Clinical Anatomy of the Back PDF

Clinical Anatomy of the Back DPM Program 1. Define pars interarticularis and identify the features of the "Scotty dog" as seen on oblique radiographs of the lumbar spine. 4.0 2. Explain lumbarization and sacralization. 4.0 3. Integrate basic anatomy with the following clinical correlates: a. low bac...

Clinical Anatomy of the Back DPM Program 1. Define pars interarticularis and identify the features of the "Scotty dog" as seen on oblique radiographs of the lumbar spine. 4.0 2. Explain lumbarization and sacralization. 4.0 3. Integrate basic anatomy with the following clinical correlates: a. low back pain 4.0 b. spina bifida 4.0 c. laminectomy 4.0 d. lumbar puncture 4.0 e. herniated nucleus pulposus 4.0 f. scoliosis 4.0 g. kyphosis 4.0 h. lordosis 4.0 i. spondylosis 4.0 j. spondylolisthesis 4.0 k. spinal stenosis 4.0 4. Rationalize the choice of sites for lumbar puncture, rhizotomy and epidural anesthesia. 4.0 5. List, in order, the structures and spaces pierced in a lumbar puncture and epidural anesthesia. 4.0 Pars Interarticularis Superior articular process The pars interarticularis is a clinical term to describe the specific region of a vertebra between the superior and inferior facet (zygapophysial) joints. This region is susceptible to trauma, especially in athletes. If a fracture occurs around the pars interarticularis, the vertebral body may slip anteriorly and compress the vertebral canal. Limitation of passive lumbar flexion with resulting pain often accompanies disease of the lumbar or lumbosacral articulations. Asymmetry of the articular facets is a cause of low back pain. SPONDYLOLYSIS—a defect (or breaking down) in the vertebral arch between the superior and inferior facets in an area called the pars interarticularis. When bilateral, results in the lumbar vertebra being divided into two pieces—is an important cause of low back pain when it occurs bilaterally in L5. In such cases, the vertebra and spinal column above it may slide forward on the sacrum (SPONDYLOLISTHESIS), throwing the vertebral column out of line. Pedicle Pars interarticularis Lumbar Pain Low back pain, which is so ubiquitous, may have a variety of causes. To determine the site and cause, inspection and palpation of the painful area as well as complete pelvic and rectal examination are necessary. Plain x-ray films (with and without intrathecal contrast), CT scans, and MRIs are usually very useful in determining the cause of the back pain when the lesion is in the spine. There may be muscle spasm and tenderness to percussion and deep pressure, particularly in association with local deformity or restriction of spinal motion. Paravertebral lumbar spasm accompanied by lumbar radiculopathy may result from several conditions, including herniated intervertebral discs, metastases to the lung (from carcinoma of the prostate or breast, lymphoma, etc.), osteoarthritis, fracture of the spine, and local trauma. Lordosis, scoliosis, or list in the lumbar region may be noted when the patient stands. Psoas muscle spasm may indicate disease of the psoas muscle, the lumbar vertebrae, or soft tissues surrounding the psoas muscle (e.g., epidural abscess). Abnormal Curvatures of the Vertebral Column KYPHOSIS (HUNCHBACK) -This is an abnormal increase in the THORACIC (1°) CURVATURE. -May result from a congenital or pathological erosion of the anterior portion of one or more of the vertebral bodies in the thoracic region. LORDOSIS (SADDLE BACK; A BENDING BACKWARD) -An abnormal increase in the LUMBAR (2°) CURVATURE. -This increase in the lumbar curvature is accompanied by a downward (i.e., anterior tilt) rotation of the pelvis and is common in obesity and pregnancy. After weight loss or birth (which is really also a weight loss when one thinks about it) the lumbar curvature will usually return to normal. SCOLIOSIS (CROOKEDNESS) -An abnormal lateral curvature or deviation most commonly seen in the thoracic region. It is typically accompanied by a rotation of the column. -May result from a multitude of etiologies, but basically scoliosis may be functional (i.e., physiological basis), e.g., muscles on one side may be stronger (i.e., related to ―handedness‖); or structural (i.e., pathological basis), e.g., hemivertebra (i.e., the failure of one-half of the vertebra to form. Most commonly, however, it is idiopathic.) Lumbarization - This refers to a spinal anomaly defined by the nonfusion of the first and second segments of the sacrum. Upon imaging, the lumbar spine will appear to have 6 vertebrae or segments instead of 5, and the sacrum will conversely appear to have only 4 