--for a deterioration of the nerve fibers themselves in sensory nerves, as opposed to deterioration of the myelin sheathing.

Of course, not all nerves have myelin coverings--the small fibers that subsume the sensations of pain and temperature do not, so damage to them is by definition axonal. There are also small, unmyelinated fibers that control many autonomic functions (such as blood pressure and sweating).

One can also have deterioration of the sensory trunks in larger, myelinated nerves--these tend to be on the periphery in these nerves (the motor nerve trunks are more in the "center of the cable").

Just labelling the condition "sensory axonal neuropathy" does not indicate which fibers are involved or what caused the situation, though.