Patients take supine position. After skin disinfection with 75% ethanol routine disinfection, the stainless needle will be inserted in GV20（Baihui) and the stainless needle will be inserted in GV26 (Shuigou), acupoints will be stimulated manually until patients feel soreness, distension or heaviness . Then, the needles are stimulated by using an acupuncture point nerve stimulator , 28 days as a course of treatment, once a day;The 20ug nerve growth factor will be dissolved in 1 ml sterile water for injection and then injected intramuscularly at gluteal muscle, once a day for 4 weeks before the EA intervention. Dose modification is not allowed for mNGF.

Other patients will receive 1ml volume of physiological saline (PS) injected into the gluteal muscle, once a day for 4 weeks.

Patients take supine position. After skin disinfection with 75% ethanol routine disinfection, the stainless needle (size 0.25mm×40mm, Hua Tuo brand, Suzhou Medical Supplies Company Ltd in Jiangsu, China) will be inserted in GV20（Baihui) and the stainless needle(size 0.25mm×25mm, described above) will be inserted in GV26 (Shuigou), acupoints will be stimulated manually until patients feel soreness, distension or heaviness (the reaction of "De Qi"). Then, the needles are stimulated by using an acupuncture point nerve stimulator (HANS-200, Nanjing Jinsheng, Ltd., China) with a frequency of 2/100 Hz and an intensity of 3 mA for 40 min (a homemade relay cycled power to the electrode for 6 sec on and 6 sec off), 28 days as a course of treatment, once a day.

The only difference between sham EA intervention and EA intervention is that the stimulator is connected to the needle handle without power for 40 min intervention.

Modified Barthel Index (MBI) is a common indicator to evaluate motor function.The maximum total score of Modified Barthel Index is 100, with a higher score meaning less dependent to help.

timed up and go test (TUGT) is a common indicator to evaluate motor function.In the timed up and go test, each patient is asked to stand up from an armchair at height 45 cm, walk a distance of 3 m, turn, walk back to the chair, and sit back down in chair . With interval of one minute rest, a patient is required to repeat the test three times to take its mean for statistical analysis.

Tinetti Performance Oriented Mobility Assessment (POMA) is a common indicator to evaluate motor function.POMA scale can be used to assess the balance with B-POMA including nine components (sitting balance, arises, attempts to arise, immediate standing balance, standing balance, nudged, eyes closed, turning 360 , and sitting down; maximum 16 points) and to evaluate the gait with G-POMA including seven components (initiation of gait, step length, step symmetry, step continuity, path, trunk, and walking stance; maximum 12 points) . A patient with POMA scored less than 24 points suggets balance dysfunction and scored less than 15 points indicates danger of falling.