A Gig Harbor neurosurgeon accused of beating a man with a thermos in an alleged road rage attack told investigators he was upset because he’d been treating a teenage kayaker critically injured Sunday on American Lake.

Dennis J. Geyer, a Madigan Army Medical Center neurosurgeon, was arraigned Tuesday in connection with the incident Monday. He pleaded not guilty to a charge of second-degree assault with a deadly weapon.

Court documents gave this account:

A van cut off Geyer, 37, while he was driving west over the Tacoma Narrows Bridge. Geyer followed the van for about 10 minutes to East Bay Drive Northwest and Wollochet Drive Northwest.

He got out of his car and knocked on the van’s window. The 60-year-old van driver later told deputies that he tried to apologize to Geyer, but said the doctor pulled him from the van and began hitting him.

A witness said Geyer hit the other man in the face with the man's thermos.

Geyer later denied using the thermos as a weapon, but the 13-inch-tall steel container was found at the scene with several dents in it.

Deputies arrived to find the van driver still at the scene. He had several cuts and chipped teeth and was taken to a local hospital.

Witnesses got the license plate number for Geyer’s Mini Cooper, and he was found and arrested at his Gig Harbor house.

Geyer told officers that the van driver and he had argued before he threw one punch. After the fight, Geyer told deputies that he panicked and left the scene.

He said he’d been upset after treating the young kayaker, according to deputies, a county prosecutor and Geyer’s attorney.

The 14-year-old boy was critically injured when his kayak was hit by a powerboat whose driverleft the boy face-down in the water. David Kenny Ross was rescuedby fisherman and taken to Madigan.

Ross, who suffered broken ribs and a large gash in his head, went through five surgeries Sunday. His ruptured spleen had to be removed, and doctors cut away part of his skull to relieve swelling of his brain. More surgery was planned.

Lakewood police were still looking for the boater Tuesday.

Geyer’s attorney, Wayne Fricke, said there was more to the story than what the court documents allege. He said Geyer wasn’t the aggressor in the incident, but that he regrets being involved in it.

Brian Everstine: 253-597-8374 blogs.thenewstribune.com/crime