A radiographic computed tomography–based study to determine the ideal entry point, trajectory, and length for safe fixation using C-2 pars interarticularis screws

2010 ◽  
Vol 12 (6) ◽  
pp. 602-612 ◽  
Author(s):  
Daniel J. Hoh ◽  
Charles Y. Liu ◽  
Michael Y. Wang
Keyword(s):  
Entry Point ◽  
Ct Scans ◽  
Lateral Mass ◽  
Transverse Foramen ◽  
Inferior Aspect ◽  
Significant Difference ◽  
Pars Interarticularis ◽  
Entry Points ◽  
The Mean ◽  
Inferior Edge

Object Effective methods for fixation of the axis include C1–2 transarticular and C-2 pedicle screw placement. Both techniques pose a risk of vertebral artery (VA) injury in patients with narrow pedicles or an enlarged, high-riding VA. Pars screws at C-2 avoid the pedicle, but can cause VA injury with excessively long screws. Therefore, the authors evaluated various entry points and trajectories to determine ideal pars screw lengths that avoid breaching the transverse foramen. Methods Both pars were studied on 50 CT scans (100 total). Various pars lengths were assessed using 2 entry points and 3 trajectories (6 measurements). Entry point A was the superior one-fourth of the lateral mass. Entry point B was 3-mm rostral to the inferior aspect of the lateral mass. Using entry points A and B, Trajectory 1 was the minimum distance to the transverse foramen; Trajectory 2 was the maximum distance to the transverse foramen; and Trajectory 3 was the steepest angle to the pars/C-2 superior facet junction without transverse foramen breach. Results The mean patient age was 46 ± 17 years, and 84% of the CT scans reviewed were obtained in men. There was no significant difference in right or left measurements. Entry point B demonstrated greater pars lengths for each trajectory compared with entry point A (p < 0.0001). For both entry points, Trajectory 3 provided the greatest pars length. Using Trajectory 3 with entry point B, 84, 95, and 99% had a pars length that measured ≥ 18, 16, and 14 mm, respectively. Using Trajectory 3 with Entry point A, only 41, 64, and 87% had a pars length that measured ≥ 18, 16, and 14 mm, respectively. Conclusions Using an entry point 3-mm rostral to the inferior edge of the lateral mass and a trajectory directed toward the superior facet/pars junction, 99% of partes interarticularis in this study would tolerate a 14-mm screw without breach of the transverse foramen.

Computed tomography morphometric analysis for C-1 lateral mass screw placement in children

2009 ◽  
Vol 3 (1) ◽  
pp. 20-23 ◽  
Author(s):  
Roukoz B. Chamoun ◽  
William E. Whitehead ◽  
Daniel J. Curry ◽  
Thomas G. Luerssen ◽  
Andrew Jea
Keyword(s):  
Morphometric Analysis ◽  
Entry Point ◽  
Posterior Arch ◽  
Lateral Mass ◽  
Confined Space ◽  
Lateral Mass Screw ◽  
Screw Length ◽  
Entry Points ◽  
Left And Right ◽  
The Mean

