Vertebrocarotid collateral in extracranial carotid artery occlusions: digital subtraction angiography findings

Anatomical research of the clavicular pedicled flap for mandibular reconstruction: vascularization and harvesting technique

PURPOSE

Mandibular reconstruction remains a challenging procedure despite the availability of various flaps and grafts. The ultimate objective is to restore oral functioning and attain acceptable morphological outcomes while considering donor site morbidity. This study describes the vascular supply and harvesting technique of a pedicled clavicular bone. The proximity of the clavicle is conducive to a mandibular replacement and allows the use of vascularized bone with a single surgical field.

METHODS

The osteoperiosteal clavicular pedicled flap was harvested on the right side of ten fresh cadaver specimens. The cervical transverse artery was injected with colored latex in some cases and methylene blue in others.

RESULTS

The vascular periosteal supply of the clavicular flap was highlighted. The clavicular bone was linked to its pedicle which was composed of vascular and adipose-fascial tissues, without any overlying skin paddle. Its vasculature was supplied by a reverse flow from the ascending cervical artery. The pedicled clavicular bone readily reached the mandible in all dissections.

CONCLUSION

The osteoperiosteal vasculature of the clavicular flap is based on the transverse cervical artery which receives a reverse blood supply from the ascending cervical artery. This vascular pattern is reliable because of the existence of the sub-occipital microvascular network named the "Bosniak node." This pedicled clavicular flap seems to be a robust perspective in both mandibular and facial bone reconstruction. We do not claim that it will replace the existing approaches, but it will expand the surgical panel of mandibular reconstruction. Its clinical realisation will judge its functionality.

Effect of Aging and Carotid Atherosclerosis on Multifractality of Dental Pulp Blood Flow Oscillations

INTRODUCTION

Age-related changes of dental pulp tissue and atherosclerosis of carotid arteries as its feeding arteries could influence the functionality of pulpal circulation. The objective of our study was to evaluate the effect of aging (physiological process) and carotid bifurcation atherosclerosis (pathologic process) on the pulpal microcirculatory system using multifractal analysis of the laser Doppler flowmetry signal.

METHODS

Three groups of 10 subjects were enrolled in the study: the young group (healthy subjects, 20-25 years), the middle-aged group (healthy subjects, 50-60 years), and the clinical group (subjects with carotid bifurcation atherosclerosis, 50-60 years). Pulpal blood flow (PBF) signals recorded by laser Doppler flowmetry were assessed by multifractal analysis that estimates Hölder exponents of the signal. PBF levels, the average mean values, and the range of Hölder exponents were obtained.

RESULTS

PBF levels were significantly higher in the young group compared with the middle-aged and clinical groups, and the difference between the middle-aged and clinical groups was not statistically significant. The range of the Hölder exponents was narrower in the middle-aged and clinical groups than in the young group and narrower in the clinical group than in the middle-aged group. The average mean value of Hölder exponents was significantly higher in the young group than in the middle-aged and clinical groups, whereas there was no significant difference between the middle-aged and clinical groups.

CONCLUSIONS

Our study investigating the multifractality of the PBF signal showed that the aging process and carotid atherosclerosis could affect the complex structure of PBF oscillations and contribute to a better understanding of pulpal hemodynamics.

Paravertebral Collateral Arteries in Patients with Carotid Stenosis: Is There a Safe Space for Transforaminal Cervical Nerve Root Injections?

AIM

Image-guided cervical nerve root injections can cause serious complications including spinal cord infarction. This risk may be increased in patients with carotid stenosis who develop collateral arteries. The aim of this study is to describe the prevalence, and anatomical location, of arterial collateral vessels in relation to the optimal needle tip position in cervical nerve root injections.

MATERIALS AND METHODS

This retrospective study included 25 patients who had > 70% stenosis on a carotid CT angiogram. For each foramen the position of collateral arteries and the most anterior point of the facet joint were recorded, as Cartesian coordinates, by two independent observers. Descriptive statistics were used to analyse and present the results.

