Pregnancy-Related Restless Legs Syndrome May Recur & Stay

Pregnancy-Related Restless Legs Syndrome May Recur, Become Chronic

by Megan Brooks

December 6, 2010 — Women who develop transient restless legs syndrome (RLS) while pregnant are at significantly increased risk not only of having it recur in a future pregnancy but also of developing chronic idiopathic RLS.

This observation "radically changes the concept of prognosis" of pregnancy-related RLS, the study team writes in a report in the December 7 issue of Neurology.

"Women who experience RLS during pregnancy should be warned that symptoms will almost certainly vanish during the puerperium but might reappear later on," they advise.

RLS affects up to 10% of the adult general population, with a female predominance. Pregnancy is a known risk factor for RLS, with up to 30% of women experiencing transient RLS while pregnant, although symptoms usually subside after delivery.

"No studies have been done so far on the long-term follow-up of pregnant women with RLS," Mauro Manconi, MD, PhD, of Vita-Salute University in Milan, Italy, notes in an email to Medscape Medical News.

Transient RLS May Become Chronic

In a planned extension of a prior study on RLS during pregnancy, Dr. Manconi and colleagues reinterviewed 207 women an average of 6.5 years later. Seventy-four of the women had experienced RLS during pregnancy, whereas 133 had not (the control group).

Among all 207 women, a total of 28 reported RLS symptoms during the 2 months before the follow-up interview (total prevalence rate, 13.5%; 95% confidence interval [CI], 9.2 – 19).

Eighteen of the women who had pregnancy-related RLS (24.3%; 95% CI, 15.6% – 35%) also had RLS at follow-up, compared with only 10 of the women who did not have pregnancy-related RLS (7.5%; 95% CI, 3.9% – 13%).

Women who experienced pregnancy-related RLS were roughly 4 times more likely to have RLS at follow-up as women who did not experience RLS in pregnancy (odds ratio [OR], 3.9; 95% CI, 1.7 – 9.4), the study team notes.

They also note that 24 women from the pregnancy-related RLS group had a new pregnancy during follow-up and 14 (58.3%) reported RLS in the new pregnancy. By contrast, only 1 of 33 women from the control group who had a new pregnancy during follow-up reported RLS symptoms during this pregnancy (3%). "The OR was significant (44.8%; 95% CI, 6.2% – 981%)," the study authors report.

"On the basis of our study," Dr. Manconi said, "we now know that the majority of women who had RLS during pregnancy will experience the same symptoms in a further pregnancy and, overall, that after about 7 years, they will [be more likely] to develop a chronic idiopathic form of RLS than women who did not experience RLS during pregnancy."

Pregnancy a Trigger?

Reached for outside comment, Joanna A. Cooper, MD, a neurologist with East Bay Physicians Medical Group in Berkeley, California, and member of the American Academy of Neurology, said she is not surprised by these observations. "I have seen the disappearance of the RLS after delivery but reappearance later in life [and] reappearance in subsequent pregnancies."

Dr. Manconi said it is likely, given emerging research, that "women with pregnancy-related RLS are in some way predisposed to the disease, maybe by their genetic profile. Pregnancy, in an unknown way, may trigger the symptoms only in a subgroup of pregnant women already predisposed, who have more chances to develop later the chronic form."

This new long-term data on recurrence of RLS after pregnancy, Dr. Manconi said, will allow clinicians to be "more precise in terms of prognosis when a pregnant women asks them about the course of symptoms.

"Moreover, clinicians, especially neurologists and sleep specialists, can exploit these results in the assessment of RLS in difficult diagnostic cases," Dr. Manconi said. If clinicians are unsure about concerns about possible RLS symptoms in a female patient, she said, "ask her if she experienced the same symptoms during a previous pregnancy; this may help you in confirming or not your diagnostic hypothesis."

A limitation of the study, according to Dr. Cooper, is the lack of information on iron deficiency in the women.

"Sometimes iron deficiency, which is not so uncommon in pregnancy and can reoccur later in life, can be a risk factor for RLS. It is then secondary RLS and not primary, but they did not rule it out," she noted.

The study authors and Dr. Cooper have disclosed no relevant financial relationships.

Neurology. 2010;75:2117-2120.