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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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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.
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.
Treatment depends upon the underlying disorder. Movement disorders have been known to be associated with a variety of autoimmune diseases.
Step I : Decide the dominant type of movement disorder
Step II : Make differential diagnosis of the particular disorder
Step II: Confirm the diagnosis by lab tests
- Metabolic screening
- Microbiology
- Immunology
- CSF examination
- Genetics
- Imaging
- Neurophysiological tests
- Pharmacological tests
Embryos produced using in vitro fertilization may be genetically tested for HD using preimplantation genetic diagnosis (PGD). This technique, where one or two cells are extracted from a typically 4- to 8-cell embryo and then tested for the genetic abnormality, can then be used to ensure embryos affected with HD genes are not implanted, and therefore any offspring will not inherit the disease. Some forms of preimplantation genetic diagnosis—non-disclosure or exclusion testing—allow at-risk people to have HD-free offspring "without" revealing their own parental genotype, giving no information about whether they themselves are destined to develop HD. In exclusion testing, the embryos' DNA is compared with that of the parents and grandparents to avoid inheritance of the chromosomal region containing the HD gene from the affected grandparent. In non-disclosure testing, only disease-free embryos are replaced in the uterus while the parental genotype and hence parental risk for HD are never disclosed.
It is also possible to obtain a prenatal diagnosis for an embryo or fetus in the womb, using fetal genetic material acquired through chorionic villus sampling. An amniocentesis can be performed if the pregnancy is further along, within 14–18 weeks. This procedure looks at the amniotic fluid surrounding the baby for indicators of the HD mutation. This, too, can be paired with exclusion testing to avoid disclosure of parental genotype. Prenatal testing can be done when a parent has been diagnosed with HD, when they have had genetic testing showing the expansion of the HTT gene, or when they have a 50% chance of inheriting the disease. The parents can be counseled on their options, which include termination of pregnancy, and on the difficulties of a child with the identified gene.
In addition, in at-risk pregnancies due to an affected male partner, non-invasive prenatal diagnosis can be performed by analyzing cell-free fetal DNA in a blood sample taken from the mother (via venipuncture) between six and twelve weeks of pregnancy. It has no procedure-related risk of miscarriage (excepting via needle contamination).
Diagnosis is similar, but slightly different for each type of PD. Some types are more understood than others, and therefore have more criteria for diagnosis.
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.
The guidelines for diagnosing PKD were reviewed and confirmed by Unterberger and Trinka. PKD consists of unexpected forms of involuntary movements of the body. The patient is usually diagnosed sometime before their 20's, and is more likely diagnosed during childhood than early adulthood. Almost all PKD's are idiopathic, but there have been examples of autosomal dominant inheritance as well. Physical examination and brain imaging examinations show normal results, and an EEG shows no specific abnormalities as well. However, the negative synchronous EEG results can be used to prove that PKD is not a sort of reflex epilepsy, but a different disease.
PKD is the most prevalent subtype of paroxysmal dyskinesia, encompassing over 80% of all given PD diagnosis. PKD is more prevalent in boys, usually as high as 3.75:1.
Leukoaraiosis (LA) refers to the imaging finding of white matter changes that are common in Binswanger disease. However, LA can be found in many different diseases and even in normal patients, especially in people older than 65 years of age.
There is controversy whether LA and mental deterioration actually have a cause and effect relationship. Recent research is showing that different types of LA can affect the brain differently, and that proton MR spectroscopy would be able to distinguish the different types more effectively and better diagnosis and treat the issue. Because of this information, white matter changes indicated by an MRI or CT cannot alone diagnose Binswanger disease, but can aid to a bigger picture in the diagnosis process. There are many diseases similar to Binswanger's disease including CADASIL syndrome and Alzheimer's disease, which makes this specific type of white matter damage hard to diagnose. Binswanger disease is best when diagnosed of a team by experts including a neurologist and psychiatrist to rule out other psychological or neurological problems. Because doctors must successfully detect enough white matter alterations to accompany dementia as well as an appropriate level of dementia, two separate technological systems are needed in the diagnosing process.
