How many vertebrae make up the spine

Combined Spinal-Epidural Analgesia

Combined spinal-epidural (CSE) analgesia has become increasingly popular in the past 20 years. Onset of complete analgesia is significantly faster than with epidural techniques (2 to 5 minutes versus 10 to 15 minutes, respectively).24 In a meta-analysis of the onset time of CSE compared with low-dose epidural analgesia,24 the mean difference in onset was –5.4 minutes (95% confidence interval [CI], –7.3 to –3.6). More women with spinal analgesia than with epidural analgesia had effective analgesia at 10 minutes (relative risk [RR], 1.9; 95% CI, 1.5 to 2.5). In particular, the onset of sacral analgesia is significantly slower after the initiation of lumbar epidural analgesia than with spinal analgesia. It may take several hours of lumbar epidural infusion, or several bolus injections of local anesthetic into the lumbar epidural space, to achieve sacral analgesia. Rapid onset of sacral analgesia is advantageous in the parturient in whom analgesia is initiated late in the first stage of labor or in a parous parturient with rapid progress of labor. Spinal analgesia requires significantly lower drug doses to attain effective analgesia than does epidural analgesia; therefore, the risk for local anesthetic systemic toxicity is decreased. In addition, there is less systemic absorption of spinal anesthetic agents into the maternal circulation, so maternal and fetal plasma drug concentrations are lower with spinal than with epidural analgesia.

An additional advantage of spinal analgesia is that complete analgesia for early labor can be accomplished with the intrathecal injection of a lipid-soluble opioid without the addition of a local anesthetic. Thus, motor blockade is avoided and the risk for hypotension is lower.25 This method is ideal for patients who wish to ambulate or for those with preload-dependent cardiac conditions such as stenotic heart lesions. Finally, use of the CSE technique may lower the incidence of failure of epidural analgesia (e.g., a nonfunctioning epidural catheter).26,27 The likelihood of an epidural catheter placed for labor analgesia failing to provide satisfactory anesthesia for a subsequent cesarean delivery was more than five times higher for catheters placed as part of an epidural technique than for catheters placed as part of a CSE technique.28

Several studies have described a modification of CSE analgesia in which a dural puncture is made with a small-gauge spinal needle but no drug is injected into the subarachnoid space (dural puncture epidural analgesia).29–32 Results of studies are inconsistent, but two studies found that blockade of sacral dermatomes occurred more frequently after injection of epidural local anesthetic and opioid in parturients with a dural puncture than in those without.30,32 Presumably, enhanced sacral analgesia occurs because of increased migration of anesthetic solution across the dural puncture site.

Abstract

Vertebral column neoplasms can be categorized as primary or malignant in origin, based on whether they arise directly from spinal osseous structures or extra-spinal locations, respectively. The management of such tumors varies greatly from one patient to the next. Many primary spinal tumors are relatively resistant to chemotherapy and radiation, thus often necessitating extensive multidisciplinary operations to achieve maximal cytoreduction in such a way that negative margins are achieved. Unlike the treatment of primary tumors, the treatment of metastatic spine tumors remains palliative in nature. The management goal of primary vertebral column neoplasms is to provide long-term disease-free intervals and ultimately eradicate the neoplastic process. En-bloc tumor resection for most primary spinal tumors gives patients the best chance at achieving this goal. Unlike primary spinal tumors, surgical treatment of metastatic vertebral column tumors is palliative with the goals primarily being preservation or improvement of neurologic function, and restoration or maintenance of spinal stability. Complications during the resection of vertebral column neoplasms can be categorized into approach-related morbidities, challenges achieving stabilization and fusion, wound healing problems, length-of-surgery related problems, and intra-operative hemorrhage. Understanding these types of complications will hopefully help minimize patient morbidity by helping the surgical practitioner prevent the problem from happening and dealing effectively with it if it does occur.

Forward Flexion

The normal ROM of forward flexion (forward bending) in the thoracic spine is 20° to 45° (Fig. 8.21). Because the ROM at each vertebra is difficult to measure, the examiner can use a tape measure to derive an indication of overall movement (Fig. 8.22). The examiner first measures the length of the spine from the C7 spinous process to the T12 spinous process with the patient in thenormal standing posture. The patient is then asked to bend forward, and the spine is again measured. A 2.7-cm (1.1-inch) difference in tape measure length is considered normal.

If the examiner wishes, the spine may be measured from the C7 to S1 spinous process with the patient in the normal standing position. The patient is then asked to bend forward, and the spine is again measured. A 10-cm (4-inch) difference in tape measure length is considered normal. In this case, the examiner is measuring movement in the lumbar spine as well as in the thoracic spine; most movement, approximately 7.5 cm (3 inches), occurs between T12 and S1.

