Muriel Lezak, a neuropsychologist who wrote a landmark textbook in the early days of her discipline that became an essential guide to the description of brain injuries and disorders, died Oct. 6 in a memory care facility in Portland, Ore. She was 94.

Dr. Lezak became interested in patients with frontal lobe damage, which affects creativity, reasoning and the ability to relate to people and to plan and organize. As she dealt with interns and other medical personnel, she realized there was no book in her evolving field that comprehensively reviewed the major disorders caused by brain dysfunction and injury, or the techniques, tests and procedures to evaluate patients. Her book, Neuropsychological Assessment, published in 1976, filled that gap.

At the VA hospital, where she worked until 1985, she started a support group to help military wives cope with the altered behavior of their brain-injured husbands. “The people they were married to were no longer there; it was somebody else who was similar, looked pretty much the same, but was no longer the person they were able to love and interact with comfortably,” she said.

As early as 1982, Dr. Lezak sounded an alarm about the effect of head injuries incurred by athletes. “A seemingly harmless blow to the head can cause a serious injury,” she said, citing soccer players in particular because they use their heads to hit the ball.