Study of the Transverse Foramen in the Subaxial Cervical Spine in Korean Patients With Degenerative Changes: An Anatomical Note

Exploring the relationship between soft and hard tissues: The example of vertebral arteries and transverse foramina

Understanding how the brain is provided with glucose and oxygen is of particular interest in human evolutionary studies. In addition to the internal carotid arteries, vertebral arteries contribute significantly to the cerebral and cerebellar blood flow. The size of the transverse foramina has been suggested to represent a reliable proxy for assessing the size of the vertebral arteries in fossil specimens. To test this assumption, here, we statistically explore spatial relationships between the transverse foramina and the vertebral arteries in extant humans. Contrast computed tomography (CT) scans of the cervical regions of 16 living humans were collected. Cross-sectional areas of the right and left transverse foramina and the corresponding vertebral arteries were measured on each cervical vertebra from C1 to C6 within the same individuals. The cross-sectional areas of the foramina and corresponding arteries range between 13.40 and 71.25 mm² and between 4.53 and 29.40 mm² , respectively. The two variables are significantly correlated except in C1. Using regression analyses, we generate equations that can be subsequently used to estimate the size of the vertebral arteries in fossil specimens. By providing additional evidence of intra- and inter-individual size variation of the arteries and corresponding foramina in extant humans, our study introduces an essential database for a better understanding of the evolutionary story of soft tissues in the fossil record.

Stent-Assisted Coil Embolization of a Vertebro-Vertebral Arteriovenous Fistula Secondary to Oriental Acupuncture: A Case Report

A vertebro-vertebral arteriovenous fistula is an abnormal communication between the vertebral artery and adjacent venous structures. Trauma is the most common cause of vertebral arteriovenous fistulas; however, the fistulas can also occur spontaneously. We herein report a case of a traumatic vertebro-vertebral arteriovenous fistula that occurred following the application of oriental acupuncture in the posterior neck region. A 64-year-old previously healthy female patient took over-the-counter medicine for cervical pain that occurred several months before the acupuncture session but showed no improvement. She had undergone oriental acupuncture treatment in the posterior lower neck region 1 month before visiting our hospital. After the treatment, she gradually developed tinnitus, accompanied by dizziness. Abnormal aneurysmal dilated vessels were observed in the right vertebral artery on computed tomography angiography. The patient was immediately admitted and underwent diagnostic angiography. She subsequently underwent stent-assisted coil embolization, which gradually resolved her dizziness and tinnitus.

Determination of Availability of Safety Margin for Placement of C3-C6 Pedicle Screw on CT Angiography

BACKGROUND

Cervical pedicle screws (CPS) in the subaxial cervical spine (C3-C6) are faced with high incidence of perforating the lateral pedicular cortex endangering the vertebral artery (VA). The present study analyzes the pedicle width (PW) from C3 to C6 and defines the relation of VA with regard to pedicle and transverse foramen (TF) to determine the safety margin in cases of lateral pedicular breach.

METHODS

Computed tomography angiograms of 500 patients were retrospectively studied to identify the pedicle width (PW), VA area, TF area, and the lateral pedicle to vertebral artery distance (LPVA). Occupancy ratio (OR; the percentage area of transverse foramen occupied by VA) and safety margin (SM; permissible displacement of VA in TF), along with LPVA were considered to be protective parameters against VA injury if lateral pedicle breach happens.

RESULTS

PW was 4.7 mm at C3, 4.83 mm at C4, 5.26 mm at C5 and 5.41 mm at C6. Mean LPVA at different levels was between 0.97 mm and 1.15 mm, OR was around 20% at all levels, and mean SM was between 2.34 mm and 2.92 at various levels. Sex differences were statistically significant for PW but not for LPVA, SM, or OR.

CONCLUSIONS

This study gives us an idea about the various parameters in placement of cervical pedicle screw in subaxial cervical spine and the probable reasons there are few vertebral artery injuries despite high incidence of cervical pedicle breach. LPVA, safety margin, and OR may explain why even very significant CPS misplacement does not lead to vascular injury or neurologic deficit.

Anatomical Variation and Morphometric Study on Foramen Transversarium of the Upper Cervical Vertebrae in the Thai Population

Study Design

Foramen transversarium (FT) and foramen arcuale (FA) of upper cervical vertebrae (C1 and C2) in the Thai population were investigated for variation and morphometry.

Purpose

This study aimed to reveal the morphometry of FT and FA in the Thai population.

Overview of Literature

The FT and FA are structures found in the upper spine that support the vertebral neurovascular system. Clinically, the surgical approaches to achieve upper cervical stability can be affected by spine variations. FT and FA morphometries have been documented to vary by nationality. However, such reports have been limited in the Thai population.

Methods

The FT and FA of dried C1 and C2 vertebrae (identified bones; n=107, males=53 and females=54) were observed and measured using a Digital Vernier Caliper (Mitutoyo, Kawasaki, Japan). Anteroposterior (AP) and transverse diameters of the left and right FTs (n=214) were measured and compared between sexes. Variations and types of FT and FA found on the upper vertebrae were recorded and classified.

Results

The FT shape of the Thai C1 was AP elliptical, while of that of C2 was transverse elliptical. Compared to females, both diameters of the upper spine were significantly greater in males except for the AP diameter of C2 on the right side. All diameters were significantly different in both sexes and sides except for the AP diameter of C1 and C2. A common type of FT classified in C1 was type 2 (male [69.81%], female [79.63%]) whereas for C2 it was type 1 (male [63.21%], female [59.26%]). Moreover, an incomplete osseous bridge was a major FA subtype observed in the Thai spine.

Conclusions

FT morphometry has an elliptical shape and diameters are greater in males. The FT and FA variations identified in this study will be useful for surgeons treating vertebral neurovascular injuries of the posterior upper cervical spine in the Thai population.

Risk assessment of vertebral artery injury in anterior controllable antedisplacement and fusion (ACAF) surgery: a cadaveric and radiologic study

PURPOSE

We have introduced a novel surgery technique named anterior controllable antedisplacement and fusion (ACAF) for the treatment of ossification of the posterior longitudinal ligament. As reported, the satisfactory postoperative outcome can be attributed to the larger decompression width. However, it may associate with high prevalence of vertebral artery injury (VAI) theoretically. Thus, assessment of the vulnerability of vertebral artery in ACAF is of great importance.

METHODS

Computed tomographic scan data of 28 patients were retrospectively studied. Seven radiographic parameters were evaluated: uncinate process (UP) tips distance, transverse foramen (TF)-UP tips distance, TF-LWL (the ipsilateral limited wedging line) distance, the limited distance of lateral decompression, the maximum oblique angle of LWL, TF-LWG (the lateral wall of groove) distance, and width of groove. Eleven fresh cadaveric spines undergoing ACAF surgery were also studied. Two anatomic parameters were evaluated: width of groove and LWG-TF distance.

RESULTS

The UP tips distance increased from C3 to C6 and tended to be larger in males. The UP tip-TF distance and LWL-TF distance were smallest at C4, but both were larger than 2 mm. Maximum oblique angle decreased from C3 to C6. Postoperatively, both radiographic and cadaveric measurements showed the width of groove was larger than UP tips distance, but LWG-TF distance was larger than 2 mm in all levels.

CONCLUSION

UP can be used as anatomical landmarks to avoid VAI during ACAF surgery. Radiographic and cadaveric measurements verified the safety of ACAF surgery, even for those cases with wedging and lateral slotting.