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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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Criteria for CSF abnormalities:
- Increased opening pressure (> 200mm of H2O)
- Increased Leukocytes (>4/mm3)
- Elevated protein (>50 mg/dL)
- Decreased glucose (<60 mg/dL)
Tumor Markers:
- Carcinoembryonic antigin (CEA)
- alpha-fetoprotein
- beta-human chorionic gonadotropin
- carbohydrate antigen19-9
- creatine-kinase BB
- isoenzyme
- tissue polypeptide antigen
- beta2-microglobulin,
- beta-glucoronidase
- lactate dehydrogenase isoenzyme-5
- vascular endothelial growth factor
These markers can be good indirect indicator of NM but most are not sensitive enough to improve cytogical diagnosis.
Avoiding false-negative
- Draw CSF from symptomatic or radiographically demonstrated disease.
- Draw large amount of CSF (>10.5mL).
- Don't delay processing of specimen.
- Obtain at least 2 samples. The first sample has diagnostic sensitivity of 54% but with repeated sampling, diagnostic sensitivity is increased to 91%.
Ideal procedure for diagnosis:
Lumbar puntures --> cranial MRI --> spinal MRI --> radioisotope CSF flow --> ventricular or lateral cervical spine CSF analysis (if previous step yields no definitive answer)
The diagnosis of primary spinal cord tumors is difficult, mainly due to their symptoms, which in early stages mimic more common and benign degenerative spinal diseases. MRI and bone scanning are used for diagnostic purposes. This assesses not only the location of the tumor(s) but also their relationship with the spinal cord and the risk of cord compression.
The diagnosis of NM is based on the detection of malignant cells in the CSF, the demonstration of leptomeningeal tumor cell deposits on neuroimaging, or both. CSF examination is the most useful diagnostic tool for NM. Patients with suspected NM should undergo one or two lumbar punctures, cranial magnetic resonance imaging (MRI), spinal MRI, and a radioisotope CSF flow study to rule out sites of CSF block. If the cytology remains negative and radiological studies are not definitive, consideration may be given to ventricular or lateral cervical spine CSF analysis based on the suspected site of predominant disease. Consideration of signs, symptoms, and neuroimaging can help with the placement to where CSF is drawn. Median time of diagnosis from initial primary cancer diagnosis is between 76 days and 17 months. NM diagnosis has been increasing and will continue to increase due to better primary care and longer survival time of cancer patients.
Difficulties in Diagonsis:
NM is multifocal and CSF at a particular site may show no abnormalities if the pathological site is far away. Only 50% of those suspected with NM are actually diagnosed with NM and only the presence of malignant cells in the CSF is diagnosis conclusive.
Techniques:
- MRI: Meningeal findings are described with the following characteristics: Nodular meningeal tumor, meningeal thickening >3 mm and a subjectively strong contrast enhancement. A smooth contrast enhancement of the meninges was judged to be typical for inflammatory, nonneoplastic meningitis.
- CSF cytology: is performed after drawing the CSF by lumbar puncture.
- Cytogenetic: measures chromosomal content of cells and fluorescence in situ hybridization which detects numerical and structural genetic aberrations as a sign of malignancy. This is especially useful for liquid tumors such as leukemia and lymphoma. Some of the techniques that achieve this are flow cytometry and DNA single-cell cytometry. However, cytogenetic only assist in diagnosis and is less preferred.
- Meningeal Biopsy: may be performed when all of the above criteria is inconclusive. Biopsy is only effective when performed at the region where there's enhancement on the MRI.
Ganglioneuromas can be diagnosed visually by a CT scan, MRI scan, or an ultrasound of the head, abdomen, or pelvis. Blood and urine tests may be done to determine if the tumor is secreting hormones or other circulating chemicals. A biopsy of the tumor may be required to confirm the diagnosis.
Computed Tomography (CT) is generally not a recommended modality for diagnosis and evaluation of spinal cord tumors. Evaluation with Magnetic Resonance (MR) most commonly demonstrates a circumscribed solid or mixed solid and cystic mass spanning a long segment of the cord with hypointense T1 signal and hyperintense T2 signal in the solid component. Enhancement patterns are highly variable, ranging from minimal to marked, and may be solid, rim, or nodular. Adjacent cord edema and syringomyelia and peritumoral cysts may be present in addition to reactive scoliosis.
It is nearly impossible to differentiate ganglioglioma from other more common intramedullary neoplasms based on imaging alone. Astrocytoma and ependymoma are more familiar intramedullary tumors which share many similar features to ganglioglioma, including T2 hyperintensity, enhancement, tumoral cysts, and cord edema. Poorly defined margins may be more suggestive of astrocytoma, while a central location in the spinal cord, hemorrhage, and hemosiderin staining are often seen with ependymoma. Hemangioblastoma and paraganglioma are less usual intramedullary tumors, but since they are more frequently encountered than ganglioglioma, they should also be included in the differential diagnosis.