Much of the major research today is done on finding better and more efficient ways to diagnose this disease. Many researchers have divided the MRIs of the brain into different sections or quadrants. A score is given to each section depending on how severe the white matter atrophy or leukoaraiosis is. Research has shown that the higher these scores, the more of a decrease in processing speed, executive functions, and motor learning tasks.
Other researchers have begun using computers to calculate the percentage of white matter atrophy by counting the hyper-intense pixels of the MRI. These and similar reports show a correlation between the amount of white matter alterations and the decline of psychomotor functions, reduced performance on attention and executive control. One recent type of technology is called susceptibility weighted imaging (SWI) which is a magnetic resonance technique which has an unusually high degree of sensitivity and can better detect white matter alternations.
Paroxysmal kinesigenic dyskinesia is diagnosed using a strict set of guidelines. These criteria were studied and confirmed by Bruno et al. in a study of 121 individuals with PKD. The age at onset is between 1 and 20 years old. The attacks of involuntary movements last less than one minute and have a known trigger, usually a sudden voluntary movement. For example, if a PKD patient stands up or begins walking after being sedentary for a period of time, or a person goes from a walk to a run, it can trigger an attack. Persons with PKD do not lose consciousness during attacks and have a full memory of the entire attack. Lastly, people with the disorder have a good response to medication and are usually prescribed anticonvulsants. The study also found that patients with familial PKD exhibit symptoms that follow the diagnostic criteria closely, while sporadic PKD individuals may deviate slightly. Prior to criteria for diagnosis being set out, many patients with PKD were often diagnosed with some form of epilepsy. Many patients also experience an aura, similar to those experienced with epilepsy, preceding their attacks. Some patients describe it as a tingling sensation in the affected limb or “butterflies in their stomach.” Some individuals also have precipitants, such as stress and anxiety, that make it more likely for attacks to occur.
The above diagnostic criteria also set PKD apart from the other paroxysmal dyskinesias, which include paroxysmal nonkinesigenic dyskinesia (PNKD) and paroxysmal exercise-induced dyskinesia (PED). While PKD attacks last less than one minute, PNKD attacks last a few minutes to a few hours, and as the name suggests, the attacks do not occur because of a sudden voluntary movement like PKD. Additionally, PKD can almost always be managed with drug therapy, while PNKD is not as responsive to anticonvulsants. PED, on the other hand, separates itself from PKD in that it is caused by prolonged exercise. Attacks from PED will cease soon after exercise is stopped.
The following diseases that generally involve the basal ganglia do not clearly fit into being either hypo- or hyperkinetic:
- Lesch-Nyhan syndrome
- Wilson's disease
- Blepharospasm in some cases
- Athymhormic syndrome (PAP syndrome)
Surgery, such as the denervation of selected muscles, may also provide some relief; however, the destruction of nerves in the limbs or brain is not reversible and should be considered only in the most extreme cases. Recently, the procedure of deep brain stimulation (DBS) has proven successful in a number of cases of severe generalised dystonia. DBS as treatment for medication-refractory dystonia, on the other hand, may increase the risk of suicide in patients. However, reference data of patients without DBS therapy are lacking.
Binswanger's disease can usually be diagnosed with a CT scan, MRI, and a proton MR spectrography in addition to clinical examination. Indications include infarctions, lesions, or loss of intensity of central white matter and enlargement of ventricles, and leukoaraiosis. Recently a Mini Mental Test (MMT) has been created to accurately and quickly assess cognitive impairment due to vascular dementia across different cultures.
Blood tests usually come back normal in affected individuals, so they do not serve as a reliable means of diagnosis. Blood tests can show low serum ferritin levels. However, this is unreliable as method of diagnosis, as some patients show typical serum ferritin levels even at the latest stages of neuroferritinopathy. Cerebral spinal fluid tests also are typically normal.
