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Deep Learning Technology: Sebastian Arnold, Betty van Aken, Paul Grundmann, Felix A. Gers and Alexander Löser. Learning Contextualized Document Representations for Healthcare Answer Retrieval. The Web Conference 2020 (WWW'20)
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Umbilical cord compression may be relieved by the mother switching to another position. In persistent severe signs of fetal distress, Cesarean section may be needed.
The primary concern with umbilical cord prolapse is inadequate blood supply, and thus oxygen, to the fetus if the cord becomes compressed. The cord can become compressed either due to mechanical pressure (usually from the presenting fetal part) or from sudden contraction of the vessels due to decreased temperatures in the vagina in comparison to the uterus. This can lead to death of the fetus or other complications.
Historically, the rate of fetal death in the setting of cord prolapse has been as high 40%. However, these estimates occurred in the context of home or births outside of the hospital. When considering cord prolapses that have occurred in inpatient labor and delivery settings, the rate drops to as low as 0-3%, though the mortality rate remains higher than for fetuses without cord prolapse. The reduction in mortality for hospital births is likely due to the ready availability of immediate cesarean section.
Many other fetal outcomes have been studied, including Apgar score (a quick assessment of a newborn's health status) at 5 minutes and length of hospitalization after delivery. While both measures are worse for newborns delivered after cord prolapse, it is unclear what effect this has in the long-term. Relatively large studies that have tried to quantify long-term effects of cord prolapse on children found that less than 1% (1 in 120 studied) suffered a major neurologic handicap, and less than 1% (110 in 16,675) had diagnosed cerebral palsy.
Risk factors that are associated with umbilical cord prolapse tend to make it difficult for the fetus from appropriately engaging and filling the maternal pelvis or are related to abnormalities of the umbilical cord. The two major categories of risk factors are spontaneous and iatrogenic, or those that result from medical intervention.
- spontaneous factors:
- fetal malpresentation: abnormal fetal lie tends to result in space below the fetus in the maternal pelvis, which can then be occupied by the cord.
- polyhydramnios, or an abnormally high amount of amniotic fluid
- prematurity: likely related to increased chance of malpresentation and relative polyhydramnios.
- low birth weight: usually described as <2500 g at birth, though some studies will use <1500g. Cause is likely similar to those for prematurity.
- multiple gestation, or being pregnant with more than one fetus at a given time: more likely to occur in the fetus that is not born first.
- spontaneous rupture of membranes: about half of prolapses occur within 5 minutes of membrane rupture, two-thirds within 1 hour, 95% within 24 hours.
- iatrogenic factors
- artificial rupture of membranes
- placement of internal monitors (for example, internal scalp electrode or intrauterine pressure catheter)
- manual rotation of fetal head
On cardiotocography (CTG), umbilical cord compression can present with variable decelerations in fetal heart rate.
No set risk factors have been clearly defined for CES at this point in time. Individuals most at risk for disc herniation are the most likely to develop CES. Race has little influence with the notable exception that African Americans appear slightly less likely to develop CES than other groups; similarly, men are slightly more likely to develop CES than women. Middle age also appears to be a notable risk factor, as those populations are more likely to develop a herniated disc; heavy lifting can also be inferred as a risk factor for CES.
CES is often concurrent with congenital or degenerative diseases and represents a high cost of care to those admitted to the hospital for surgery. Hospital stays generally last 4 to 5 days, and cost an average of $100,000 to $150,000, unless the patient lives in a country where healthcare is free at the point of delivery.
A nuchal cord occurs when the umbilical cord becomes wrapped around the fetal neck 360 degrees. Nuchal cords are common, with prevalence rates of 6% to 37%. Up to half of nuchal cords resolve before delivery.
Retrospective data of over 182,000 births, with the statistical power to determine even mild associations, suggest that a single or multiple nuchal cords at the time of delivery is not associated with adverse perinatal outcomes, is associated with higher birthweights and fewer caesarean sections in births. Although some studies have found that a tight nuchal cord is associated with short term morbidity, it is unclear whether such outcomes are actually a result of the presence of the nuchal cord itself, or as a result of clamping and cutting the cord
Management of a presenting nuchal cord should be tailored to prevent umbilical cord compression whenever possible. Techniques to preserve an intact nuchal cord depend on how tightly the cord is wrapped around the infant’s neck. If the cord is loose, it can easily be slipped over the infant’s head. The infant can be delivered normally and placed on maternal abdomen as desired. If the cord is too tight to go over the infant’s head, the provider may be able to slip it over the infant’s shoulders and deliver the body through the cord. The cord can then be unwrapped from around the baby after birth. Finally, if the cord is too tight to slip back over the shoulders, one may use the somersault maneuver to allow the body to be delivered. The birth attendant may also choose to clamp and cut the umbilical cord to allow for vaginal delivery if other methods of nuchal cord management are not feasible.
