December 12, 2006 09:36 ET

New research suggests hysteria is real

For the first time, Canadian researchers have discovered evidence of brain dysfunction in patients with sensory conversion disorder, providing support that it's not imaginary as commonly believed.

Attention: Assignment Editor, Health/Medical Editor, News Editor, Science Editor TORONTO, ONTARIO, MEDIA RELEASE--(CCNMatthews - Dec. 12, 2006) - For the first time, Canadian researchers have discovered compelling evidence of brain dysfunction in patients with sensory conversion disorder, providing support that the disorder is not imaginary as commonly believed.

"In examining the brain scans of research participants with sensory conversion disorder, we found evidence of abnormal brain activity in response to stimulation of the areas in question," says Dr. Omar Ghaffar, principal investigator of the study and a resident in Psychiatry and doctoral candidate at Sunnybrook Health Sciences Centre. "This has important implications as it offers some solace to patients who've been told nothing is wrong with them, and it also helps physicians to conceptualize this disorder."

The study, published in the December issue of Neurology, involved three participants who complained of numbness in their left arm or foot that could not be explained by neurological testing. These patients were referred to the Neuropsychiatry clinic at Sunnybrook for further investigation.

The researchers scanned the brain of participants while doing touch-tests on their arms and feet, using two vibrating discs to stimulate both sides of the body while controlling for frequency and vibration. The areas that patients had identified as problematic and numb showed a lack of activation in the primary somatosensory region of the brain, an area responsible for sensation. When the stimulation was applied to the "normal" side of the body, the imaging showed a normal expected activation; an obvious contrast. The resulting observation is an abnormality in brain reaction in the affected side.

"The results of this research clearly indicate the need for more ongoing studies in the area," says Dr. Ghaffar. "We are looking to confirm this evidence in larger studies in the future. In addition, further research is required to study the possible effects of attention and distraction on brain activity as well."

Functional MRI (fMRI) was used to image the brain in this study. fMRI is similar to a traditional MRI in that it provides an excellent high resolution image of the brain, but it also shows brain activity through blood flow when a patient undertakes a task or reacts to stimulation.

Many patients with the disorder complain of difficulties with motor functioning, but the researchers chose to examine sensory symptoms to avoid some of the pitfalls that have bedevilled previous studies. For example, tests of motor function may require subjects to engage in tasksthat require strategy and effort which can skew results due to discrepancies between participants. In addition, too much movement can interfere with the brain scan. The study therefore examined patients with sensory symptoms, which involved passive stimulation testing that did not require any strategy on the part of the patient, in an effort to attain more accurate findings.

Initially and commonly referred to as hysteria, typical patients with sensory conversion disorder complain of neurological symptoms that clinicians can't medically explain. Patients are often told that nothing is medically wrong with them.

Until recently, only a handful of small studies examined this disorder, which showed contradictory results. These previous studies applied either unilateral or bilateral stimulation, whereas this recent study bridged the two, applying both forms of stimulation, and the resulting findings were much more robust. In addition, SPECT imaging was used in the previous research, which is not as strong of a resolution as the fMRI used for this study.

This research was made possible through a collaboration between psychiatrists at Sunnybrook and stroke experts at the hospital's Centre for Stroke Recovery. The researchers were able to apply existing equipment and devices normally used in stroke recovery in this unique way to a different population (conversion subjects).

Patients with unexplained neurological symptoms are estimated to account for up to a quarter of all neurology referrals. Longitudinal follow-up studies of patients with conversion disorder indicate the rate of misdiagnosis is very low, as patients are often not diagnosed with any other disorder or disease even 10 or 15 years after being diagnosed with sensory conversion disorder. This suggests it is not a substitute for other disorders being missed.

The study began in 2004 and was funded by a resident grant from Physicians Services Incorporated (PSI).

Sunnybrook Health Sciences Centre is transforming health care through the dedication of its more than 10,000 staff, physicians and volunteers who provide compassionate and innovative patient focused care. An internationally recognized leader in academic research and education and an affiliation with the University of Toronto distinguishes Sunnybrook as one of Canada's premier health sciences centres. Sunnybrook specializes in caring for newborns, adults and the elderly, treating and preventing cancer, neurological and psychiatric disorders, cardiovascular disease, orthopaedic and arthritic conditions and traumatic injuries.


Media contact:
Nadia Radovini
Communications & Stakeholder Relations
416.480.4040 /For further information: IN: HEALTH

Contact Information

  • Nadia Norcia Radovini, Communications Advisor, Sunnybrook Health Sciences Centre
    Primary Phone: 416-480-4040