Ferritin found in the skin, liver, kidney, and muscle tissues may help in diagnosing neuroferritinopathy. More cytochrome c oxidase-negative fibers are also often found in the muscle biopsies of affected individuals.
Genetic testing can confirm a neuroferritinopathy diagnosis. A diagnosis can be made by analyzing the protein sequences of affected individuals and comparing them to known neuroferritinopathy sequences.
Computed tomography (CT) scans of people with PD usually appear normal. MRI has become more accurate in diagnosis of the disease over time, specifically through iron-sensitive T2* and SWI sequences at a magnetic field strength of at least 3T, both of which can demonstrate absence of the characteristic 'swallow tail' imaging pattern in the dorsolateral substantia nigra. In a meta-analysis, absence of this pattern was 98% sensitive and 95% specific for the disease. Diffusion MRI has shown potential in distinguishing between PD and Parkinson plus syndromes, though its diagnostic value is still under investigation. CT and MRI are also used to rule out other diseases that can be secondary causes of parkinsonism, most commonly encephalitis and chronic ischemic insults, as well as less frequent entities such as basal ganglia tumors and hydrocephalus.
Dopamine-related activity in the basal ganglia can be directly measured with PET and SPECT scans. A finding of reduced dopamine-related activity in the basal ganglia can rule out drug-induced parkinsonism, but reduced basal ganglia dopamine-related activity is seen in both PD and the Parkinson-plus disorders so these scans are not reliable in distinguishing PD from other neurodegenerative causes of parkinsonism.
Treatment of tics present in conditions such as Tourette’s syndrome begins with patient, relative, teacher and peer education about the presentation of the tics. Sometimes, pharmacological treatment is unnecessary and tics can be reduced by behavioral therapy such as habit-reversal therapy and/or counseling. Often this route of treatment is difficult because it depends most heavily on patient compliance. Once pharmacological treatment is deemed most appropriate, lowest effective doses should be given first with gradual increases. The most effective drugs belong to the neuroleptic variety such as monoamine-depleting drugs and dopamine receptor-blocking drugs. Of the monoamine-depleting drugs, tetrabenazine is most powerful against tics and results in fewest side effects. A non-neuroleptic drug found to be safe and effective in treating tics is topiramate. Botulinum toxin injection in affected muscles can successfully treat tics; involuntary movements and vocalizations can be reduced, as well as life-threatening tics that have the potential of causing compressive myelopathy or radiculopathy. Surgical treatment for disabling Tourette’s syndrome has been proven effective in cases presenting with self-injury. Deep Brain Stimulation surgery targeting the globus pallidus, thalamus and other areas of the brain may be effective in treating involuntary and possibly life-threatening tics.
A neurological examination would show evidence of muscle rigidity; weakness; and abnormal postures, movements, and tremors. If other family members are also affected, this may help determine the diagnosis. Genetic tests can confirm an abnormal gene causing the disease. However, this test is not yet widely available. Other movement disorders and diseases must be ruled out. Individuals exhibiting any of the above listed symptoms are often tested using MRI (Magnetic Resonance Imaging) for a number of neuro-related disorders. As PKAN is a disease prominently evident in the brain, MRIs are very useful in making a sound diagnosis. An MRI usually shows iron deposits in the basal ganglia. Development of diagnostic criteria continues in the hope of further separating PKAN from other forms of neurodegenerative diseases featuring NBIA.
Survival rates for those diagnosed with typical PKAN is 11.18 years with a standard deviation of 7.8 years.
A physician will initially assess for Parkinson's disease with a careful medical history and neurological examination. People may be given levodopa, with any resulting improvement in motor impairment helping to confirm the PD diagnosis. The finding of Lewy bodies in the midbrain on autopsy is usually considered final proof that the person had PD. The clinical course of the illness over time may reveal it is not Parkinson's disease, requiring that the clinical presentation be periodically reviewed to confirm accuracy of the diagnosis.
