms: Exertional shortness of breath

Medication: —

Clinical Procedure: Direct current cardioversion

Specialty: Cardiology

Patient Factors But Not the Use of Novel Anticoagulants or Warfarin Are Associated With Internal Jugular Vein Access-Site Hematoma After Right Heart Catheterization

INTRODUCTION

Right heart catheterization (RHC) is routinely performed to assess hemodynamics. Generally, anticoagulants are held prior to the procedure. At our center, anticoagulants are continued and ultrasound guidance is always used for internal jugular vein access. A micropuncture access kit is used to place a 5 or 6 Fr sheath using the modified Seldinger technique. Manual compression is applied for 10-15 min and the patient is observed for at least 2 hours after the procedure. In a retrospective analysis, we investigated the risk of bleeding complications associated with RHC via the internal jugular vein in patients with and without full anticoagulation.

METHODS AND RESULTS

Our catheterization laboratory database was searched for adult patients who underwent RHC by a single operator between January 2012 and December 2015. A total of 571 patients were included in the analysis. Baseline characteristics, labs, relevant invasive hemodynamics, co-morbid conditions, and incidence of access-site hematoma are presented. Multivariable binary logistic regression was performed using IBM SPSS v. 23.0 software. Statistically significant associations with access-site hematoma were observed with body mass index (P=.02; 95% confidence interval [CI], 1.0-1.1), right atrial pressure (P=.03; 95% CI, 0.7-0.9), and dialysis dependence (P<.01; 95% CI, 0.1-0.6). There was no association of access-site hematoma with the use of anticoagulants (P>.99).

CONCLUSION

The incidence of internal jugular vein access-site hematoma is small when using careful access techniques for RHC even with the continued use of novel oral anticoagulants and warfarin. Patient characteristics and co-morbid conditions are related to bleeding complications.

Recurrent myocardial infarctions in a young football player secondary to thrombophilia, associated with elevated factor VIII activity

Myocardial infarction (MI) due to coronary atherosclerosis in young adults is uncommon; rare causes such as cocaine abuse, arterial dissection, and thromboembolism should be considered. A 21-year-old football player, and otherwise healthy African American man, developed chest pain during exercise while bench-pressing 400 lbs. Acute MI was diagnosed based on physical examination, electrocardiography findings, and elevated cardiac enzymes. Coronary arteriography showed a thrombus occluding the proximal left anterior descending artery (LAD). Aggressive antiplatelet therapy with aspirin, clopidogrel, and eptifibatide was pursued, in addition to standard post-MI care. This led to the successful resolution of symptoms and dissolution of the thrombus, demonstrated by repeat coronary arteriography. Five months later, he presented with similar symptoms during exercise after lifting heavy weights, and was found to have another acute MI. Coronary arteriography again showed a thrombus occluding the LAD. No evidence of coronary artery dissection or vasospasm was found. Only mild atherosclerotic plaque burden was observed on both occasions by intravascular ultrasound. A bare metal stent was placed at the site as it was thought this site had acted as a nidus for small plaque rupture and thrombus formation. Elevated serum factor VIII activity at 205% (reference range 60%–140%) was found, a rare cause of hypercoagulability. Further workup revealed a patent foramen ovale during a Valsalva maneuver by transesophageal echocardiography. Both events occurred during weight lifting, which can transiently increase right heart pressure in a similar way to the Valsalva maneuver. In light of all the findings, we concluded that an exercise-related increase in factor VIII activity led to coronary arterial thrombosis in the presence of a small ruptured plaque. Alternatively, venous clots may have traversed the patent foramen ovale and occluded the LAD. In addition to continuing aggressive risk factor modification, anticoagulation therapy with warfarin was initiated with close follow-up.

