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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)
Funded by The Federal Ministry for Economic Affairs and Energy; Grant: 01MD19013D, Smart-MD Project, Digital Technologies
At present, Nemaline myopathy does not have a cure. Nemaline myopathy is a very rare disease that only effects 1 out of 50,000 on average, although recent studies show that this number is even smaller. There are a number of treatments to minimize the symptoms of the disease. The treatments and procedures to help patients with nemaline myopathy vary depending on the severity of the disease. A possible accommodation could be the use of a stabilizer, such as a brace. Other means include moderate stretching and moderate exercise to help target muscles maintain maximum health.
As people with NM grow and develop throughout their lives, it is important for them to see a variety of health professionals regularly, including a neurologist, physical therapist, and others, such as speech therapists and psychologists, to help both the patient and family adjust to everyday life.
New research resources have become available for the NM community, such as the CMDIR (registry) and the CMD-TR (biorepository). These two resources connect families and individuals interested in participating in research with the scientists that aim to treat or cure NM. Some research on NM seeks to better understand the molecular effects the gene mutations have on muscle cells and the rest of the body and to observe any connections NM may have to other diseases and health complications.
The importance of correctly recognizing progressive muscular atrophy as opposed to ALS is important for several reasons.
- 1) the prognosis is a little better. A recent study found the 5-year survival rate in PMA to be 33% (vs 20% in ALS) and the 10-year survival rate to be 12% (vs 6% in ALS).
- 2) Patients with PMA do not suffer from the cognitive change identified in certain groups of patients with MND.
- 3) Because PMA patients do not have UMN signs, they usually do not meet the "World Federation of Neurology El Escorial Research Criteria" for “Definite” or “Probable” ALS and so are ineligible to participate in the majority of clinical research trials such as drugs trials or brain scans.
- 4) Because of its rarity (even compared to ALS) and confusion about the condition, some insurance policies or local healthcare policies may not recognize PMA as being the life-changing illness that it is. In cases where being classified as being PMA rather than ALS is likely to restrict access to services, it may be preferable to be diagnosed as "slowly progressive ALS" or "lower motor neuron predominant" ALS.
An initial diagnosis of PMA could turn out to be slowly progressive ALS many years later, sometimes even decades after the initial diagnosis. The occurrence of upper motor neurone symptoms such as brisk reflexes, spasticity, or a Babinski sign would indicate a progression to ALS; the correct diagnosis is also occasionally made on autopsy.
PMA is a diagnosis of exclusion, there is no specific test which can conclusively establish whether a patient has the condition. Instead, a number of other possibilities have to be ruled out, such as multifocal motor neuropathy or spinal muscular atrophy. Tests used in the diagnostic process include MRI, clinical examination, and EMG. EMG tests in patients who do have PMA usually show denervation (neurone death) in most affected body parts, and in some unaffected parts too.
It typically takes longer to be diagnosed with PMA than ALS, an average of 20 months for PMA vs 15 months in ALS/MND.
Diabetic peripheral neuropathy is the most likely diagnosis for someone with diabetes who has pain in a leg or foot, although it may also be caused by vitamin B deficiency or osteoarthritis. A 2010 review in the Journal of the American Medical Association's "Rational Clinical Examination Series" evaluated the usefulness of the clinical examination in diagnosing diabetic peripheral neuropathy. While the physician typically assesses the appearance of the feet, presence of ulceration, and ankle reflexes, the most useful physical examination findings for large fiber neuropathy are an abnormally decreased vibration perception to a 128-Hz tuning fork (likelihood ratio (LR) range, 16–35) or pressure sensation with a 5.07 Semmes-Weinstein monofilament (LR range, 11–16). Normal results on vibration testing (LR range, 0.33–0.51) or monofilament (LR range, 0.09–0.54) make large fiber peripheral neuropathy from diabetes less likely. Combinations of signs do not perform better than these 2 individual findings. Nerve conduction tests may show reduced functioning of the peripheral nerves, but seldom correlate with the severity of diabetic peripheral neuropathy and are not appropriate as routine tests for the condition.
