A woman we'll call Sally lived in a small town deep in the heart of Texas hill country, a long, rippled patch of land wet with creeks and big oaks growing right out of the water. It's mostly middle class, mostly Christian, the sort of place where you don't have to lock your doors because you already know all your nosy neighbors. She lived with her husband and her kids were grown.

One day her husband took her out for a ride on his motorcycle. When they picked up speed, she was sucked off the back. Sally flew through the air, legs akimbo, and landed on her bottom. The doctors at the ER told her she had compressed a number of disks in her spine, broken her tailbone and snapped her wrist in three places. “Yeah, I messed myself up pretty good,” she says.

After running a gauntlet of surgeries, drugs and physical therapy, her spine started to heal. Things were looking up. She was having some trouble with her bladder—“felt like I needed to pee all the time”—but doctors were taking care of that.

Then it happened.

Sally got really, really horny.

But she didn't want to be. Though she didn't know it at the time, Sally had restless genital syndrome (ReGS), a recently discovered, mysterious disease that causes maddening sexual arousal for thousands of men and women worldwide. It's not sex addiction. It has little to do with conscious desire. Though it causes psychological distress—many patients become suicidally depressed—ReGS is a peripheral wiring problem.

Triggered by some combination of physical trauma, medication and hormonal changes, the nerves of the pelvis send waves of unwanted and disturbing signals to the brain. For example, you might feel the need to masturbate for 12 hours at a stretch. You might feel a constant buzzing, tingling sensation in your crotch. You might have an orgasm because your jeans brushed you the wrong way in the supermarket. You might start to avoid both your jeans and the supermarket. Soon your life will be nearly impossible to manage.

The renowned sexologist Sandra R. Leiblum originally discovered ReGS in 2001. Though most scientists think the disorder is fairly rare, clinicians in the field say diagnoses are on the rise, at least in part because it is becoming better known. Irwin Goldstein, director of sexual medicine at Alvarado Hospital in San Diego, has seen hundreds of patients with ReGS in his practice. At national conferences, he will ask from the podium how many clinicians believe they have seen patients with ReGS, and two thirds of the audience will raise their hands. David Goldmeier, a sexologist at St. Mary's Hospital in London, conducted a survey at a walk-in clinic for sexual disorders and found that a full third of the women had some kind of spontaneous or persistent genital arousal. But far fewer of his subjects fully qualified for a ReGS diagnosis, and none of these tiny samples can tell us how many people really have it.

Like many patients with sexual dysfunction, Sally found herself deep in the American heartland with a startling realization: she was not entirely “in charge down there.” But sexuality is not a top-down system. The brain doesn't just decide to become sexually excited and then send signals to the appropriate spots. The brain and the peripheral nervous system work together to build an individual's sexuality—and their rapid-fire conversation can become prickly when the two disagree.

Searching for a Diagnosis

Sally calls her husband a “trooper.” In the beginning, he was very supportive, even as his wife alternated between crazed sexpot and withdrawn depressive, even though he didn't really—couldn't really—understand. He drove her to doctor after doctor, although driving was the worst. The low vibration of a car seat had become unbearable for her.

There are essentially four places in the world where doctors know the latest about ReGS: California, New Jersey, the U.K. and the Netherlands. Sally did not live in any of these places. Though eventually she would discover all the top names in this burgeoning field, the only doctor she knew at first was her urologist. She still felt like she had to pee all the time.

Like many people suffering from ReGS, Sally described her symptoms with electrical metaphors—a “shock,” “buzzing” or a “zap,” that feeling of being right at the edge of an orgasm, the itchy, breathless before. It wasn't pleasurable, however. It was painful—and once it started, it wouldn't stop. It came in waves, sometimes for hours a day. If Sally had an orgasm, it only got better for a minute or two, and then the pain returned. “I couldn't think of anything worse to happen to a human being,” Goldstein says. “To be at the throes of high arousal, almost anything pushes you into it, and [that] brief refractory period hoping you can get some respite, but you don't, it comes right back.”

The accepted wisdom is that ReGS involves some malfunction of the pudendal nerve complex. Hooking onto the bottom of the spine, the pudendal nerve is a thick bundle of fibers that branches out to innervate the lower pelvis. One branch controls the anal sphincter, another the urethral sphincter and a third dorsal branch extends, in men, to the end of the penis and, in women, to the fat club of the clitoris. It's generally a well-liked part of the peripheral nervous system.

