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Trigeminal neuralgia and atypical facial pain: Use of the McGill pain questionnaire for discrimination and diagnosis
Pain, 27 (1986)
297
297-302
Elsevier
PAI 00977
Trigeminal Neuralgia and Atypical Facial Pain: Use of the McGill Pain Questionnaire for Discrimination and Diagnosis Ronald Melzack *, Christopher Terrence **, Gerhard Fromm ** and Rhonda Amsel * * Department
of Psychology, McGill
Univer+,
Montreal
H3A IBl
(Canada),
** Department
of Neurology,
Universily of Pittsburgh School of Medicine, Pittsburgh, PA 15261, and Neurology Service, V.A. Medical Center, Pittsburgh, PA 15240 (U.S.A.)
(Received
1 May 1986, accepted
4 June 1986)
Summary Although trigeminal neuralgia and atypical facial pain can usually be distinguished on the basis of several well-established criteria, differential diagnosis is difficult in a small number of patients. The purpose of this study was to determine whether the McGill Pain Questionnaire (MPQ) is capable of discriminating between the two syndromes and might therefore serve as a diagnostic aid. The MPQ was administered to 74 patients in Pittsburgh and the data were analyzed statistically in Montreal. In an analysis of the data of 53 patients, 91% of the patients were correctly classified on the basis of 7 descriptors. To determine whether the key descriptors were able to predict the diagnosis of a second group, the discriminant function derived from the first analysis was applied to a new group of 21 patients. A correct prediction was made for 90% of the patients. The results indicate that, in difficult cases, the MPQ may be a useful tool to aid in differential diagnosis. Key words:
McGill
Pain Questionnaire;
facial pain;
trigeminal
neuralgia
Introduction Trigeminal ferences that
neuralgia and atypical facial help the physician in making to: Dr. Ronald Melzack, Department Montreal, Que. H3A IBl, Canada.
Correspondence
Penfield
Avenue,
0304-3959/86/$03.50
0 1986 Elsevier
Science Publishers
pain are characterized by many difthe appropriate diagnosis [2,8,10,16]. of Psychology,
B.V. (Biomedical
McGill
Division)
University,
1205 Dr.
However. the boundaries between these two clinical entities are not as sharp as one might wish [4,10,17]. Usually a diagnosis of atypical facial pain is made after trigeminal neuralgia, postherpetic neuralgia, dental pathology and temporomandibular joint dysfunction have been excluded by history, physical examination and appropriate diagnostic tests. In a significant number of patients it is nevertheless difficult to be absolutely certain as to whether they are suffering from a somewhat atypical case of trigeminal neuralgia or have the atypical facial pain syndrome. As Loeser [lo, p. 4261 has noted, ‘It is unfortunately true that . . differential diagnosis may not be as easy in the examining room as it is in the literature.’ Establishing a correct diagnosis is crucial in the management of these patients as the treatment for trigeminal neuralgia and for atypical facial pain is quite different. Thus, every bit of information that aids in making an accurate diagnosis is important. A potential aid to diagnosis that merits investigation is the different verbal descriptors used by patients to describe their pain. Whether the pain is localized or diffuse is an important differentiating feature. So too is the temporal quality: whether the pain is constant or intermittent. However, neither of these spatial or temporal features is invariable for one or the other of these pains. Other types or patterns of descriptors may also provide valuable information to aid in diagnosis. Typically, trigeminal neuralgia is characterized by ‘electric shock-like, brief, stabbing pain’ while atypical facial pain has a ‘constant burning’ quality; however, both of these kinds of qualities may occur together, making differential diagnosis difficult [LOI. Dubuisson and Melzack [3] found that the McGill Pain Questionnaire (MPQ) can be used to discriminate among different kinds of pain. Using the MPQ, a discriminant analysis was 77% correct in making a prediction of the patients’ clinical pain problem on the basis of verbal descriptors alone. Several other studies have confirmed the discriminative capacity of the MPQ [1,5,6,12,15], while a few have found that severe pain may obscure the MPQ’s discriminative ability [7,14]. The purpose of this study was to see whether the MPQ is capable of discriminating between patients with trigeminal neuralgia and those with atypical facial pain, and whether it can further serve as a predictive aid in the differential diagnosis between the two syndromes.
