One major characteristic used to identify a lower motor neuron lesion is flaccid paralysis – paralysis accompanied by loss of muscle tone. This is in contrast to an upper motor neuron lesion, which often presents with spastic paralysis – paralysis accompanied by severe hypertonia.
The extensor plantar reflex (Babinski sign) is usually absent. Muscle paresis/paralysis, hypotonia/atonia, and hyporeflexia/areflexia are usually seen immediately following an insult. Muscle wasting, fasciculations and fibrillations are typically signs of end-stage muscle denervation and are seen over a longer time period. Another feature is the segmentation of symptoms – only muscles innervated by the damaged nerves will be symptomatic.
Causesedit
The most common causes of lower motor neuron injuries are trauma to peripheral nerves that serve the axons, and viruses that selectively attack ventral horn cells. Disuse atrophy of the muscle occurs i.e., shrinkage of muscle fibre finally replaced by fibrous tissue (fibrous muscle) Other causes include Guillain–Barré syndrome, West Nile fever, C. botulism, polio, and cauda equina syndrome; another common cause of lower motor neuron degeneration is amyotrophic lateral sclerosis.
Diagnosisedit
Differential diagnosisedit
Myasthenia gravis – synaptic transmission at motor end-plate is impaired
Amyotrophic lateral sclerosis – causes death of motor neurons, although exact cause is unknown it has been suggested that abnormal build-up of proteins proves toxic for the neurons.
lower, motor, neuron, lesion, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jsto. This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Lower motor neuron lesion news newspapers books scholar JSTOR October 2019 Learn how and when to remove this template message A lower motor neuron lesion is a lesion which affects nerve fibers traveling from the lower motor neuron s in the anterior horn anterior grey column of the spinal cord or in the motor nuclei of the cranial nerves to the relevant muscle s 1 Lower motor neuron lesionLower motor neuron in redOne major characteristic used to identify a lower motor neuron lesion is flaccid paralysis paralysis accompanied by loss of muscle tone This is in contrast to an upper motor neuron lesion which often presents with spastic paralysis paralysis accompanied by severe hypertonia Contents 1 Signs and symptoms 2 Causes 3 Diagnosis 3 1 Differential diagnosis 4 See also 5 References 6 External linksSigns and symptoms editMuscle paresis or paralysis Fibrillations Fasciculations caused by increased receptor concentration on muscles to compensate for lack of innervation Hypotonia or atonia Tone is not velocity dependent Hyporeflexia Along with deep reflexes even cutaneous reflexes are also decreased or absent Strength weakness is limited to segmental or focal pattern Root innervated pattern clarification needed The extensor plantar reflex Babinski sign is usually absent Muscle paresis paralysis hypotonia atonia and hyporeflexia areflexia are usually seen immediately following an insult Muscle wasting fasciculations and fibrillations are typically signs of end stage muscle denervation and are seen over a longer time period Another feature is the segmentation of symptoms only muscles innervated by the damaged nerves will be symptomatic Causes editThe most common causes of lower motor neuron injuries are trauma to peripheral nerves that serve the axons and viruses that selectively attack ventral horn cells Disuse atrophy of the muscle occurs i e shrinkage of muscle fibre finally replaced by fibrous tissue fibrous muscle Other causes include Guillain Barre syndrome West Nile fever C botulism polio and cauda equina syndrome another common cause of lower motor neuron degeneration is amyotrophic lateral sclerosis Diagnosis editDifferential diagnosis edit Myasthenia gravis synaptic transmission at motor end plate is impaired Amyotrophic lateral sclerosis causes death of motor neurons although exact cause is unknown it has been suggested that abnormal build up of proteins proves toxic for the neurons See also editLower motor neuron Upper motor neuron Upper motor neuron lesionReferences edit James D Fix 1 October 2007 Neuroanatomy Lippincott Williams amp Wilkins pp 120 ISBN 978 0 7817 7245 7 Retrieved 17 November 2010 External links edithttp library med utah edu neurologicexam html motor anatomy html 06 Retrieved from https en wikipedia org w index php title Lower motor neuron lesion amp oldid 1153459283, wikipedia, wiki, book, books, library,
