1. Handout of Sensory Lesions Handout of Sensory Lesions Dr. Taha Sadig ahmed

2. 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 ?

3. 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 Romberg’s Test. A positive Romberg’s 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 ? Why ?

4. 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 ). 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 : 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 ) A/ Ipsilaterally ( on the same side of lesion ) (1) 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 ? (2) at the level of the lesion : Loss of all sensations +/_ hyperesthesia.

5. 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 temperature sensibility Why ?

6. 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. 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. 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 يحتفظ ب touch and pressure sense as well as vibration and position sensations (why are they spared ?)  However, the patient retains يحتفظ ب touch and pressure sense as well as vibration and position sensations (why are they spared ?) 

7. Syringomyelia (2) The loss of pain and temperature sensations extends to several segmental levels. Therefore, we get Segmental Loss of pain and temperature sensations. The loss of pain and temperature sensations extends to several segmental levels. Therefore, we get Segmental Loss of pain and temperature sensations. This selective إنتقائي loss of pain and temperature while sparing touch and proprioception is called Dissociated sensory Loss ( or Dissiciated Anesthesia) This selective إنتقائي loss of pain and temperature while sparing touch and proprioception is called Dissociated sensory Loss ( or Dissiciated Anesthesia)

8. 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. 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. 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. 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. These vesicles dry up in 5-6 days, and the pain subsides. Sometimes small scars and anesthesia remains in the affected segment Sometimes small scars and anesthesia remains in the affected segment