Abstract 295: Sodium Restriction Increases Ophthalmic Artery Systolic Velocity in Healthy Subjects

Changes in ocular blood flow occur in systemic diseases. A high peak systolic velocity (PSV) in the ophthalmic artery (OA) has been observed in diabetes mellitus and hypertension, conditions often associated with high tissue renin-angiotensin system (RAS) activity and reduced renal plasma flow (RPF). Since our group has demonstrated that sodium restriction ( a high RAS state ) is associated with a decrease in RPF which is correctable with ACE inhibition, we hypothesized that sodium restriction would result in higher ophthalmic PSV. Sixteen healthy volunteers (age 46.2±13.2, male 69%, white 75%, BMI 26±3.7) were placed on a low sodium (LS) diet (10 mmol/day) for 1 week followed by high sodium (HS) diet (200 mmol/day). Sodium balance was assessed by 24hr urine collection. BP, RPF (PAH clearance) and OA hemodynamic measurements (Multigon, NY) were made after overnight fasting and rest in the supine position. Sodium restriction did not affect BP (systolic/diastolic LS: 121/73 ± 12/7 vs HS: 122/72 ± 15/9 mmHg, mean ± SD, NS) or heart rate (69 ± 16 vs 70 ± 15/min, NS). As expected, RPF was lower on LS compared with HS (599.2 ± 89.8 vs 633.4 ± 93.5ml/min/1.73 m 2 , p=0.006). Sodium restriction was associated with higher OA peak (38.8 ± 6.4 vs 33.2 ± 6.0 cm/sec, p=0.018) and mean (19.7±2.9 vs 17.1±3.5, p=0.003) systolic velocity ( Figure ). There was no change in end-diastolic velocity (10.6±2.5 vs 9.7±2.4, p=0.266) with sodium restriction. In conclusion, sodium restriction was associated with an increase in OA peak and mean systolic velocity in healthy individuals. Further studies are required to investigate the potential relevance of our results to diabetic and hypertensive retinopathy.

Abstract 236: Reduced Epigastric Artery Reactivity in a Non-Modulator Phenotype of Human Hypertension

In normal and modulator hypertensive individuals sodium intake modifies plasma levels and target tissue response to ANG II. This sodium-mediated modulation is defective in 25-30% of the hypertensive population, termed non-modulators. Non-modulators have insulin resistance (IR), abnormal renal function, polymorphisms in the renin-angiotensin-aldosterone system (RAAS) genes, increased tissue levels of ANG II particularly during liberal dietary sodium intake, and increased risk of cardiovascular (CV) damage. We hypothesized that the increased risk of CV damage in non-modulators reflects abnormalities in vascular function. Male hypertensive subjects were placed on restricted salt diet 10 mmol/day for 7 days and phenotyped as modulators (PRA 8.7 ng/ml/hr, HOMA-IR 1.0, ALDO 18.85 ng/dl, n=4, age ≈48) and non-modulators (PRA 8.8 ng/ml/hr, HOMA-IR 1.7, ALDO 8.52 ng/dl, n=3, age ≈60). The subjects were then placed on liberal salt diet (HS, 200 mmol/day for 7 days), BP was measured, then underwent subcutaneous surgery to isolate the superficial inferior epigastric artery for ex vivo vascular function studies. Systolic BP was 144.8 in modulators and 142.0 mmHg in non-modulators. Diastolic BP was 88.5 in modulators and 87.3 mmHg in non-modulators. In epigastric arteries, contraction to ANG II, phenylephrine (Phe), and KCl was less in non-modulators (0.24, 0.56, and 0.53) than in modulators (0.8, 1.43, and 1.1 g/mg tissue). Endothelium-dependent relaxation to acetylcholine (ACh) was not different between non-modulators (22.1) and modulators (22.6%). Bradykinin caused larger endothelium-dependent relaxation than ACh, but was still not different in non-modulators (57.8) vs. modulators (46.3%). In contrast, endothelium-independent relaxation to the nitric oxide (NO) donor sodium nitroprusside was reduced in non-modulators (64.2) vs. modulators (92.5%). The reduced vascular responsiveness to ANG II in non-modulators is consistent with increased vascular tissue RAAS activity, and desensitization to ANG II. The reduced vascular reactivity to the vasoconstrictors Phe and KCl and the vasodilator NO donors is consistent with vascular smooth muscle dysfunction and may explain the increased risk of CV damage in non-modulators during HS dietary intake.

