What does it mean when an emg states that lateral plantar cutaneous sensory responses are absent on the left?

Lateral plantar : It means that the nerve is not sending the appropriate nerve messages back to the spinal cord & brain. It probably means you have either numbness or pain of the inner heel area. I imagine you had this test done so the doc could decide if you had lateral plantar nerve entrapment amoung other possibilities.

EMG: The question is why the EMG was done? But in general means you have a damage to the nerve and therefore you have a neuropathy. Sometimes the nerve becomes entrapped and causes the neuropathy.