Diabetic neuropathy encompasses a series of different neuropathic syndromes which can be schematized in the following way:
- Focal and multifocal neuropathies:
- Mononeuropathy
- Amyotrophy, radiculopathy
- Multiple lesions "mononeuritis multiplex"
- Entrapment (e.g. median, ulnar, peroneal)
- Symmetrical neuropathies:
- Acute sensory
- Autonomic
- Distal symmetrical polyneuropathy (DSPN), the diabetic type of which is also known as diabetic peripheral neuropathy (DPN) (most common presentation)
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.
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)
As of June 2014 (the latest update on HFM in GeneReviews) a total of 32 families had been reported with a clinical diagnosis of HFM of which there was genotypic confirmation in 24 families. Since then, another two confirmed cases have been reported and an additional case was reported based on a clinical diagnosis alone. Most cases emerge from consanguineous parents with homozygous mutations. There are three instances of HFM from non-consanguineous parents in which there were heterozygous mutations. HFM cases are worldwide with mostly private mutations. However, a number of families of Puerto Rican ancestry have been reported with a common pathogenic variant at a splice receptor site resulting in the deletion of exon 3 and the absence of transport function. A subsequent population-based study of newborn infants in Puerto Rico identified the presence of the same variant on the island. Most of the pathogenic variants result in a complete loss of the PCFT protein or point mutations that result in the complete loss of function. However, residual function can be detected with some of the point mutants.
HFM must be distinguished from cerebral folate deficiency (CFD)– a condition in which there is normal intestinal folate absorption, without systemic folate deficiency, but a decrease in CSF folate levels. This can accompany a variety of disorders. One form of CFD is due to loss-of-mutations in folate receptor-α, (FRα), which transports folates via an endocytic process. While PCFT is expressed primarily at the basolateral membrane of the choroid plexus, FRα, is expressed primarily at the apical brush-border membrane. Unlike subjects with HFM, patients with CFD present with neurological signs a few years after birth. The basis for the delay in the appearance of clinical manifestations due to loss of FRα function is not clear; the normal blood folate levels may be protective, although for a limited time.
Most patients with thin basement membrane disease need only reassurance. Indeed, this disease was previously referred to as "benign familial hematuria" because of its usually benign course. Angiotensin converting enzyme inhibitors have been suggested to reduce the episodes of hematuria, though controlled studies are lacking. Treating co-existing hypercalciuria and hyperuricosuria will also be helpful in reducing hematuria.
The molecular basis for thin basement membrane disease has yet to be elucidated fully; however, defects in the gene encoding the a4 chain of type IV collagen have been reported in some families.
Thin basement membrane disease must be differentiated from the other two common causes of glomerular hematuria, IgA nephropathy and Alport syndrome. The history and presentation are helpful in this regard:
- In Alport syndrome, there is often a family history of kidney failure, which may be associated with hearing impairment. Also, males tend to be more affected as Alport syndrome is X-linked in most cases.
- In IgA nephropathy, episodes of frank hematuria are more common, and a family history is less common.
A kidney biopsy is the only way to diagnose thin basement membrane disease. It reveals thinning of the glomerular basement membrane from the normal 300 to 400 nanometers (nm) to 150 to 250 nm. However, a biopsy is rarely done in cases where the patient has isolated microscopic hematuria, normal kidney function, and no proteinuria. The prognosis is excellent in this setting unless the clinical manifestations progress, as occurs in most males and some females with Alport syndrome and many patients with IgA nephropathy.
The diagnosis of CJD is suspected when there are typical clinical symptoms and signs such as rapidly progressing dementia with startle myoclonus. Further investigation can then be performed to support the diagnosis including
- Electroencephalography—often has characteristic generalized periodic sharp wave pattern (~80% of pts by 6 months)
- Cerebrospinal fluid analysis for 14-3-3 protein
- MRI of the brain—often shows high signal intensity in the caudate nucleus and putamen bilaterally on T2-weighted images.
- Research in 2010 and 2011 identified a possible blood test for CJD. The test attempts to identify the prion responsible for the disease. However, it has not yet been demonstrated if it is able to detect the prions in early stages of the disease.
Diffusion Weighted Imaging (DWI) images are the most sensitive. In about 24% of cases DWI shows only cortical hyperintensity; in 68%, cortical and subcortical abnormalities; and in 5%, only subcortical anomalies.
The involvement of the thalamus can be found in sCJD, is even stronger and constant in vCJD.