Abstract 241: Influence of Dietary Salt and Renin-angiotensin System activity on plasma Retinol-binding Protein 4 in Healthy Human Subjects

Introduction: Retinol-binding protein 4 (RBP-4) is a circulating adipokine associated with insulin resistance, obesity and cardiovascular risk. Previous evidence suggests a negative impact on insulin sensitivity via an interaction with the insulin-stimulated glucose transporter (GLUT-4), specifically in adipocytes. Since angiotensin-2 (ANG-2) impairs GLUT-4 presentation and insulin sensitivity, we hypothesized that renin-angiotensin system (RAS) activity might affect RBP-4 expression as well. Furthermore, both RAS activity and insulin sensitivity are affected by dietary salt, but the relationship between these factors and RBP-4 expression is unknown. We hypothesized that liberal salt diet, via suppression of RAS activity, would be associated with reduced RBP-4 levels compared to salt restriction.

METHODS: Healthy subjects (7 men, 7 women, mean age 24 yr, BMI 22.6) were studied on low salt (LS 10 mmol Na/day) diet and then liberal salt (HS 200 mmol Na/day) diet for 1 week each. Samples were drawn after overnight rest in the supine position for plasma renin activity (PRA), serum Aldosterone (Aldo) and plasma RBP-4 and again after ANG-2 infusion (3ng/kg/min x 45 mins).

Results: Salt manipulation predictably modified RAS activity (HS v. LS Aldo, 4.5 ± 3.8 v. 19.5 ± 8.5 ng/dl [p<0.01]; HS v. LS PRA, 0.5 ± 0.4 v. 2.7 ± 1.4 ng/ml/hr [p<0.01]). RBP-4 was significantly lower on a HS compared to LS diet (35.4 ± 6.6 v. 38.6 ± 7.9 mg/L, p= 0.017). No significant change was observed in RBP-4 level after ANG-2 infusion on either diet. Fasting insulin levels trended lower on HS compared to LS (3.9 ± 6.8 v. 4.4 ± 1.2 μIU/ml, p=0.09), but there was no difference in fasting glucose (81.9 ± 6.8 v. 82.1 ± 4.7 mg/dl, p=0.92).

Conclusion: RBP-4 levels are modified by dietary salt intake. RBP-4 levels were lower under HS conditions (suppressed RAS) as compared to LS conditions. Acute administration of ANG-2 does not increase RBP-4 levels in this healthy population. Insulin response was similar to prior reports suggesting that the connection between RAS activity, dietary salt and insulin sensitivity may include RBP-4. Future work exploring the relationship between RBP-4, GLUT-4 and insulin sensitivity should take into consideration the effect of dietary salt intake.

Abstract 165: Angiotensinogen M235T Modifies the Relationship between PAI-1 and Renal Blood Flow in Caucasian Hypertensive Individuals

