An Initial clarification of what "loss of sensation" means:
The history in the patient with “numbness” is extremely important. First of all, as with most neurologic complaints, you must determine what the patient means by “numbness.” Some patients are describing loss of sensitivity (anesthesia or hypesthesia) or distorted sensations (paresthesia), which is often described as tingling. Actual loss of sensitivity is more likely to represent true damage to sensory pathways in the nervous system, while paresthesia has a much broader differential. Dysesthesia, that is the perception of an unpleasant (often burning) sensation or allodynia (the perception of innocuous stimuli as being painful) may result from damage to the nervous system or, more commonly, be the manifestation of an underlying painful condition.
Some properties of numbness
The pattern of numbness may help define its origin. Numbness confined to a specific nerve or nerve root distribution (see the maps of dermatomes and peripheral nerve sensory innervation) lead to consideration of peripheral nerve or nerve root damage. Loss of sensation on one side of the body is more likely to result from central nervous system damage and if the sensory loss also involves the same side of the face, you can be sure that the cause is located above the level of the pons.
When there is a clear sensory level (a line on the body, below which sensations are lost), a spinal cord lesion must be suspected. Loss of sensation over the upper limbs or upper part of the trunk bilaterally, with preservation over the lower limbs and buttocks, suggests an expanding intraspinal mass. This so-called “sacral sparing” is seen with intraspinal tumors or syrinxes. Numbness over one side of the face, while being a relatively common presentation of psychiatric disease, can also be caused by damage to the lateral part of the brain stem, or upper spinal cord (spinal tract of the trigeminal). Lateral brain stem damage can also produce a picture of sensory decrease on one side of the head and on the opposite side of the body.
But the article concludes
In summary, the evaluation of numbness can be quite frustrating due to its subjective nature.
So it is in essence a term that can have specific meanings uncertain contexts, but one must be careful to clarify exactly how the term is being used since there isn't one single meaning.
This is all from this link here