Surgical and Other Procedures
Harold G. Koenig in Chronic Pain, 2013
In certain places on the body, nerves are easily accessible to injection with a local anesthetic. This procedure is based on the notion that temporarily blocking nerve function can bring relief from pain or muscle spasm. Nerve endings deeply imbedded in skin, muscles, bone, or internal organs transmit pain impulses along their axons to the spinal cord or brainstem, and then to the brain. If the function of these nerves can be interrupted somewhere along their pathways, this will help prevent the pain signals from reaching the brain. This interruption of nerve function is temporary and accomplished by numbing or blocking the nerve through the injection of a local anesthetic. Peripheral nerve blocks can also be used diagnostically to identify from where pain is originating. For example, if pain is caused by a problem in the spinal cord or brain, then blocking a peripheral nerve will cause the area to feel numb, but will not relieve the pain.
ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
Touch is the class of sensations produced by mechanical disturbances of the skin from physical contact or thermal stimulation. Vibration, PAIN, pressure, and TEMPERATURE are encoded via fine nerve endings and the MECHANORECEPTOR system. The most sensitive body regions (tongue, lips, fingers) have the greatest density of mechanoreceptors and the largest cortical representation. Impulses travel along sensory nerve fibres to SOMATOSENSORY PATHWAYS, the THALAMUS, and SOMATOSENSORY CORTEX (Kaas, 1988). Somatosensory cortex maintains somatotopic organization. Primary somatosensory cortex (S-I) processes primary sensations; damage to S-I produces numbness. Secondary somatosensory cortex (S-II) processes complex tactile information; damage to S-II or higher-level association areas may produce TACTILE AGNOSIA.
Introduction to Cancer
David E. Thurston, Ilona Pysz in Chemistry and Pharmacology of Anticancer Drugs, 2021
Metastasis is the term used to describe the ability of solid tumors to spread to new sites in the body and establish secondary tumors. Many patients who die of cancer do so as a consequence of metastatic spread to vital organs rather than from their primary tumor. Tumor cells commonly penetrate the walls of lymphatic vessels, distribute to draining lymph nodes, and then move to distant sites. They can also directly invade blood vessels because capillaries have thin walls that offer little resistance. Furthermore, both primary and secondary tumors can expand in size and infiltrate surrounding tissues. When nerve endings are affected, pain and discomfort are experienced. A tumor can also spread across body cavities from one organ to another (e.g., stomach to ovary).
Advantages and feasibility of intercostal nerve block in uniportal video-assisted thoracoscopic surgery (VATS)
Published in Postgraduate Medicine, 2023
The 4th or 5th intercostal space is used as the surgical incision site in uniportal VATS in clinical practice. Intraoperative injury to the intercostal nerve may lead to postoperative pain. The intercostal nerve is a mixed nerve branch formed by the union of the anterior and posterior roots after the thoracic spinal cord. Each intercostal nerve emerges from the intervertebral foramen and travels at the lower edge of the rib angle to the costal groove accompanying the intercostal artery. The pain felt by the nerve endings travels from the intercostal nerve to the nerve roots, spinal cord, and cerebral cortex. Therefore, ICNB is performed primarily from the rib angle. In addition, the adjacent intercostal skin is innervated by the intercostal nerve; therefore, the surrounding skin should also be blocked. Various regional analgesic techniques have been used to improve postoperative pain management in VATS and promote the normalization of the concept of rapid recovery [23,24].
Anatomic variations of the human falx cerebelli and its association with occipital venous sinuses
Published in British Journal of Neurosurgery, 2021
Safiye Çavdar, Bilgehan Solmaz, Özgül Taniş, Orhan Ulas Guler, Hakkı Dalçık, Evren Aydoğmuş, Leyla Altunkaya, Erdoğan Kara, Hızır Aslıyüksek
Falx cerebelli, is composed of fibroelastic, dense irregular connective tissue. The connective tissue consisted of cells predominantly of fibroblast which produced the ground substance and collagen fibers. Additionally, the connective tissue contained sensory nerve endings and blood vessels. The arterioles were composed of 1–2 layers of smooth muscle cells in the tunica media and the venules were composed of a single layer of endothelium with many erythrocytes in their lumens (Figure 10a). Furthermore, a large number of lymphatic vessels appeared to be undulated with a single layer of endothelium and a subendothelial layer (Figure 10b). Extravagated lymphocytes surrounding the lymphatic vessels were observed (Figure 10b). Near the vessels, a peripheral nerve characteristically formed a round bundle of nerve processes surrounded by connective tissue sheath perineurium was detected (Figure 10a).
Spinal cord involvement in COVID-19: A review
Published in The Journal of Spinal Cord Medicine, 2023
Ravindra Kumar Garg, Vimal Kumar Paliwal, Ankit Gupta
The SARS-CoV-2 virus can enter the spinal cord via the hematogenous route infecting the endothelial cells and invading the spinal cord. The SARS-CoV-2 virus can bypass the blood-brain-barrier since it uses the inflammatory cells as a Trojan horse.7 The inflammatory changes produced by the virus thus result in spinal cord inflammation. It has been observed that the virus enters inside the sensory neurons after peripheral inoculation, resulting in ganglionitis.42 Shiers et al. have also demonstrated that the human dorsal root ganglia contain the angiotensin-converting enzyme 2 receptors that help the SARS-CoV-2 virus to spread to the spinal cord. The entry point can be free-nerve endings present in the skin as well as the intestinal mucosa.43