Object The use of C-1 lateral mass screws provides an alternative to C1–2 transarticular screws in the pediatric population. However, the confined space of the local anatomy and unfamiliarity with the technique may make the placement of a C-1 lateral mass screw more challenging, especially in the juvenile or growing spine. Methods A CT morphometric analysis was performed in 76 pediatric atlases imaged at Texas Children's Hospital from October 1, 2007 until April 30, 2008. Critical measurements were determined for potential screw entry points, trajectories, and lengths, with the goal of replicating the operative technique described by Harms and Melcher for adult patients. Results The mean height and width for screw entry on the posterior surface of the lateral mass were 2.6 and 8.5 mm, respectively. The mean medially angled screw trajectory from an idealized entry point on the lateral mass was 16° (range 4 to 27°). The mean maximal screw depth from this same ideal entry point was 20.3 mm. The overhang of the posterior arch averaged 6.3 mm (range 2.1–12.4 mm). The measurement between the left- and right-side lateral masses was significantly different for the maximum medially angled screw trajectory (p = 0.003) and the maximum inferiorly directed angle (p = 0.045). Those measurements in children < 8 years of age were statistically significant for the entry point height (p = 0.038) and maximum laterally angled screw trajectory (p = 0.025) compared with older children. The differences between boys and girls were statistically significant for the minimum screw length (p = 0.04) and the anterior lateral mass height (p < 0.001). Conclusions A significant variation in the morphological features of C-1 exists, especially between the left and right sides and in younger children. The differences between boys and girls are clinically insignificant. The critical measurement of whether the C-1 lateral mass in a child could accommodate a 3.5-mm-diameter screw is the width of the lateral mass and its proximity to the vertebral artery. Only 1 of 152 lateral masses studied would not have been able to accommodate a lateral mass screw. This study reemphasizes the importance of a preoperative CT scan of the upper cervical spine to assure safe and effective placement of the instrumentation at this level.

Computed tomography–based determination of a safe trajectory for placement of transarticular facet screws in the subaxial cervical spine

2012 ◽  
Vol 16 (4) ◽  
pp. 334-339 ◽  
Author(s):  
Gregory F. Jost ◽  
Erica F. Bisson ◽  
Meic H. Schmidt
Keyword(s):  
Cervical Spine ◽  
Facet Joint ◽  
Entry Point ◽  
Ct Scans ◽  
Screw Placement ◽  
Exit Point ◽  
Lateral Mass ◽  
Subaxial Cervical Spine ◽  
Clinical Series ◽  
The Mean

Object Placement of transarticular facet screws is one option for stabilization of the subaxial cervical spine. Small clinical series and biomechanical data support their role as a substitute for other posterior stabilization techniques; however, the application of transarticular facet screws in the subaxial cervical spine has not been widely adopted, possibly because of surgeon unfamiliarity with the trajectory. In this study, the authors' objective is to define insertion points and angles of safe trajectory for transarticular facet screw placement in the subaxial cervical spine. Methods Thirty fine-cut CT scans of cervical spines were reconstructed in the multiplanar mode and evaluated for safe transarticular screw placement in the subaxial cervical spine (C2–3, C3–4, C4–5, C5–6, C6–7). As in placement of lateral mass screws, the vertebral artery and exiting nerve root were bypassed posterolaterally. The entry point was set 1 mm medial and 1 mm caudal to the center of the lateral mass. From this entry point, the sagittal angulation was set to traverse the facet joint plane approximately perpendicularly. For the axial angulation, the exit point was set posterolaterally to the transverse process. After ideal insertion angles and screw lengths were identified, the trajectory was simulated on CT scans of 20 different cervical spines to confirm safe screw placement. Results The mean optimal mediolateral insertion angles (± SD) were as follows: 23° ± 5° at C2–3; 24° ± 4° at C3–4; 25° ± 5° at C4–5; 25° ± 4° at C5–6; and 33° ± 6° at C6–7. The mean sagittal insertion angles measured to the sagittal projection of the facet joint space were as follows: 77° ± 10° at C2–3; 77° ± 10° at C3–4; 80° ± 11° at C4–5; 81°± 8° at C5–6; and 100° ± 11° at C6–7. The mean trajectory lengths were 15 ± 2 mm at C2–3; 14 ± 1 mm at C3–4; 15 ± 1 mm at C4–5; 16 ± 2 mm at C5–6; and 23 ± 4 mm at C6–7. Simulation of these insertion angles on 20 different cervical spine CTs yielded a safe trajectory in 85%–95% of spines for C2–3, C3–4, C4–5, C5–6, and C6–7. Conclusions The calculated optimal insertion angles and lengths for each level may guide the safe placement of subaxial cervical transfacet screws.