Studies have reported an association of angiotensinogen (AGT) gene polymorphisms with hypertension and renal blood flow (RBF). The T allele of rs699 (AGT 235T) is associated with increased levels of angiotensinogen and reduced RBF. Plasminogen activator inhibitor-1 (PAI-1) is an inhibitor of the fibrinolytic pathway. Elevated PAI-1 is associated with increased renin-angiotensin system (RAS) activity and cardiovascular damage. We hypothesized that hypertensive individuals with the TT genotype of AGT 235 would display higher levels of PAI-1. We further hypothesized an inverse relationship would be observed between PAI-1 and RBF, and that the strength of this correlation would be dependent on genotype status. A total of 159 Caucasian hypertensive participants (mean age 49.3y, BMI 27.6) had data available for AGT235, PAI-1 and RBF from the HyperPATH study. RBF was measured by para-aminohippurate clearance method while on a liberal salt diet (>200 mmol Na/day for 1 week). Genotype frequencies were in Hardy-Weinberg Equilibrium (MM 41/MT 94/TT 24). Multivariate regression demonstrated the TT genotype was associated with higher PAI-1 levels compared with MT + MM (41.0±8.1 v. 26.9±7.1ng/ml, p=0.005). Genotype status modified the relationship between PAI-1 and RBF whereby only the TT genotype showed a significant correlation after adjusting for age, BMI and BP (TT pr2=0.22, Beta= -1.66 p=0.001 v. MT+MM pr2=0.05, Beta= -0.82, p=0.21). AGT 235T is associated with elevated PAI-1 and influences the relationship between PAI-1 and RBF in Caucasian hypertensives. This provides mechanistic clues to explain the genetic underpinnings involving AGT polymorphisms and hypertension.

Coexistence of anomalous m. peroneus tertius and longitudinal tear in the m. peroneus brevis tendon

The longitudinal tear in the m. peroneus brevis tendon is frequently observed as a less common cause of chronic ankle pain and disability. In this case the rare association of a longitudinal tear in the m. peroneus brevis tendon and an anomalous m. peroneus tertius origin of muscle bulk and insertion were detected during a routine dissection of the lower left extremity. The m. peroneus tertius was originating separately from the fibula rather than as a slip from extensor digitorum longus. The muscle bulk was also bulkier than normal. The fanned-out m. peroneus tertius tendon adhered almost on the entire dorsal surface of the fifth metatarsal bone. According to our case report one of the possible causes of the longitudinal tear in the m. peroneus brevis tendon can be an anomalous m. peroneus tertius with its different origin and insertion points and muscle bulk, via changing the ankle motion mechanism. This anomaly should be considered in the patients presenting with ankle pain in the clinic.

Three-dimensional volume rendering of tibiofibular joint space and quantitative analysis of change in volume due to tibiofibular syndesmosis diastases

OBJECTIVE

The diagnosis of ankle syndesmosis injuries is made by various imaging techniques. The present study was undertaken to examine whether the three-dimensional reconstruction of axial CT images and calculation of the volume of tibiofibular joint space enhances the sensitivity of diastases diagnoses or not.

DESIGN

Six adult cadaveric ankle specimens were used for spiral CT-scan assessment of tibiofibular syndesmosis. After the specimens were dissected, external fixation was performed and diastases of 1, 2, and 3 mm was simulated by a precalibrated device. Helical CT scans were obtained with 1.0-mm slice thickness. The data was transferred to the computer software AcquariusNET. Then the contours of the tibiofibular syndesmosis joint space were outlined on each axial CT slice and the collection of these slices were stacked using the computer software AutoCAD 2005, according to the spatial arrangement and geometrical coordinates between each slice, to produce a three-dimensional reconstruction of the joint space. The area of each slice and the volume of the entire tibiofibular joint space were calculated. The tibiofibular joint space at the 10th-mm slice level was also measured on axial CT scan images at normal, 1, 2 and 3-mm joint space diastases.

RESULTS

The three-dimensional volume-rendering of the tibiofibular syndesmosis joint space from the spiral CT data demonstrated the shape of the joint space and has been found to be a sensitive method for calculating joint space volume. We found that, from normal to 1 mm, a 1-mm diastasis increases approximately 43% of the joint space volume, while from 1 to 3 mm, there is about a 20% increase for each 1-mm increase.

CONCLUSIONS

Volume calculation using this method can be performed in cases of syndesmotic instability after ankle injuries and for preoperative and postoperative evaluation of the integrity of the tibiofibular syndesmosis.

