A passenger is alleging that an American Airlines flight attendant punched him in the face and back of his head, resulting in traumatic brain injury and severe headaches, according to a new lawsuit.

Gregory Lagana alleges that a flight attendant on flight 1798 from Charlotte, North Carolina, to Philadelphia on Jan. 5, 2018, pinned down his right arm and repeatedly punched him in the face and back of the head while he was seated with his seatbelt fastened. The lawsuit states Lagana suffered "scalp hematomas, abrasions, swelling, redness, bruising and defensive wounds to his hand," and he received care at Princeton Medical Center in New Jersey, including neurological, neurosurgical and chiropractic treatments.

"As a result of the accident, plaintiff suffered severe, serious and permanent personal injuries, as well as mental and emotional injuries rendering him permanently and severely injured," according to the lawsuit obtained by USA TODAY, which was filed in the U.S. District Court for the District of New Jersey on Friday.

The lawsuit contends American is liable for no less than approximately $161,000. American was issued a summons on Monday.

“We are reviewing the lawsuit and the details of the flight," American Airlines spokesman Matt Miller told USA TODAY.

American Airlines declined to comment further.

Lagana, a New Jersey resident, claims in the complaint that his "injuries were caused by an unexpected or unusual event."

He originally booked his flights in June 2017: A United flight from Newark to Bonaire scheduled to leave Dec. 23, 2017, and an American Airlines return flight from Aruba to Philadelphia scheduled for Jan. 3, 2018. Flight delays and cancellations resulted in Lagana being rebooked on multiple flights on his return trip: Aruba to Charlotte and Charlotte to Philadelphia.

The alleged altercation occurred when the flight attendant came through with a drink cart, Lagana's attorney Edward P. Capozzi of Brach Eichler, L.L.C. in New Jersey told USA TODAY. The two argued about his drink order, and the situation escalated from there.

"The guy literally beat the crap out of him," Capozzi said.

The lawsuit says Lagana "was not involved in any wrongdoing that jeopardized the safety of the aircraft."