Other causes that can secondarily produce parkinsonism are stroke and drugs. Parkinson plus syndromes such as progressive supranuclear palsy and multiple system atrophy must be ruled out. Anti-Parkinson's medications are typically less effective at controlling symptoms in Parkinson plus syndromes. Faster progression rates, early cognitive dysfunction or postural instability, minimal tremor or symmetry at onset may indicate a Parkinson plus disease rather than PD itself. Genetic forms with an autosomal dominant or recessive pattern of inheritance are sometimes referred to as familial Parkinson's disease or familial parkinsonism.
Medical organizations have created diagnostic criteria to ease and standardize the diagnostic process, especially in the early stages of the disease. The most widely known criteria come from the UK Queen Square Brain Bank for Neurological Disorders and the U.S. National Institute of Neurological Disorders and Stroke. The Queen Square Brain Bank criteria require slowness of movement (bradykinesia) plus either rigidity, resting tremor, or postural instability. Other possible causes of these symptoms need to be ruled out. Finally, three or more of the following supportive features are required during onset or evolution: unilateral onset, tremor at rest, progression in time, asymmetry of motor symptoms, response to levodopa for at least five years, clinical course of at least ten years and appearance of dyskinesias induced by the intake of excessive levodopa.
When PD diagnoses are checked by autopsy, movement disorders experts are found on average to be 79.6% accurate at initial assessment and 83.9% accurate after they have refined their diagnosis at a follow-up examination. When clinical diagnoses performed mainly by nonexperts are checked by autopsy, average accuracy is 73.8%. Overall, 80.6% of PD diagnoses are accurate, and 82.7% of diagnoses using the Brain Bank criteria are accurate.
A task force of the International Parkinson and Movement Disorder Society (MDS) has proposed diagnostic criteria for Parkinson’s disease as well as research criteria for the diagnosis of prodromal disease, but these will require validation against the more established criteria.
Treatment of primary dystonia is aimed at reducing symptoms such as involuntary movements, pain, contracture, embarrassment, and to restore normal posture and improve the patient’s function. This treatment is therefore not neuroprotective. According to the European Federation of Neurological Sciences and Movement Disorder Society, there is no evidence-based recommendation for treating primary dystonia with antidopaminergic or anticholinergic drugs although recommendations have been based on empirical evidence. Anticholinergic drugs prove to be most effective in treating generalized and segmental dystonia, especially if dose starts out low and increases gradually. Generalized dystonia has also been treated with such muscle relaxants as the benzodiazepines. Another muscle relaxant, baclofen, can help reduce spasticity seen in cerebral palsy such as dystonia in the leg and trunk. Treatment of secondary dystonia by administering levodopa in dopamine-responsive dystonia, copper chelation in Wilson’s disease, or stopping the administration of drugs that may induce dystonia have been proven effective in a small number of cases. Physical therapy has been used to improve posture and prevent contractures via braces and casting, although in some cases, immobilization of limbs can induce dystonia, which is by definition known as peripherally induced dystonia. There are not many clinical trials that show significant efficacy for particular drugs, so medical of dystonia must be planned on a case-by-case basis. Botulinum toxin B, or Myobloc, has been approved by the US Food and Drug Administration to treat cervical dystonia due to level A evidential support by the scientific community. Surgery known as GPi DBS (Globus Pallidus Pars Interna Deep Brain Stimulation) has come to be popular in treating phasic forms of dystonia, although cases involving posturing and tonic contractions have improved to a lesser extent with this surgery. A follow-up study has found that movement score improvements observed one year after the surgery was maintained after three years in 58% of the cases. It has also been proven effective in treating cervical and cranial-cervical dystonia.
In the past, the prognosis for patients with this disease had been very poor; with many patients suffering from severe disability or death. Now, patients are responding remarkably well to current treatments and the majority of patients go into spontaneous remission. For those that do not go into remission, the symptoms of hemiballismus can generally be very well controlled with medication.
