HOUSTON – Even if he survives a horrific head injury suffered in a bus crash, Grammy-winning Tejano singer Emilio Navaira faces a long recovery and an uncertain future, his doctors say.

Navaira, 45, known to his fans simply as Emilio, was behind the wheel of his tour bus before dawn Sunday following a weekend show when it slammed into an interchange barrier on a Houston-area freeway, propelling him through the windshield.

He remained in critical condition Tuesday, said Ann Brimberry, a spokeswoman for Memorial Hermann-Texas Medical Center hospital.

Police said while the crash remained under investigation, their preliminary probe showed Navaira was not licensed to drive the 26,000-pound bus. His agent said the singer loved to drive it and normally did.

The neurosurgeon who operated on the San Antonio-born Navaira to remove a blood clot warned that the performer “might not make it.” Physicians hoped a research technique using hypothermia to lower his body temperature would keep Navaira’s brain from further swelling and help his recovery.

“It’s very difficult to predict any one person, how they’re going to do,” Dr. Alex Valadka, director of neurotrauma services at Memorial Hermann-Texas Medical Center and vice chair of neurosciences at the University of Texas Health Science Center at Houston, said Monday.

“I think it is a good sign so far the pressures in his brain have not risen and have been controlled. The longer we can keep doing that the better it is for him.”

Even if Navaira pulls through, the effects on his health “can be as bad as not surviving,” Valadka said. They could include a coma, vegetative state, weakness or paralysis, difficulty speaking, memory loss and inability to concentrate.

He put the survival rate for those suffering similar severe brain injuries at 30 to 35 percent.

The singer was among six people – all but one of them band members – aboard the bus and hurt in the crash on Interstate 610 in Bellaire, an enclave in Houston. They were returning home to San Antonio after playing at a Houston club Saturday night.

The singer’s blood will be tested for alcohol but the results likely wouldn’t be known for a couple of weeks, he said. Also under consideration was the possibility that Navaira fell asleep.

Of those also hurt on the bus, bass player Rick Vega remained hospitalized Monday with undetermined abdominal injuries, said Joe Casias, Navaira’s friend and agent. The others, including Navaira’s brother, Raul, who sang in the band, were treated for cuts and bruises and released.