About 16% of deliveries where shoulder dystocia occurs will have conventional risk factors.
There are well-recognized risk factors, such as diabetes, fetal macrosomia, and maternal obesity, but it is often difficult to predict, despite recognised risk factors. Despite appropriate obstetric management, fetal injury (such as brachial plexus injury) or even fetal death can be a complication of this obstetric emergency.
Risk factors:
- Age >35
- Short in stature
- Small or abnormal pelvis
- More than 42 weeks gestation
- Estimated fetal weight > 4500g
- Maternal diabetes (2-4 fold increase in risk)
Factors which increase the risk/are warning signs:
- the need for oxytocics
- a prolonged first or second stage of labour
- turtle sign
- head bobbing in the second stage
- failure to restitute
- No shoulder rotation or descent
- Instrumental delivery
Recurrence rates are relatively high (if you had shoulder dystocia in a previous delivery the risk is now 10% higher than in the general population).
Vehicle-related SCI is prevented with measures including societal and individual efforts to reduce driving under the influence of drugs or alcohol, distracted driving, and drowsy driving. Other efforts include increasing road safety (such as marking hazards and adding lighting) and vehicle safety, both to prevent accidents (such as routine maintenance and antilock brakes) and to mitigate the damage of crashes (such as head restraints, air bags, seat belts, and child safety seats). Falls can be prevented by making changes to the environment, such as nonslip materials and grab bars in bathtubs and showers, railings for stairs, child and safety gates for windows. Gun-related injuries can be prevented with conflict resolution training, gun safety education campaigns, and changes to the technology of guns (such as trigger locks) to improve their safety. Sports injuries can be prevented with changes to sports rules and equipment to increase safety, and education campaigns to reduce risky practices such as diving into water of unknown depth or head-first tackling in association football.
Spinal cord injuries are most often caused by physical trauma. Forces involved can be hyperflexion (forward movement of the head); hyperextension (backward movement); lateral stress (sideways movement); rotation (twisting of the head); compression (force along the axis of the spine downward from the head or upward from the pelvis); or distraction (pulling apart of the vertebrae). Traumatic SCI can result in contusion, compression, or stretch injury. It is a major risk of many types of vertebral fracture. Pre-existing asymptomatic congenital anomalies can cause major neurological deficits, such as hemiparesis, to result from otherwise minor trauma.
In the US, Motor vehicle accidents are the most common cause of SCIs; second are falls, then violence such as gunshot wounds, then sports injuries. In some countries falls are more common, even surpassing vehicle crashes as the leading cause of SCI. The rates of violence-related SCI depend heavily on place and time. Of all sports-related SCIs, shallow water dives are the most common cause; winter sports and water sports have been increasing as causes while association football and trampoline injuries have been declining. Hanging can cause injury to the cervical spine, as may occur in attempted suicide. Military conflicts are another cause, and when they occur they are associated with increased rates of SCI. Another potential cause of SCI is iatrogenic injury, caused by an improperly done medical procedure such as an injection into the spinal column.
SCI can also be of a nontraumatic origin. Nontraumatic lesions cause anywhere from 30 to 80% of all SCI; the percentage varies by locale, influenced by efforts to prevent trauma. Developed countries have higher percentages of SCI due to degenerative conditions and tumors than developing countries. In developed countries, the most common cause of nontraumatic SCI is degenerative diseases, followed by tumors; in many developing countries the leading cause is infection such as HIV and tuberculosis. SCI may occur in intervertebral disc disease, and spinal cord vascular disease. Spontaneous bleeding can occur within or outside of the protective membranes that line the cord, and intervertebral disks can herniate. Damage can result from dysfunction of the blood vessels, as in arteriovenous malformation, or when a blood clot becomes lodged in a blood vessel and cuts off blood supply to the cord. When systemic blood pressure drops, blood flow to the spinal cord may be reduced, potentially causing a loss of sensation and voluntary movement in the areas supplied by the affected level of the spinal cord. Congenital conditions and tumors that compress the cord can also cause SCI, as can vertebral spondylosis and ischemia. Multiple sclerosis is a disease that can damage the spinal cord, as can infectious or inflammatory conditions such as tuberculosis, herpes zoster or herpes simplex, meningitis, myelitis, and syphilis.
Certain maternal health issues can cause birth injuries. For example, gestational diabetes can cause premature birth, macrosomia, or stillbirth.
Dexamethasone (a potent glucocorticoid) in doses of 16 mg/day may reduce edema around the lesion and protect the cord from injury. It may be given orally or intravenously for this indication.