Due to the rarity of this disorder, scientists know very little about the details of hemiballismus. There are still many unanswered questions such as:
•There appears to be a discrepancy between this disorder in humans and animals that has yet to be explained.
•Hemiballismus can also be induced by damage to other areas of the basal ganglia besides the subthalamic nucleus. Why is this? Research is being done in these areas in order to give scientists and clinicians a better model for this disease that will ultimately lead to better diagnosis and treatment of this disorder.
•Research is also being done on why certain treatments seem to help hemiballistic patients when they should seemingly do more harm. An example of this is why lesioning the globus pallidus seems to reduce hemiballistic movements.
•Why does blocking dopamine help reduce patients’ symptoms?
Almost all patients respond positively to antiepileptic (anticonvulsant) drugs. One of the drugs most often mentioned in the literature is carbamazepine, and is the most widely used drug for treating PKD. Other anticonvulsants like valproic acid, phenytoin and clonazepam are common alternatives. Other categories of drugs have also been used, such as dopamine affecting drugs like Levodopa or Tetrabenazine. Individuals with the disorder can also modify their behavior to lessen their attacks without the influence of drug therapy. For example, decreasing stress to avoid precipitants can help patients decrease the number of attacks. In addition, avoiding any sudden movements can also prevent an attack. In order to prevent an attack, some individuals use their auras as a warning, while others purposefully perform slow gestures or movements prior to a triggering movement. Many, if not most, individuals end up growing out of the attacks with age, even without medicinal therapy, but some patients will go back to having attacks after a period of remission. In regards to secondary PKD, treatment of the primary condition can lessen the PKD attacks in those individuals.
When treating hemiballismus, it is first important to treat whatever may be causing the manifestation of this disorder. This could be hyperglycemia, infections, or neoplastic lesions. Some patients may not even need treatment because the disorder is not severe and can be self – limited.
Dopamine Blockers
When pharmacological treatment is necessary, the most standard type of drug to use is an antidopaminergic drug. Blocking dopamine is effective in about ninety percent of patients. Perphenazine, pimozide, haloperidol, and chlorpromazine are standard choices for treatment. Scientists are still unsure as to why this form of treatment works, as dopamine has not been directly linked to hemiballismus.
Anticonvulsants
An anticonvulsant called topiramate has helped patients in three cases and may be a viable treatment for the future.
ITB Therapy
Intrathecal baclofen (ITB) therapy is used to treat a variety of movement disorders such as cerebral palsy and multiple sclerosis. It can also be a possibility to help treat hemiballismus. In one case, before ITB the patient had an average of 10-12 ballism episodes of the right lower limb per hour. During episodes, the right hip would flex up to about 90 degrees, with a fully extended knee. After an ITB pump was implanted and the correct dosage was found, the frequency of ballistic right leg movements decreased to about three per day, and the right hip flexed to only 30 degrees. The patient was also able to better isolate individual distal joint movements in the right lower limb. The patient currently receives 202.4 microg/day of ITB and continues to benefit almost 6 years after the ITB pump was implanted.
Botulinum Injections
New uses for botulinum toxin have included treatment of hemiballismus. However, this is still in the early stages of testing. This treatment deals with the muscular manifestations of hemiballismus as opposed to the neurological causes.
Tetrabenazine
Tetrabenazine has been used to treat other movement disorders, but is now being used to treat hemiballismus. Patients using this medication have had a dramatic response. However, lowering the dosage leads to a return of symptoms. This drug works by depleting dopamine.
Antipsychotics
In one case, a patient had not been responding to haloperidol, thus the physician tried olanzapine. The patient made a significant recovery. More research is being performed on the use of these types of drugs in treating hemiballismus.
Functional Neurosurgery
Surgery as a treatment should only be used on patients with severe hemiballismus that has not responded to treatment. Lesioning of the globus pallidus or deep brain stimulation of the globus pallidus are procedures that can be used on humans. Usually, lesioning is favored over deep brain stimulation because of the maintenance required to continue stimulating the brain correctly and effectively.