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30 Cards in this Set
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- Back
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Q1 |
Clinical features of ALS include Median age of onset of 60 yrs Combination of muscle wasting and exaggerated reflexes Fasciculations in non wasted muscles Emotional lability External ophthalmoplegia
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Q2 |
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Q3 |
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Q5 |
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What is ALS |
the most common degenerative disease of the motor neuron system. Due to not be considered a single disease entity, but rather a clinical diagnosis for different pathophysiologic cascades that share the common consequence of causing preferential progressive loss of motor neurons and the orderly dismantling of the motor neuron system. It is incurable and fatal. |
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Why we bother to diagnose and treat |
Although ALS is incurable and fatal, with median survival of 3 years, treatment can extend the length and meaningful quality of life for patients. |
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U |
Axonal degeneration centrally Premotor and motor cortex Cerebrospinal tracts Anterior nerve roots peripherally Axonal fibers supplying muscles
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T |
Motor axons die by Wallerian degeneration in ALS, and large motor neurons are affected to a greater extent than smaller ones. This process occurs as a result of the death of the anterior horn cell body, leading to degeneration of the associated motor axon. As the axon breaks down, surrounding Schwann cells catabolize the axon's myelin sheath and engulf the axon, breaking it into fragments. |
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In typical ALS, certain motor neurons are spared until very late in the disease process.what are they |
In the brain stem, these include the oculomotor, trochlear, and abducens nerves. In the spinal cord, the posterior columns, spinocerebellar tracts, nucleus of Onuf (which controls bowel and bladder function), and the Clarke column generally are spared. |
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What are the causes of cell death |
•Oxidative damage •Mitochondrial dysfunction •Caspase-mediated cell death (apoptosis) •Defects in axonal transport •Abnormal growth factor expression •Glial cell pathology •Glutamate excitotoxicity •Aggregation of abnormal proteins
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Aetiology |
Most ALS cases are sporadic, and the specific cause of sporadic ALS is unknown. interactions between genetic, environmental, and age-dependent risk factors trigger disease onset in sporadic form.
Many abnormal genes have been identified in familial cases and are considered causal, although the precise mechanism by which they cause ALS is unknown for most. |
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How does the disease Progress |
Early in the disease, surviving nerve fibers establish connections and reinnervate motor units that have lost their connection to axons that have died; as a result, larger motor units are formed. Later in the disease, when the motor neurons that supply the large motor units die, group atrophy ensues.As long as reinnervation can keep up with denervation, clinical weakness may not be detectable, although loss of dexterity may occur. However, as the motor units grow larger and their numbers decrease, the earliest consequence is that affected muscle may fatigue faster than muscle with normal motor units; consequently, one of the first symptoms of ALS may be fatigability of function in the region of onset (for example, “his speech would become muffled toward the end of his sermons”).As the number of motor units innervating a muscle decreases further, reinnervation can no longer keep up with denervation, permanent weakness develops and progresses, and the affected muscles gradually atrophy. In general, loss of cortical neurons may also result in weakness, but spasticity manifesting as stiffness is a more prominent and disabling UMN symptom
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What are the 4 levels of muscle groups |
Bulbar (muscles of the face, mouth, and throat); cervical (muscles of the back of the head and the neck, the shoulders and upper back, and the upper extremities); thoracic (muscles of the chest and abdomen and the middle portion of the spinal muscles); lumbosacral (muscles of the lower back, groin, and lower extremities). |
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What are the special features of signs and symptoms |
In 75-80% of patients, symptoms begin with limb involvement.
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Initial symptoms of LL |
•Tripping, stumbling, or awkwardness when running •Foot drop; patients may report a "slapping" gait
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Initial symptoms of UL |
•Reduced finger dexterity, cramping, stiffness, and weakness or wasting of intrinsic hand muscles •Wrist drop interfering with work performance
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Symptoms with the bulbar involvement |
•Slurred speech, hoarseness, or decreased volume of speech •Aspiration or choking during a meal
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Emotional and special cognitive difficulties in some patients are patients are
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•Involuntary laughing or crying •Depression •Impaired executive function •Maladaptive social behavior
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Features of more advanced disease are |
•Muscle atrophy becomes more apparent •Spasticity may compromise gait and manual dexterity •Muscle cramps are common •Rarely, painful joint contractures may result from immobility
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Progression of bulbar disease leads to the following |
•Voice changes: Hypernasality and development of a strained, strangled vocal quality; eventually, speech may be loss •Swallowing difficulties, usually starting with liquids •Drooling
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How is the diagnosis made with time |
Definitive diagnosis may not be possible with early ALS. Confirmation of the disease may require a period of observation to document its progressive nature and to exclude alternative diagnoses.
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What are the changes in muscle and the reasons behind |
Fatigue Atrophy Fasciculations
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What does Amyotrophic lateral sclerosis mean |
amyotrophy” referring to the atrophy of muscle fibers, which are denervated as their corresponding anterior horn cells degenerate. “Lateral sclerosis” refers to the changes seen in the lateral columns of the spinal cord as upper motor neuron (UMN) axons in these areas degenerate and are replaced by fibrous astrocytes (gliosis) |
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What is the classic form |
In its classic form, ALS affects motor neurons at 2 or more levels of the motor neuron network supplying multiple regions of the body. |
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What are the neurons involved in the degeneration |
lower motor neurons (LMNs) that reside in the anterior horn of the spinal cord and in the brain stem, corticospinal UMNs that reside in the precentral gyrus, frequently, prefrontal motor neurons that are involved in planning or orchestrating the work of the upper and lower motor neurons. |
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What are effects of losing lower motor neurons |
progressive muscle weakness, wasting (atrophy) fasciculations loss of reflexes and muscle tone. |
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Effects of losing corticospinal UMNs |
milder weakness associated with stiffness (spasticity), which may be severe, and abnormally brisk reflexes. |
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Epidemiology |
For most of the lifespan, the incidence of ALS is higher in men than in women, with an overall male-to-female ratio of 1.5-2:1. Later in life, the incidence tends to equalize; this occurs at age 40-50 years in some populations and after the age of 65-70 years in others. Onset of ALS may occur from the teenage years to the late 80s; the incidence rises with increasing age until approximately age 75-80 years. Mean age of onset of sporadic ALS is 65 years; mean age of onset of familial ALS ranges from 46-55 years |
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ALS |
💪Mostly motor symptoms Weakness mostly a lower motor type Both UMN and LMN type weaknesses are there 1)Limb involvement 2)bulber- speech and swallowing 😔 😅 Emotional lability Pseudobulbar symptoms 💂👷👮 Cognitive impairment 15% have criteria compatible with front temporal dementia |
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