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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
The types of imaging techniques that are most prominently utilized when studying and/or diagnosing CBD are:
- magnetic resonance imaging (MRI)
- single-photon emission computed tomography (SPECT)
- fluorodopa positron emission tomography (FDOPA PET)
Developments or improvements in imaging techniques provide the future possibility for definitive clinical diagnosis prior to death. However, despite their benefits, information learned from MRI and SPECT during the beginning of CBD progression tend to show no irregularities that would indicate the presence of such a neurodegenerative disease. FDOPA PET is used to study the efficacy of the dopamine pathway.
Despite the undoubted presence of cortical atrophy (as determined through MRI and SPECT) in individuals experiencing the symptoms of CBD, this is not an exclusive indicator for the disease. Thus, the utilization of this factor in the diagnosis of CBD should be used only in combination with other clinically present dysfunctions.
At this time the cause of PCA is unknown; similarly, there are no fully accepted diagnostic criteria for the disease. This is partially due to the gradual onset of PCA symptoms, the variety of symptoms, the rare nature of the disease and younger age of patients (initial symptoms appear in patients of 50–60 years old). In 2012, the first international conference on PCA was held in Vancouver, Canada. Continued research and testing will hopefully result in accepted and standardized criteria for diagnosis.
PCA patients are often initially misdiagnosed with an anxiety disorder or depression. Some believe that patients may experience depression or anxiety due to their awareness of their symptoms, such as decrease in their vision capabilities, yet they are unable to control this decline in their vision or the progressive nature of the disease. The early visual impairments of a PCA patient have often led to an incorrect referral to an ophthalmologist, which can result in unnecessary cataract surgery.
Due to the lack of biological marks of PCA, neuropsychological examinations should be used for diagnosis. Neuroimaging can also assist in diagnosis of PCA. The common tools used for Neuroimaging of both PCA and AD patients are magnetic resonance imaging (MRI's), a popular form of medical imaging that uses magnetic fields and radio waves, as well as single-photon emission computed tomography, an imaging form that uses gamma rays, and positron emission tomography, another imaging tool that creates 3D images with a pair of gamma rays and a tracer. Images of PCA patient’s brains are often compared to AD patient images to assist diagnosis. Due to the early onset of PCA in comparison to AD, images taken at the early stages of the disease will vary from brain images of AD patients. At this early stage PCA patients will show brain atrophy more centrally located in the right posterior lobe and occipital gyrus, while AD brain images show the majority of atrophy in the medial temporal cortex. This variation within the images will assist in early diagnosis of PCA; however, as the years go on the images will become increasingly similar, due to the majority of PCA patients also having AD later in life because of continued brain atrophy. A key aspect found through brain imaging of PCA patients is a loss of grey matter (collections of neuronal cell bodies) in the posterior and occipital temporal cortices within the right hemisphere.
For some PCA patients, neuroimaging may not result with a clear diagnosis; therefore, careful observation of the patient in relation to PCA symptoms can also assist in the diagnosis of the patient. The variation and lack of organized clinical testing has led to continued difficulties and delays in the diagnosis of PCA in patients.
Diagnosing a patient can be difficult as they are often frustrated from ineffective therapy and being told they have mental illnesses. Some patients actually have trouble deciding whether they have a taste or smell problem. In this case asking questions about food choices will help determine whether a patient has a smell or taste disorder. It is important to identify whether the distortion applies to an inhaled odorant or if an odor exists without the stimulus. The distortion of an odorant is presented in two types: the stimuli are different from what one remembers and in the second, everything has a similar smell. A clinical history can also help determine what kind of disorder one has because events such as respiratory infection and head trauma are usually indications of parosmia where as phantosmias usually have no history of such events and occur spontaneously. Unfortunately there are no accurate diagnostic tests or methods for dysosmia. Evaluation must be done through questionnaires and medical history.
One of the most significant problems associated with CBD is the inability to perform a definitive diagnosis while an individual exhibiting the symptoms associated with CBD is still alive. A clinical diagnosis of CBD is performed based upon the specified diagnostic criteria, which focus mainly on the symptoms correlated with the disease. However, this often results in complications as these symptoms often overlap with numerous other neurodegenerative diseases. Frequently, a differential diagnosis for CBD is performed, in which other diseases are eliminated based on specific symptoms that do not overlap. However, some of the symptoms of CBD used in this process are rare to the disease, and thus the differential diagnosis cannot always be used.
