Development and Properties of the Dutch

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ARTICLE

Development and Properties of the Dutch Neurophysiology of Pain Test in Patients with Chronic Fatigue Syndrome Mira Meeus, PhD Jo Nijs, PhD Kim Soon Elsemans, PT Steven Truijen, PhD Kenny De Meirleir, PhD, MD

ABSTRACT. Objectives: This investigation aimed at determining the validity and reliability of the Dutch neurophysiology of pain test in chronic fatigue syndrome [CFS] patients with chronic widespread pain. Methods: The Dutch neurophysiology of pain test was completed by 61 CFS patients with chronic pain and 31 health care professionals. Patients repeated the test 24 hours later. Results: Performance on the test was better [p < 0.001] for professionals [10.71 ± 3.08] than for patients [5.95 ± 2.99], supporting the validity of the test. Test–retest reliability [ICC = 0.756] and internal consistency [Cronbach’s α = 0.769] were fair for CFS patients. Conclusion: The Dutch neurophysiology of pain test appears valid and reliable in CFS patients with chronic pain. KEYWORDS. reliability

Chronic fatigue syndrome, chronic pain, neurophysiology pain test, validity,

Mira Meeus, PT and Jo Nijs, PhD, Division of Musculoskeletal Physiotherapy, Department of Health Care Sciences, Artesis University College, Belgium Department of Human Physiology, Faculty of Physical Education and Physiotherapy, Vrije Universiteit Brussel [VUB], Belgium. Kim Soon Elsemans, PT, and Steven Truijen, PhD, Division of Musculoskeletal Physiotherapy, Department of Health Care Sciences, University College Antwerp, Belgium. Kenny De Meirleir, PhD, MD, Department of Human Physiology, Faculty of Physical Education and Physiotherapy, Vrije Universiteit Brussel [VUB], Belgium. Address correspondence to: Jo Nijs, PhD, Vrije Universiteit Brussel, MFYS - building L, Pleinlaan 2, BE-1050 Brussels, Belgium. E-mail: [email protected]

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Journal of Musculoskeletal Pain, Vol. 18(1), 2010 Available online at www.informaworld.com/WJMP © 2010 by Informa Healthcare USA, Inc. All rights reserved. doi: 10.3109/10582450903495908

Meeus et al.

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INTRODUCTION As the majority of patients with chronic fatigue syndrome [CFS] report chronic widespread pain [CWP] (1–4) and present with abnormal heightened reactions to pain, like kinesiophobia [fear of movement] and catastrophic thoughts about pain (5–7), it may be useful to evaluate the patients’ knowledge on the neurophysiology of pain. Accurate thoughts on pain and knowledge of the function, origin, and modulation of pain may reduce negative thoughts and pain behavior, and in consequence, pain itself. Poor understanding of pain may lead to the acquisition of maladaptive attitudes and behavior in relation to pain (8). Patients’ incorrect beliefs on the threatening nature of pain could cause catastrophic thoughts and inappropriate coping strategies. In the study of Geisser and Roth (8), the lack of knowledge or the disagreement regarding pain etiology was predictive for maladaptive cognitions about pain and greater affective distress (8). The vagueness regarding the etiology of their pain complaints may be common in CFS patients because they often experience CWP in the absence of any injury. There is often no clear cause of the pain, and even the medical world does not yet agree concerning the exact etiology of the chronic pain. Furthermore, CFS patients are often confronted with incomprehension of the outside world. Therefore, it may not be surprising that this lack of clarity can lead to maladaptive pain cognitions, which are often seen in CFS patients, i.e. fear avoidance (7) and catastrophic thinking (9). Catastrophizing is related to pain (10, 11) or even predictive for pain and disability (12), and has more of an effect on desired treatment outcomes than the use of any single positive coping skill (13). As therapeutic exercise and increased physical function are important components in the approach of chronic musculoskeletal pain, patients who view movement-induced pain as a signal of harm or threat will be less compliant. Therefore, an accurate knowledge concerning pain etiology could remove some therapy barriers, and thus increase therapy compliance. Furthermore, it is known that altered pain beliefs lead to increased confidence, which in turn leads to increased activity levels (14) and are directly associated with altered movement performance (15). Changing cognitions, particularly catastrophizing, by improving patients’ knowl-

