Neurovascular anatomy: Spine

A comprehensive review of the vertebral artery anatomy

BACKGROUND

The vertebral arteries (VA) play a critical role by supplying nearly one-third of the brain's blood flow, predominantly contributing to the posterior circulation. These arteries may need to be exposed in a various cranial and cervical procedures and offers access to investigate or treat vascular lesions by endovascular means related to the posterior circulation. Given its complex anatomy, which is subject to numerous variations, and its role in supplying vital brain regions, a thorough understanding of the VA's anatomy is paramount for any related procedure.

OBJECTIVE

To provide a comprehensive overview of vertebral artery anatomy and its relevance in contemporary clinical practice.

METHODS

Dissection of the entire vertebral artery length using cadaveric specimen, combined with a comprehensive literature review.

RESULTS

The vertebral artery can be subdivided into four segments. Each of these segments has its own unique topographic anatomy with its variations, anastomoses, and significance in surgery.

CONCLUSION

As surgical and endovascular techniques continue to evolve with technological improvements, we are now more equipped than ever to manage complex lesions involving the VA. However, with its increasingly complexity comes the necessity for a deeper and more comprehensive understanding of the VA. Possessing the detailed knowledge of the VA is vital for the successful execution of any procedure involving it.

The Dominant Anterior Thoracic Artery of the Spinal Cord

BACKGROUND AND PURPOSE

Dominant radiculomedullary arteries such as the artery of lumbar enlargement and the artery of cervical enlargement are well-documented. However, variability exists as to the size, number, and location of other radiculomedullary arteries contributing supply to the anterior spinal artery. The aim of this anatomic study was to document the prevalence and characteristics of the dominant anterior thoracic artery in cadaveric specimens.

MATERIALS AND METHODS

Microsurgical dissection of cadaveric human spinal cord specimens (n = 50) was conducted. The artery of lumbar enlargement was injected with colored latex until the small-caliber arterial vessels were filled. The dominant anterior thoracic artery was identified, injected, and filled with diluted industrial paint. The course, diameter, and location of the dominant anterior thoracic artery, artery of lumbar enlargement, and artery of cervical enlargement were documented.

RESULTS

The artery of lumbar enlargement was identified between T3 and L2 in all 50 specimens (100%), and the artery of cervical enlargement was identified in 84% of specimens (42/50). At least 1 dominant anterior thoracic artery distinct from the artery of lumbar enlargement and the artery of cervical enlargement was identified between T1 and T11 in 47 of the 50 specimens (94%). The most frequent origin of the dominant anterior thoracic artery was at the level of T4 on the left. The average size of the dominant anterior thoracic artery was 0.446 mm (range, 0.300-0.759 mm on the left and 0.270-0.569 mm on the right).

CONCLUSIONS

A dominant anterior thoracic artery is present in 94% of individuals. Variations of the arterial supply to the anterior thoracic cord are of great importance due to their implications for ischemic events as well as surgical and endovascular procedures.

Spinal cord motor disorders

Spinal cord diseases are frequently devastating due to the precipitous and often permanently debilitating nature of the deficits. Spastic or flaccid paraparesis accompanied by dermatomal and myotomal signatures complementary to the incurred deficits facilitates localization of the insult within the cord. However, laboratory studies often employing disease-specific serology, neuroradiology, neurophysiology, and cerebrospinal fluid analysis aid in the etiologic diagnosis. While many spinal cord diseases are reversible and treatable, especially when recognized early, more than ever, neuroscientists are being called to investigate endogenous mechanisms of neural plasticity. This chapter is a review of the embryology, neuroanatomy, clinical localization, evaluation, and management of adult and childhood spinal cord motor disorders.

The ROCK inhibitor Y-27632 ameliorates blood-spinal cord barrier disruption by reducing tight junction protein degradation via the MYPT1-MLC2 pathway after spinal cord injury in rats

The blood-spinal cord barrier (BSCB) is a physiological barrier between the blood and spinal cord parenchyma. This study aims to determine whether Y-27632, a Rho-associated protein kinase (ROCK) inhibitor, can protect the BSCB using in vivo models. The Evans blue fluorescence assay was used to detect leakage of the BSCB. Western blotting was used to define alterations in ROCK-related and tight junction (TJ) protein expression. Immunofluorescence triple-staining was used to evaluate histologic alterations in TJs. Locomotor function was evaluated using the open-field test, the Basso-Beattie-Bresnahan score, and footprint analysis. Two peaks of BSCB leakage after spinal cord injury (SCI) occurred at 24 h and 5 days. The ROCK inhibitor reduced the BSCB leakage at the second peak after SCI. Moreover, the ROCK inhibitor ameliorated the integrity of the BSCB and improved motor function recovery after SCI by regulating the phosphorylation of myosin phosphatase subunit-1 (MYPT1) and cofilin. ROCK inhibitors might protect the BSCB, which provides a new strategy for transitioning SCI treatment from the bench to bedside.