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Jimbo suffers a lesion to the entire right half of the spinal cord at the T6 level. A few weeks after his injury, his doctor tests his right and left legs for somatic sensation and tone. fill out her chart concerning the absence or presence of different sensations and muscle tone in the lower limbs. Mark a for absent, P for present

Right leg: Light touch, Pain, Proprioception, Temperature, Hypertonicity, Hypotonicity Left Leg: Light touch, Pain, Proprioception, Temperature, Hypertonicity, Hypotonicity

what about if the lesion is in C1 or L5? where would it affect (leg/hand..) and fill out the above chart?

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Is this a homework question? If so, please use the tag and show how far you got with an answer so far. –  Chris Mar 16 '14 at 14:49
    
it's a practice question. I have no clue how to proceed... –  user3281911 Mar 16 '14 at 15:17
    
For the sensation aspect, dermatomes are a big hint. They will give you a rough idea of some of the motor neuron projections. I'd recommend trying to fill in all that you can and ask specific questions about the portions you don't understand (in the form of "Okay, I know that X ascending tract has been likely damaged, so there's likely to not be any information about Y propagating above a certain level...so, will this mean...") rather than just dropping off the assignment. This is a very useful exercise :) –  jonsca Mar 16 '14 at 22:24

1 Answer 1

This is a classic Brown-Sequard syndrome well- studied in the field of neurology. To answer your question, you would need to know what tracts are being severed and what sensations each tract is responsible for. A clean R hemi-section of the spinal cord at the level of T6 would affect the 1) R lateral corticospinal tract, 2) R spinothalamic tract, and 3) R dorsal columns.

  1. The R lateral corticopsinal tract is an upper motor neuron (UMN) pathway, which relays messages from your brain to the periphery. If severed, it would lead to paralysis of muscles below the lesion on the ipsilateral side. This would result in UMN signs such as increased reflexes, increased spasticity, and muscle weakness.
  2. The spinothalamic tract is a sensory pathway connecting peripheral sensations and bringing them up to the brain. Specifically, it communicates sensations of pain, temperature, and gross touch. If severed on the R side, these sensations would be lost on the contralateral side a few levels below the site of the lesion. The reason for this is due to the decussation, or crossing over, of the tract at or slightly above the level of entry of the nerve fibers into the spinal cord from the periphery.
  3. The dorsal columns are similar to the spinothalamic tract, except the sensations communicated are vibration, fine touch, and proprioception. If severed, this would cause loss of these sensations below the level of the lesion but on the same side. A patient would not be able to balance himself/herself without support.

Regarding what areas of the body would be affected based on a lesion in T6, C1, or L5, just as mentioned by jonsca, one would need a dermatome to understand what areas of skin sensation would be affected, and know the nerve root origins of different nerves of muscles. A great book to read to locate these answers in a table format is Neurology BluePrints.

Otherwise, feel free to open any Neurology textbook for a reference, and look for Brown-Sequard Syndrome to read in more detail.

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