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edge, counted for 77 percent and 60 percent of the variance in straight leg raise performance and forward bending, respectively, in chronic low back pain patients (15). Pain education was more efficient in improving motor performance of the deepest abdominal muscle transversus abdominis during abdominal drawing-in task, than one week training (14). It may be clear that the knowledge of pain influences pain cognitions and behavior, which in turn have an impact on treatment outcomes. Consequently, it may be useful to develop an instrument for assessing the knowledge on the neurophysiology of pain. Moseley (16) evaluated the ability of patients with chronic low back pain to understand information on the neurophysiology of pain with the neurophysiology of pain test, which was created and published by Moseley in Australia. The items on the test were based on examination papers given to postgraduate pain medicine students and were directly related to the material that was presented in the education sessions. The tests given to patients and professionals were identical, apart from semantic points [e.g., “nociception” for professionals was “danger reception” for patients]. The questions of the original English neurophysiology of pain test as developed by Moseley (16) are shown in Appendix 1. The questions concern the mechanism of nociceptors, adaptation of nociceptors, modulation of pain, etc. The neurophysiology of pain test was designed to assess pain patients in general rather than chronic low back pain patients alone, although the questionnaire has only been mentioned in publications on chronic low back pain patients (16–19). But given the use of this questionnaire, it seems plausible to use this self-assessment tool for the assessment of the understanding of pain neurophysiology in CFS patients suffering from CWP. However, the authors of the present manuscript are unaware of published data addressing the clinimetric properties of the neurophysiology of pain test in either low back pain subjects or patients with CFS. The way the test was constructed (16) supports its validity, but further studying of the clinimetric properties is warranted. The goal of this study was to translate the neurophysiology of pain test into Dutch and examine the reliability and validity in patients with CFS and CWP. A test–retest design with a time interval of 24 hours was applied for examining the reliability. In order to

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examine the validity, it was hypothesized that if the neurophysiology of pain test is valid, then health care workers should perform better on the test than patients with CFS experiencing CWP. METHODS

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Translation of the Neurophysiology of Pain Test The original English version of the neurophysiology of pain test (16) was translated into Dutch by two Dutch speaking independent researchers [KSE and JN]. Afterwards, the two Dutch versions were compared and discussed in order to develop a common version, as presented in Appendix 2. Subject Recruitment Chronic fatigue syndrome patients suffering from CWP, visiting a university-based CFS clinic, and screened for compliance with the inclusion criteria, were willing to participate. Patients were allocated from consecutive referrals to a specialized chronic fatigue clinic [sample of convenience]. To fulfill the inclusion criteria, patients had to be diagnosed with CFS [by same physician specialized in internal medicine] following the diagnostic criteria of the Center of Disease Control and Prevention (20) and suffer from CWP following the criteria of the American College of Rheumatology (21). Patients were between 18 and 65 years of age and spoke Dutch. Healthy control subjects were recruited among the staff of the Academic Hospital of the Vrije Universiteit Brussel, staff and students of the physiotherapy department of the University College Antwerp, and among physical therapists and physicians working in private practices and hospitals in and around the city of Antwerp. Since the inclusion of a control group was required for the validation process, the included control subjects had to dispose of a sufficient knowledge of pain neurophysiology. Therefore, control subjects were only recruited among medical students and professionals, based on the assumption of a sufficient educational level in [pain] neurophysiology. They were only recruited if they received at least 20 hours of pain neurophysiology during their education.

