Handout of Sensory Lesions

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Handout of Sensory Lesions

• Dr. Taha Sadig ahmed

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Tabes Dorsalis (1)

• Is a form of Neurosyphilis ( syphilis is a
  sexually-transmitted disease , STD).
• It is characterized by damage to the dorsal root
  ganglia ? damaged dorsal roots and dorsal columns
  . Consequently ,there will be
• (1) impairment or loss of proprioception (
  vibration , position senses ) and two-point
  discrimunation sense .
• (2) Absent tendon reflexes . Why ?

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Tabes Dorsalis (2)

• (3) Sensory ataxia ( ataxia means loss of
  coordinated muscular contractions required for
  the production of smooth movements) . Why ?
• Q How do we ascertain the presence of sensory
  ataxia ?
• By performing Rombergs Test .
• A positive Rombergs Test (Sign) means that ?
• keeping the feet together , the patient can stand
  steadily with the eyes open but when if he closes
  his eyes he become unsteady and tends to fall .
• Why ?

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Brown Sequard Syndrome (1)

• Occurs as a result of unilateral lesion or
  hemisection of the spinal cord ( e.g. due to stab
  injury , gunshot ( bullet ) wound, or tumor ).
• The example shown here is a lesion on the left
  side at the thoracic level of the spinal cord
• A/ Ipsilaterally ( on the same side of lesion )
• There is motor weakness ( lower motor neuron type
  at the same level of the lesion spastic lower
  limb (with upper motor neuron type of lesion ).
  Why ?
• at the level of the lesion Loss of all
  sensations /_ hyperesthesia.

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Brown Sequard Syndrome (2)

• (3) Below the level of the lesion loss of
  vibration , position and two-point discrimination
  . Why ?
• B/ Contralaterally (on the opposite side ) loss
  of pain and
• temperature sensibility
• Why ?

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Syringomyelia (1)

• This disease is due to presence of one or more
  cysts ( fluid-filled cavities , called syrinx )
  near the central canal of the spinal cord.
• The expanding cysts damage second-order
  spinothalamic fibers which cross directly if
  front of the central canal , at first affecting
  temperaure fibers( why ?) and, later, pain
  fibers.
• However , the patient retains ????? ? touch and
  pressure sense as well as vibration and position
  sensations (why are they spared ?) ?

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Syringomyelia (2)

• The loss of pain and temperature sensations
  extends to several segmental levels . Therefore ,
  we get Segmental Loss of pain and temperature
  sensations .
• This selective ??????? loss of pain and
  temperature while sparing touch and
  proprioception is called Dissociated sensory Loss
  ( or Dissiciated Anesthesia)

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Herpes Zoster

• This disease results from reactivation of the
  varicella virus which has lain dormant in
  posterior root ganglia following chickenpox
  infection earlier in life .
• The first symptom is severe , continuous pain in
  the dermatomal distribution of the affected nerve
  root .
• After 3-4 days the skin becomes red and vesicles
  appear in the affected area .
• These vesicles dry up in 5-6 days , and the pain
  subsides .
• Sometimes small scars and anesthesia remains in
  the affected segment