Clinical testing for CJD has always been an issue. Diagnosis has been based mostly on clinical and physical examination of symptoms. In recent years, studies have shown that the tumour marker Neuron-specific enolase (NSE) is often elevated in CJD cases, however its diagnostic utility is seen primarily when combined with a test for the 14-3-3 protein. , screening tests to identify infected asymptomatic individuals, such as blood donors, are not yet available, though methods have been proposed and evaluated.
In 2010, a team from New York described detection of PrP even when initially present at only one part in one hundred billion (10) in brain tissue. The method combines amplification with a novel technology called surround optical fiber immunoassay (SOFIA) and some specific antibodies against PrP. After amplifying and then concentrating any PrP, the samples are labelled with a fluorescent dye using an antibody for specificity and then finally loaded into a micro-capillary tube. This tube is placed in a specially constructed apparatus so that it is totally surrounded by optical fibres to capture all light emitted once the dye is excited using a laser. The technique allowed detection of PrP after many fewer cycles of conversion than others have achieved, substantially reducing the possibility of artefacts, as well as speeding up the assay. The researchers also tested their method on blood samples from apparently healthy sheep that went on to develop scrapie. The animals’ brains were analysed once any symptoms became apparent. The researchers could therefore compare results from brain tissue and blood taken once the animals exhibited symptoms of the diseases, with blood obtained earlier in the animals’ lives, and from uninfected animals. The results showed very clearly that PrP could be detected in the blood of animals long before the symptoms appeared. After further development and testing, this method could be of
great value in surveillance as a blood or urine-based screening test for CJD. In 2014, a human study showed a nasal brushing method that can accurately detect PrP in the olfactory epithelial of CJD patients. .
This finding creates new opportunities for minimally invasive detection of CJD.
In one-third of patients with sporadic CJD, deposits of "prion protein (scrapie)," PrP, can be found in the skeletal muscle and/or the spleen. Diagnosis of vCJD can be supported by biopsy of the tonsils, which harbour significant amounts of PrP; however, biopsy of brain tissue is the definitive diagnostic test for all other forms of prion disease. Due to its invasiveness, biopsy will not be done if clinical suspicion is sufficiently high or low. A negative biopsy does not rule out CJD, since it may predominate in a specific part of the brain.
The classic histologic appearance is spongiform change in the gray matter: the presence of many round vacuoles from one to 50 micrometres in the neuropil, in all six cortical layers in the cerebral cortex or with diffuse involvement of the cerebellar molecular layer. These vacuoles appear glassy or eosinophilic and may coalesce. Neuronal loss and gliosis are also seen. Plaques of amyloid-like material can be seen in the neocortex in some cases of CJD.
However, extra-neuronal vacuolization can also be seen in other disease states. Diffuse cortical vacuolization occurs in Alzheimer's disease, and superficial cortical vacuolization occurs in ischemia and frontotemporal dementia. These vacuoles appear clear and punched-out. Larger vacuoles encircling neurons, vessels, and glia are a possible processing artifact.
- Clinical and Pathologic Characteristics:
- An abnormal signal in the posterior thalamus on T2- and diffusion-weighted images and fluid-attenuated inversion recovery sequences on brain magnetic resonance imaging (MRI); in the appropriate clinical context, this signal is highly specific for vCJD. (Source: CDC)
Types of CJD include:
- sporadic (sCJD), caused by the spontaneous misfolding of prion-protein in an individual. This accounts for 85% of cases of CJD.
- familial (fCJD), caused by an inherited mutation in the prion-protein gene. This accounts for the majority of the other 15% of cases of CJD.
- acquired CJD, caused by contamination with tissue from an infected person, usually as the result of a medical procedure (iatrogenic CJD). Medical procedures that are associated with the spread of this form of CJD include blood transfusion from the infected person, use of human-derived pituitary growth hormones, gonadotropin hormone therapy, and corneal and meningeal transplants.
Variant Creutzfeldt–Jakob disease (vCJD) is a different condition which is potentially acquired from Bovine spongiform encephalopathy or caused by consuming food contaminated with prions.
Electron microscopy can reveal the bullet-shaped rhabdovirus, but is not
adequate for definitive diagnosis.