At Haga Hospital in the Hague, neuropsychiatrist Marcel D. Waldinger runs one of the world's only clinics specializing in ReGS. He noticed in 2008 that ReGS symptoms tended to occur together with an overactive bladder and restless legs syndrome—the persistent, nervous urge to twitch one's legs because they feel “strange” or “tingly.” Thinking of the way the sacrum serves as a nerve hub for both the pelvis and the legs, Waldinger realized these disorders could be essentially the same problem: chronic aberrant neural activity around the sacrum, just referring to different places—the sciatic nerve for restless legs or the pudendal nerve complex for restless genitals or overactive bladders. Sally fit this profile: her bladder was what led her to a urologist in the first place.

Such academic discussions are all well and good, but the sciatic nerve doesn't challenge a woman's self-worth quite the way the pudendal does. One quiet night in Texas, Sally did not know what was wrong with her yet. She had taken to drinking wine alone at home because it seemed to numb her a little. She also took pills to sleep. She remembers talking on the phone with her sister, drinking from the bottle, taking some pills, and then drinking more and taking more pills. Her sister was telling her to stop, to hang in there, that it wasn't worth it. Did she want to die? Maybe? Maybe. They found her in time.

Luckily, Sally's urologist had recently gone to a conference where she had heard Goldstein speak about his research on ReGS. Sally had her first glimmer of hope in years. Now she had a diagnosis that felt right to her—“I wasn't crazy. It was real. A real thing,” she says. Finally she could find a doctor for what she was actually suffering from: not her bladder, but her nervous system. As for why her body went haywire, the accident wasn't the only culprit. It probably also had something to do with her uterus: Sally didn't have one.

The Many Lives of Serotonin

Sally had been artificially menopausal for many years before the accident. She had had a hysterectomy at age 27, with little in the way of hormone therapy since. Men and women both have a wide variety of sex hormones—estrogens, androgens and progestogens—in a sex-typical balance. In women, that balance changes with menopause. Women diagnosed with ReGS vastly outnumber men, with menopausal women forming the largest segment of ReGS cases. And Sally's body was in a kind of extreme menopause because she had neither a uterus nor ovaries.

One of the many roles of estrogens in the body is their influence on serotonin, a neurotransmitter that, among other duties, helps to regulate blood flow. Vasoregulation is incredibly important for sexual function. Just as it enables erections in men, the dilation of blood vessels in a woman's pelvis swells tissue in and around the vagina and spurs the production of lubricating mucus. The nerves of the genitals become extra responsive, and the entire area gets ready for coitus. In part through their actions on serotonin, the estrogens—especially estradiol—normally facilitate this process. In women of reproductive age, blood levels of estradiol correlate positively with serotonin levels. As estradiol decreases with menopause, the genitals can become less sexually responsive—not from any psychological predetermination, but because of what is essentially a plumbing problem.

Menopause is not the only way to manipulate serotonin levels, however. The most popular type of antidepressant, selective serotonin reuptake inhibitors (SSRIs), also targets serotonin. These medications can similarly diminish blood flow in the pelvis, thereby blunting sexual responsiveness. Erectile dysfunction and its analogue in women are such common side effects of SSRIs that some doctors are now in the habit of prescribing a cocktail of antidepressants and Viagra.

Many patients with ReGS link SSRIs to the start of their symptoms. Goldmeier and Leiblum published a paper on the link between SSRIs and ReGS in 2008; more papers have followed. In most cases, symptoms seem to start after either reducing dosage or discontinuing SSRIs. It has been known for some time that going off these drugs can cause negative side effects, including problems with mood, dizziness, headaches, digestion and sexuality. In 1996 the Eli Lilly company—flush with recent Prozac money—held a symposium on these issues. One study found that up to 80 percent of patients suffered from withdrawal symptoms, although after the symposium these were called “discontinuation syndrome.”

