The five-time major champion was forced to pull out in Canada after experiencing discomfort, but has since had scans on his cervical spine in New York on Monday and the results reportedly came back clear.
The scans focused on the C5 and C6 vertebrae - previously herniated in 2021 - as well as the C6 and C7 area.
Koepka maintains there is no doubt over his participation at Shinnecock, where he will target a third US Open title, and did not practice on Monday as he continues to manage the issue.
According to reports, his medical team believes there are two possible explanations for the problem: a flare-up of the ulnar nerve, which can cause pain, numbness and weakness in the arm and hand, or thoracic outlet syndrome, where nerves or blood vessels are compressed between the neck and shoulder.
Despite the concern, Koepka made clear there is no consideration of missing the tournament. When asked if withdrawal was a possibility, he responded simply: "I'm gonna go this week."
Wyndham Clark returns to US Open duty this week seeking redemption after a challenging moment at last year's championship, where frustration boiled over following his missed cut.
Jackson Suber will take a narrow one-stroke lead into the wide-open final round of the RBC Canadian Open on Sunday.
Plagued by health issues since November, Marco Penge has been forced to skip next week's US Open at Shinnecock Hills.
Seventeen-year-old Miles Russell secured his US Open place on Monday, with Charlie Woods - son of Tiger Woods - on the bag during his 36-hole final qualifier.