The vertebral artery and the cervical pedicle: morphometric analysis of a critical neighborhood

2010 ◽  
Vol 13 (1) ◽  
pp. 52-60 ◽  
Author(s):  
Andre Tomasino ◽  
Karishma Parikh ◽  
Heiko Koller ◽  
Walter Zink ◽  
A. John Tsiouris ◽  
...  
Keyword(s):  
Vertebral Artery ◽  
Ct Angiography ◽  
Posterior Instrumentation ◽  
Pedicle Screws ◽  
Safe Zone ◽  
Transverse Foramen ◽  
Sagittal Diameter ◽  
Entry Points ◽  
Cervical Pedicle ◽  
The Mean

Object The purpose of this retrospective study was to quantify the anatomical relationship between the vertebral artery (VA), the cervical pedicle, and its surrounding structures, including the incidence of irregularities. Additionally, data delineating a “safe zone,” and these data's application during instrumentation with transpedicular cervical screw fixation were considered. The anatomical proximity of the VA to the cervical pedicle prevents spine surgeons from preferring cervical pedicle screws (CPSs) over lateral mass screws at levels C3–6. Accurate placement of CPSs is often difficult to determine, because this definition can vary between 1 and 4 mm of lateral “noncritical” and “critical” pedicle breaches. No previous study in a western population has investigated the VA's proximity to the cervical pedicle, its percentage of occupancy in the transverse foramen (TF), and the incidence of irregular VA pathways. Methods One hundred twenty-seven consecutive patients who underwent CT angiography of the neck were enrolled in this study. The measurements included the following: medial pedicle border to VA; lateral pedicle border to VA; pedicle diameter (PD); sagittal diameter of the VA; coronal diameter of the VA; sagittal diameter of the TF; and coronal diameter of the TF. The cross-sections of the VA and the TF were measured to determine the occupation ratio of the VA. In addition, a safe zone was defined based on all lateral pedicle border to VA measurements in which the VA was within the TF. The level of entry of the VA into the TF as well as irregularities of the VA and the cervical pedicles were recorded. Results Vertebral artery dominance on the left side was seen in 69.3% of cases. The mean PD increased from 4.9 to 6.5 mm (from C-3 to C-7, respectively). Statistically significantly bigger PDs were seen in males. The mean PD at C-2 was 5.6 mm. Entry of the VA at C-6 was seen in approximately 80% of cases. The TF occupation ratio of the VA was found to be the greatest in C-4 and C-7 (37.1 and 74.2%, respectively). The safe zone increased from C-2 to C-6 (1.1 to 1.7 mm, respectively), but was only 0.65 mm at C-7. In 23.6% of cases, an irregular pathway of the VA or irregular anatomy of a cervical pedicle was seen, with the highest incidence of irregularities found at C-2. Conclusions Computed tomography angiography is a valuable tool that can help determine the relationships between cervical pedicles and the VA as well as irregular VA pathways. Pedicle diameter, safe zone, and occupational ratio of the VA in the foramen determine the risk associated with instrumentation and should be assessed individually. Based on the authors' measurements, C-4 and C-7 can be considered critical levels for CPS placement. Because of this and the high incidence of irregular VA pathways and different entry points, it may be helpful to review neck CT angiography studies before considering posterior instrumentation procedures in the cervical spine.

Evaluation of Reduction Accuracy of Suture-Button and Screw Fixation Techniques for Syndesmotic Injuries

2016 ◽  
Vol 37 (12) ◽  
pp. 1317-1325 ◽  
Author(s):  
Onur Kocadal ◽  
Mehmet Yucel ◽  
Murad Pepe ◽  
Ertugrul Aksahin ◽  
Cem Nuri Aktekin
Keyword(s):  
Screw Fixation ◽  
Ct Scans ◽  
Functional Evaluation ◽  
Level Of Evidence ◽  
Cross Sectional ◽  
Suture Button ◽  
Fixation Group ◽  
Significant Difference ◽  
The Mean