The Manual or Diagnostic for Aquatic Animals, 2006, is the standard
reference for definitive tests. In most cases, cell culturization
is recommended for surveillance, with antibody tests and reverse transcription
polymerase chain reaction (RT-PCR) and genetic sequencing and comparison
for definitive confirmation and genotype classification.
Virus neutralisation is another important method of diagnosis, especially for carrier fish.
Preliminary diagnosis involves histopathological examination,
observing tissues through a microscope. Most tissue changes can be observed
as minor to major necrosis (cell death) in the liver, kidneys, spleen, and
skeletal muscle. The hematopoietic (blood-forming) areas of the kidney and
spleen are the initial area of infection, and should show necrosis.
The gill may have thickened lamellae, and the liver may have pyknotic nuclei.
Skeletal muscle accumulates blood but does not suffer much damage.
Solar urticaria can be difficult to diagnose, but its presence can be confirmed by the process of phototesting. There are several forms of these tests including photopatch tests, phototests, photoprovocation tests, and laboratory tests. All of these are necessary to determine the exact infliction that the patient is suffering from. Photopatch tests are patch tests conducted when it is believed that a patient is experiencing certain symptoms due to an allergy that will only occur when in contact with sunlight. After the procedure, the patient is given a low dosage of UVA radiation.
Another test known as a phototest is the most useful in identifying solar urticaria. In this test, one centimeter segments of skin are subject to varying amounts of UVA and UVB radiation in order to determine the specific dosage of the certain form of radiation that causes the urticaria to form. When testing for its less intense form (fixed solar urticaria), phototesting should be conducted only in the areas where the hives have appeared to avoid the possibility of getting false-negative results.
A third form of testing is the photoprovocation test which is used to identify disorders instigated by sun burns. The process of this test involves exposing one area of a patient's arm to certain dosage of UVB radiation and one area on the other arm to a certain dosage of UVA radiation. The amount of radiation that the patient is exposed to is equal to that "received in an hour of midday summer sun." If the procedure produces a rash, then the patient will undergo a biopsy. Finally, there are laboratory tests which generally involve procedures such as blood, urine, and fecal biochemical tests. In some situations, a skin biopsy may be performed.
There are two main types of protein C assays, activity and antigen (immunoassays). Commercially available activity assays are based on chromogenic assays that use activation by snake venom in an activating reagent, or clotting and enzyme-linked immunosorbant assays. Repeated testing for protein C functional activity allows differentiation between transient and congenital deficiency of protein C.
Initially, a protein C activity (functional) assay can be performed, and if the result is low, a protein C antigen assay can be considered to determine the deficiency subtype (Type I or Type II). In type I deficiencies, normally functioning protein C molecules are made in reduced quantity. In type II deficiencies normal amounts of dysfunctional protein C are synthesized.
Antigen assays are immunoassays designed to measure the quantity of protein C regardless of its function. Type I deficiencies are therefore characterized by a decrease in both activity and antigen protein C assays whereas type II deficiencies exhibit normal protein C antigen levels with decreased activity levels.
The human protein C gene (PROC) comprises 9 exons, and protein C deficiency has been linked to over 160 mutations to date. Therefore, DNA testing for protein C deficiency is generally not available outside of specialized research laboratories.
Manifestation of purpura fulminans as it is usually associated with reduced protein C plasma concentrations of <5 mg IU/dL. The normal concentration of plasma protein C is 70 nM (4 µg/mL) with a half live of approximately 8 hours. Healthy term neonates, however, have lower (and more variable) physiological levels of protein C (ranging between 15-55 IU/dL) than older children or adults, and these concentrations progressively increase throughout the first 6 months of life. Protein C levels may be <10 IU/dL in preterm or twin neonates or those with respiratory distress without manifesting either purpura fulminans or disseminated intravascular coagulation.
Heterozygous protein C deficiency occurs in 0.14–0.50% of the general population. Based on an estimated carrier rate of 0.2%, a homozygous or compound heterozygous protein C deficiency incidence of 1 per 4 million births could be predicted, although far fewer living patients have been identified. This low prevalence of patients with severe genetic protein C deficiency may be explained by excessive fetal demise, early postnatal deaths before diagnosis, heterogeneity in the cause of low concentrations of protein C among healthy individuals and under-reporting.
The incidence of protein C deficiency in individuals who present with clinical symptoms has been reported to be estimated at 1 in 20,000.