A third method of measuring spinal flexion is to ask the patient to bend forward and try to touch the toes while keeping the knees straight. The examiner then measures from the fingertips to the floor and records the distance. The examiner must keep in mind that with this method, in addition to the thoracic spine movement, the movement may also occur in the lumbar spine and hips; in fact, movement could occur totally in the hips.

Each of these methods is indirect. To measure the ROM at each vertebral segment, a series of radiographs would be necessary. The examiner can decide which method to use. However, it is of primary importance to note on the patient’s chart how the measuring was done and which reference points were used.

While the patient is flexed forward, the examiner can observe the spine from the “skyline” view (Fig. 8.23). Withnonstructural scoliosis, the scoliotic curve disappears on forward flexion; with structural scoliosis, it remains. With the skyline view, the examiner is looking for a hump on one side (convex side of curve) and a hollow (concave side of curve) on the other. This “hump and hollow” sequence is caused by vertebral rotation in idiopathic scoliosis, which pushes the ribs and muscles out on one side and causes the paravertebral valley on the opposite side. The vertebral rotation is most evident in the flexed position.

When the patient flexes forward, the thoracic spine should curve forward in a smooth, even manner with no rotation or side flexion (Fig. 8.24). The examiner should look for any apparent tightness or sharp angulation, such as a gibbus, when the movement is performed. If the patient has an excessive kyphosis to begin with, very little forward flexion movement occurs in the thoracic spine. McKenzie10 advocates doing flexion while sitting to decrease pelvic and hip movements. The patient then slouches forward flexing the thoracicspine. The patient can put the hands around the neck to apply overpressure at the end of flexion. If symptoms arise from forward flexion on the spine with the neck flexed by the hands, the examiner should repeat the movement with the neck slightly extended and the hands removed. This will help to differentiate between cervical and thoracic pain.

Summary

The vertebral column is involved with many functions that are essential to the normal kinesiology of the body. Its semi-rigid structure provides a stable axis for the entire trunk, head, and neck, and, indirectly, the upper extremities. In addition, the vertebral column serves as the primary source of protection for the delicate spinal cord and exiting spinal nerves, from the atlas to the lower sacrum. Fractures or dislocations anywhere along the vertebral column can result in spinal cord injury and subsequent quadriplegia or paraplegia.

The joints and vertebrae of the cranial end of the vertebral column are highly specialized. The atlanto-occipital, atlanto-axial, and intracervical joints interact to provide extensive three-dimensional placement of the head and neck, which is essential for optimal spatial orientation of the special senses. In fact, range of motion of the craniocervical region exceeds that of any other region of the vertebral column. The highly specialized muscles that control fine movements in the craniocervical region often become painful and inflamed when stressed as a result of poor posture, cervical arthritis, or compressed exiting spinal nerves.

The thoracolumbar region has three major requirements. First, the thoracic region must protect many important organs such as the heart and lungs. Second, joints and muscles in the region must be sufficiently mobile and coordinated to function as a mechanical chamber for breathing, which includes coughing and forced exhalation. And third, abdominal muscles, posterior trunk muscles, iliopsoas, and quadratus must provide core stability to the trunk and body as a whole. Controlling such core stability establishes a firm base of support for the extremities, as well as mechanical support for the vulnerable and naturally highly stressed lumbar and lumbosacral regions.

The most inferior (or caudal) end of the vertebral column is specialized for two important and interrelated functions. First, the lumbosacral junction and sacroiliac (SI) joints must transfer, at times, large forces from body weight and activated muscle through the pelvis and to the lower extremities. These large forces may exceed the physical tolerance of the region, causing impairments such as anterior spondylolisthesis or partial dislocation of the SI joints. Second, the more caudal end of the vertebral column must interact mechanically with the hip joint (pelvis or femur) to maximize movement of the trunk. The ability to reach and touch the floor while standing, for instance, requires ample forward bend in the lumbar region, as well as in the pelvis, relative to the femurs. A limitation in either region can increase the range of motion demands on the other, possibly leading to arthritis of the hip or disc herniation and inflamed facet joints in the lumbar spine.

Pain with limited mobility anywhere within the vertebral column can originate from many sources such as tight or weakened muscles, torn ligaments, herniated discs, bone spurs compressing nerve roots, inflamed joints, or, most likely, a combination of these pathologies. Regardless of the actual cause of the impairment, physical therapy is often the first line of conservative treatment for pain and dysfunction of the vertebral column. Understanding not only the medical diagnosis but also the rationale behind the many treatment approaches requires a sound understanding of anatomy and kinesiology.

Skeletal System

This section reviews the bony components of trunk anatomy, including articulations and range of motion (ROM).