Correspondence

More on the Restless Legs Syndrome and Spinal Anesthesia

N Engl J Med 2009; 360:1155-1156March 12, 2009

Article

To the Editor:

In their letter about the restless legs syndrome (RLS) and spinal anesthesia (Nov. 20 issue), Crozier et al.1 report that spinal or general anesthesia does not induce or exacerbate RLS, in contrast to the 8.7% incidence after spinal anesthesia in our earlier study.2 As an explanation, they suggest that we misdiagnosed RLS. In our study, RLS was diagnosed according to strict clinical criteria involving several personal interviews, whereas Crozier et al. used a questionnaire in which questions regarding RLS symptoms were included in a much longer list of heterogeneous items. Their method has not been validated for diagnosing RLS, and Crozier et al. do not detail the exact criteria they used to determine the presence or absence of RLS. Their assessment did not include measures of the severity of RLS, making it impossible to conclude that “no patients had . . . worsening of preexisting symptoms.” In addition, no attempts were made to control for postoperative opioid use. Opioids are a well-established, effective treatment for RLS.3

Birgit Högl, M.D.
Innsbruck Medical University, 6020 Innsbruck, Austria
birgit.ho@i-med.ac.at

Claudia Trenkwalder, M.D.
Paracelsus Elena Klinik, 34128 Kassel, Germany

Werner Poewe, M.D.
Innsbruck Medical University, 6020 Innsbruck, Austria

Dr. Trenkwalder reports receiving advisory fees from Mundipharm. No other potential conflict of interest relevant to this letter was reported.

3 References

1. 1

   Crozier TA, Karimdadian D, Happe S. Restless legs syndrome and spinal anesthesia. N Engl J Med 2008;359:2294-2296
   Full Text | Web of Science | Medline

2. 2

   Hogl B, Frauscher B, Seppi K, Ulmer H, Poewe W. Transient restless legs syndrome after spinal anesthesia: a prospective study. Neurology 2002;59:1705-1707
   Web of Science | Medline

3. 3

   Trenkwalder C, Hening WA, Montagna P, et al. Treatment of restless legs syndrome: an evidence-based review and implications for clinical practice. Mov Disord 2008;23:2267-2302
   CrossRef | Web of Science | Medline

Author/Editor Response

We do not agree with the points that Högl et al. make in their objections to our methods and conclusions. We consider the conclusion in their article,1 that spinal anesthesia causes RLS, unjustified — not because they misdiagnosed RLS symptoms, but because there was no control group undergoing similar surgery with general or local anesthesia. In addition, they did not differentiate, for example, between RLS and akathisia caused by neuroleptic antiemetic agents,2 which were very likely to have been administered to a large number of their patients, nor did they allow for other perioperative causes of secondary RLS. We also contend that omitting the preoperative interview and then attempting to determine the incidence of preoperative RLS in the postoperative setting might easily result in the introduction of an error of uncertain magnitude.

Högl et al. claim that we did not detail our diagnostic criteria. This is incorrect: our questionnaire is provided as a Supplementary Appendix, available with our article at NEJM.org. We used the standard minimal International RLS criteria from a validated German translation,3 together with questionnaires for depression and sleepiness, as has been done previously.3 Using this method, we found an RLS prevalence of about 9%, which is similar to prevalences described elsewhere.3,4 A presumptive diagnosis of RLS was confirmed by a neurologist.

Högl et al. claim that we could not detect a worsening of the symptoms, since we did not quantify severity. We considered the qualitative approach of asking patients whether their symptoms had worsened to be adequate for clinical purposes. No patient received opioids after the first postoperative day, and opioids are not known to have a prophylactic effect on RLS.

Thomas A. Crozier, M.D., Ph.D.
Desiree Karimdadian, M.D.
University of Göttingen Medical School, 37075 Göttingen, Germany
tcrozie@gwdg.de

Svenja Happe, M.D.
Klinikum Bremen-Ost, 28325 Bremen, Germany

4 References

1. 1

   Hogl B, Frauscher B, Seppi K, Ulmer H, Poewe W. Transient restless legs syndrome after spinal anesthesia: a prospective study. Neurology 2002;59:1705-1707
   Web of Science | Medline

2. 2

   Walters AS, Hening W, Rubinstein M, Chokroverty S. A clinical and polysomnographic comparison of neuroleptic-induced akathisia and the idiopathic restless legs syndrome. Sleep 1991;14:339-345
   Web of Science | Medline

3. 3

   Rothdach AJ, Trenkwalder C, Haberstock J, Keil U, Berger K. Prevalence and risk factors of RLS in an elderly population: the MEMO study. Neurology 2000;54:1064-1068
   Web of Science | Medline

4. 4

   Hogl B, Kiechl S, Willeit J, et al. Restless legs syndrome: a community-based study of prevalence, severity, and risk factors. Neurology 2005;64:1920-1924
   CrossRef | Web of Science | Medline

Citing Articles (1)

Citing Articles

1. 1

   Mathieu Raux, Elias G. Karroum, Isabelle Arnulf. (2010) Case Scenario: Anesthetic Implications of Restless Legs Syndrome. Anesthesiology 112:6, 1511-1517
   CrossRef