Methods
The subjects were 74 patients who were admitted to the Presbyterian University Hospital or attended the Hospital Pam Clinic for treatment of facial pain. Forty-three patients (9 M, 34 F) were diagnosed as having trigeminal neuralgia, and 31 patients (5 M, 26 F) were diagnosed as having atypical facial pain. McGill Pain Questionnaire The McGill Pain Questionnaire [ll] consists of 20 sets of words describing sensory, affective, evaluative and miscellaneous dimensions of the experience of pain. Recent studies have shown the questionnaire to be reliable, to be sensitive to
299
the effects of different therapies on chronic pain, and to discriminate between different pain syndromes [14]. The questionnaire was given to the patients as part of the standard informationgathering procedure at the hospital or clinic. The patients were told to read the instructions carefully and were reminded to choose only those words that best described a typical episode of pain. In the present study, two additional words ‘diffuse’ and ‘localized’ - were added to the list of descriptors. Two major indexes can be obtained from the questionnaire. The first is the pain rating index (PRI), which is the sum of the rank values of the words chosen, which are based on the positions of the words in each category. The PRI can be computed separately for the sensory (categories l-lo), affective (categories ll-15) evaluative (category 16) and miscellaneous (categories 17-20) words or as a total score for categories l-20. The second is an index of present pain intensity (PPI), a measure of the overall pain intensity on a scale of O-5: 0 represents no pain, 1 mild, 2 discomforting, 3 distressing, 4 horrible and 5 excruciating pain. Procedure
Each patient received a thorough neurological examination which led to a diagnosis of trigeminal neuralgia or atypical facial pain. In addition, each patient was given the McGill Pain Questionnaire (MPQ) together with instructions on the procedure for choosing the appropriate verbal descriptors. The patient then filled in the MPQ. Photocopies of the MPQs for the first 53 patients were sent to Melzack and Amsel, and the data were entered into the computer for statistical analysis. This group consisted of 28 patients with trigeminal neuralgia (7 M, 21 F) and 25 with atypical facial pain (3 M, 22 F). A second group of patients filled out the MPQ in a similar way, and copies were sent to Melzack and Amsel without indication of the diagnosis. This group comprised 21 patients: 15 with trigeminal neuralgia (2 M, 13 F); 6 with atypical facial pain (2 M, 4 F). Statistical analyses were carried out to predict the diagnosis. After the prediction was made, Terrence and Fromm provided the code that permitted a comparison of the predictions and diagnoses.
Results The data of group I were analyzed by using a discriminant analysis to determine the pattern of descriptors that best discriminated between the patients with trigeminal neuralgia and those with atypical facial pain. Table I provides the key words and their weights which comprised the equation used to discriminate between the two sets of patients. Relatively higher weights indicate that a higher proportion of patients in that group chose that particular descriptor. Thus, patients with trigeminal neuralgia tended to choose flashing, terrifying, blinding and torturing, while patients with atypical facial pain tended to choose vicious, diffuse and excruciating, In the analysis of group I, 91% of the patients were correctly classified using the 7 descriptors and the constants in Table I.
TABLE
I
CLASSIFICATION Descriptors
Flashing Terrifying Vicious Blinding Torturing Diffuse Excruciating Constant (c)
FUNCTION
COEFFICIENTS Trigeminal neuralgia 0.67
I .99 2.53 -0.14 1.53 11.63 2.41 -X.66
Atypical facial pain
-_I____
- 1.91 0.61 6.19 - 2.98 0.03 21.44 5.10 -21.X6
To determine whether the key descriptors were able to predict the diagnosis of group II, the discriminant function derived from the analysis of group I was applied to the patients of group II. The results showed a correct prediction for 90% of the patients. One patient in each group was misclassified.
