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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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Since astasis itself is more a symptom than a disease, it is more often seen associated with other signs and symptoms. People who have astasis often experience
- Odd gyrations
- Tightrope balancing deficits (in which a person attempts to balance on a tightrope in order to test balance and motor coordination)
- Near falling deficits (which is a test in which the patient is slightly pushed in order to check their ability to regain posture)
- Exaggerated effort deficits (which is an overcompensation test used to determine motor coordination ability)
- Atypical postures and weakness
- Paralysis
- Jumping fits (in which motor control is partially or totally lost)
- Tremors
One study described a patient with astasis as lying in bed with a normal body posture. When the patient was sitting, he tilted his body to the left. When he was asked to stand up, the patient rotated his trunk axis to the left (left shoulder going backwards), and tilted his body to that same side, showing resistance to passive correction of posture in both of these planes. He was unable to stand and fell backwards and towards the left.
Weakness of the triceps surae muscle has been seen in many patients who have been diagnosed with astasis. This weakness can be caused by a myopathy to that muscle group. The bilateral triceps surae muscle, made up of the gastrocnemius and the soleus, is essential to maintain a straight posture while standing. This indicates that weakness to this muscle is the cause of the swaying and impaired posture in patients with astasis. This weakness is seen regardless of whether somatosensory feedback from the legs is impaired, suggesting it is one of the main causes of astasia without abasia.
Tandem gait is a gait (method of walking or running) where the toes of the back foot touch the heel of the front foot at each step. Neurologists sometimes ask patients to walk in a straight line using tandem gait as a test to help diagnose ataxia, especially truncal ataxia, because sufferers of these disorders will have an unsteady gait. However, the results are not definitive, because many disorders or problems can cause unsteady gait (such as vision difficulties and problems with the motor neurons or associative cortex). Therefore, inability to walk correctly in tandem gait does not prove the presence of ataxia.
Profoundly affected tandem gait with no other perceptible deficits is a defining feature of posterior vermal split syndrome.
Suspects may also be asked to perform a tandem gait walk during the "walk and turn" part of a field sobriety test.
Unlike ataxias of cerebellar origin, Bruns apraxia exhibits many frontal lobe ataxia characteristics, with some or all present.
- Difficulty in initiating movement
- Poor truncal mobility
- Falls due to minor balance disturbances
- Greatly hindered postural responses
- Characteristic magnetic gait, the inability to raise one's foot off of the floor.
- Wide base, poor balance control when in stance
- Short stride
- En bloc turns
Often patients with frontal lobe ataxia may experience minute cognitive changes that accompany the gait disturbances, such as frontal dementia and presentation of frontal release signs (Plantar reflex). Urinary incontinence may also be present.
Bruns apraxia can be distinguished from Parkinsonian ataxia and cerebellar ataxia in a number of ways. Patients typically afflicted with Parkinsonian ataxia typically have irregular arm swing, a symptom not typically present in frontal ataxia. Walking stride in cerebellar ataxia varies dramatically, accompanied by erratic foot placement and sudden, uncontrolled lurching, not generally characteristic of Bruns apraxia.
Parkinsonian gait (or festinating gait, from Latin "festinare" [to hurry]) is the type of gait exhibited by patients suffering from Parkinson's disease (PD). This disorder is caused by a deficiency of dopamine in the basal ganglia circuit leading to motor deficits. Gait is one of the most affected motor characteristics of this disorder although symptoms of Parkinson's disease are varied.
Parkinsonian gait is characterized by small shuffling steps and a general slowness of movement (hypokinesia), or even the total loss of movement (akinesia) in the extreme cases. Patients with PD demonstrate reduced stride length and walking speed during free ambulation while double support duration and cadence rate are increased. The patient has difficulty starting, but also has difficulty stopping after starting. This is due to muscle hypertonicity.
Patients with Parkinson's disease exhibit gait characteristics that are markedly different from normal gait. While the list of abnormal gait characteristics given below is the most discussed, it is certainly not exhaustive.
Bruns apraxia, or frontal ataxia is a gait apraxia found in patients with bilateral frontal lobe disorders. It is characterised by an inability to initiate the process of walking, despite the power and coordination of the legs being normal when tested in the seated or lying position. The gait is broad-based with short steps with a tendency to fall backwards. It was originally described in patients with frontal lobe tumours, but is now more commonly seen in patients with cerebrovascular disease.
It is named after Ludwig Bruns.
Dysmetria () refers to a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye. It is a type of ataxia. It is sometimes described as an inability to judge distance or scale.
Hypermetria and hypometria refer, respectively, to overshooting and undershooting the intended position.
Hyporeflexia refers to below normal or absent reflexes (areflexia). It can be detected through the use of a reflex hammer. It is the opposite of hyperreflexia.