Because ganglioneuromas are benign, treatment may not be necessary, as it would expose patients to more risk than leaving it alone. If there are symptoms or major physical deformity, treatment usually consists of surgery to remove the tumor.
Pain is the most common symptom at presentation. The symptoms seen are due to spinal nerve compression and weakening of the vertebral structure. Incontinence and decreased sensitivity in the "saddle area" (buttocks) are generally considered warning signs of spinal cord compression by the tumor. Other symptoms of spinal cord compression include lower extremity weakness, sensory loss, numbness in hands and legs and rapid onset paralysis. The diagnosis of primary spinal cord tumors is very difficult, mainly due to its symptoms, which tend to be wrongly attributed to more common and benign degenerative spinal diseases.
Spinal cord compression is commonly found in patients with metastatic malignancy. Back pain is a primary symptom of spinal cord compression in patients with known malignancy. It may prompt a bone scan to confirm or exclude spinal metastasis. Rapid identification and intervention of malignant spinal tumors, often causing spinal cord compression, is key to maintaining quality of life in patients.
Diagnosis is by X-rays but preferably magnetic resonance imaging (MRI) of the whole spine. The most common causes of cord compression are tumors, but abscesses and granulomas (e.g. in tuberculosis) are equally capable of producing the syndrome. Tumors that commonly cause cord compression are lung cancer (non-small cell type), breast cancer, prostate cancer, renal cell carcinoma, thyroid cancer, lymphoma and multiple myeloma.
Physicians now use magnetic resonance imaging (MRI) to diagnose syringomyelia. The MRI radiographer takes images of body anatomy, such as the brain and spinal cord, in vivid detail. This test will show the syrinx in the spine or any other conditions, such as the presence of a tumor. MRI is safe, painless, and informative and has greatly improved the diagnosis of syringomyelia.
The physician may order additional tests to help confirm the diagnosis. One of these is called electromyography (EMG), which show possible lower motor neuron damage. In addition, computed axial tomography (CT) scans of a patient's head may reveal the presence of tumors and other abnormalities such as hydrocephalus.
Like MRI and CT scans, another test, called a myelogram, uses radiographs and requires a contrast medium to be injected into the subarachnoid space. Since the introduction of MRI this test is rarely necessary to diagnose syringomyelia.
The possible causes are trauma, tumors and congenital defects. It is most usually observed in the part of the spinal cord corresponding to the neck area. Symptoms are due to spinal cord damage and are: pain, decreased sensation of touch, weakness and loss of muscle tissue. The diagnosis is confirmed with a spinal CT, myelogram or MRI of the spinal cord. The cavity may be reduced by surgical decompression.
Furthermore, evidence also suggests that impact injuries to the thorax area highly correlate with the occurrence of a cervical-located syrinx.
Definitive treatment for ganglioglioma requires gross total surgical resection, and a good prognosis is generally expected when this is achieved. However, indistinct tumor margins and the desire to preserve normal spinal cord tissue, motor and sensory function may preclude complete resection of tumor. According to a series by Lang et al., reviewing several patients with resected spinal cord ganglioglioma, the 5- and 10-year survival rates after total resection were 89% and 83%, respectively. In that study, patients with spinal cord ganglioglioma had a 3.5-fold higher relative risk of tumor recurrence compared to patients with supratentorial ganglioglioma. It has been recognized that postoperative results correlate closely with preoperative neurological status as well as the ability to achieve complete resection.
With the exception of WHO grade III anaplastic ganglioglioma, radiation therapy is generally regarded to have no role in the treatment of ganglioglioma. In fact, radiation therapy may induce malignant transformation of a recurrent ganglioglioma several years later. Adjuvant chemotherapy is also typically reserved for anaplastic ganglioglioma, but has been used anecdotally in partially resected low grade spinal cord gangliogliomas which show evidence of disease progression.
MRI has become the most frequently used study to diagnose spinal stenosis. The MRI uses electromagnetic signals to produce images of the spine. MRIs are helpful because they show more structures, including nerves, muscles, and ligaments, than seen on x-rays or CT scans. MRIs are helpful at showing exactly what is causing spinal nerve compression.
A spinal tap is performed in the low back with dye injected into the spinal fluid. X-Rays are performed followed by a CT scan of the spine to help see narrowing of the spinal canal.
This is a very effective study in cases of lateral recess stenosis. It is also necessary for patients in which MRI is contraindicated, such as those with implanted pacemakers.