Postmortem diagnosis provides the only true indication of the presence of CBD. Most of these diagnoses utilize the Gallyas-Braak staining method, which is effective in identifying the presence of astroglial inclusions and coincidental tauopathy.
From the knowledge of the sensimotor development a number of other automatic reactions were distinguished, such as balance, support and automatic adaptations of muscle power changes to postures. Patients with hemiplegia have movements that are lower level and less motor coordination, and often must relearn these movements to continue or gain normal automatic transitions in the body. Neuro developmental treatment (NDT) often improves daily functioning and self-help. This treatment centers on reversing disabilities, specifically for patients who are hemiplegic with impaired sensimotor and neuropsychological functions. Muscle regulation that is disturbed, often called hypo or hypertonic, causes abnormal movement patterns. These automatic reactions are impaired, and patients must learn these movements and remember mentally and physically the positions.
NDT uses muscle power techniques through inhibiting and stimulating certain muscle groups, which aims to lower or increase muscle tone. For facial expression, therapists often help the patient make facial expressions by manipulating specific muscles with their fingers. The patient then tries to imitate the facial expressions. Speech therapy helps correct word pronunciation. NDT is directed at the functioning of the whole body, and not just the face. Understanding the direct mechanisms of the face is required to determine the dysfunction of specific muscles. NDT seems to be effective, but spontaneous motor movement that is controlled was not examined.
Expensive and invasive, the above treatments are not guaranteed to work, and are not meeting the needs of patients. There is a need for a new, less expensive, less invasive form of treatment, two of which are postulated below.
- Spinal cord stimulation has been studied in the last couple of years. In a long case study, 8 patients were given spinal cord stimulation via insertion of a percutaneous lead at the appropriate level of the cervical or thoracic spine. Between 36 and 149 months after the stimulations, the patients were interviewed. 6 of the 8 had received initial pain relief, and three experienced long-term pain relief. Spinal cord stimulation is cheaper than brain stimulation and less invasive, and is thus a more promising option for pain treatment.
- In 2007, Dr. V. S. Ramachandran and his lab proposed that caloric stimulation might be effective in treating Dejerine–Roussy syndrome. They hypothesized that if cold water was streamed into the ear down the auditory canal, the symptoms associated with Dejerine–Roussy syndrome would be alleviated. Ramachandran stated that he had carried out provisional experiments on two patients and believed that their reactions supported his theory.
CARASIL is diagnosed by MRI scans of the brain. Diffuse white matter changes (leukoencephalopathy) and multiple lacunar infarcts in basal ganglia of thalamus are usually determining factors seen on MRI scans of affected individuals. Further genetic testing can be used to confirm the presence of the disease.
Specific and accepted scientific treatment for PCA has yet to be discovered; this may be due to the rarity and variations of the disease. At times PCA patients are treated with prescriptions originally created for treatment of AD such as, cholinesterase inhibitors, Donepezil, Rivastigmine and Galantamine, and Memantine. Antidepressant drugs have also provided some positive effects.
Patients may find success with non-prescription treatments such as psychological treatments. PCA patients may find assistance in meeting with an occupational therapist or sensory team for aid in adapting to the PCA symptoms, especially for visual changes. People with PCA and their caregivers are likely to have different needs to more typical cases of Alzheimer's disease, and may benefit from specialized support groups such as the PCA Support Group based at University College London, or other groups for young people with dementia. No study to date has been definitive to provide accepted conclusive analysis on treatment options.
Dejerine-Roussy is a rare pain syndrome. Individuals with emerging Dejerine–Roussy syndrome usually report they are experiencing unusual pain or sensitivity that can be allodynic in nature or triggered by seemingly unrelated stimuli (sounds, tastes). Symptoms are typically lateralized and may include vision loss or loss of balance (position sense). Workup should be performed by a neurologist and brain imaging to look for evidence of infarction or tumor should be obtained.
Normal olfactory acuity will usually return over time if the cause is environmental, even if it is untreated. The hyperosmic person may need to be removed from strong odorants for a period of time if the sensation becomes unbearable. Before they had been discontinued due to undesirable side effects, butyrophenones or thioridazine hydrochloride, both of which are dopamine antagonists, have been used to treat hyperosmia.