segments instead of 5. Sacralization of L5 - Sacralization is a congenital anomaly where the transverse process of L5 fuses to the sacrum on one or both sides, to the ilium, or to both sacrum and ilium. This anomaly usually presents bilaterally. While sacralization can cause lower back pain, it is often asymptomatic, especially in bilateral presentations since the biomechanics will not be as destabilized as a non-bilateral presentation. Finally, the L5-S1 intervertebral disc also may be thin and narrow. Laminectomy A prolapsed intervertebral disc may impinge upon the meningeal (thecal) sac, cord, and most commonly the nerve root, producing symptoms attributable to that level. In some instances the disc protrusion will undergo a degree of involution that may allow symptoms to resolve without intervention. In some instances pain, loss of function, and failure to resolve may require surgery to remove the disc protrusion. It is of the utmost importance that the level of the disc protrusion is identified before surgery. This may require MRI scanning and on-table fluoroscopy to prevent operating on the wrong level. A midline approach to the right or to the left of the spinous processes will depend upon the most prominent site of the disc bulge. In some instances removal of the lamina will increase the potential space and may relieve symptoms. Some surgeons perform a small fenestration (windowing) within the ligamentum flavum. This provides access to the canal. The meningeal sac and its contents are gently retracted, exposing the nerve root and the offending disc. The disc is dissected free, removing its effect on the nerve root and the canal. Herniated Disc Degenerative Changes in the Discs with Age At birth, the nucleus pulposus is comprised of 70% - 88% water. As we age the water content progressively decreases (through dehydration as a consequence of the pressure exerted upon the discs) such that the discs lose turgidity and become thinner. The latter accounting for the apparent decrease in height as we age. The annulus fibrosus is also subject to degenerative changes. These changes, resulting from constant wear and tear, being fairly early in life (i.e., typically during the third decade). The changes lead to a weakening of the annulus making it more prone to rupturing. Herniated (Prolapsed) Disc In addition to the normal changes which occur with age, the discs are also subject to pathological changes as well as mechanical injuries. -This is actually a protrusion of the nucleus pulposus into, or through, the annulus fibrosus. -Intervertebral discs may protrude or rupture in any direction, but most common is a posterolateral direction, just lateral to the strong central portion of the posterior longitudinal ligament. This typically represents the weakest part of the disc, since the annulus is thinner here and is not supported by other ligaments. -Since spinal nerves pass over the posterolateral part of the disc, a protruded or ruptured disc often causes irritation of one or more of the nerve roots. For example, if in the lumbar region (which is typically where ruptured discs occur) it may result in sciatica with the accompanying leg pain and/or low-back pain. -May occur by attempting to lift too much weight and/or by lifting incorrectly. Spina Bifida Spina bifida is a developmental defect in the vertebral column in which there is an absence of the vertebral arches. Through this defect the spinal meninges, with or without spinal cord tissue, may protrude. Spina bifida Occulta is a defect of the vertebral arch which results from the failure of the development and fusion of the halves of the vertebral arch. Often, only one vertebra is affected and the spinal cord and spinal nerves are typically normal as is neurological function. Spina bifida occulta of the S1 is found in approximately 10% of the population and usually causes no serious physiological perturbations. The skin over the defect is intact and the only external evidence of the abnormality may be a dimple or a tuft of hair on the skin overlying the area. Spina Bifida Cystica Severe form of spina bifida that involves the herniation of the spinal cord and/or meninges through a defect in a number of vertebral arches. It is referred to as cystica because the protrusion is in the form of a cyst, or sac. SPINAL BIFIDA WITH MENINGOCELE: when the sac contains meninges and cerebrospinal fluid SPINAL BIFIDA WITH MENINGOMYELOCELE: If the spinal cord and/or spinal nerve roots are included in the sac Spina bifida cystica occurs approximately once in every 1000 births. Meningomyelocele is unfortunately more common and is a