2.5. Study groups

One hundred twenty patients were sequentially allocated to be in one of 2 groups (60 in each). Group I: Each patient in this group treated with PRF on the affected DRG at 42°C for 120 seconds.^[22] Group II: Each patient in this group treated with PRF as in group I plus oral ALA 600 mg (Thiotacid 600 mg, EVA PHARMA, Egypt) three times per day (1800 mg/day) for 3 weeks then the dose was reduced to 600 mg once daily for 2 weeks. Studies showed that a dose of up to 1800 mg of ALA for 3 weeks are safe,^[23] after that the dose should be reduced to avoid oxidative damage of chronic high dose.^[24,25]