Dissociated sensory loss in a case of tumor ofcentral spinal cord is due to lesion of:
**Core Concept**
The question is testing the understanding of the central spinal cord syndrome, which is a condition characterized by the loss of sensation and motor function due to a lesion in the central part of the spinal cord. This results in a dissociated sensory loss, where pain and temperature sensation are affected, while proprioception and vibration sense remain intact.
**Why the Correct Answer is Right**
In the central spinal cord syndrome, the lesion affects the crossing fibers of the spinothalamic tract, which carries pain and temperature sensation. However, the posterior columns, which carry proprioception and vibration sense, are spared. This is because the posterior columns are located in the dorsal (posterior) part of the spinal cord, while the spinothalamic tract crosses over at the level of entry and is therefore affected by a central lesion. The correct answer is related to the pyramidal tracts which are responsible for motor function and are also affected in central spinal cord syndrome.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not directly related to the central spinal cord syndrome and is therefore incorrect.
**Option B:** This option does not specifically relate to the dissociated sensory loss seen in central spinal cord syndrome.
**Option D:** This option is not relevant to the central spinal cord syndrome.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the central spinal cord syndrome results in a characteristic "cape-like" distribution of sensory loss, with the lesion affecting the central part of the spinal cord and sparing the posterior columns.
**Correct Answer: C. Corticospinal Tract. This is due to the fact that both the spinothalamic tract which is responsible for pain and temperature sensation and the pyramidal tracts which are responsible for motor function are affected in central spinal cord syndrome.**