During the first surgery, a third of Leone's skull was removed to alleviate the swelling suffered from the beating.
"It was really close for him, real but he pulled through," said Nathan Leone, Matthew's brother.
Wednesday's surgery was to reapply the removed portion of the skull.
"He is in agonizing pain and kind of in and out of consciousness," Nathan Leone said.
"It was wonderful to see him, very difficult, and it was for a very brief moment that is about all I could handle," said Ajay Gosain, Matthew's friend and advisor.
Leone was hospitalized in June with severe brain trauma after intervening to stop a man beating his wife in the 1300-block of West Ohio.
His insurance had lapsed two months prior to the incident.
The Smashing Pumpkins return to Chicago Tuesday to perform a benefit concert to raise money for Matthew's medical needs.
"The got us into music in the first place. There are no words to explain how incredibly compassionate everyone has been, and for someone like Billy of the Smashing Pumpkins-- who has meant so much to us -- to come forward and do this," said Nathan Leone.
"He was trying to good and do the right thing. Now, people are trying to do the right thing to help him," Gosain said.
And it's not just local musicians rallying to help Leone pay for his growing medical costs.
"Madonna, Lady Gaga, Metallica, Gene Simmons from Kiss, tons of them have all donated items for auction to help raise money for Matthew," Nathan Leone said.
Justin Pivec, 33, is charged with aggravated battery causing great bodily harm in the attack on Leone.
Raffle tickets to benefit concert are being sold for $10 and can be purchased online at metrochicago.com.
The raffle ends at 2 p.m. Saturday.
Matthew Leone Benefit Concert
3730 N. Clark St.