For children younger than eight weeks of age (and possibly in utero), a tethered cord may be observed using ultrasonography. Ultrasonography may still be useful through age 5 in limited circumstances.
MRI imaging appears to be the gold standard for diagnosing a tethered cord.
A tethered cord is often diagnosed as a "low conus." The conus medullaris (or lower termination of the spinal cord) normally terminates at or above the L1-2 disk space (where L1 is the first, or topmost lumbar vertebra). After about 3 months of age, a conus below the L1-2 disk space may indicate a tethered cord and termination below L3-4 is unmistakably tethered. "Cord tethering is often assumed when the conus is below the normal L2-3 level.
TCS, however, is a clinical diagnosis that should be based on "neurological and musculoskeletal signs and symptoms. Imaging features are in general obtained to support rather than make the diagnosis." Clinical evaluation may include a simple rectal examination and may also include invasive or non-invasive urological examination. "Bladder dysfunction occurs in ~40% of patients affected by tethered cord syndrome. ... [I]t may be the earliest sign of the syndrome."
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.
A doctor will base his or her diagnosis on the symptoms the patient has and the results of tests, including:
- An X-ray
- Magnetic resonance imaging (MRI), which usually provides the most information
- Computed tomography (CT) scan
The precise causes of syringomyelia are still unknown although blockage to the flow of cerebrospinal fluid has been known to be an important factor since the 1970s. Scientists in the UK and America continue to explore the mechanisms that lead to the formation of syrinxes in the spinal cord. It has been demonstrated a block to the free flow of cerebrospinal fluid is a contributory factor in the pathogenesis of the disease. Duke University in America and Warwick University are conducting research to explore genetic features of syringomyelia.
Surgical techniques are also being refined by the neurosurgical research community. Successful procedures expand the area around the cerebellum and spinal cord, thus improving the flow of cerebrospinal fluid thereby reducing the syrinx.
It is also important to understand the role of birth defects in the development of hindbrain malformations that can lead to syringomyelia as syringomyelia is a feature of intrauterine life and is also associated with spina bifida. Learning when these defects occur during the development of the fetus can help us understand this and similar disorders, and may lead to preventive treatment that can stop the formation of some birth abnormalities. Dietary supplements of folic acid prior to pregnancy have been found to reduce the number of cases of spina bifida and are also implicated in prevention of cleft palate and some cardiac defects.
Diagnostic technology is another area for continued research. MRI has enabled scientists to see conditions in the spine, including syringomyelia before symptoms appear. A new technology, known as dynamic MRI, allows investigators to view spinal fluid flow within the syrinx. CT scans allow physicians to see abnormalities in the brain, and other diagnostic tests have also improved greatly with the availability of new, non-toxic, contrast dyes.
Adult presentation in diastematomyelia is unusual. With modern imaging techniques, various types of spinal dysraphism are being diagnosed in adults with increasing frequency. The commonest location of the lesion is at first to third lumbar vertebrae. Lumbosacral adult diastematomyelia is even rarer. Bony malformations and dysplasias are generally recognized on plain x-rays. MRI scanning is often the first choice of screening and diagnosis. MRI generally give adequate analysis of the spinal cord deformities although it has some limitations in giving detailed bone anatomy. Combined myelographic and post-myelographic CT scan is the most effective diagnostic tool in demonstrating the detailed bone, intradural and extradural pathological anatomy of the affected and adjacent spinal canal levels and of the bony spur.
Prenatal ultrasound diagnosis of this anomaly is usually possible in the early to mid third-trimester. An extra posterior echogenic focus between the fetal spinal laminae is seen with splaying of the posterior elements, thus allowing for early surgical intervention and have a favorable prognosis. Prenate ultrasound could also detect whether the diastematomyelia is isolated, with the skin intact or association with any serious neural tube defects. Progressive neurological lesions may result from the "tethering cord syndrome" (fixation of the spinal cord) by the diastematomyelia phenomenon or any of the associated disorders such as myelodysplasia, dysraphia of the spinal cord.
The disorder progresses with age, but the aforementioned treatments can help prevent or sometimes relieve symptoms. With treatment, individuals with tethered spinal cord syndrome have a normal life expectancy. However, most neurological and motor impairments are irreversible.
Surgery
Surgical intervention is warranted in patients who present with new onset neurological signs and symptoms or have a history of progressive neurological manifestations which can be related to this abnormality. The surgical procedure required for the effective treatment of diastematomyelia includes decompression (surgery) of neural elements and removal of bony spur. This may be accomplished with or without resection and repair of the duplicated dural sacs. Resection and repair of the duplicated dural sacs is preferred since the dural abnormality may partly contribute to the "tethering" process responsible for the symptoms of this condition.
