Dave, a 22-year-old cinematography student, goes into his bedroom about once a month and strangles himself to the point of unconsciousness with a woman's leotard.

He is one of a small but significant number of people who routinely choke themselves to heighten sexual pleasure during masturbation.

The practice, known as autoerotic asphyxiation and often referred to as "scarfing" or "head rushing," kills at least 500 to 1,000 people by accidental strangulation every year in the United States, according to a 1983 FBI study. It is of increasing concern to parents of young white males, the group that most commonly engages in the behavior.

"I think the only reason I'm not dead now is because I don't use a rope," says Dave, who on the advice of his physician agreed to be interviewed on the condition that his real name not be used. "I choke myself instead." Most victims of autoerotic death are found hanging with a noose or belt around the neck.

While experts agree that autoerotic asphyxiation is not a common practice, they also say it could be symptomatic of society's inability to recognize and discuss the healthy sexual development of children.

"Parents will bring their children to the doctor for the slightest physical problem," says Dr. Richard Brookman, director of Adolescent Health Services at the Medical College of Virginia in Richmond. "But they're embarrassed to ever bring up anything that they think might be a sexual abnormality. Even professionals are reluctant" to ask teen-agers about their sexual development, he says -- "or else they don't know how."

It is ironic, says Brookman, that those who deal with the victims of autoerotic death -- coroners, insurance agents and police officials -- are often more familiar with the practice than parents and medical professionals, who might be able to prevent it.

The number of autoerotic deaths that occur every year is difficult to gauge because experts believe many are mistaken for suicides or murders.

Last year there were an estimated eight cases in the metropolitan area -- none in the District, two in the Maryland suburbs and six in Northern Virginia -- local medical examiners say. The latest autoerotic fatality in Northern Virginia occurred two weeks ago.

Dr. William Enos, former chief medical examiner for Northern Virginia, says that most relatives of autoerotic victims he encountered "preferred not to have it known to be an autoerotic death. Many went to lengths to disguise any telltale signs" from police officials and coroners.

"I think people were ashamed because of the connotations of sexual abnormality," says Enos, "and would rather have everybody think it was a suicide."

Experts can tell if the cause of death was autoerotic asphyxiation by one or a combination of the following signs, says Robert Hazelwood, a behavioral scientist who conducted the FBI study:

The victim is found in a secluded location either nude, dressed in women's clothes, or with articles of women's clothing nearby.

The victim had devised an escape mechanism or is found hanging in a position of "non-total suspension," with part of the body touching the ground.

The victim has left records or sketches that indicate a fascination with asphyxia, but usually has left no suicide note.

Photos of nude women, other forms of erotica, mirrors or "fetish" items are found near the victim.

Frequently, the victim had placed some sort of scarf around the neck underneath the strangulation device to prevent welts and scars.

Occurrences of the practice can be traced as far back as A.D. 1000. "There are four different ways that people can hear about this," Hazelwood says. "Word of mouth, literature [writings of the Marquis de Sade and William S. Burroughs are often cited as examples], experimentation and learning by accident."

Experimentation is the most common method of discovery, he says, followed by word of mouth.

"I never learned it from anyone," says Dave. "It started with fantasies I used to have of people choking each other or me choking somebody else and just got more and more elaborate.

"I've been actually choking myself with a leotard for about two years. I'm not trying to commit suicide, but sometimes I come so close to the edge. Every time I do it, I wonder why and I promise myself I won't do it again."

Dr. John Money, a professor of medical psychology and pediatrics at Johns Hopkins University, says there is a "double-barreled explanation" for the practice.

"Perhaps the depletion of oxygen to the brain somehow enhances the feeling of erection in the brain," he says. "However, it is an important point that these people are often punishing themselves for committing what they perceive to be a sexual sin. The punishment is supposed to stop at the last moment. They have no intention of killing themselves."

Autoerotic asphyxiation is a type of sexual deviation known as a paraphilia. There are about 30 paraphilias, Money says, including sadism, masochism and pedophilia (child molesting). They are "an addiction, or the equivalent of an addiction," he says, "and they are defiantly persistent."

Paraphilic behavior can develop, he says, "when adults punish or shame children engaged in normal sexual play."

Paraphilic practices occur much more frequently in males than in females, and experts are unsure why. Money also stresses that paraphilias are not "socially contagious." As a society, he says, "we should not refrain from discussing sexual abnormalities for fear of causing them to spread."

Possible signs of autoerotic behavior, says the FBI's Hazelwood, can include trauma around the neck, shortness of breath and "coming out of his room with red eyes, in a dazed condition."

If parents suspect sexually aberrant behavior in their children, Hazelwood advises them to remain calm and seek advice from a professional. "Children are naturally curious and experimental," he says. "Don't approach them in an accusatory manner. Education is the key here."

Two families from Wisconsin agree. Dennis and Susan Danielson and Carol and Gerald Dusick are parents of sons who were victims of autoerotic asphyxiation. Both couples believe their children might be alive today if they had known about the practice.

"Now looking back," says Dennis Danielson, whose 18-year-old son died on Christmas Day 1982, "we remember coming home early from a party when Bill was 14. We found him in the basement, nude and with a rope around his neck. We thought he was trying to commit suicide, and went about getting him the kind of therapy we thought he needed.

"The coroner who examined him the day he died knew immediately what had happened. When he told me, I was completely caught off guard."

After her 15-year-old son's death in 1983, Carol Dusick decided to research autoerotic asphyxiation. She contacted mental health associations, psychiatrists, pediatricians and the family's personal physician but says no one knew what she was talking about.

"We were always taught to worry about the sexual development of our daughters," she says. "It never occurred to us that boys could have sexual problems.

"I think Brad was trying to signal me, but I wasn't reading the signs. I still don't understand why he didn't say anything outright, but maybe he thought, 'Mom and Dad will think I'm some kind of weirdo.' "

The Dusicks and the Danielsons eventually heard about one another and together decided to speak out about their personal tragedies in hopes of helping others.

Dave -- the cinematography student -- happened to read Susan Danielson's story in his local paper. It was the first time he realized he wasn't the only person in the world with his problem. Eager to seek help, he contacted Danielson, and she put him in touch with a physician who knew about the practice.

Dave is now receiving therapy and says he feels better about himself and his future. "It helps a lot to know why you're doing it," he says. "It's a lot easier to fight off when you know exactly what it is. Now I think I can eventually overcome this."