pt. with acute onset of left side weakness and loss of sensation over left side of body with facial sparing. on protrusion of tongue , detes to the right side which aery involved ?
**Core Concept**
The question tests the understanding of the motor and sensory pathways in the brain and the clinical presentation of a specific type of stroke. The corticospinal tract and the spinothalamic tract are responsible for motor and sensory functions, respectively. The cerebral cortex, particularly the motor cortex, is involved in controlling voluntary movements.
**Why the Correct Answer is Right**
The patient's symptoms, including left side weakness and loss of sensation with facial sparing, suggest a lateral medullary syndrome (also known as Wallenberg's syndrome) or a cortical lesion. However, the presence of detes (deviation of the tongue) to the right side during protrusion points towards a cortical lesion. The corticospinal tract is responsible for motor functions, and a lesion in the left motor cortex would result in weakness on the opposite side of the body (left side weakness). The spinothalamic tract is responsible for sensory functions, and a lesion in the left spinothalamic tract would result in loss of sensation on the opposite side of the body (left side loss of sensation). The facial sparing is due to the decussation of the facial nerve fibers at the level of the pons.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the clinical scenario described.
* **Option B:** This option is incorrect because the symptoms described do not match a lesion in the posterior inferior cerebellar artery (PICA).
* **Option C:** This option is incorrect because the symptoms described do not match a lesion in the superior cerebellar artery (SCA).
**Clinical Pearl / High-Yield Fact**
The clinical presentation of a cortical lesion, such as a stroke, can be remembered using the mnemonic "CARRS": Contralateral weakness, Altered sensation, Righting (deviation) of the tongue, and Speech disturbances.
**Correct Answer:** C. Middle cerebral artery (MCA)