Lesions of the nervous system
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Lesions of the nervous system

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    Lesions of the nervous system Lesions of the nervous system Presentation Transcript

    • LESIONS OF THE NERVOUSSYSTEMProf. Vajira WeerasingheDept of physiologyFaculty of MedicineUniversity of PeradeniyaSri Lanka
    • UppermotorneuronLowermotorneuronextrapyramidal tractspyramidal tractsalpha motor neuronegamma motor neurone
    • • Lower motor neuron lesion causes– flaccid paralysis• Upper motor neuron lesion causes– spastic paralysis
    • Lower motor neuron lesion• muscle weakness• flaccid paralysis• muscle wasting (disuse atrophy)• reduced muscle tone (hypotonia)• reflexes: reduced or absent• spontaneous muscle contractions(fasciculations)• plantar reflex: flexor• superficial abdominal reflexes: present
    • Upper motor neuron lesion• muscle weakness• spastic paralysis• increased muscle tone (hypertonia)• reflexes: exaggerated• Babinski sign: positive• superficial abdominal reflexes: absent• muscle wasting is very rare
    • tendon jerks (reflexes)• reflex level• biceps jerk C 5 6• triceps jerk C 6 7 8• supinator jerk C 6 7• knee jerk L 2 3 4• ankle jerk S 1 2
    • Babinski sign• when outer border of the sole of thefoot is scratched• upward movement of big toe• fanning out of other toes
    • positive Babinski sign
    • positive Babinski signdorsiflexion of big toefanning outof other toes
    • Babinski sign• feature of upper motor neuronlesion• extensor plantar reflex• seen in infants during 1st year oflife (becuase of immaturecorticospinal tract)
    • clonus• rhythmical series of contractions inresponse to sudden stretch• feature of upper motor neuron lesion
    • superficial abdominal reflexes• light scratch of the abdominal skin• brisk unilateral contraction of the abdominalwall• upper motor neuron lesion causes reducedor loss of these reflexes
    • Different types of lesionsmonoplegiaonly 1 limb is affected either UL or LL,lower motor neuron lesionhemiplegiaon half of the body includingUL and LLlesion in the Internal capsuleparaplegiaboth lower limbsthoracic cord lesionquadriplegia (tetraplegia)all 4 limbs are affectedcervical cord or brain stem lesion
    • Site of lesionsCortexInternal capsuleBrain stemSpinal cordAnterior horn cellMotor nerveNeuromuscular junctionMuscle
    • CortexInternal capsuleBrain stemSpinal cordAnterior horn cellMotor nerveNeuromuscular junctionMusclemuscle disorders• myopathymuscle wastingmuscle weaknessmostly hereditary
    • CortexInternal capsuleBrain stemSpinal cordAnterior horn cellMotor nerveNeuromuscular junctionMuscleneuromusculardisorders• myasthenia gravismuscle fatigue• snake poisoning• insecticide poisoning
    • CortexInternal capsuleBrain stemSpinal cordAnterior horn cellMotor nerveNeuromuscular junctionMusclemotor nerve• peripheral neuropathy(eg. diabetic neuropathy)muscle weaknesssensory featureslower motor neuron lesion
    • CortexInternal capsuleBrain stemSpinal cordAnterior horn cellMotor nerveNeuromuscular junctionMuscleanterior horn celldisorders• motor neuron diseasefasciculations (eg.tongue)muscle weaknesslower motor neuron lesion
    • CortexInternal capsuleBrain stemSpinal cordAnterior horn cellMotor nerveNeuromuscular junctionMusclespinal cord• injuriesspinal shock• spinal root compression• spinal cord compressionsensory lossmuscle weaknessupper motor neuron lesion
    • CortexInternal capsuleBrain stemSpinal cordAnterior horn cellMotor nerveNeuromuscular junctionMusclebrain stem• brain stem lesionmuscle weaknessupper motor neuron lesionbulbar palsy (cranial nerve palsy)•brain stem transection•at pons level•decerebrate rigidity•at midbrain level•righting reflexes
    • CortexInternal capsuleBrain stemSpinal cordAnterior horn cellMotor nerveNeuromuscular junctionMuscleinternal capsulecortical level• stroke (cerebrovascular accident)upper motor neuron lesion