Spondylolisthesis
Spondylolisthesis is the displacement of one spinal vertebra compared to another. While some medical dictionaries define spondylolisthesis specifically as the forward or anterior displacement of a vertebra over the vertebra inferior to it (or the sacrum), it is often defined in medical textbooks as displacement in any direction. Spondylolisthesis is graded based upon the degree of slippage of one vertebral body relative to the subsequent adjacent vertebral body. Spondylolisthesis is classified as one of the six major etiologies: degenerative, traumatic, dysplastic, , pathologic, or post-surgical. Spondylolisthesis most commonly occurs in the lumbar spine, primarily at the L5-S1 level  with the L5 vertebral body anteriorly translating over the S1 vertebral body. Types. Olisthesis (synonym olisthy) is a term that more explicitly denotes displacement in any direction. Forward or anterior displacement can specifically be called anterolisthesis. Anterolisthesis commonly involves the fifth lumbar vertebra. Backward displacement is called retrolisthesis. Lateral displacement is called lateral listhesis or laterolisthesis. A "hangman's fracture" is a specific type of spondylolisthesis where the second cervical vertebra (C2) is displaced anteriorly relative to the C3 vertebra due to fractures of the C2 vertebra's pedicles. Anterolisthesis. Classification. Anterolisthesis can be categorized by cause, location and severity . By location. Anterolisthesis location includes which vertebrae are involved, and may also specify which parts of the vertebrae are affected. "Isthmic" anterolisthesis is where there is a defect in the pars interarticularis. It is the most common form of spondylolisthesis; also called spondylolytic spondylolisthesis, it occurs with a reported prevalence of 5–7 percent in the US population. A slip or fracture of the intravertebral joint is usually acquired between the ages of 6 and 16 years, but remains unnoticed until adulthood. Roughly 90 percent of these isthmic slips are low-grade (less than 50 percent slip) and 10 percent are  high-grade (greater than 50 percent slip). It is divided into three subtypes: Severity. Classification by degree of the slippage, as measured as percentage of the width of the vertebral body: Grade I spondylolisthesis accounts for approximately 75% of all cases. Signs and symptoms. Symptoms of lumbar anterolisthesis include: Other symptoms may include tingling and numbness. Coughing and sneezing can intensify the pain. An individual may also note a "slipping sensation" when moving into an upright position. Sitting and trying to stand up may be painful and difficult. Physical Exam. The major components of the physical exam for spondylolisthesis consists  of observation, palpation, and maneuvers. The most common finding is pain with lumbar extension. The following physical involves specific assessment for spondylolisthesis. However, a general examination, most importantly neurological examination, must be done to rule out alternative causes for signs and symptoms. Neurological examination is often normal in patients with spondylolisthesis, but lumbosacral radiculopathy is commonly seen in patients with degenerate spondylolisthesis. Observation. The patient should be observed walking and standing. Most patients present with a normal gait. An abnormal gait is often the sign of a high grade case. A patient with high grade spondylolisthesis may present with a  posterior pelvic tilt causing a loss in the normal contour of the buttocks. An antalgic gait, rounded back and decreased hip extension, can result from severe pain. While standing, the patient should be observed from the front, back, and sides. Increased and decreased lumbar lordosis, inward curvature of the lower spine, has been seen. Palpation. Detection of spondylolisthesis by palpation is most often done by palpating for the spinous process. Each level of the lumbar spine should be palpated. Spinous process palpation by itself is not a definitive method for the detection of spondylolisthesis. Diagnostic Imaging. In adults with non -specific low back pain, strong evidence suggests medical imaging should not be done within the first six weeks. It is also suggested to avoid advanced imaging, such as CT or MRI, for adults without neurological symptoms or "red flags" in the patient's history. General recommendations for initial low back pain treatment is remaining active, avoiding twisting and bending, avoiding activities that worsen pain, avoiding bed rest, and possibly initiating a trial of non-steroidal anti-inflammatory drugs after consulting a physician. Children and adolescents with persistent low back pain may require earlier imaging and should be seen by physician . Once imaging is deemed necessary, a combination of plain radiography, computed tomography, and magnetic resonance imaging may be used. Images are most often taken of the lumbar spine due to spondylolisthesis most commonly involving the lumbar region. Images of the thoracic spine can be taken if a patient's history and physical suggest thoracic involvement. Plain Radiography (X-Ray). Plain radiography is often the first step in medical imaging. Anteroposterior (front-back) and lateral (side) images are used to allow the physician to view the spine at multiple angles. Oblique view are no longer recommended. In evaluating for spondylolithesis, plain  radiographs provide information on the positioning and structural integrity of the spine. Therefore, if further detail is needed a physician may request advanced imaging. Magnetic Resonance Imaging (MRI). Magnetic resonance imaging is the preferred advanced imaging technique for evaluation of spondylolisthesis. Preference is due to effectiveness, lack of radiation exposure, and ability to evaluate for soft tissue abnormalities and spinal canal involvement. MRI is limited in its ability to evaluate fractures in great detail, compared to other advanced imaging modalities. Computed Tomography (CT). Computed tomography can be helpful in evaluating bony vertebral abnormalities, such as fractures. This can be helpful  in determining if the fracture is a new, old, and/or progressing fracture. CT use in spondylolisthesis evaluation is controversial due to high radiation exposure. Treatment. Spondylolisthesis patients without symptoms do not need to be treated. Conservative. Non-operative management, also referred to as conservative treatment, is the recommended treatment for spondylolisthesis in most cases with or without neurological symptoms. Most patients with spondylolisthesis respond to conservative treatment. Conservative treatment consists primarily of physical therapy, intermittent bracing, aerobic exercise, pharmacological intervention, and epidural steroid injections. The majority of patients with degenerative spondylolisthesis do not require surgical intervention. Surgical. There are no  clear radiological or medical guidelines or indications for surgical interventions in degenerative spondylolisthesis. A minimum of three months of conservative management should be completed prior to considering surgical intervention. Three indications for potential surgical treatment are as follows: persistent or recurrent back pain or neurologic pain with a persistent reduction of quality of life despite a reasonable trial of conservative (non-operative) management, new or worsening bladder or bowel symptoms, or a new or worsening neurological deficit. Both minimally invasive and open surgical techniques are used to treat anterolisthesis. Retrolisthesis. A retrolisthesis is a posterior displacement of one vertebral body  with respect to the subjacent vertebra to a degree less than a luxation (dislocation). Retrolistheses are most easily diagnosed on lateral x-ray views of the spine. Views, where care has been taken to expose for a true lateral view without any rotation, offer the best diagnostic quality. Retrolistheses are found most prominently in the cervical and lumbar region, but can also be seen in the thoracic area. History. Spondylolisthesis was first described in 1782 by Belgian obstetrician Herbinaux. He reported a bony prominence anterior to the sacrum that obstructed the vagina of a small number of patients. The term  “spondylolisthesis” was coined in 1854 from the Greek σπονδυλος, "spondylos" = "vertebra" and ὀλίσθησης "olisthesis" = "slipping, sliding,"