Background: Among the most important predictors of functional results of treatment of syndesmotic injuries is the accurate restoration of the syndesmotic space. The purpose of this study was to investigate the reduction performance of screw fixation and suture-button techniques using images obtained from computed tomography (CT) scans. Methods: Patients at or below 65 years who were treated with screw or suture-button fixation for syndesmotic injuries accompanying ankle fractures between January 2012 and March 2015 were retrospectively reviewed in our regional trauma unit. A total of 52 patients were included in the present study. Fixation was performed with syndesmotic screws in 26 patients and suture-button fixation in 26 patients. The patients were divided into 2 groups according to the fixation methods. Postoperative CT scans were used for radiologic evaluation. Four parameters (anteroposterior reduction, rotational reduction, the cross-sectional syndesmotic area, and the distal tibiofibular volumes) were taken into consideration for the radiologic assessment. Functional evaluation of patients was done using the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scale at the final follow-up. The mean follow-up period was 16.7 ± 11.0 months, and the mean age was 44.1 ± 13.2. Results: There was a statistically significant decrease in the degree of fibular rotation ( P = .03) and an increase in the upper syndesmotic area ( P = .006) compared with the contralateral limb in the screw fixation group. In the suture-button fixation group, there was a statistically significant increase in the lower syndesmotic area ( P = .02) and distal tibiofibular volumes ( P = .04) compared with the contralateral limbs. The mean AOFAS scores were 88.4 ± 9.2 and 86.1 ± 14.0 in the suture-button fixation and screw fixation group, respectively. There was no statistically significant difference in the functional ankle joint scores between the groups. Conclusion: Although the functional outcomes were similar, the restoration of the fibular rotation in the treatment of syndesmotic injuries by screw fixation was troublesome and the volume of the distal tibiofibular space increased with the suture-button fixation technique. Level of Evidence: Level III, retrospective comparative study.

scholarly journals Dimensions and Anatomical Variants of the Foramen Transversarium of Typical Cervical Vertebrae

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Santosh Kaur Sangari ◽  
Paul-Michel Dossous ◽  
Thomas Heineman ◽  
Estomih Phillip Mtui
Keyword(s):  
Vertebral Artery ◽  
Thrombus Formation ◽  
Cervical Vertebrae ◽  
Uncinate Process ◽  
Vertebrobasilar Insufficiency ◽  
Transverse Foramen ◽  
Medial Margin ◽  
Significant Difference ◽  
The Mean ◽  
The Right

The study was conducted on random sample of seventy-one dried, typical cervical vertebrae (C3–C6). The data on the age, sex, and built was not available. Using vernier calipers with 0.01 mm accuracy, the anteroposterior and transverse diameters of transverse foramina and their distance from the medial margin of the uncinate process were measured bilaterally. The mean diameter of the right/left transverse foramen varied from 2.54 mm to 7.79 mm (mean = 5.55 ± 0.87 mm) and from 2.65 mm to 7.35 mm (mean = 5.48 ± 0.77 mm), respectively. The transverse foramen was less than 3.5 mm in three vertebrae on the right and two on the left. The osteocytes observed in 21.3% of specimens and the narrow transverse foramen may place patients at risk for vertebrobasilar insufficiency or thrombus formation. The mean distance of the transverse foramen from the medial margin of uncinate process is an important landmark to avoid vertebral artery laceration and was 5.0 ± 0.87 mm (range: 3.5–7.9 mm) on the right and 5.0 ± 1.0 mm (range: 3.2–7.7 mm) on the left side. No statistically significant difference was observed between the right and left sides. The accessory transverse foramina seen in 24% of vertebrae suggest duplications or fenestrations in the vertebral artery.