Anatomy of lateral ankle ligaments and their relationship to bony landmarks

This study was designed to determine and describe precise anatomy of the lateral ankle ligaments and their relationship to adjacent osseous structures. This study was performed on 42 legs of 22 adult human embalmed cadavers. The lateral ankle ligaments were carefully dissected using a 2.5x surgical loupe. Mean values for the length, width and angle of the individual lateral ankle ligaments were measured. The precise location of insertion points and course of each ligament was observed and noted with ankle placed in neutral position. The anterior talofibular and calcaneofibular ligaments were coated with radio-opaque material. Radiographs were then taken in the anteroposterior, mortise and lateral projections. The anterior talofibular ligament (ATFL) was a flat, quadrilateral ligament and it made mean angle of 25 degrees (range 5 degrees -45 degrees ) with horizontal plane, and a mean angle of 47 degrees (range 45 degrees -56 degrees ) with sagittal plane. The posterior talofibular ligament was oriented in a nearly horizontal plane. Calcaneofibular ligament (CFL) was a flat oval ligament. It made a mean angle of 40 degrees (range 30 degrees -58 degrees ) with horizontal plane, and mean angle of 51 degrees (range 32 degrees -60 degrees ) with sagittal plane. The angle between CFL and ATFL was approximately 132 degrees (range 118 degrees -145 degrees ). These data provides important information for diagnosing injury and reconstructing lateral ankle ligaments.

Effect of the increase in the height of lumbar disc space on facet joint articulation area in sagittal plane

STUDY DESIGN

Computerized tomography (CT) of the lumbar spine cadaveric specimens was used to evaluate the effect of increasing the height of the disc space in the lumbar spine to the facet joint articulation in the sagittal plane.

OBJECTIVE

To show how the facet joint articulation is affected by increasing the height of the disc space in the lumbar spine.

SUMMARY OF BACKGROUND DATA

The Charité Artificial Disc (DePuy Spine, Inc., Raynham, MA) was successful in relieving low back pain in the majority of patients, yet there was still a significant number of patients who did not obtain pain relief, or their pain even worsened. The etiology of their pain is still not known. To our knowledge, no study has addressed the effect on the facet joints when the disc height is increased.

METHODS

CT images passing through the center of the L3-S1 facet joints (sagittal plane) were obtained from 15 cadaveric lumbar spine specimens. The articulation overlap of facet joints in sagittal plane from the L3 to S1 was measured. A 1-mm incremental increase to a total 5 mm in disc space height was performed to simulate the changes seen in disc replacement. The change in the facet joint articulation overlap in sagittal plane at normal and each displacement was then measured. There were 5 lumbar spine specimens dissected to validate the technique and standardize the measurements. Mean, percentages, and standard deviation values were calculated for all measured dimensions.

RESULTS

No significant difference was found between the measurements on CT and gross specimens (P > 0.05). In 15 specimens, the mean facet joint articulation overlap on the sagittal plane was: 16.29 +/- 1.20 mm (left) and 16.22 +/- 1.16 (right) at the L3-L4 level; 17.81 +/- 1.18 mm (left) and 17.74 +/- 1.18 mm (right) at the L4-L5 level; and 18.18 +/- 1.18 mm (left) and 18.23 +/- 1.15 mm (right) at the L5-S1 level. There is no significant difference between the measured values on left and right sides (P > 0.05). Each 1-mm incremental increase in disc space at the L3-L4 level translated to a decrease in the facet joint articulation overlap in the sagittal plane by 6%, and the mean facet joint space increased 0.4 mm. At the L4-L5 level, the articulation overlap decreased by 6%, and the facet joint space increased 0.5 mm. At the L5-S1 level, the articulation overlap decreased by 4%, and the facet joint space increased 0.7 mm.

CONCLUSIONS

There is a significant decrease of the facet joint articulation overlap in sagittal plane and an increase in the facet joint space following an increase in the lumbar disc space. The inappropriate increase of the height of disc space will result in facet joint subluxation.