There are currently no quantitative methods for diagnosing simultanagnosia. To establish the presence of simultanagnosic symptoms, patients are asked to describe complex visual displays, such as the commonly used "Boston Cookie Theft" picture, which is a component of the Boston Diagnostic Aphasia Examination. In the picture, the sink in the kitchen is overflowing as a boy and a girl attempt to steal cookies from the cookie jar without their mother noticing.
Patients take a clearly piecemeal approach to interpreting the scene by reporting isolated items from the image. For instance, a patient may report seeing a "boy," "stool," and a "woman." However, when asked to interpret the overall meaning of the picture, the patient fails to comprehend the global whole. Another picture used to assess visual impairments of patients with simultanagnosia is the "Telegraph Boy" picture. Upon examination of higher nervous system functions, patients display no general intellectual impairments.
Central facial palsy (colloquially referred to as central seven) is a symptom or finding characterized by paralysis or paresis of the lower half of one side of the face. It usually results from damage to upper motor neurons of the facial nerve.
The facial motor nucleus has dorsal and ventral divisions that contain lower motor neurons supplying the muscles of the upper and lower face, respectively. The dorsal division receives upper motor neuron input (i.e. from both sides of the brain) while the ventral division receives only contralateral input (i.e. from the opposite side of the brain).
Thus, lesions of the corticobulbar tract between the cerebral cortex and pons and the facial motor nucleus destroy or reduce input to the ventral division, but ipsilateral input (i.e. from the same side) to the dorsal division is retained. As a result, central facial palsy is characterized by hemiparalysis or hemiparesis of the contralateral muscles of facial expression, but not the muscles of the forehead.
Diagnosis for aboulia can be quite difficult because it falls between two other disorders of diminished motivation, and one could easily see an extreme case of aboulia as akinetic mutism or a lesser case of aboulia as apathy and therefore, not treat the patient appropriately. If it were to be confused with apathy, it might lead to attempts to involve the patient with physical rehabilitation or other interventions where a source of strong motivation would be necessary to succeed but would still be absent. The best way to diagnose aboulia is through clinical observation of the patient as well as questioning of close relatives and loved ones to give the doctor a frame of reference with which they can compare the patient's new behavior to see if there is in fact a case of diminished motivation. In recent years, imaging studies using a CT or MRI scan have been shown to be quite helpful in localizing brain lesions which have been shown to be one of the main causes of aboulia.
Even though dysosmia often goes away on its own over time, there are both medical and surgical treatments for dysosmia for patients that want immediate relief. Medical treatments include the use of topical nasal drops and oxymetazoline HCL, which give an upper nasal block so that the air flow can't reach the olfactory cleft. Other medications suggested include sedatives, anti-depressants, and anti-epileptic drugs. The medications may or may not work and for some patients, the side effects may not be tolerable. Most patients benefit from medical treatment but for some surgical treatment is required. Options include a bifrontal craniotomy and an excision of the olfactory epithelium, which cuts all of the fila olfactoria. According to some studies, transnasal endoscopic excision of the olfactory epithelium has been described as a safe and effective phantosmia treatment. The bifrontal craniotomy results in permanent anosmia and both surgeries are accompanied with the risks associated with general surgery.
The doctor will review the person's medical history and perform a complete physical and neurological examination that will include an evaluation of the gait. The doctor may ask the patient to walk in a corridor or climb stairs to observe specific features including:
1. Stance, posture, and base (wide or narrow).
2. Gait initiation (including start hesitation or freezing).
3. Walking speed, stride length, step height, foot clearance.
4. Continuity, symmetry, trunk sway, path deviation, arm swing.
5. Involuntary movements.
6. Ability to turn.
7. Ability to rise from a chair (without using the arms).
8. Chair Testing: Each patient was asked to walk 20–30 feet forward and backward toward the examiner. Patients were then asked to sit in a swivel chair with wheels and to propel the chair forward and backward.
Treatment is directed at the pathology causing the paralysis. If it is because of trauma such as a gunshot or knife wound, there may be other life-threatening conditions such as bleeding or major organ damage which should be dealt with on an emergent basis. If the syndrome is caused by a spinal fracture, this should be identified and treated appropriately. Although steroids may be used to decrease cord swelling and inflammation, the usual therapy for spinal cord injury is expectant.