Hydroquinone-induced exogenous ochronosis is an avoidable dermatosis that is exceedingly difficult to treat.
However, some studies show that treatment may be possible with a Q-switched alexandrite (755 nm) laser.
It is recommended that individuals with this disorder stop using hydroquinone-containing compounds. It is important to be aware of this as dermatologists may think the symptoms a patient is exhibiting are a melasma, and prescribe a hydroquinone-containing cream.
Frontotemporal lobar degeneration (FTLD) is a pathological process that occurs in frontotemporal dementia. It is characterized by atrophy in the frontal lobe and temporal lobe of the brain, with sparing of the parietal and occipital lobes.
Common proteinopathies that are found in FTLD include the accumulation of Tau proteins and TARDBPs. Mutations in the C9orf72 gene have been established as a major genetic contribution of FTLD, although defects in the GRN and MAPT genes are also associated with it.
Treatment is predominantly preventive. Avoidance of topical phenols and diets low in tyrosine may help. Replacement and repair of damaged tissue is also possible.
Many laboratories rely on only the color of the cerebrospinal fluid to determine the presence or absence of xanthochromia. However, recent guidelines suggest that spectrophotometry should be performed. Spectrophotometry relies on the different transmittance, or conversely, absorbance, of light by different substances or materials, including solutes. Bilirubin absorbs light at wavelengths between 450–460 nm. Spectrophotometry can also detect the presence of oxyhemoglobin and methemoglobin, which absorb light at 410-418 nm and 403-410 nm, respectively, and also may indicate that bleeding has occurred; to identify substances in cerebrospinal fluid that absorb light at other wavelengths but are not due to bleeding, such as carotenoids; and to detect very small amounts of yellow color saturation (about 0.62%) which may be missed by visual inspection, especially when the cerebrospinal fluid has been examined under incandescent lighting or a tungsten desk lamp (corresponding to International Commission on Illumination standard illuminant A).
Visual inspection is the most frequent method used in the United States to assess cerebrospinal fluid for xanthochromia, while spectrophotometry is used on up to 94% of specimens in the United Kingdom. There is still disagreement about whether or not to routinely use spectrophotometry or whether visual inspection is adequate, and one group of authors has even advocated measuring bilirubin levels.
There are 3 main histological subtypes found at post-mortem:
- FTLD-tau is characterised by tau positive inclusions often referred to as Pick-bodies. Examples of FTLD-tau include; Pick's disease, corticobasal degeneration, progressive supranuclear palsy.
- FTLD-TDP (or FTLD-U ) is characterised by ubiquitin and TDP-43 positive, tau negative, FUS negative inclusions. The pathological histology of this subtype is so diverse it is subdivided into four subtypes based on the detailed histological findings:
Two physicians independently categorized the various forms of TDP-43 associated disorders. Both classifications were considered equally valid by the medical community, but the physicians in question have jointly proposed a compromise classification to avoid confusion.
- FTLD-FUS; which is characterised by FUS positive cytoplasmic inclusions, intra nuclear inclusions, and neuritic threads. All of which are present in the cortex, medulla, hippocampus, and motor cells of the spinal cord and XIIth cranial nerve.
Dementia lacking distinctive histology (DLDH) is a rare and controversial entity. New analyses have allowed many cases previously described as DLDH to be reclassified into one of the positively defined subgroups.
EPP is generally suspected by the presence of acute photosensitivity of the skin and can be confirmed by detection of a plasmatic fluorescence peak at 634 nm. It is also useful to find increased levels of protoporphyrin in feces and the demonstration of an excess of free protoporphyrin in erythrocytes.
Screening for "FECH" mutation on one allele or aminolevulinic acid synthase 2 gain-of-function mutation in selected family members may be useful, especially in genetic counseling.
Liver biopsy confirms hepatic disease in EPP by the presence of protoporphyrin deposits in the hepatocytes that can be observed as a brown pigment within the biliary canaliculi and the portal macrophages. Macroscopically, the cirrhotic liver can have a black color due to protoporphyrin deposits. Using polarized light the characteristic Maltese cross shape of birefringent crystalline pigment deposits is found. The examination of liver tissue under a Wood’s lamp reveals a red fluorescence due to protoporphyrin. Liver biopsy is not helpful for estimation of prognosis of liver disease.