MONDAY, Dec. 11 (HealthDay News) -- Hysteria, where patients complain of an ailment with no discernable cause, is not an imaginary disorder, say Canadian researchers.

The team used brain imaging scans to detect evidence of cerebral dysfunction in three women with the condition, more formally known as "sensory conversion disorder."

The findings, published in the Dec. 12 issue of the journal Neurology, improve understanding of conversion disorder, a neurological disorder in which a patient complains of symptoms, but doctors are unable to find anything medically wrong with the patient.

The three women in this study complained of numbness in their left hand or foot. The researchers used MRI to observe how the women's brains responded to stimulation of the numb body parts.

In all three women, stimulation of the numb body part failed to activate the part of the brain that responds to touch. But that brain area did respond when the researchers stimulated both the numb hand or foot and another hand or foot with normal sensation.

"The principal finding is that stimulation of the numb body part did not activate the somatosensory region of the brain, while stimulating both limbs did," study author Dr. Omar Ghaffar, of Sunnybrook Health Sciences Center in Toronto, said in a prepared statement.

Stimulating both the numb and normal-sensing limbs may act as distraction, shifting the patient's attention, and thereby overcoming the inhibition.

"Future studies plan to build on these findings by scanning more subjects and health controls," Ghaffar said. "In addition, a study examining the role of distraction in conversion disorder is under way."