Hyporeflexia is generally associated with a lower motor neuron deficit (at the alpha motor neurons from spinal cord to muscle), whereas hyperreflexia is often attributed to upper motor neuron lesions (along the long, motor tracts from the brain). The upper motor neurons are thought to inhibit the reflex arc, which is formed by sensory neurons from intrafusal fibers of muscles, lower motor neurons (including alpha and gamma motor fibers) and appurtenant interneurons. Therefore, damage to lower motor neurons will subsequently result in hyporeflexia and/or areflexia.
Note that, in spinal shock, which is commonly seen in the transection of the spinal cord (Spinal cord injury), areflexia can transiently occur below the level of the lesion and can , after some time, become hyperreflexic. Furthermore, cases of severe muscle atrophy or destruction could render the muscle too weak to show any reflex and should not be confused with a neuronal cause.
Hyporeflexia may have other causes, including hypothyroidism, electrolyte imbalance (e.g. excess magnesium), drug induced (e.g. the symptoms of benzodiazepine intoxication include confusion, slurred speech, ataxia, drowsiness, dyspnea, and hyporeflexia).
Diseases associated with hyporeflexia include
- Centronuclear myopathy
- Guillain–Barré syndrome
- Lambert-Eaton myasthenic syndrome
- Polyneuropathy (Achilles and plantar reflexes)
Ataxia is a motor disorder that affects the spinal cord, brain and brainstem. Symptoms of ataxia include tremors, lack of coordination, loss of balance, instability, inaccuracy, clumsiness, gait problems, speech problems, and involuntary eye movements. Medication is the main treatment of ataxia. Some of these medicines include selegiline, amantadine, entacapone, dopamine agonists, and anticholinergics (“Movement Disorders”).
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.
Tremor is the uncontrollable shaking of an arm or a leg. Twitches or jerks of body parts may occur due to a startling sound or unexpected, sudden pain. Spasms and contractions are temporary abnormal resting positions of hands or feet. Spasms are temporary while contractions could be permanent. Gait problems are problems with the way one walks or runs. This can mean an unsteady pace or dragging of the feet along with other possible irregularities (Stone).
Foot drop is characterized by steppage gait. While walking, people suffering the condition drag their toes along the ground or bend their knees to lift their foot higher than usual to avoid the dragging. This serves to raise the foot high enough to prevent the toe from dragging and prevents the slapping. To accommodate the toe drop, the patient may use a characteristic tiptoe walk on the opposite leg, raising the thigh excessively, as if walking upstairs, while letting the toe drop. Other gaits such as a wide outward leg swing (to avoid lifting the thigh excessively or to turn corners in the opposite direction of the affected limb) may also indicate foot drop.
Patients with painful disorders of sensation (dysesthesia) of the soles of the feet may have a similar gait but do not have foot drop. Because of the extreme pain evoked by even the slightest pressure on the feet, the patient walks as if walking barefoot on hot sand.
Stomping gait (or sensory ataxia gait) is a form of gait abnormality.
Dystonia is a movement disorder in which involuntarily sustained or intermittent muscle contractions cause twisting or repetitive movements, abnormal postures, or both. Such abnormal postures include foot inversion, wrist ulnar deviation, or lordotic trunk twisting. They can be localized to specific parts of the body or be generalized to many different muscle groups. These postures are often sustained for long periods of time and can be combined in time. Dystonic movements can augment hyperkinetic movements, especially when linked to voluntary movements.
Blepharospasm is a type of dystonia characterized by involuntary contraction of the muscles controlling the eyelids. Symptoms can range from a simple increased frequency of blinking to constant, painful eye closure leading to functional blindness.
Oromandibular dystonia is a type of dystonia marked by forceful contractions of the lower face, which causes the mouth to open or close. Chewing motions and unusual tongue movements may also occur with this type of dystonia.
Laryngeal dystonia or spasmodic dysphonia results from abnormal contraction of muscles in the voice box, resulting in altered voice production. Patients may have a strained-strangled quality to their voice or, in some cases, a whispering or breathy quality.
Cervical dystonia (CD) or spasmodic torticollis is characterized by muscle spasms of the head and neck, which may be painful and cause the neck to twist into unusual positions or postures.
Writer's cramp and musician’s cramp is a task-specific dystonia, meaning that it only occurs when performing certain tasks. Writer’s cramp is a contraction of hand and/or arm muscles that happens only when a patient is writing. It does not occur in other situations, such as when a patient is typing or eating. Musician’s cramp occurs only when a musician plays an instrument, and the type of cramp experienced is specific to the instrument. For example, pianists may experience cramping of their hands when playing, while brass players may have cramping or contractions of their mouth muscles.