Instrumentation An information leaflet explaining the goal, the procedure, the risks [complaints due to mental activity], the guarantee on anonymity, and the possibility to stop study participation was handed to the participants prior to the completion of the questionnaires. The neurophysiology pain test is a questionnaire assessing the knowledge on the neurophysiology of pain. It contains 19 questions that need to be answered with “true”, “false”, or “undecided”. Every correct answer is worth one point. The maximum score is 19. Procedure Patients were asked to read the information folder carefully and to sign the informed consent form to indicate agreement of participation in the study. The study protocol was approved by the Ethical Committee of the Academic Hospital of the Vrije Universiteit Brussel. Demographical data were collected and recorded, including age, gender, illness duration, profession, education, and number of hours of neurophysiology education. Afterward, patients filled in the Dutch neurophysiology of pain test [patient version] and received a stamped envelope with a second copy of the questionnaire. The second questionnaire was modified by changing the font and the question sequence. This second questionnaire needed to be filled in within 24 hours and sent back to the researchers in a preaddressed envelope provided by the researchers. The healthy controls were subjected to the same protocol. They were asked to sign the informed consent and the demographic data were collected. Afterwards they completed the first copy of the neurophysiology pain test [professional version]. Statistical Analysis All data were analyzed using SPSS 13.0© for Windows [SPSS, Inc. Headquarters, Chicago, Illinois, US]. Appropriate descriptive statistics were calculated. These included mean, medians, percentiles, and range and standard deviation for age, duration of the illness, hours of neurophysiology, and scores on the neurophysiology of pain test. In order to evaluate the test–retest reliability

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of the test, the two-way mixed intraclass correlation coefficient [ICC] and the standard error was determined. Internal consistency was evaluated with the α coefficient of Cronbach. The validity of the test was assessed by comparing the test results of “professionals” familiar with neurophysiology and “patients,” normally laymen in that matter. Comparison of the test results was done with an independent sample t-test. Significance level was set on 0.01. RESULTS The number of CFS patients agreed to participate in the study and filled in the first copy of the test was 61 [51 females, which is 83.6 percent]. The patients had a mean age of 39.95 years with a standard deviation of 9.64 years and reported an average illness duration of 85.43 months with a standard deviation of 56.23 months. The number of healthy professionals participated in the study was 31: 15 women [48.4 percent] and 16 men [51.6 percent], with a mean age of 35.77 years and a standard deviation of 12.67 years. A total of 27 subjects were professionally active and 4 participants were physiotherapy students. Prior to study participation, they received an average of 29.94 hours of neurophysiology education. The two groups were comparable in respect of age characteristics [t = −1.745, df = 89, p = 0.084]. Validity When the mean results of neurophysiology of pain test were compared between the CFS patients [5.95 ± 2.99] and the professionals [10.71 ± 3.08], the Levene’s test showed a similar variance [F = 0.246, p = 0.62], and the t-test revealed a significant difference between the two groups [t = 7.151, df = 90, p < 0.001]. Patients performed significantly worse on the neurophysiology of pain test than the professionals. Reliability Forty-two of the 61 patients filled in and sent back the second copy of the questionnaire. Mean score for the second version was 6.33 ± 2.96. The ICC, used to define test–retest reliability, amounted to 0.756 [p = 0.00]. The standard er-

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ror was 1.83. Cronbach’s α, in order to assess internal consistency, amounted to 0.769. DISCUSSION The goals of the study were to translate the neurophysiology of pain test into Dutch and to examine the validity and test–retest reliability. The Dutch neurophysiology of pain test showed fair reliability by retesting within 24 hours in this sample of CFS patients with CWP. The ICC amounted to 0.756, indicating an acceptable level of test–retest reliability. Internal consistency was even so adequate [Chronbach’s α = 0.77] that it supported the one dimensionality of the questionnaire. Validity was assessed by comparing the test results of the professional group and the patients. The validity of the neurophysiology of pain test in CFS patients with CWP can be suggested by the significant difference between the test results of professionals and patients. As hypothesized, professional health care workers scored better than the CFS patients. But prudence is in order when drawing conclusions: Just because health care workers perform better does not have to mean that the test is valid. Further research in to the validity of the test is advisable. Despite some shortcomings, such as potential bias originating from the use of a sample of convenience and the fact that the test–retest analysis were based solely on the data of the responders, it is concluded that the Dutch neurophysiology of pain test is a valid and reliable assessment tool for evaluating the knowledge and understanding of the neurophysiology of pain in CFS patients with widespread pain. The reason why the test was evaluated in CFS patients is partly explained in the introduction. A lot of CFS patients are known to have incorrect beliefs about the etiology of their disease or their pain, leading to catastrophic thinking. It is known that such maladaptive pain behavior or pain cognitions are responsible for disability (22) and persistent changes in motor patterns, which promote chronicity (23). It is therefore important to recognize these therapy barriers in order to adjust treatment strategies, if necessary. If pain cognitions can be changed by educating patients, increased exposure to activity is allowed, leading to increased performances (23). It is hypothesized that altered pain cognitions