Post-myelographic CT scanning provides individualized detailed maps that enable surgical treatment of cervical diastematomyelia, first performed in 1983.
Observation
Asymptomatic patients do not require surgical treatment. These patients should have regular neurological examinations since it is known that the condition can deteriorate. If any progression is identified, then a resection should be performed.
A CT scan can detect bone metastases before becoming symptomatic in patients diagnosed with tumors with risk of spread to the bones. Even sclerotic bone metastases are generally less radiodense than enostoses, and it has been suggested that bone metastasis should be the favored diagnosis between the two for bone lesions lower than a cutoff of 1060 Hounsfield units (HU).
If there aren't neurological symptoms (such as difficulties moving, loss of sensation, confusion, etc.) and there is no evidence of pressure on the spinal cord, a conservative approach may be taken such as:
- Drugs, such as aspirin, without steroids to relieve inflammation
- Cervical traction, in which the neck is pulled along its length, thus relieving pressure on the spinal cord
- Using a neck collar or cervical-thoracic suit
If there is pressure on the spinal cord or life-threatening symptoms are present, surgery is recommended.
Whole spine MR imaging may be used to evaluate the extent of syrinx formation (fluid filled cavity within the spinal cord) in CM dogs, developing a thermal camera-based screening test for the disorder and a method of measuring the actual syrinx volume from MR images.
Before the introduction of MRI, the diagnosis of CM and SM were commonly confused with that of allergic skin disorders, disk disease, ear infections and epilepsy. After CM was reported in human patients, the initial research was provided for the diagnosis of animals. MRI in animals is safe, however, to ensure that the patient remains motionless, light general anesthesia is required.
According to recent studies, thermography may be a useful tool in the diagnosis of CM and SM. Thermography requires no sedation or clipping of hair for a dog to be imaged by the infrared camera. After the image is captured, computer software is used to assess changes in the temperature and color pattern to detect abnormality.
Myelopathy is primarily diagnosed by clinical exam findings. Because the term "myelopathy" describes a clinical syndrome that can be caused by many pathologies the differential diagnosis of myelopathy is extensive. In some cases the onset of myelopathy is rapid, in others, such as CSM, the course may be insidious with symptoms developing slowly over a period of months. As a consequence, the diagnosis of CSM is often delayed. As the disease is thought to be progressive, this may impact negatively on outcome.
Once the clinical diagnosis "myelopathy" has been established, the underlying cause needs to be investigated. Most commonly this involves the use of medical imaging techniques. The best way of visualising the spinal cord is Magnetic Resonance Imaging (MRI). Apart from T1 and T2 MRI images, which are commonly used for routine diagnosis, more recently the use quantitative MRI signals is being investigated. Further imaging modalities used for evaluating myelopathy include plain X-rays for detecting arthritic changes of the bones, and Computer Tomography, which is often used for pre-operative planning of surgical interventions for cervical spondylotic myelopathy. Angiography is used to examine blood vessels in suspected cases of vascular myelopathy.
The presence and severity of myelopathy can also be evaluated by means of Transcranial Magnetic Stimulation (TMS), a neurophysiological method that allows the measurement of the time required for a neural impulse to cross the pyramidal tracts, starting from the cerebral cortex and ending at the anterior horn cells of the cervical, thoracic or lumbar spinal cord. This measurement is called "Central Conduction Time" ("CCT"). TMS can aid physicians to:
- determine whether myelopathy exists
- identify the level of the spinal cord where myelopathy is located. This is especially useful in cases where more than two lesions may be responsible for the clinical symptoms and signs, such as in patients with two or more cervical disc hernias
- follow-up the progression of myelopathy in time, for example before and after cervical spine surgery
TMS can also help in the differential diagnosis of different causes of pyramidal tract damage.
Wobblers is definitively diagnosed by x-ray, nuclear scintography or bone scan. X-rays will show channel widening or filling the easiest and are often most cost effective to horse owners. X-rays will also show any structural anomaly, arthritis, facet remodeling, or bone spurs present. Preliminary diagnosis can be made by ultrasound but x-rays are needed to measure the true depth of facet involvement. For extent of damage to associated structures, veterinarians may opt to have the horse undergo a bone scan or nuclear scintography.
There are two tests that can provide a definite diagnosis of myelomalacia; magnetic resonance imaging (MRI), or myelography. Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to visualize the internal structure of the body used in the diagnosing of myelomalacia. Certain MRI findings can detect where bone density and matter has been lost in people with spinal cord injuries. Diffuse hyperintensity appreciated on T2-weighted imaging of the spinal cord can be an indication of the onset or progression of myelomalacia