Chorea is a continuous, random-appearing sequence of one or more discrete involuntary movements or movement fragments. Although chorea consists of discrete movements, many are often strung together in time, thus making it difficult to identify each movement's start and end point. These movements can involve the face, trunk, neck, tongue, and extremities. Unlike dystonic movements, chorea-associated movements are often more rapid, random and unpredictable. Movements are repeated, but not rhythmic in nature. Children with chorea appear fidgety and will often try to disguise the random movements by voluntarily turning the involuntary, abnormal movement into a seemingly more normal, purposeful motion. Chorea may result specifically from disorders of the basal ganglia, cerebral cortex, thalamus, and cerebellum. It has also been associated with encephalitis, hyperthyroidism, anticholinergic toxicity, and other genetic and metabolic disorders. Chorea is also the prominent movement featured in Huntington's disease.
Cerebellar ataxia can occur as a result of many diseases and presents with symptoms of an inability to coordinate balance, gait, extremity and eye movements. Lesions to the cerebellum can cause dyssynergia, dysmetria, dysdiadochokinesia, dysarthria and ataxia of stance and gait. Deficits are observed with movements on the same side of the body as the lesion (ipsilateral). Clinicians often use visual observation of people performing motor tasks in order to look for signs of ataxia.
Foot drop is a gait abnormality in which the dropping of the forefoot happens due to weakness, irritation or damage to the common fibular nerve including the sciatic nerve, or paralysis of the muscles in the anterior portion of the lower leg. It is usually a symptom of a greater problem, not a disease in itself. Foot drop is characterized by inability or impaired ability to raise the toes or raise the foot from the ankle (dorsiflexion). Foot drop may be temporary or permanent, depending on the extent of muscle weakness or paralysis and it can occur in one or both feet. In walking, the raised leg is slightly bent at the knee to prevent the foot from dragging along the ground.
Foot drop can be caused by nerve damage alone or by muscle or spinal cord trauma, abnormal anatomy, toxins, or disease. Toxins include organophosphate compounds which have been used as pesticides and as chemical agents in warfare. The poison can lead to further damage to the body such as a neurodegenerative disorder called organophosphorus induced delayed polyneuropathy. This disorder causes loss of function of the motor and sensory neural pathways. In this case, foot drop could be the result of paralysis due to neurological dysfunction. Diseases that can cause foot drop include trauma to the posterolateral neck of fibula, stroke, amyotrophic lateral sclerosis, muscular dystrophy, poliomyelitis, Charcot Marie Tooth disease, multiple sclerosis, cerebral palsy, hereditary spastic paraplegia, Guillain–Barré syndrome, and Friedreich's ataxia. It may also occur as a result of hip replacement surgery or knee ligament reconstruction surgery.
Damage to the cerebellum, particularly to the cerebrocerebellum area and the cerebellar vermis, is very often associated with clinical depression and often with alcoholism. Due to difficulties in mobility, self-care, everyday activities, and pain/discomfort, those with cerebellar ataxia are more likely to be diagnosed with anxiety and depression. Almost a third of patients with isolated, late onset cerebellar ataxia go on to develop multiple system atrophy.
In recent years the cerebellum's role has been observed as not purely motor. It is intimately combined with intellect, emotion and planning.
The cerebellum is the area of the brain that contributes to coordination and motor processes and is anatomically inferior to the cerebrum. Sensorimotor integration is the brain’s way of integrating the information received from the sensory (or proprioceptive) neurons from the body, including any visual information. To be more specific, information needed to perform a motor task comes from retinal information pertaining to the eyes’ position and has to be translated into spatial information. Sensorimotor integration is crucial for performing any motor task and takes place in the post parietal cortex. After the visual information has been translated into spatial information, the cerebellum must use this information to perform the motor task. If there is damage to any pathways that connect the pathways, dysmetria may result.
Symptoms depend on the type of HSP inherited. The main feature of the disease is progressive spasticity in the lower limbs due to pyramidal tract dysfunction. This also results in brisk reflexes, extensor plantar reflexes, muscle weakness, and variable bladder disturbances. Furthermore, among the core symptoms of HSP are also included abnormal gait and difficulty in walking, decreased vibratory sense at the ankles, and paresthesia.
Initial symptoms are typically difficulty with balance, stubbing the toe or stumbling. Symptoms of HSP may begin at any age, from infancy to older than 60 years. If symptoms begin during the teenage years or later, then spastic gait disturbance usually progresses over many years. Canes, walkers, and wheelchairs may eventually be required, although some people never require assistance devices.
More specifically, patients with the autosomal dominant pure form of HSP reveal normal facial and extraocular movement. Although jaw jerk may be brisk in older subjects, there is no speech disturbance or difficulty of swallowing. Upper extremity muscle tone and strength are normal. In the lower extremities, muscle tone is increased at the hamstrings, quadriceps and ankles. Weakness is most notable at the iliopsoas, tibialis anterior, and to a lesser extent, hamstring muscles.