Biomechanical comparison of C1–2 posterior fixation techniques

2005 ◽  
Vol 2 (2) ◽  
pp. 175-181 ◽  
Author(s):  
Jonathan S. Hott ◽  
James J. Lynch ◽  
Robert H. Chamberlain ◽  
Volker K. H. Sonntag ◽  
Neil R. Crawford
Keyword(s):  
Screw Fixation ◽  
Graft Fixation ◽  
Lateral Mass ◽  
Transarticular Screw ◽  
Content Type ◽  
Transarticular Screw Fixation ◽  
Significant Difference ◽  
Pars Interarticularis ◽  
Flexion And Extension ◽  
Fine Print

Object. In a nondestructive, repeated-measures in vitro flexibility experiment, the authors compared the acute stability of C1–2 after placement of C-1 lateral mass and C-2 pars interarticularis (LC1—PC2) instrumentation with that of C1–2 transarticular screw fixation. Methods. The effect of C-1 laminectomy and C1–2 interspinous cable/graft fixation on LC1—PC2 stability was studied. Screw pullout strengths were also compared. Seven human cadaveric occiput—C3 specimens were loaded nondestructively with pure moments while measuring nonconstrained atlantoaxial motion. Specimens were tested with graft alone, LC1—PC2 alone, LC1—PC2 combined with C-1 laminectomy, and graft-augmented LC1—PC2. Interspinous cable/graft fixation significantly enhanced LC1—PC2 stability during extension. After C-1 laminectomy, the LC1—PC2 construct allowed increased motion during flexion and extension. There was no significant difference in lax zone or range of motion between LC1—PC2 fixation and transarticular screw fixation, but graft-assisted transarticular screws yielded a significantly smaller stiff zone during extension. The difference in pullout resistance between C-1 lateral mass screws and C-2 pars interarticularis screws was insignificant. The LC1—PC2 region restricted motion to within the normal range during all loading modes. Atlantal laminectomy reduced LC1—PC2 stability during flexion and extension. Conclusions. The instrumentation-augmented LC1—PC2 construct performed biomechanically similarly to the C1–2 transarticular screw fixation. The LC1—PC2 construct resisted flexion, lateral bending, and axial rotation well. The weakness of the LC1—PC2 fixation in resisting extension can be overcome by adding an interspinous graft to the construct.

Subaxial sagittal alignment and adjacent-segment degeneration after atlantoaxial fixation performed using C-1 lateral mass and C-2 pedicle screws or transarticular screws

2010 ◽  
Vol 13 (4) ◽  
pp. 443-450 ◽  
Author(s):  
Go Yoshida ◽  
Mituhiro Kamiya ◽  
Hisatake Yoshihara ◽  
Tokumi Kanemura ◽  
Fumihiko Kato ◽  
...  
Keyword(s):  
Sagittal Alignment ◽  
Screw Fixation ◽  
Adjacent Segment ◽  
Lateral Mass ◽  
Transarticular Screw ◽  
Transarticular Screw Fixation ◽  
Significant Difference ◽  
Atlantoaxial Fixation ◽  
The Mean ◽  
The Difference