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will change the meaning of nociceptive information, decreasing pain production and increasing performance (15). Recently, confidence in this biopsychosocial approach towards pain is growing, manifested in concepts as the Back Book (24) and the Whiplash Book (25). Over the last three decades, there have been hundreds of booklets and leaflets produced for patients with back pain (26), but mainly based on the traditional biomedical model, explaining biomechanics spine anatomy etc. The newer educational concepts like the Back Book (24) and Whiplash Book (25) emphasize the role of psychological and social factors in the development and maintenance of complaints (27). The message is focused on patients’ beliefs, attitudes, and reassurances that there is likely nothing seriously wrong by explaining pain. In the systematic review of Henrotin et al. (27), information based on the biopsychosocial model, but probably not the biomedical model, is found to be an efficient strategy to modify patients’ beliefs, decreasing catastrophic thoughts and kinesiophobia, leading to reduced disability and medical costs. There is currently good evidence supporting the use of pain physiology education in patients with chronic low back pain. Studies examining the possible benefits of pain physiology education in people with CFS are under way. We should consider that educating CFS patients may be more difficult given their memory and concentration problems. Therefore, it is necessary to be able to assess their knowledge and to assess whether they are able to understand the complicated matter of pain neurophysiology (27). Consequently, this test can be used in further investigations and therapeutic interventions where the assessment of this knowledge is required, i.e. in investigations or therapeutic interventions aiming at evaluating the efficacy of pain neurophysiology education in CFS patients. ACKNOWLEDGEMENTS Mira Meeus is financially supported by a PhD grant [G807: “Chronic pain in chronic fatigue syndrome: A biopsychosocial approach”] supplied by the Higher Institute of Physiotherapy, Department of Health Sciences, University College Antwerp, Belgium and cofinanced by Faculty of Physical Education

and Physiotherapy—Vrije Universiteit Brussel [VUB], Brussels, Belgium [OZR project OZ.R. 1234/MFYS Wer2]. Declaration of interest: The author reports no conflict of interest. The author alone is responsible for the content and writing of this paper. REFERENCES 1. Morriss RK, Ahmed M, Wearden AJ, Mullis R, Strickland P, Appleby L, et al.: The role of depression in pain, psychophysiological syndromes and medically unexplained symptoms associated with chronic fatigue syndrome. J Affect Disord 55: 143–148, 1999. 2. Nishikai M, Tomomatsu S, Hankins RW, Takagi S, Miyachi K, Kosaka S, et al.: Autoantibodies to a 68/48 kDa protein in chronic fatigue syndrome and primary fibromyalgia: A possible marker for hypersomnia and cognitive disorders. Rheumatology 40: 806–810, 2001. 3. Jason LA, Torres-Harding SR, Carrico AW, Taylor RR: Symptom occurrence in persons with chronic fatigue syndrome. Biol Psychol 59: 15–27, 2002. 4. Nijs J, De Meirleir K, Truyen S: Hypermobility in patients with chronic fatigue syndrome: Preliminary observations. J Musculoskel Pain 12: 9–17, 2004. 5. Petrie K, Moss-Morris R, Weinman J: The impact of catastrophic beliefs on functioning in chronic fatigue syndrome. J Psychosom Res 39: 31–37, 1995. 6. Silver A, Haeney M, Vijayadurai P, Wilks D, Pattrick M, Main CJ: The role of fear of physical movement and activity in chronic fatigue syndrome. J Psychosom Res 52: 485–493, 2002. 7. Nijs J, De Meirleir K, Duquet W: Kinesiophobia in chronic fatigue syndrome: Assessment and associations with disability. Arch Phys Med Rehabil 85: 1586–1592, 2004. 8. Geisser ME, Roth RS: Knowledge of and agreement with chronic pain diagnosis: Relation to affective distress, pain beliefs and coping, pain intensity and disability. J Occup Rehab 8: 73–88, 1998. 9. Petrie K, Moss-Morriss R, Weinman J: The impact of catastrophic beliefs on functioning in chronic fatigue syndrome. J Psychosom Res 39: 31–37, 1995. 10. Sullivan MJL, Neish N: The effects of disclosure on pain during dental hygiene treatment: The moderating role of catastrophizing. Pain 79: 155–163, 1999. 11. Hasset A, Cone JD, Patella SJ, Sigal LH: The role of catastrophizing in the pain and depression of women with fibromyalgia syndrome. Arthritis Rheum 11: 2493–2500, 2000. 12. Flor H, Truk DC: Chronic back pain and rheumatoid arthritis: Predicting pain and disability from cognitive variables. J Behav Med 11: 251–265, 1988. 13. Nelson PJ, Tucker S: Developing an intervention to alter catastrophising in persons with fibromyalgia. Orthop Nurs 25: 205–215, 2006.