Discussion
The results show convincingly that verbal descriptors can aid in the diagnosis of trigeminal neuralgia and atypical facial pain. Each of these disorders is characterized by a constellation of descriptors that differs from the other. It was noted in the introduction that most patients with these two syndromes can be accurately diagnosed on the basis of several criteria, which are outlined in traditional neurological texts [2,8,16]. However, in that small group that defies easy characterization, and in which the usual criteria may be obscured by exceptional presenting symptoms, the MPQ provides an additional aid that may lead to a correct diagnosis (and, therefore, appropriate treatment). It is interesting that only a single sensory word - flashing - is included in the key descriptors of the discriminant analysis. The remaining words are predominantly affective, with different subsets being characteristic of either trigeminal neuralgia or atypical facial pain. It is evident that the two syndromes are not discriminated by any simple sensory/affective dichotomy but, rather, each appears to have a different emotional impact on the patient which is characterized by different subsets of words. The differences are sufficiently large that they were 91% correct in discriminating between the two types of patients in group I, and 90% correct in predicting the diagnosis of the patients in group II. The results lend further support to the discriminant capacity of the MPQ. This capacity has been demonstrated in several studies involving a variety of clinical pain syndromes [3,5,6,12,15] as well as in a recent study of acute laboratory pains [l]. It is evident, however, that this discrirninant capacity has limits. High levels of anxiety and other psychological disturbance, which may produce high affective scores, may
301
obscure the discriminative capacity [7]. Moreover, certain key words that discriminate among specific syndromes may be absent [13]. In the present study, for example, it was important to add the words localized and diffuse. Other syndromes may require the addition of other words such as the temporal descriptors intermittent and continuous. Experimenters are encouraged to modify the questionnaire to suit the needs of the particular syndromes being studied. The most important requirement of a measuring instrument is its utility. It is possible to tailor the MPQ to meet particular needs - thus, we now have the Low-Back Pain Scale [9] and the Headache Scale [6]. The present study provides a Facial Pain Scale to help in the diagnosis of difficult cases of trigeminal neuralgia and atypical facial pain.
Acknowledgements It is a pleasure to thank Dr. Ruben Tenicela and Dr. Peter Jannetta for allowing us to test their patients, and Ms. Darlene Lovasika and Mrs. Myriam Edelman for their help in acquiring and analyzing the data. This study was supported by Grant A7891 from the Natural Sciences and Engineering Research Council of Canada. References 1 Chen, A.C.N. and Treede, R.-D., The McGill Pain Questionnaire in the assessment of phasic and tonic experimental pain: behavioral evaluation of the ‘pain inhibiting pain’ effect, Pain, 22 (1985) 67-79. 2 Diamond, S. and Friedman, A.P., Headache, Medical Examination Publishing Co., New York, 1983. 3 Dubuisson, D. and Melzack, R., Classification of clinical pain descriptions by multiple group discriminant analysis, Exp. Neurol., 51 (1976) 480-487. 4 Friedman, A.P., Atypical facial pain, Headache, 9 (1969) 27-30. 5 Grushka, M. and Sessle, B.J., Applicability of the McGill Pain Questionnaire to the differentiation of ‘toothache’ pain, Pain, 19 (1984) 49-57. 6 Hunter, M., The headache scale: a new approach to the assessment of headache pain based on pain descriptions, Pain, 16 (1983) 361-373. 7 Kremer, E.F. and Atkinson, J.H., Pain language as a measure of affect in chronic pain patients. In: R. Melzack (Ed.), Pain Me~urement and Assessment, Raven Press, New York, 1983, pp. 119-127. 8 Lance, J.W., M~h~srn and Management of Headache, 4th edn., Bntte~orth, London, 1982. 9 Leavitt, F., Detecting psychological disturbance using verbal pain measurement: the back pain classification scale. In: R. Melzack (Ed.), Pain Measurement and Assessment, Raven Press, New York, 1985, pp. 79-84. 10 Loeser, J.D., Tic douloureux and atypical facial pain. In: P.D. Wall and R. Melzack (Eds.), Textbook of Pain, Churchill Livingstone, Edinburgh, 1984, pp. 426-434. 11 Melzack, R., The McGill Pain Questionnaire: major properties and scoring methods, Pain, 1 (1975) 277-299. 12 Melzack, R., Discriminative capacity of the McGill Pain Questionnaire (Letter to the Editor), Pain, 23 (1985) 201-203. 13 Reading, A.E., An analysis of the language of pain in chronic and acute patient groups, Pain, 13 (1982) 185-192. 14 Reading, A.E., Testing pain mechanisms in persons in pain. In: P.D. Wall and R. Melzack (Eds.), Textbook of Pain, Churchill Livingstone, Edinburgh, 1984, pp. 195-204.