very much more severe malformation than meningocele in that there is usually a marked neurological deficit present. Lumbar Puncture Spinal puncture for the purpose of withdrawing fluid for diagnostic objectives or for the introduction of medication (e.g., antibiotics) or anesthesia is performed at a site below L2. The reason for this, of course, is that the spinal cord ends at or above L2 and thus injury to the spinal cord will be avoided since the subarachnoid space is still present. Typically, spinal puncture is performed at the level of L4 (which is why it is usually referred to as lumbar puncture) which can be located by drawing an imaginary line across the level of the highest points of the iliac crests. Structures and Spaces Pierced in Lumbar Puncture Performed at: LIV/LV level Surface landmarks used: iliac crests Which structures does the needle pass through to enter the subarachnoid space? (superficial to deep) Skin Superficial fascia Supraspinous ligament Interspinous ligament (interspinales mm.) Ligamentum flavum Epidural (extradural) space Dura Arachnoid Subarachnoid space Epidural Anesthesia Epidural anesthesia is a local anesthetic is injected near the spinal cord and nerve roots. It is infiltrated in the fat tissue that surrounds the spinal nerve roots in the epidural space using a catheter inserted in the space through an epidural needle. Epidural anesthesia can be used to supplement general anesthesia or as the main anesthesia in certain surgical procedures involving thoracic, abdominal, pelvic, or lower extremity regions. are used mainly for surgery of the lower belly and the legs. Epidural anesthesia is often used in childbirth. But it can also be used to help control pain after major surgery to the belly or chest. Performed at: can be performed at any level of the vertebral column and the choice of placement depends on the desired anesthetic level. Epidural space is reached by inserting an epidural needle between two vertebrae in the cervical, thoracic, or lumbar spine. Epidural anesthesia involves the insertion of a hollow needle and a small, flexible catheter into the space between the spinal column and outer membrane of the spinal cord (epidural space) in the middle or lower back. The area where the needle will be inserted is numbed with a local anesthetic. Then the needle is inserted and removed after the catheter has passed through it. The catheter remains in place. The anesthetic medicine is injected into the catheter to numb the body above and below the point of injection as needed. The catheter is secured on the back so it can be used again if more medicine is needed. Rhizotomy is a minimally invasive surgical procedure to remove sensation from a painful nerve by killing nerve fibers responsible for sending pain signals to the brain. The nerve fibers can be destroyed by severing them with a surgical instrument or burning them with a chemical or electrical current. In most cases, rhizotomy provides immediate pain relief that can last up to several years until the nerve recovers and is able to transmit pain again. Rhizotomy can also be called ablation or neurotomy — all of these terms describe removal or deadening of tissue. Rhizotomy can be used to address different types of pain and abnormal nerve activity, such as: Back and neck pain from arthritis, herniated discs, spinal stenosis and other degenerative spine conditions. The procedure for these issues is called facet rhizotomy, as it involves the nerves traveling through the facet joints of the spine. Trigeminal neuralgia--facial pain due to the irritation of the trigeminal nerve. Pain in joints, such as the hip and knee, resulting from arthritis. Other conditions affecting the peripheral nerves. Spasticity (abnormal muscle tightness and spasms). For spasticity caused by cerebral palsy, a procedure called selective dorsal rhizotomy can help improve communication between the spine and muscles. Spinal Stenosis A narrowing of the spaces within your spine, which can put pressure on the nerves that travel through the spine. Spinal stenosis occurs most often in the lower back and the neck. Some people with spinal stenosis may not have symptoms. Others may experience pain, tingling, numbness and muscle weakness. Symptoms can worsen over time. Spinal stenosis is most commonly caused by wearand-tear changes in the spine related to osteoarthritis. In severe cases of spinal stenosis, doctors may recommend surgery to create additional space for the spinal cord or nerves. Cervical stenosis: numbness or tingling in hand, arm/neck pain Lumbar stenosis: numbness or tingling in foot or leg/back pain