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14. Moseley GL: Widespread brain activity during and abdominal task markedly reduced after pain physiology education: fMRI evaluation of a single patient with chronic low back pain. Aust J Physiother 51: 49–52, 2005. 15. Moseley GL: Evidence for a direct relationship between cognitive and physical change during an education intervention in people with chronic low back pain. Eur J Pain 8: 39–45, 2004. 16. Moseley L: Unraveling the barriers to reconceptualization of the problem in chronic pain: The actual and perceived ability of patients and health professionals to understand the neurophysiology. J Pain 4: 184–189, 2003. 17. Moseley L: Combined physiotherapy and education is efficacious for chronic low back pain. Aust J Physiother 48: 297–302, 2002. 18. Moseley GL, Nicholas MK, Hodges PW: A randomized controlled trial of intensive neurophysiology education in chronic low back pain. Clin J Pain 20: 324–330, 2004. 19. Moseley GL: Evidence for a direct relationship between cognitive and physical change during an education intervention in people with chronic low back pain. Eur J Pain 8: 39–45, 2004. 20. Fukuda K, Strauss SE, Hickie I, Sharpe MC, Dobbins JG, Komaroff A: The chronic fatigue syndrome: A comprehensive approach to its definition and study. Ann Intern Med 124: 53–959, 1994.

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21. Wolfe F, Smythe HA, Yunus MB, Bennett RM, Bombardier C, Goldenberg DL, et al.: The American College of Rheumatology 1990 criteria for the classification of fibromyalgia: Report of the multicentre criteria committee. Arthritis Rheum 33: 160–172, 1990. 22. Stroud MW, Thorn BE, Jensen MP, Boothby JL. The relation between pain beliefs, negative thoughts, and psychosocial functioning in chronic pain patients. Pain 84: 347–352, 2000. 23. Watson PJ, Booker CK, Main CJ. Evidence for the role of psychological factors in abnormal paraspinal activity in patients with chronic low back pain. J Musculoske Pain 4: 41–56, 1997. 24. Burton K, Waddell G, Burtt R, Blair S: Patient educational material in the management of low back pain in primary care. Hosp Jt Dis 55: 138–141, 1996. 25. McClune T, Burton AK, Waddell G: Whiplash associated disorders: A review of the literature to guide patient information and advice. Emerg Med J 19: 499–506, 2002. 26. Padiyar A, Pandipati S, Kim T, Haig AJ. An objective review of consumers books bout back pain. J Neurosci Nurs 33: 326–337, 2001. 27. Henrotin YE, Cedraschi C, Duplan B, Bazin T, Duquesnoy B: Information and low back pain management. Spine 31: E326–E334, 2006.