SSRIs boost levels of serotonin at synapses (the junctions between neurons) by blocking neurons from corralling leftover serotonin after the neurotransmitter has done its job. The body may adapt to the excess by reducing sensitivity to serotonin overall. After a patient quits or lowers the dose of an SSRI, neurons can quickly scoop up the free-floating molecule, causing serotonin levels to drop even while the nervous system might still be less sensitive to serotonin—a double whammy. In patients who go on to develop ReGS, this change could lead to a vascular system that neither constricts enough nor dilates enough under the appropriate circumstances. The pelvic nerves may also go on the fritz, becoming chronically hyperstimulated. For some, ReGS will mysteriously go away after a month or two. For others, such as Sally, the disease gets progressively worse. Even more inexplicably, some patients get relief from taking an SSRI when their symptoms flare up.

As Waldinger describes it, ReGS is a kind of umbrella diagnosis: lots of different things can cause the neuronal misfiring associated with ReGS. No one knows for sure why Sally got it, but she had risk factors. Sally had once taken SSRIs for depression, but she was not on them when her ReGS symptoms developed; she had experienced dramatic hormonal changes after her hysterectomy, however, and, of course, she had suffered severe trauma to the pelvis.

Finding the Code

Newly armed with a name for her disorder, Sally wasn't sure what to do. But she couldn't do nothing. She was tired of feeling like a “live wire.”

Sally had already quit her job. Many ReGS patients lose their jobs. As she says, “You just can't function.” Unfortunately, they are also unlikely to be eligible for disability benefits in the U.S. Although ReGS is now fairly well documented in the scientific literature, the disorder is not yet named in the current Diagnostic and Statistical Manual of Mental Disorders (DSM-5) or the International Classification of Diseases. These two bibles of medical diagnosis—one for mental disorders, one for more general epidemiology—are the main points of reference for how American Medicare and insurance companies generate “codes” for claims.

In the DSM-5, a condition called “substance/medication-induced sexual dysfunction” mentions the SSRI fluoxetine, but the diagnosis refers to problems of diminished libido such as erectile dysfunction, not rampant, life-crippling sexual sensations. And, of course, ReGS is not always caused by medication.

Like any bible, the DSM is slow to change. The book still listed homosexuality as a pathological “sexual deviation” in 1973. Conditions based on physical neuralgias move a bit faster, but debates about sexual disorders tend to linger on a strange bridge between psychological and physiological, which could leave ReGS without an official stamp for some time. The result: insurance will not cover it. Instead some patients are diagnosed with interstitial cystitis—inflammation of the bladder, producing pain and the constant need to urinate.

Waldinger has a novel theory for why patients like Sally always feel on the verge of an orgasm. He thinks the transmission of sexual signals along the dorsal nerve to the lower spine may be turned on, not off, by default. House lamps work that way: once the lamp's cord is plugged in, electricity always runs between the wall and the lamp. The switch simply permits that energy to reach the bulb's filament. In this line of thought, your dorsal nerve may be, under normal circumstances, always ready to send signals to your spine that say, “Hey, orgasm incoming.” Yet because of a complex inhibitory system surrounding the nerve, we only “hear” that signal at the right time.

Much of the human nervous system relies on complex arrangements of excitation and inhibition. One neuroscientist in Eric R. Kandel's laboratory at Columbia University estimates that roughly 20 percent of the neurons in the brain are inhibitory. For some patients with ReGS, Waldinger suspects that a specific kind of neuropathy—a problem with small fibers around the dorsal nerve—interrupts an inhibitory system, leaving the switch jammed on.

Whatever the underlying mechanism for the neural misfiring, dampening or interfering with that signal is the goal of every type of treatment available for patients like Sally. Every clinician in the know will prescribe a combination of psychotherapy to cope with the pain and embarrassment, hormonal or neurotransmitter drug therapies to deal with the nerves, and sometimes mechanical intervention. Some patients receive anesthetic nerve blocks to mute the dorsal nerve or the pudendal complex overall, but these blocks tend to wear off over time, and the injections can be phenomenally painful.

Waldinger's practice has seen some success with TENS units, small boxes that send electrical signals down to nerves through the skin—in this case, wiring up women's genitals like something out of a steampunk magazine. (“TENS” stands for transcutaneous electrical nerve stimulation.) Goldstein sends some of his patients to a hospital in Michigan for a $60,000-plus surgery in which a kind of pacemaker is installed near the buttocks, sending controlled bursts of electricity down toward the sacrum. Both interventions are designed to interfere with, and thus impede, the errant nerve signal. Among other remedies, patients may try botulinum toxin, electroconvulsive therapy, or surgery to aspirate and seal cysts in the lower spine—a condition that behavioral neuroscientist Barry Komisaruk of Rutgers University has recently linked to ReGS.

