Kurt Busch To Miss Fourth Straight Race As Troubling Concussion Symptoms Linger

Kurt Busch can't clear concussion protocols and is set to miss his fourth straight NASCAR Cup Series race this weekend at Richmond. 

The former Cup champion took to Twitter late Wednesday, saying he pushed to get his "heart rate and body in a race simulation type environment, and it's clear that I'm not ready to be back in a race car."

Ty Gibbs, the grandson of Joe Gibbs, will once again drive Busch's No. 45 Toyota.

Kurt Busch hasn't raced since New Hampshire

Busch, 44, hasn't raced since finishing 10th at New Hampshire on July 17.

He was involved in a huge crash during qualifying the following week at Pocono, missed that race and hasn't been cleared since.

Related:Bubba Wallace goes nuts after Michigan loss

Last week, Busch, who won earlier this year and will receive a playoff exemption, tweeted out a video of him attending a Charlotte FC soccer game as part of his recovery.

Dale Earnhardt Jr. involved with Kurt Busch's recovery

It's also been reported that Busch is working with Dale Earnhardt Jr.'s medical team, which helped Junior when he missed the second half of the 2016 season with a concussion.

Earnhardt Jr. returned the following season for all 36 races before retiring.

"Kurt’s patience and transparency is a massive relief," Junior tweeted Wednesday. "I’m so thankful he is making sure he will be 100% for a return."

Kurt Busch has a playoff waiver, but will it last? (Photo by Matt Sullivan/Getty Images)

Earnhardt Jr. also tweeted in support of Busch last week ahead of the Cup race at Michigan.

"Going to complex environments challenges the brain," he said of Busch attending the Charlotte FC game. "It exposes symptoms and produces opportunities to control anxiety and emotions. Concerts, grocery stores, all the busy places are great ways to push yourself in rehab. Way to go Kurt."

There is still no timetable for Busch's Cup return, but it's worth nothing there are only three regular season races left before the playoffs begin Labor Day weekend.

Kurt Busch hasn't been in a car since a scary qualifying crash at Pocono. (Photo by Tim Nwachukwu/Getty Images)

Is Kurt Busch's playoff spot in jeopardy?

It's also worth nothing that while NASCAR granted Busch a playoff exemption, meaning his missed races don't count against him, that doesn't protect him if more than 16 drivers win and the playoff cutline shifts to most points earned.

Right now, Busch sits 20th place in the points after missing three races, despite his win at Kansas in May. The next lowest single-race winner is Daytona 500 winner Austin Cindric, who is 46 points ahead of Busch.