In the complex form of the disorder, additional symptoms are present. These include: peripheral neuropathy, amyotrophy, ataxia, mental retardation, ichthyosis, epilepsy, optic neuropathy, dementia, deafness, or problems with speech, swallowing or breathing.
Anita Harding classified the HSP in a pure and complicated form. Pure HSP presents with spasticity in the lower limbs, associated with neurogenic bladder disturbance as well as lack of vibration sensitivity (pallhypesthesia). On the other hand, HSP is classified as complex when lower limb spasticity is combined with any additional neurological symptom.
This classification is subjective and patients with complex HSPs are sometimes diagnosed as having cerebellar ataxia with spasticity, mental retardation (with spasticity), or leukodystrophy. Some of the genes listed below have been described in other diseases than HSP before. Therefore, some key genes overlap with other disease groups.
Most cases of autosomal recessive cerebellar ataxia are early onset, usually around the age of 20. People with this type of ataxia share many characteristic symptoms including:
- frequent falls due to poor balance
- imprecise hand coordination
- postural or kinetic tremor of extremities or trunk
- dysarthria
- dysphasia
- vertigo
- diplopia
- lower extremity tendon reflexes
- dysmetria
- minor abnormalities in ocular saccades
- attention defects
- impaired verbal working memory and visuospatial skills
- Normal life expectancy
Autosomal recessive ataxias are generally associated with a loss of proprioception and vibration sense. Arreflexia is more common in autosomal recessive ataxia than autosomal dominant ataxias. Also, they tend to have more involvement outside of the nervous system. Mutations in subunit of the mitochondrial DNA polymerase (POLG) have been found to be a potential cause of autosomal recessive cerebellar ataxia.
Symptoms typically begin sometime between the ages of 5 to 15 years, but in Late Onset FA may occur in the 20s or 30s. Symptoms include any combination, but not necessarily all, of the following:
- Muscle weakness in the arms and legs
- Loss of coordination
- Vision impairment
- Hearing impairment
- Slurred speech
- Curvature of the spine (scoliosis)
- High plantar arches (pes cavus deformity of the foot)
- Diabetes (about 20% of people with Friedreich's ataxia develop carbohydrate intolerance and 10% develop diabetes mellitus)
- Heart disorders (e.g., atrial fibrillation, and resultant tachycardia (fast heart rate) and hypertrophic cardiomyopathy)
It presents before 22 years of age with progressive staggering or stumbling gait and frequent falling. Lower extremities are more severely involved. The symptoms are slow and progressive. Long-term observation shows that many patients reach a plateau in symptoms in the patient's early adulthood. On average, after 10–15 years with the disease, patients are usually wheelchair bound and require assistance with all activities of daily living.
The following physical signs may be detected on physical examination:
- Cerebellar: nystagmus, fast saccadic eye movements, truncal ataxia, dysarthria, dysmetria.
- Lower motor neuron lesion: absent deep tendon reflexes.
- Pyramidal: extensor plantar responses, and distal weakness are commonly found.
- Dorsal column: Loss of vibratory and proprioceptive sensation occurs.
- Cardiac involvement occurs in 91% of patients, including cardiomegaly (up to dilated cardiomyopathy), symmetrical hypertrophy, heart murmurs, and conduction defects. Median age of death is 35 years, while females have better prognosis with a 20-year survival of 100% as compared to 63% in men.
20% of cases are found in association with diabetes mellitus.
Onset usually occurs within the first two decades of life, commonly in the teenage years or the twenties. Life expectancy is normal. High arch of the foot (pes cavus) is common. Patients also have trouble controlling their hands, due to muscle loss on the thumb side of the index finger and palm below the thumb. It is rare for a person with this disorder to lose the ability to walk, though changes in gait may occur later in life.
Frequency of this disorder is unknown.
Scanning speech, also known as explosive speech, is a type of ataxic dysarthria in which spoken words are broken up into separate syllables, often separated by a noticeable pause, and spoken with varying force. The sentence "Walking is good exercise", for example, might be pronounced as "Walk (pause) ing is good ex (pause) er (pause) cise". Additionally, stress may be placed on unusual syllables.
The name is derived from literary scansion, because the speech pattern separates the syllables in a phrase much like scanning a poem counts the syllables in a line of poetry.
There is no universal agreement about the exact definition of this term. Some sources require only a noticeable pause between syllables, while others require other speech abnormalities, such as the unusual stress pattern on syllables. Some sources consider it a common, but not necessary, feature of ataxic dysarthria; others consider it exactly synonymous with ataxic dysarthria.