Surgery is indicated in localised compression as long as there is some hope of regaining function. It is also occasionally indicated in patients with little hope of regaining function but with uncontrolled pain. Postoperative radiation is delivered within 2–3 weeks of surgical decompression. Emergency radiation therapy (usually 20 Gray in 5 fractions, 30 Gray in 10 fractions or 8 Gray in 1 fraction) is the mainstay of treatment for malignant spinal cord compression. It is very effective as pain control and local disease control. Some tumours are highly sensitive to chemotherapy (e.g. lymphomas, small-cell lung cancer) and may be treated with chemotherapy alone.
Once complete paralysis has been present for more than about 24 hours before treatment, the chances of useful recovery are greatly diminished, although slow recovery, sometimes months after radiotherapy, is well recognised.
The median survival of patients with metastatic spinal cord compression is about 12 weeks, reflecting the generally advanced nature of the underlying malignant disease.
Complications such as placenta previa, placental abruption, anemia, and preeclampsia can limit the supply of oxygen and nutrients to the fetus, increasing the risk of birth defects. Severe cases may be fatal to the fetus.
The most common forms are cervical spinal stenosis, which are at the level of the neck, and lumbar spinal stenosis, at the level of the lower back. Thoracic spinal stenosis, at the level of the mid-back, is much less common.
In lumbar stenosis, the spinal nerve roots in the lower back are compressed which can lead to symptoms of sciatica (tingling, weakness, or numbness that radiates from the low back and into the buttocks and legs).
Cervical spinal stenosis can be far more dangerous by compressing the spinal cord. Cervical canal stenosis may lead to myelopathy, a serious conditions causing symptoms including major body weakness and paralysis. Such severe spinal stenosis symptoms are virtually absent in lumbar stenosis, however, as the spinal cord terminates at the top end of the adult lumbar spine, with only nerve roots (cauda equina) continuing further down. Cervical spinal stenosis is a condition involving narrowing of the spinal canal at the level of the neck. It is frequently due to chronic degeneration, but may also be congenital or traumatic. Treatment frequently is surgical.
Spinal stenosis is an abnormal narrowing of the spinal canal or neural foramen that results in pressure on the spinal cord or nerve roots. Symptoms may include pain, numbness, or weakness in the arms or legs. Symptoms are typically gradual in onset and improve with bending forwards. Severe symptoms may include loss of bladder control, loss of bowel control, or sexual dysfunction.
Causes may include osteoarthritis, rheumatoid arthritis, spinal tumors, trauma, Paget's disease of the bone, scoliosis, spondylolisthesis, and the genetic condition achondroplasia. It can be classified by the part of the spine affected into cervical, thoracic, and lumbar stenosis. Lumbar stenosis is the most common followed by cervical stenosis. Diagnosis is generally based on symptoms and medical imaging.
Treatment may involve medications, bracing, or surgery. Medications may include NSAIDs, acetaminophen, or steroid injections. Stretching and strengthening exercises may also be useful. Limiting certain activities may be recommended. Surgery is typically only done if other treatments are not affected, with the usual procedure being a decompressive laminectomy.
Spinal stenosis occurs in as many as 8% of people. It occurs most commonly in people over the age of 50. Males and females are affected equally commonly. The first modern description of the condition is from 1803 by Antoine Portal. Evidence of the condition, however, dates back to Ancient Egypt.
The prevalence of congenital Chiari I malformation, defined as tonsilar herniations of 3 to 5 mm or greater, was previously believed to be in the range of one per 1000 births, but is likely much higher. Women are three times more likely than men to have a congenital Chiari malformation. Type II malformations are more prevalent in people of Celtic descent. A study using upright MRI found cerebellar tonsillar ectopia in 23% of adults with headache from motor-vehicle-accident head trauma. Upright MRI was more than twice as sensitive as standard MRI, likely because gravity affects cerebellar position.
Cases of congenital Chiari malformation may be explained by evolutionary and genetic factors. Typically, an infant's brain weighs around 400g at birth and triples to 1100-1400g by age 11. At the same time the cranium triples in volume from 500 cm to 1500 cm to accommodate the growing brain. During human evolution, the skull underwent numerous changes to accommodate the growing brain. The evolutionary changes included increased size and shape of the skull, decreased basal angle and basicranial length. These modifications resulted in significant reduction of the size of the posterior fossa in modern humans. In normal adults, the posterior fossa comprises 27% of the total intracranial space, while in adults with Chiari Type I, it is only 21%. If a modern brain is paired with a less modern skull, the posterior fossa may be too small, so that the only place where the cerebellum can expand is the foramen magnum, leading to development of Chiari Type I. H. neanderthalensis had platycephalic (flattened) skull. Some cases of Chiari are associated with platybasia (flattening of the skull base).
