The numbness in the back may be caused by the following reasons: 1. Long-term cold stimulation in daily life, or local muscle damage, can cause fasciitis in the back and cause numbness. 2. The numbness may also be caused by a herniated disc in the lumbar spine. The back is numb, the patient is best to go to the hospital in a timely manner for a film examination, to see specifically due to which cause, and then give targeted treatment.