Brain changes associated with menstrual pain

Brain morphological changes associated with cyclic menstrual pain
Published in the journal Pain
Volume 150, Issue 3, September 2010, Pages 462-468
Cheng-Hao Tu, David M. Niddam, Hsiang-Tai Chao, Li-Fen Chen, Yong-Sheng Chen, Yu-Te Wu, Tzu-Chen Yeh, Jiing-Feng Lirng and Jen-Chuen Hsieh

Abstract
Primary dysmenorrhea (PDM) is the most prevalent gynecological disorder for women in the reproductive age. PDM patients suffer from lower abdominal pain that starts with the onset of the menstrual flow.

Prolonged nociceptive input to the central nervous system can induce functional and structural alterations throughout the nervous system.

In PDM, a chronic viscero-nociceptive drive of cyclic nature, indications of central sensitization and altered brain metabolism suggest a substantial central reorganization.

Previously, we hypothesized that disinhibition of orbitofrontal networks could be responsible for increased pain and negative affect in PDM. Here, we further tested this hypothesis. We used an optimized voxel-based morphometry (VBM) approach to compare total and regional gray matter (GM) increases and decreases in 32 PDM patients with 32 healthy age and menstrual cycle matched (peri-ovulatory phase) controls.

Abnormal decreases were found in regions involved in pain transmission, higher level sensory processing, and affect regulation while increases were found in regions involved in pain modulation and in regulation of endocrine function.

Moreover, GM changes in regions involved in top-down pain modulation and in generation of negative affect were related to the severity of the experienced PDM pain.

Our results demonstrate that abnormal GM volume changes are present in PDM patients even in the absence of pain. These changes may underpin a combination of impaired pain inhibition, increased pain facilitation and increased affect. Our findings highlight that longer lasting central changes may occur not only in sustained chronic pain conditions but also in cyclic occurring pain conditions.

Menstrual Cramps May Alter Brain Structure
ScienceDaily (Aug. 11, 2010)

“Primary dysmenorrhea (PDM), or menstrual cramps, is the most common gynecological disorder in women of childbearing age. Lower abdominal pain starts with the onset of menstrual flow and this ongoing pain stimulus can cause alterations throughout the nervous system.

In a study scheduled for publication in the September issue of the journal Pain, researchers report abnormal changes in the structure of the brain in PDM patients, whether or not they are in fact experiencing pain.
Lead investigator, Professor Jen-Chuen Hsieh, MD, PhD, Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan, commented, “Our results demonstrated that abnormal GM [gray matter] changes were present in PDM patients even in absence of pain. This shows that not only sustained pain but also cyclic occurring menstrual pain can result in longer-lasting central changes. Although the functional consequences remain to be established, these results indicate that the adolescent brain is vulnerable to menstrual pain. Longitudinal studies are needed to probe hormonal interaction, fast-changing adaptation (intra-menstrual cycle) and whether such changes are reversible or not.”
32 PDM patients and 32 age- and menstrual-cycle-matched controls participated in the study. MRI scans of each subject were obtained when the PDM patients were not experiencing pain, and maps of gray matter (GM) were created. Both the total GM volume and the GM volume of specific brain areas were determined for both PDM patients and controls.
In these anatomical maps, significant GM volume changes were observed in the PDM patients. Abnormal decreases were found in regions involved in pain transmission, higher level sensory processing, and affect regulation while increases were found in regions involved in pain modulation and in regulation of endocrine function.”

Menstrual cramps may alter women’s brains
Posted 8/13/2010 9:00 AM
By Jenifer Goodwin, HealthDay

“Menstrual cramps are often dismissed as a mere nuisance, but new research suggests the monthly misery may be altering women’s brains.
Researchers in Taiwan used a type of brain scan known as optimized voxel-based morphometry to analyze the anatomy of the brains of 32 young women who reported experiencing moderate to severe menstrual cramps on a regular basis for several years, and 32 young women who did not experience much menstrual pain.

Even when they weren’t experiencing pain, women who had reported having bad cramps had abnormalities in their gray matter (a type of brain tissue), said study author Dr. Jen-Chuen Hsieh, a professor of neuroscience at the Institute of Brain Science at National Yang-Ming University in Taipei, Taiwan.

Those differences included abnormal decreases in volume in regions of the brain believed to be involved in pain processing, higher-level sensory processing and emotional regulation, as well as increases in regions involved in pain modulation and regulation of endocrine function.

Exactly how the changes in the brain could affect women’s experience of pain is unknown, researchers said. But the brain abnormalities suggest that menstrual pain may have similarities with other chronic pain conditions in that over time, repeated bouts of excruciating aches make the brain unusually sensitive to pain — in effect, making the experience of pain worse.

“A long-term bombardment by peripheral pain can elicit plastic changes in the central brain as a reactive adaptation,” Hsieh explained. “It can also be a crucial mechanism that perpetuates the ‘chronification’ of pain” — that is, a mechanism that can turn pain into a lingering affliction.

The study is published in the September issue of PAIN.

Menstrual cramps, or pain in the lower abdomen that occurs when the uterus contracts during menstruation, is the most common gynecological disorder in women of childbearing age, according to background information in the article.

Karen J. Berkley, a professor emeritus of neuroscience and psychology at Florida State University, said menstrual pain is too often not taken seriously.

“This is one of the first groups to call attention to menstrual cramps, the fact that the condition can have an impact on women’s lives, and it’s accompanied by changes in brain anatomy and function,” Berkley said.

Previously, the Taiwanese team reported that women suffering from menstrual cramps also have differences in brain activity as seen by positron emission tomography, another type of brain scan.

“Taken together, those two studies point to the fact that this continual cyclical pain in women is not unimportant,” Berkley said. “”