Object The purpose of this study was to evaluate the effect of a fixed atlantoaxial angle on subaxial sagittal alignment, and that of atlantoaxial fixation on adjacent-segment motion and degeneration. Methods The authors retrospectively reviewed 65 patients in whom atlantoaxial instability was treated with atlantoaxial fixation by C-1 lateral mass and C-2 pedicle screw fixation (30 patients, Goel-Harms [GH] group) or a combination of transarticular screw fixation and posterior wiring (35 patients, Magerl-Brooks [MB] group). Angles of Oc–C1, C1–2, C2–3, and C2–7 were determined based on an upright lateral radiograph in flexion, neutral, and extension positions. The range of motion (ROM) at Oc–C1 and C2–3 was also determined. All patients were examined before and 2 years after surgery. Results The mean preoperative atlantoaxial angles in the GH and MB groups were 20.9 ± 8.3° and 18.3 ± 7.2°, respectively, and the mean postoperative atlantoaxial angles in the same groups were 23.5 ± 5.6° and 29.7 ± 6.3°, respectively, with a statistically significant difference between the 2 groups (p < 0.05). The mean preoperative angles of C2–7 in the GH and MB groups were 15.4 ± 7.8° and 13.7 ± 9.5°, respectively, and after surgery, the angles were 11.8 ± 12° and 2.48 ± 12°, respectively, with a statistically significant difference between the 2 groups (p < 0.05). The postoperative angle of C1–2 showed a negative correlation with the extent of change observed in the C2–7 angle preand postoperatively in each of these 2 surgical procedures. The Oc–C1 ROM increased after surgery in both groups, but the difference was not statistically significant (p = 0.38). The C2–3 ROM decreased after surgery in both groups, and the difference was statistically significant (p < 0.05). Conclusions Atlantoaxial fixation in a hyperlordotic position produced kyphotic sagittal alignment after surgery in both GH and MB groups. Reduction of the atlantoaxial joint can be easily achieved through screw fixation at an optimal angle, thereby ameliorating the risk for subsequent subaxial kyphosis. Degeneration of lower adjacent segments appeared to be less with this procedure compared with using a combination of transarticular screw fixation and posterior wiring.

scholarly journals Subtalar Nonunion Following Tibiotalocalcaneal Fusion Using an Intramedullary Nail: A Case Series of Errant Entry Points

2019 ◽  
Vol 4 (4) ◽  
pp. 2473011419S0029
Author(s):  
Anthony Martella ◽  
Ruixian Yue ◽  
Michael Boin ◽  
Jonathan Rogozinski ◽  
Trenden Flanigan ◽  
...  
Keyword(s):  
Intraoperative Imaging ◽  
Case Series ◽  
Valgus Deformity ◽  
Entry Point ◽  
Medial Wall ◽  
Ct Scans ◽  
Patient Demographics ◽  
Entry Points ◽  
Hindfoot Deformity ◽  
Valgus Alignment

Category: Hindfoot Introduction/Purpose: Tibiotalocalcaneal (TTC) arthrodesis is a procedure used to treat hindfoot deformity and/or arthritis. Retrograde intramedullary nails have been used as a method of fixation. The nails are either straight or have a bend to accommodate valgus alignment of the hindfoot. Studies comparing nail types or analysis of nonunions are lacking in the available literature on the subject despite a reported nonunion rate of up to 20%. The purpose of this study was to report a series of subtalar nonunions that all had an entry point that was too medial on the calcaneus resulting in inadequate purchase of the nail in the calcaneus. Methods: Six cases of subtalar nonunion were retrospectively reviewed. All were referred for second opinion. Evaluation consisted of examination, radiographs and CT scans. Patient demographics, comorbidities and findings common to all cases were recorded. Results: Presenting complaints in all cases were persistent swelling. Non-neuropathic cases all had hindfoot pain. In this series, all the implants were straight nails. Radiographs and CT scans revealed that all cases were done for severe valgus deformity with subtalar subluxation. In each of the cases, the deformity was under corrected and the nail entry point was too medial on the calcaneus which resulted in reaming out the medial wall of the calcaneus, decreasing the amount of fixation obtained with the nail. In each of the cases, the medial wall of the calcaneus was deficient and the nail had no medial containment. Conclusion: Severe valgus deformity with subtalar subluxation is a risk factor for subtalar nonunion when the deformity is under corrected and a straight nail is used. Ensuring that the tibia talus and calcaneus are collinear and that the entry point in the calcaneus is sufficiently lateral are important factors to consider when addressing this type of deformity. Accurate intraoperative imaging is essential to ensure proper positioning of the entry point to avoid reaming out the medial wall of the calcaneus and to ensure adequate purchase of the nail in the calcaneus.