Submitted: May 15, 2007 Revision Accepted: July 9, 2007

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APPENDIX 1: Original Questions of English Neurophysiology of Pain Test (10)

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T Receptors on nerves work by opening ion channels (gates) in the wall of the nerve. When part of your body is injured, special pain receptors convey the pain message to your brain. Pain only occurs when you are injured. The timing and intensity of pain matches the timing and number of signals in nociceptors (danger receptors). Nerves have to connect a body part to your brain in order for that body part to be in pain. In chronic pain, the central nervous system becomes more sensitive to nociception (danger messages). The body tells the brain when it is in pain. The brain sends messages down your spinal cord that can increase the nociception (danger message) going up your spinal cord. The brain decides when you will experience pain. Nerves adapt by increasing their resting level of excitement. Chronic pain means that an injury has not healed properly. Nerves can adapt by making more ion channels (gates). Worse injuries always result in worse pain. Nerves adapt by making ion channels (gates) stay open longer. Second-order nociceptor (messenger nerve) postsynaptic membrane potential is dependent on descending modulation. When you are injured, the environment that you are in will not have an effect on the amount of pain you experience. It is possible to have pain and not know about it. When you are injured, chemicals in your tissue can make nerves more sensitive. In chronic pain, chemicals associated with stress can directly activate nociception pathways (danger messenger nerves).

F

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Terms in parentheses were used for patients. Hash mark denotes the correct answer. Abbreviations: T, true; F, false; U, undecided.

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APPENDIX 2: Dutch Neurophysiology of Pain Test NEUROFYSIOLOGIE PIJNTEST

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STELLING Receptoren op zenuwen werken door in de wand van de zenuw ionenkanalen (poorten) te openen. Wanneer een deel van je lichaam gekwetst raakt, voeren speciale pijnreceptoren het pijnsignaal naar je hersenen. Pijn komt enkel voor bij schade aan het lichaam. De timing en intensiteit van de pijn stemmen overeen met de timing en de hoeveelheid aan signalen van de nociceptoren (pijn/gevaarboodschappers). Zenuwen moeten een lichaamsdeel met je hersenen verbinden opdat dat lichaamsdeel pijn kan voelen. Bij chronische pijn wordt het centrale zenuwstelsel gevoeliger voor nociceptie (pijn/gevaarboodschap). Het lichaam zegt de hersenen wanneer het pijn ervaart. De hersenen sturen boodschappen doorheen het ruggenmerg naar beneden, die in staat zijn om de nociceptie (pijngewaarwording) te versterken. De hersenen beslissen wanneer je pijn zal ervaren. Zenuwen passen zich aan door hun rustwaarde van ontlading (ontladingsdrempel) te verhogen. Chronische pijn wil zeggen dat een lichamelijk letsel/aandoening niet volledig genezen is. Zenuwen kunnen zich aanpassen door meer ionenkanalen (poorten) aan te maken. Ergere lichamelijke letsels/aandoeningen resulteren altijd in meer pijn. Zenuwen passen zich aan door de ionenkanalen (poorten) langer open te houden. Het post-synaptisch membraanpotentiaal van secundaire nociceptoren is afhankelijk van descenderende modulatie (be¨ınvloeding van bovenaf). Wanneer je lichamelijke schade/aandoening hebt opgelopen, zal de omgeving waarin je je bevindt geen effect hebben op de hoeveelheid pijn die je ervaart. Het is mogelijk om pijn te hebben zonder het te beseffen. Wanneer je lichamelijke schade/aandoening hebt opgelopen, kunnen chemische stoffen in je weefsel zenuwen gevoeliger maken Bij chronische pijn kunnen chemische stoffen, geassocieerd met stress, rechtstreeks nociceptorische wegen (de wegen van pijn/gevaarboodschapperszenuwen) activeren.

JUIST

FOUT

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Terms in parentheses were used for patients. Hash mark denotes the correct answer.

GEEN MENING