RESULTS

14 patients had unilateral and 11 had bilateral stenoses. A total of 85 collaterals were identified at all levels, the most common being C2/3. The median distance from collateral to optimal needle tip placement was 9.6 mm (95% CI median: 6.7-12.4, IQR: 5.6-15.6). The minimum distance was 2.9 mm. Inter-observer reliability was "substantial" (ICC 0.78, 95% CI 0.71-0.83).

CONCLUSION

Collateral arteries were common in our cohort of patients with carotid artery stenosis and half lay within 10 mm of the optimal position for transforaminal cervical nerve root injection.

Carotid artery stenting for patients with occipital-vertebral anastomosis

BACKGROUND AND PURPOSE

We report the outcomes of carotid artery stenting for patients with angiographically visible occipital artery-vertebral artery anastomosis.

METHODS

Among 47 consecutive patients who underwent carotid artery stenting from January 2007 to December 2010, seven patients for whom cerebral angiograms clearly showed occipital artery-vertebral artery anastomosis were selected. Four different protection methods were used: distal internal carotid artery protection; carotid flow reversal; seatbelt and airbag technique; and double protection method of protecting both the external and internal carotid artery.

RESULTS

One patient with distal internal carotid artery protection showed a high-intensity lesion at the border of the upper thalamus, internal capsule and lateral ventricle wall after carotid artery stenting. The other patient with the double protection method did not show any high-intensity lesions on postoperative diffusion-weighted imaging in the vertebrobasilar territory. All seven patients with visible occipital artery-vertebral artery anastomosis showed ipsilateral vertebral artery severe stenosis or occlusion.

CONCLUSION

Large occipital artery-vertebral artery anastomosis may be a pathway for embolic materials during carotid artery stenting. External carotid artery protection is recommended for carotid artery stenting in such patients.

Dual Origin of Extradural Posterior Inferior Cerebellar Artery From Vertebral and Occipital Arteries: Anatomic Case Report

BACKGROUND

Small anastomotic channels exist between the occipital artery (OA) and muscular branches of the vertebral artery; however, no direct connection has been reported between an extradural origin of the posterior inferior cerebellar artery (PICA) and the OA.

OBJECTIVE

To describe a rare anatomic connection between the extradural PICA and the OA.

METHODS

A far lateral exposure was completed on a cadaveric head prepared for surgical simulation. The course and branches of the OA were followed, and the relations to their immediate anatomic structures were studied.

RESULTS

The origin of the PICA was found at the second segment of the vertebral artery, between the C1 and C2 transverse foramina. There was a large anastomotic connection between the superficial descending branch of the occipital artery and the PICA 12 mm proximal to the dural entrance of the artery.

CONCLUSION

Awareness of the angioarchitecture of the suboccipital region and the existence of patent vertebrocarotid anastomotic connections is important to avoid complications during surgical or endovascular interventions. When present, a pre-existing OA-PICA anastomosis can be exploited to facilitate treatment in certain vascular pathologies (eg, vertebral artery aneurysms). Awareness of the existence of both an extradural origin of the PICA and a direct connection of this vessel with the OA is of great relevance to the muscular stage of surgical approaches to the posterior craniovertebral junction.

External carotid dissection and external carotid proatlantal intersegmental artery with subclavian steal prompting external carotid and subclavian artery stenting

BACKGROUND AND PURPOSE

The authors describe a case of a proatlantal intersegmental artery seen in the setting of external carotid artery dissection and subclavian steal due to proximal subclavian artery stenosis.

METHODS

An 83-year-old woman presented with left homonymous hemianopsia and a right posterior cerebral artery distribution stroke. She was found to have severe left subclavian artery stenosis proximal to the vertebral artery (VA) and an occluded contralateral VA. Doppler ultrasonography and angiography both showed a dissection of the proximal left external carotid artery. Left common carotid artery angiography also demonstrated a connection between the external carotid and vertebral arteries at the C1 level with anterograde flow into the vertebrobasilar system and retrograde flow toward the vertebral origin, consistent with subclavian steal.

RESULTS

The patient underwent successful stenting of the subclavian and external carotid arteries with resolution of anterograde flow in the left VA.