Antibiotic Use and Computed Tomography Imaging for Rhinosinusitis as Quality Metrics in Modern Health Care

2019 ◽  
Vol 33 (6) ◽  
pp. 700-705 ◽  
Author(s):  
Christopher C. Xiao ◽  
Rijul S. Kshirsagar ◽  
Jonathan Liang
Keyword(s):  
Public Information ◽  
Antibiotic Use ◽  
Neck Surgery ◽  
Quality Metrics ◽  
Ct Scans ◽  
Incentive Payment ◽  
Quality Reporting ◽  
Significant Difference ◽  
The Mean ◽  
Mean Compliance

Background American Academy of Otolaryngology-Head and Neck Surgery rhinosinusitis guidelines have been adapted into quality measures intended to be a basis for adjusting physician reimbursement and as public information to help patients select physicians. Early and continual evaluation of these measures is therefore important, given the impacts these may have. Objective To examine the metrics used in by Medicare for reimbursement in the Physician Quality Reporting System (PQRS) used in Merit-based Incentive Payment System (MIPS). Methods This study is a retrospective review of the 2015–2016 Center for Medicare and Medicaid Services Physician Compare Initiative regarding quality metrics for acute and chronic rhinosinusitis for providers participating in MIPS. Results Data for 726 providers were extracted from the PQRS database. Otolaryngologists had a low enrollment with less than 50 responding for any 1 measure. Of the reported quality metrics, otolaryngologists prescribed a significantly greater number of antibiotics than other providers within 7 days of diagnosis or within 10 days after symptom onset (48.3% vs 11.3%, P < .001). There was a significant difference in the mean compliance between otolaryngologists and all other providers for the use of CT scans within 28 days of diagnosis (2.3% vs 0.2%, P < .001). There was no significant difference in the mean compliance for the use of multiple CT scans within 90 days of diagnosis (2.0% vs 2.3%, P = .8). Inverse metrics comprise 3 out of 4 measures. Conclusion This review of the quality metrics used in MIPS shows several differences between otolaryngologists and nonspecialists, but raise concerns regarding applicability.

scholarly journals Anatomical landmarks for localizing the otic ganglion: A possible new treatment target for headache disorders

2019 ◽  
Vol 2 ◽  
pp. 251581631985076
Author(s):  
Joan Crespi ◽  
Daniel Bratbak ◽  
David W. Dodick ◽  
Manjit S. Matharu ◽  
Miriam Senger ◽  
...  
Keyword(s):  
Average Distance ◽  
Infratemporal Fossa ◽  
Mandibular Nerve ◽  
Ct Scans ◽  
Anatomical Landmarks ◽  
Medial Part ◽  
Headache Disorders ◽  
Parasympathetic Innervation ◽  
The Mean ◽  
Inferior Edge

Background: The otic ganglion (OG) is a cranial parasympathetic ganglion located in the infratemporal fossa under the foramen ovale (FO) and adjacent to the medial part of the mandibular nerve. Parasympathetic innervation of intracranial vessels from the OG has been shown both in animal and human models and evidence suggests that the OG plays an important role in the cranial vasomotor response. We review the evidence that positions the OG as a viable target for headache disorders. The OG is a small structure and not detectable on medical imaging. The FO is easily identifiable on CT scans and the mandibular nerve on MRI, hence, the position of the OG may be predicted if the mean distance from the FO is known. Objective: The objective is to describe the average distance between the FO and the OG in a sample of 18 infratemporal fossae from 21 cadavers. Methods: A total of 21 high definition photographs of 21 infratemporal fossae from 18 cadavers were analyzed. The distance between the inferior edge of the medial part of the FO to the OG was measured. Results: Four photographs of infratemporal fossae of four cadavers were excluded due to the inability to localize the inferior edge of the FO. A total of 15 infratemporal fossae from 17 cadavers were measured. The mean distance from the FO to the OG was 4.5 mm (SD 1.7), range 2.1–7.7 mm. Conclusions: We have described the average distance from the OG to an easily identifiable anatomical landmark that is visible in CT scans, the FO. This anatomical study may aid in the development of strategies to localize the OG in order to explore its role as a therapeutic target for headache disorders.

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