The most widely accepted pathophysiological mechanism by which Chiari type I malformations occur is by a reduction or lack of development of the posterior fossa as a result of congenital or acquired disorders. Congenital causes include hydrocephalus, craniosynostosis (especially of the lambdoid suture), hyperostosis (such as craniometaphyseal dysplasia, osteopetrosis, erythroid hyperplasia), X-linked vitamin D-resistant rickets, and neurofibromatosis type I. Acquired disorders include space occupying lesions due to one of several potential causes ranging from brain tumors to hematomas.
Head trauma may cause cerebellar tonsillar ectopia, possibly because of dural strain. Additionally, ectopia may be present but asymptomatic until whiplash causes it to become symptomatic. Posterior fossa hypoplasia causes reduced cerebral and spinal compliance.
Vascular myelopathy (vascular disease of the spinal cord) refers to an abnormality of the spinal cord in regard to its blood supply. The blood supply is complicated and supplied by two major vessel groups: the posterior spinal arteries and the anterior spinal arteries—of which the Artery of Adamkiewicz is the largest. Both the posterior and anterior spinal arteries run the entire length of the spinal cord and receive anastomotic (conjoined) vessels in many places. The anterior spinal artery has a less efficient supply of blood and is therefore more susceptible to vascular disease. Whilst atherosclerosis of spinal arteries is rare, necrosis (death of tissue) in the anterior artery can be caused by disease in vessels originating from the segmental arteries such as atheroma (arterial wall swelling) or aortic dissection (a tear in the aorta).
Anterior spinal artery syndrome is necrosis of tissue in the anterior spinal artery or its branches. It is characterised by pain which radiates at onset and sudden quadraplegia (paralysis of all four limbs) or paraplegia (paralysis of the lower body). Within days, flaccid limbs become spastic and hyporeflexia (underactive nerve responses) turns into hyperreflexia (overactive nerve responses) and extensor plantar nerve responses. Sensory loss to pain and temperature also occurs up to the level of damage on the spinal cord, as damage to different areas will affect different parts of the body.
In diagnosis, other causes of abrupt paralysis should be excluded such as cord compression, transverse myelitis (inflammation of the spinal cord) and Guillain–Barré syndrome. A specific cause of the infarction should be looked for, such as diabetes, polyarteritis nodosa (inflammatory damage of vessels) or systemic lupus erythematosus. Neurosyphilis is also a known cause. Other causes include:
Treatment is supportive and aims to relieve symptoms. The prognosis is dependent upon individual circumstances and factors.
Cervical spinal stenosis is a bone disease involving the narrowing of the spinal canal at the level of the neck. It is frequently due to chronic degeneration, but may also be congenital. Treatment is frequently surgical.
Cervical spinal stenosis is one of the most common forms of spinal stenosis, along with lumbar spinal stenosis (which occurs at the level of the lower back instead of in the neck). Thoracic spinal stenosis, at the level of the mid-back, is much less common. Cervical spinal stenosis can be far more dangerous by compressing the spinal cord. Cervical canal stenosis may lead to serious symptoms such as major body weakness and paralysis. Such severe spinal stenosis symptoms are virtually absent in lumbar stenosis, however, as the spinal cord terminates at the top end of the adult lumbar spine, with only nerve roots (cauda equina) continuing further down. Cervical spinal stenosis is a condition involving narrowing of the spinal canal at the level of the neck. It is frequently due to chronic degeneration, but may also be congenital or traumatic. Treatment frequently is surgical.
The most common way the disorder occurs is from a result of hemorrhaging (bleeding within) or inadequate blood supply to the spinal cord, making it weak and susceptible to damage.
Because myelomalacia involves a damaged spinal cord, it may occur in any individual. Those most at risk are the geriatric population due to weaker bone density. Once the spinal injury has occurred, one of two things may happen. Firstly, hemorrhaging within the spinal cord may cause compression, which damages the spinal cord even further. Another consequence of myelomalacia is improper circulation of blood to the area damaged, resulting in further damage to the spinal cord.
Due to extensive physical contact and activity, many athletes become victim to myelomalacia. Any accidents or injuries attained during athletic competition to the spinal cord may result in myelomalacia. Accounts of awkward landing on the ground or being hit intensively have attested to spinal cord injury.
Although the definition is imprecise, it occurs in approximately 0.3-1% of vaginal births.
Potential non-surgical treatments include:
- Education about the course of the condition and how to relieve symptoms
- Medicines to relieve pain and inflammation, such as acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs)
- Exercise, to maintain or achieve overall good health, aerobic exercise, such as riding a stationary bicycle, which allows for a forward lean, walking, or swimming can relieve symptoms
- Weight loss, to relieve symptoms and slow progression of the stenosis
- Physical therapy, to provide education, instruction, and support for self-care; physical therapy instructs on stretching and strength exercises that may lead to a decrease in pain and other symptoms