Every patient's treatment is a bit of an experiment. No single intervention has been proved effective in the majority of cases, so doctors have to approach treatment for ReGS as trial and error, taking account of each individual's particular history and symptomatology.

Sally didn't have many options. Based on a recommendation from her urologist, she was starting to think a visit to Goldstein in San Diego sounded pretty good. She just wasn't sure she could afford it. Texas is a long way from California, and Goldstein's clinic is expensive. Yet his patients hold him in a kind of reverence. Of all the scientists and clinicians who work with ReGS, he is the most hopeful about treatment outcomes, and many patients of his have seen some relief. Without insurance, however, trial-and-error treatments rack up significant medical bills. One woman took out a second mortgage on her home to afford it all.

“I Wish My Wife Had That Problem”

Shame is a huge barrier to more comprehensive clinical research into ReGS. Sally needed to be called “Sally” in this story, rather than her real name, because she lives in a small, conservative town. Other patients with ReGS have even stronger motivations to keep quiet. Goldstein says people could be fired: “A kindergarten teacher having sexual feelings in her classroom—can you imagine?” Women with the disorder often feel ashamed to come forward and speak with their (frequently male) doctors. Among those who have, many feel frustrated by the responses they receive. One physician Sally had consulted told her, “Gosh, I wish my wife had that problem.”

Perhaps we can forgive that particular faux pas. His patient was a middle-aged woman, and people continue to conflate a woman's menopause—the cessation of her menstrual cycle—with the death of her sex life. Libido naturally decreases with age in many populations, but there is no evidence that it goes away entirely. Nor does it wane particularly in women, although many women expect it to. It is unclear whether this very belief—that they are not supposed to be aroused so often—is part of why women vastly outnumber men right now in the rank and file of ReGS. Maybe women are more likely to report their symptoms to their doctors. Men with the disease typically say they felt ashamed to go to the doctor with a complaint because sexual desire is supposed to be “manly.” Even Sally's husband, who loved her deeply, struggled to reconcile his wife's illness with old ideas about women's sexuality. He worried, Sally says, that he “wasn't enough” for her, that maybe she just wanted to sleep with other people, that she was not taking care of him like a wife should. They were fighting a lot.

Sally wasn't sure why she took the car. She had reasons—she would need a car in California, planes were expensive—but mostly she was scared her husband would leave her and take the car, and she'd be left with nothing.

Sometimes you just make a decision in the middle of Crazy, and that decision anchors you. For Sally, that decision meant driving to California sitting on big bags of ice from gas stations to numb her labia and clitoris. She had a sister in California, a place to stay. It's a 26-hour drive, with two ways to do it: I-10, which takes you through western Texas badlands and the White Sands Missile Range, or up north to I-40 for Albuquerque and Flagstaff, just south of the Grand Canyon. The northern route takes a little longer, but it goes through more proper towns, and proper towns have ice machines. Sally went north. It took her four days.

Sally kept driving. The long, black throat of the road squeezing her little car forward, forward, through the desert, over mountains, one gas station after another, stopping only to pee, to barely sleep, her crotch numbed by an ice pack and still pulsing, still there, the anesthesia of the road dulling her brain, her husband on the phone, crazy with rage, Sally kept driving. Maybe he'd leave her. Maybe he wouldn't. Just drive. Her sister was waiting for her. That new doctor, waiting for her. Just drive. Drive.

Sally still has ReGS—or, as Goldstein calls it, persistent genital arousal disorder (PGAD), the syndrome's original name. Since becoming a patient at Goldstein's clinic, Sally has tried a number of treatments, including hormones, talk therapy and nerve blocks, with little success. She eventually got the surgery in Michigan, which helped greatly. Sex is still a trigger, but she can swim, do Zumba and even drive again without pain. Time will tell if the improvement lasts. For now, she is struggling with the medical bills—her husband is the breadwinner, and there isn't much bread to go around.