Lower Motor Neuron Lesion

Aka: Lower Motor Neuron Lesion, Lower Motor Neuron Deficit, Lower Motor Neuron

II. Physiology

  1. Corticospinal tract (motor, lateral cord) transmits motor signals from the cerebral cortex
    1. Fibers cross the midline at the Brain Stem and course to the contralateral muscles
  2. Motor fibers Synapse in the anterior horn (grey matter of the spinal cord)
    1. Upper Motor Neurons (UMN) are from the cerebral cortex to the Synapse
      1. Affect the cerebral cortex, Brainstem and Corticospinal tracts
    2. Lower Motor Neurons (LMN) are from the Synapse to the muscle
      1. Affect the anterior horn (spinal cord), nerve roots, and peripheral nerves

III. Causes: Examples

  1. See Muscle Weakness Causes
  2. Myasthenia Gravis
  3. Lambert-Eaton Syndrome
  4. Guillain-Barre (other autoimmune polyneuropathies)
  5. Neuropathy
    1. See Peripheral Neuropathy
    2. See Symmetric Peripheral Neuropathy
    3. See Asymmetric Peripheral Neuropathy
    4. Diabetic Neuropathy
    5. Peripheral Nerve Injury or Compression Neuropathy (e.g. Carpal Tunnel Syndrome, Lumbar Radiculopathy)

IV. Signs: Lower Motor Neuron Lesion findings

  1. Flaccid Paralysis
  2. Muscular atrophy
  3. Muscle fasciculations and fibrillations
  4. Hyporeflexia
  5. Absent Babinski reflex

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Related Studies

Ontology: Lower motor neurone lesion (C0442865)

Concepts Pathologic Function (T046)
SnomedCT 264077003, 299737009
Italian Lesione del motoneurone inferiore, Lesione del motoneurone inferiore NAS
Dutch lagere motorische neuronlaesie NAO, lagere motorische neuronlaesie
French Lésion des motoneurones inférieurs SAI, LESION DU MOTONEURONE INFERIEUR, Lésion du motoneurone inférieur
German untere Motorneuronlaesion NNB, NEURONENSCHAEDIGUNG MOTORISCHE UN, untere Motorneuronlaesion
Portuguese Lesão traumática do neurónio motor inferior NE, LESAO DO NEURONIO MOTOR PERIFERIC, Lesão do neurónio motor inferior
Spanish Lesión de neurona motor inferior NEOM, lesión de la neurona motora inferior (hallazgo), lesión de la neurona motora inferior, Lesión de la segunda motoneurona
Japanese 下位運動ニューロンの病変ＮＯＳ, 下位運動ニューロンの病変, ｶｲｳﾝﾄﾞｳﾆｭｰﾛﾝﾉﾋﾞｮｳﾍﾝ, ｶｲｳﾝﾄﾞｳﾆｭｰﾛﾝﾉﾋﾞｮｳﾍﾝNOS
English LOWER MOTOR NEURONE LESION, Lower motor neurone lesion NOS, Lower motor neurone lesion (disorder), Lower motor neurone lesion, Lower motor neurone lesion (finding)
Czech Léze dolního motorického neuronu, Léze dolního motorického neuronu NOS
Hungarian Alsó motoneuron laesio, Alsó motoneuron laesio k.m.n.
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Lower motor neuron (C0524459)

Concepts Cell (T025)
SnomedCT 91770004
English lower motor neurons, lower motor neuron, neuron lower motor, Lower motor neuron, Lower motor neuron (cell)
Spanish neurona motora inferior (célula), neurona motora inferior
Derived from the NIH UMLS (Unified Medical Language System)

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