Anatomical evaluation and clinical importance of the tibiofibular syndesmosis ligaments

The aim of this study was to describe the detailed anatomical arrangement of ligaments of the tibiofibular syndesmosis and to highlight the clinical aspects of fracture dislocations. This study was performed on 42 legs of adult human embalmed cadavers. Tibiofibular syndesmosis ligaments attachments and their mutual relationships were described and their dimensions were measured. The anterior tibiofibular ligament is usually composed of three parts. This ligament runs obliquely at laterodistaly direction making 35 degrees angle with horizontal plane and posteriorly 65 degrees angle with sagittal plane. The posterior tibiofibular ligament runs almost horizontally 20 degrees angle with horizontal plane. The mean thicknesses of tibial and fibular attachments are 6.38+/-1.91 mm and 9.67+/-1.74 mm, respectively. The inferior transverse ligament originates from just below the posterior tibiofibular ligament, which has variations on the shape and dimensions due to its attachment points. The average length is 36.60+/-9.51 mm. The network between the fibular notch and the distal fibula has been filled with the interosseous tibiofibular ligament whose fibers follow the laterodistal and anterior direction from the tibia to the fibula. It lies proximally 30-40 mm from the mortise. At the inferior view of the tibiofibular syndesmosis a pyramidal shaped cartilaginous facet was observed which was attached to the fibula. The length of this cartilage was variable. Some of synovial plicas from the ankle joints synovial membrane were observed at this view. We conclude that the results of this study may be useful to both orthopedic surgeons and radiologists for anatomic evaluation of the tibiofibular syndesmosis area.

Quantitative analysis of changes in cervical intervertebral foramen size with vertebral translation

STUDY DESIGN

Simulated translation of the C5 vertebra was performed in 20 embalmed cadaveric cervical spines, and cross-sectional areas of the C4-C5 and C5-C6 intervertebral foramina were measured and compared before and after translation of the C5 vertebra.

OBJECTIVE

To determine the relationship of cross-sectional intervertebral foraminal areas to the degrees of vertebral translation.

SUMMARY OF BACKGROUND DATA

The common feature of clinical instability and adjacent diseases of the cervical spine is malalignment of the cervical spine (i.e., there is ventral and dorsal translation of vertebral body with respect to the adjacent upper and lower vertebral body, respectively). To our knowledge, no previous study has analyzed the quantitative effect of vertebral translation on the size of the intervertebral foramina.

METHODS

The cross-sectional areas of the intervertebral foramina at C4-C5 and C5-C6 were measured on computerized tomography. The images were then transferred to the personal computer, where consecutive dorsal translations of C5 vertebrae with a 1-mm increment from 1 to 5-mm displacements were performed using Microsoft paint software (Microsoft, Corp., Redmond, WA). National Institutes of Health (Bethesda, MD) Image J software (V1.33m) was then used to measure the areas of both sides of C4-C5 and C4-C6 foramina at normal and each displacement level in the computer.

RESULTS

Following dorsal translation of C5 vertebra, anterolisthesis of C4 relative to C5 and retrolisthesis of C5 relative to C6 was noted. No significant difference was found between the measured values using Aquarius Image software (Microsoft, Corp.) on computerized tomography and National Institutes of Health image J software on the desktop computer (P > 0.05). When compared with normal values, there was an increase in the C4-C5 intervertebral foraminal area (i.e., 6%, 14%, 18%, 21%, and 26% with anterolisthesis of C4 relative to C5 following 1, 2, 3, 4, and 5-mm dorsal translation of the C5 vertebra, respectively). There was a 12% decrease in the C5-C6 intervertebral foraminal area, with each 1-mm incremental retrolisthesis of C5 relative to C6 vertebra. Statistically significant differences were found among residual cross-sectional foraminal areas following different degrees of dorsal translation (P < 0.05).

CONCLUSION

There is a significant increase in size with anterolisthesis and decrease in size with retrolisthesis of upper and lower adjacent vertebral intervertebral foramina, respectively.