Many disorders of the basal ganglia are due to the dysfunction of a localized area. For this reason gene therapy seems viable for neurodegenerative disorders. Gene therapy is performed by replacing diseased phenotypes with new genetic material. This process is still in the early stages but early results are promising. An example of this therapy might involve implanting cells genetically modified to express tyrosine hydroxylase which, in the body, could be converted to dopamine. Increasing dopamine levels in the basal ganglia could possibly offset the effects of the Parkinson’s Disease.
Blocq's disease was first considered by Paul Blocq (1860–1896), who described this phenomenon as the loss of memory of specialized movements causing the inability to maintain an upright posture, despite normal function of the legs in the bed. The patient is able to stand up, but as soon as the feet are on the ground, the patient cannot hold himself upright nor walk; however when lying down, the subject conserved the integrity of muscular force and the precision of movements of the lower limbs. The motivation of this study came when a fellow student Georges Marinesco (1864) and Paul published a case of parkinsonian tremor (1893) due to a tumor located in the substantia nigra.
In the third paper published by Paul Blocq, he was trying to determine the neurophysiology behind this disease by relating the cerebral cortex (the decision making) and the spinal cord (the decision executer). His hypothesis was that there would exist an inhibitory influence which exerted and influenced the cortical or spinal centers for standing and walking.
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)
A lack of motivation has been reported in 25–50% of patients with Alzheimer's disease. While depression is also common in patients with this disease, aboulia is not a mere symptom of depressions because more than half of the patients with Alzheimer's disease with aboulia do not suffer from depression. Several studies have shown that aboulia is most prevalent in cases of severe dementia which may result from reduced metabolic activity in the prefrontal regions of the brain. Patients with Alzheimer's disease and aboulia are significantly older than patients with Alzheimer's who do not lack motivation. Going along with that, the prevalence of aboulia increased from 14% in patients with a mild case Alzheimer's disease to 61% in patients with a severe case of Alzheimer's disease, which most likely developed over time as the patient got older.
The eye findings of Parinaud's Syndrome generally improve slowly over months, especially with resolution of the causative factor; continued resolution after the first 3–6 months of onset is uncommon. However, rapid resolution after normalization of intracranial pressure following placement of a ventriculoperitoneal shunt has been reported.
Treatment is primarily directed towards etiology of the dorsal midbrain syndrome. A thorough workup, including neuroimaging is essential to rule out anatomic lesions or other causes of this syndrome. Visually significant upgaze palsy can be relieved with bilateral inferior rectus recessions. Retraction nystagmus and convergence movement are usually improved with this procedure as well.
Diagnosis is made upon history of absence seizures during early childhood and the observation of ~3 Hz spike-and-wave discharges on an EEG.
Lesionsing is the intentional destruction of neuronal cells in a particular area used for therapeutic purposes. Though this seems dangerous, vast improvements have been achieved in patients with movement disorders. The exact process generally involves unilateral lesioning in the sensorimotor territory of the GPi. This process is called pallidotomy. It is believed that the success of pallidotomies in reducing the effects of movement disorders may result from the interruption of abnormal neuronal activity in the GPi. This ablation technique can be viewed as simply removing a faulty piece of a circuit. With the damaged piece of the circuit removed, the healthy area of the circuit can continue normal function.
There has not been extensive research into environmental causes of hyperosmia, but there are some theories of some possible causes.
In a study by Atianjoh et al., it has been found that amphetamines decrease levels of dopamine in the olfactory bulbs of rodents. On this basis, it has been hypothesized that amphetamine use may cause hyperosmia in rodents and humans, but further research is still needed. Anecdotal support for the belief that amphetamines may cause hyperosmia comes from Oliver Sacks's account of a patient with a heightened sense of smell after taking amphetamines.
It has been observed that the inhalation of hydrocarbons can cause hyperosmia, most likely due to the destruction of dopaminergic neurons in the olfactory bulb.
Methotrexate, administered in the treatment of psoriasis, has been known to cause hyperosmia, and may be more likely to do so in patients with a history of migraines. However, this is only an observation and not part of a study, therefore it is yet to be verified.
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.