CONCLUSIONS

This case represents an interesting presentation of both subclavian steal and an external carotid artery to VA anastomosis. Also, the presence of a dissection of the external carotid artery represents a rare finding.

Blood flow in the internal carotid artery with common carotid artery-occluding lesions in Takayasu arteritis

OBJECTIVE

The purpose of this study was to investigate carotid artery hemodynamics and blood flow involving external carotid artery (ECA) and internal carotid artery (ICA) patency in patients with Takayasu arteritis (TA).

METHODS

The common carotid artery (CCA), ECA, ICA, and vertebral artery (VA) were examined in 19 patients with TA involving ECA and ICA patency and in 19 healthy control participants. Bilateral carotid sonographic studies were performed with the use of 5- to 8-MHz linear transducers.

RESULTS

Patency of the ECA and ICA was noted in 14 bilateral, 2 right-sided, and 3 left-sided CCA lesions. Flow in the ECA was retrograde, whereas flow in the ICA was directed cephalad and showed a low-frequency, damped waveform or even a veinlike waveform. The peak systolic velocity (PSV) of the ICA in the patients was significantly lower than that in the control participants (P < .001). A good correlation was observed in the PSV between the ECA and ICA (r = 0.77). The VA displayed normally directed flow, a significantly larger diameter, and a higher flow velocity (P < .001).

CONCLUSIONS

Color duplex sonography can identify special features of TA with CCA-occluding lesions and permit quantification of carotid artery flow velocities and VA diameters both efficiently and practically.

Sonographic diagnosis of congenital variations of the extracranial vertebral artery and assessment of its circulation

OBJECTIVE

The purpose of this study was to assess the value of sonographic examination of congenital variations of the extracranial vertebral artery associated with posterior circulation ischemia in children.

METHODS

Sonography was performed on the vertebral arteries of 82 patients aged 2.5 to 14 years with a history of headache, vertigo, and syncope. An additional 86 unaffected children aged 2 to 14 years were included as a control group. Indices such as the diameter, passage, and morphologic characteristics of the vertebral artery were measured, as well as the arterial volume. The median values of these parameters were used for comparisons.

RESULTS

A comparison between the control and 5 case groups showed that the bilateral diameter and volume in these 6 groups had significant variations (P < .05). A narrow diameter and abnormal passage of the vertebral artery resulted in reduced blood flow and an inadequate blood supply in the posterior circulation. There were 42 cases found to have congenital variations of the extracranial vertebral artery, 12 cases of congenital asymmetry, 15 cases of tortuosity, 5 cases of bilateral congenital asymmetry with tortuosity, 6 cases of congenital hypoplasticity, and 4 cases of an abnormal path.

CONCLUSIONS

Certain children with a history of recurrent signs of vertigo, headache, and syncope were found to be afflicted with congenital variations of the extracranial vertebral artery. Sonography not only revealed the morphologic variations of the extracranial vertebral artery but also allowed an assessment of changes in blood flow such that posterior circulation ischemia could be determined.

Proatlantal intersegmental artery: a review of normal and pathological features

OBJECTS

Primitive carotid-vertebral and carotid-basilar anastomoses are formed early during human embryogenesis at approximately 24 days. From cephalic to caudal direction, these anastomoses are cranial extensions of the primitive internal carotid, trigeminal, otic, hypoglossal and proatlantal intersegmental arteries.

MATERIALS AND METHODS

Normal and/or abnormal morphofunctional aspects of prenatal and postnatal forms of the proatlantal intersegmental artery, from the 24th day of gestation to postnatal eight decades, are described according to personal and literature data. Many (ab) normal carotid-vertebral anastomoses are also marked in differential diagnosis of the proatlantal intersegmental artery.

CONCLUSIONS

The proatlantal intersegmental artery maintains the posterior circulation until the vertebral arteries are fully developed between the seventh and eighth gestational weeks. When this artery fails to obliterate, it becomes persistent one. The proatlantal intersegmental artery, most commonly, is an incidental finding or it may be of clinical significance in some patients.