Enlarged perforating branch of peroneal artery and extra crural fascia in close relationship with the tibiofibular syndesmosis

We found an extremely large perforating branch of peroneal artery in an 89-year-old female cadaver's left ankle. The anterior tibial artery could not reach to supply the ankle and dorsum of the foot. The perforating branch of peroneal artery continued as the dorsalis pedis after giving off an anterior lateral malleolar artery branch. The posterior tibial artery was thinner than usual. On the anterior side of the ankle, there was an extra crural fascia in addition to the regular crural fascia, under the anterior crural muscles. This strong fascia was tightly overlying the perforating branch of peroneal artery and anterior tibiofibular ligament. It is important to know the relationship of these vessels to the surrounding structures. Surgeons must be careful while dissecting this area since the perforating branch of peroneal artery might be anomalously enlarged as well as crossing in front of the tibiofibular syndesmosis in order to prevent vascular injury.

Value of intraoperative true lateral radiograph of C2 pedicle for C1-2 transarticular screw insertion

BACKGROUND CONTEXT

Transarticular C1-2 screws are widely used in posterior cervical spine instrumentation. Injury to the vertebral artery during insertion of transarticular Cl-2 screw remains a serious complication. Use of a computer-assisted surgery system decreases this complication considerably. However, this system encounters problems in ensuring complete accuracy because of positional variations during preoperative and intraoperative imaging generation. Therefore, intraoperative fluoroscopy still is one of the commonly used methods to guide insertion of transarticular Cl-2 screw. Evaluation of a true lateral radiographic view of the C2 pedicle for screw trajectory during C1-2 transarticular screw insertion may help to minimize this potential complication.

PURPOSE

To evaluate the value of intraoperative true lateral radiograph of the C2 pedicle for screw trajectory during C1-2 transarticular screw insertion.

STUDY DESIGN

To compare the height of the C2 pedicle area allowing instrumentation on true lateral view radiograph of the C2 pedicle and computed tomographic (CT) scan with multiplanar reconstruction.

METHODS

Twenty embalmed human cadaveric cervical spine specimens were used to insert a total of 40 C1-2 transarticular screws using Magerl and Seemann technique. One side of the C2 transverse foramen was filled with radiopaque material (lead oxide) to simulate the artery and to demarcate the danger zone for better visualization on radiography. Measurements and calculation of the mean and standard deviation of the height of the area allowing instrumentation of the C2 pedicle were done on true lateral view radiograph of the C2 pedicle, the sagittal and 30 degrees sagittal views relative to the frontal plane passing exactly through the center of the C2 pedicle of CT scans. Student t test was applied to calculate the statistical significance of measured values. Statistical significance was defined as p<or=.001.

RESULTS

On true lateral radiographic views of the C2 pedicle, the height of the area allowing instrumentation of the pedicle was 7.75+/-0.92 mm (right) and 7.64+/-0.63 (left), p>or=.36. Using sagittal CT scan views, the height of pedicles was 7.71+/-0.7 mm (right) and 7.58+/-1.01 mm (left), p>or=.23. On 30 degrees sagittal CT scan views, the height of pedicles was 7.84+/-1.00 mm (right) and 7.76+/-1.02 mm (left), p>or=.27. The p value was >or=.78, >or=.56, and >or=.49 for true lateral radiographic view and sagittal CT scan view, true lateral radiographic view and 30 degrees sagittal CT scan view, and sagittal CT scan view and 30 degrees sagittal CT scan views, respectively. On lateral view of cervical spine, the decline angle of the transarticular screw was 51.3+/-0.50 degrees (right) and 50.68+/-0.41 degrees (left), p>or=.17. Mean decline angle was 51+/-0.43 degrees . On the anteroposterior (AP) view, radiograph median angle was 6.87+/-0.53 degrees (right) and 6.0+/-0.59 degrees (left), p>or=.25. Mean median angle was 6.44+/-0.62 degrees.

CONCLUSIONS

True lateral radiographic views of the pedicles provide useful information for defining screw trajectory intraoperatively. Using this view along with AP and lateral view of cervical spine and preoperative three-dimensional CT scan may narrow the margin of error in this delicate area.