Final answer:
Unilateral lesions of the spinothalamic tract in the spinal cord or brain stem will present on the contra-lateral side, 1-2 segments below the lesion.
Step-by-step explanation:
Unilateral lesions of the spinothalamic tract in the spinal cord or brain stem will indeed present on the contra-lateral side 1-2 segments below the lesion. This means that if there is a lesion on the left side of the spinal cord, the sensory deficits will be experienced on the right side of the body, 1-2 segments below the lesion. For example, if the lesion is in the thoracic region, the patient may lose pain sensation on the right leg but retain normal function on the left leg.