In the famous painting of Jean-Martin Charcot by André Brouillet, the doctor stands lecturing an intently observing group of seated men; an unconscious woman is draped over another doctor's arm, with her shoulders bare and her laced corset revealed.

The inert woman is "Blanche" (Marie Wittman), one of the celebrity hysterics who were photographed, sculpted, painted, fictionalised in novels and written about in newspapers in the mid-19th century. The display of hysterics became a public spectacle, with crowds arriving at the Salpêtrière hospital eager to attend the charismatic Charcot's demonstrations of the paralyses, spasms and convulsions that characterised their condition.

Hysteria had traditionally been seen as caused by the womb rising to choke a woman, who was helpless before her anatomy. Now the enlightened Dr Charcot said it was a disorder of the nervous system with a physical cause. It could even be found in men, but only as a result of trauma; in women it was self-generating.

Blanche, one of three women whose stories are told by Asti Hustvedt, became "the queen of hysterics". She had endured a wretched childhood marked by poverty, disease and cruelty, and worked as a laundress then as a hospital "ward girl", doing menial chores. For Blanche at 18, being a hysterical patient was a promise of some security and even freedom within the confines of the hospital, which was the size of a small town.

If she behaved badly she was imprisoned in a locked ward where the mad women were kept. She therefore adjusted her behaviour to suit, and became increasingly not just an ordinary hysteric but an exemplary one, displaying medically perfect symptoms of the condition.

She was able to demonstrate "hysterogenic zones": areas on the body thought to trigger hysterical fits. The use of a vice-like device called the "ovary compressor" suggested that Charcot had not really moved away from the belief in hysteria as a disease of female organs. Blanche became so attuned to the compressor that Charcot could play her like a mechanical toy: ovary compressed  no hysteria; pressure released  hysteria comes back. It was apparently a remarkable demonstration of the truth of his theory, as was "demographism", where in a Kafkaesque display, the diagnosis was literally written on the patient's body in raised red welts.

She was also a star of hypnosis, for Charcot believed their ability to be hypnotised easily was a diagnostic characteristic of hysterics. Hypnotism was used not to treat a patient but to induce her to display her symptoms for onlookers. Blanche was told to become an animal  a dog or a bird; or told to kiss the statue of a man; or to undress.

One side-show, in a book already packed with wonders, is the story of Jean Avril (later to be painted by Toulouse-Lautrec) who was an inmate at Salpêtrière, and was, as she proudly said, "among the great stars of hysteria". She described their petty rivalries and how they competed for lead parts in Charcot's demonstrations.

Even when Charcot was alive, some suspected Blanche was performing a script authored by the doctor himself; others felt she was a fraud, deceiving everyone including Charcot. In fact, he developed his understanding of the illness with her; his interest in hysteria coincided with her arrival at the hospital as a very disturbed young women.

In an absurd parody of the doctor-patient relationship, Charcot's patients were not there to be cured, but to improve their ability to be ill: to learn how to become better hysterics. When they wanted to punish Charcot, they withheld their symptoms from him. Blanche never left the Salpêtrière hospital, but her fits stopped when hysteria ceased to be a medical fashion, soon after the death of the charismatic Dr Charcot in 1893.

Hustvedt had intended to produce a book about exploited women and exploiting men, but she found something more nuanced. The celebrity hysterics were indeed exploited but they also exploited the system, participating in a hospital culture that was in many ways less oppressive than the world beyond it.

This turns Hustvedt's book into a study of how the diagnosis of illness can be chosen, a negotiation between doctor and patient. With a nod to contemporary life, Hustvedt points out that "no drug exists to cure anorexia, bulimia, self-mutilation, chronic fatigue syndrome and multiple personality disorder and no genetic flaw has been found to explain them. Furthermore, as was true for hysteria, these contemporary disorders are thought to be contagious, spread by suggestion, imitation and therapy."

In a work of painstaking research there are also depictions of Charcot's students and colleagues including the celebrated Georges Gilles de la Tourette, Alfred Binet and Sigmund Freud, who, two years after Charcot's death, claimed that his mentor was wrong. Freud now said hysterics were not suffering from a lesion in the nervous system but from repressed memories and ideas. This was something it was possible to verify to some extent because of Charcot's insistence on taking detailed case histories, which were also invaluable to Hustvedt in writing this fascinating book.

Jad Adams's Gandhi: Naked Ambition is published by Quercus.