15 Wagstaff. S.. Smith. O.V. and Wood, P.H.N.. Verbal pain descriptors used by patlenta with arthrltls. Ann. rheum. Dis., 44 (1985) 262-265. 16 Wartenberg, R., Neuritis, Sensory Neuritis, Neuralgia, Oxford University Press, New York, 19.58. 17 Weddington, W.W. and Blazer, D., Atypical facial pain and trigeminal neuralgia: a comparison study. Psychosomatics. 20 (1979) 348-356.
297
297-302
Elsevier
PAI 00977
Trigeminal Neuralgia and Atypical Facial Pain: Use of the McGill Pain Questionnaire for Discrimination and Diagnosis Ronald Melzack *, Christopher Terrence **, Gerhard Fromm ** and Rhonda Amsel * * Department
of Psychology, McGill
Univer+,
Montreal
H3A IBl
(Canada),
** Department
of Neurology,
Universily of Pittsburgh School of Medicine, Pittsburgh, PA 15261, and Neurology Service, V.A. Medical Center, Pittsburgh, PA 15240 (U.S.A.)
(Received
1 May 1986, accepted
4 June 1986)
Summary Although trigeminal neuralgia and atypical facial pain can usually be distinguished on the basis of several well-established criteria, differential diagnosis is difficult in a small number of patients. The purpose of this study was to determine whether the McGill Pain Questionnaire (MPQ) is capable of discriminating between the two syndromes and might therefore serve as a diagnostic aid. The MPQ was administered to 74 patients in Pittsburgh and the data were analyzed statistically in Montreal. In an analysis of the data of 53 patients, 91% of the patients were correctly classified on the basis of 7 descriptors. To determine whether the key descriptors were able to predict the diagnosis of a second group, the discriminant function derived from the first analysis was applied to a new group of 21 patients. A correct prediction was made for 90% of the patients. The results indicate that, in difficult cases, the MPQ may be a useful tool to aid in differential diagnosis. Key words:
McGill
Pain Questionnaire;
facial pain;
trigeminal
neuralgia
Introduction Trigeminal ferences that
neuralgia and atypical facial help the physician in making to: Dr. Ronald Melzack, Department Montreal, Que. H3A IBl, Canada.
Correspondence
Penfield
Avenue,
0304-3959/86/$03.50
0 1986 Elsevier
Science Publishers
pain are characterized by many difthe appropriate diagnosis [2,8,10,16]. of Psychology,
B.V. (Biomedical
McGill
Division)
University,
1205 Dr.
However. the boundaries between these two clinical entities are not as sharp as one might wish [4,10,17]. Usually a diagnosis of atypical facial pain is made after trigeminal neuralgia, postherpetic neuralgia, dental pathology and temporomandibular joint dysfunction have been excluded by history, physical examination and appropriate diagnostic tests. In a significant number of patients it is nevertheless difficult to be absolutely certain as to whether they are suffering from a somewhat atypical case of trigeminal neuralgia or have the atypical facial pain syndrome. As Loeser [lo, p. 4261 has noted, ‘It is unfortunately true that . . differential diagnosis may not be as easy in the examining room as it is in the literature.’ Establishing a correct diagnosis is crucial in the management of these patients as the treatment for trigeminal neuralgia and for atypical facial pain is quite different. Thus, every bit of information that aids in making an accurate diagnosis is important. A potential aid to diagnosis that merits investigation is the different verbal descriptors used by patients to describe their pain. Whether the pain is localized or diffuse is an important differentiating feature. So too is the temporal quality: whether the pain is constant or intermittent. However, neither of these spatial or temporal features is invariable for one or the other of these pains. Other types or patterns of descriptors may also provide valuable information to aid in diagnosis. Typically, trigeminal neuralgia is characterized by ‘electric shock-like, brief, stabbing pain’ while atypical facial pain has a ‘constant burning’ quality; however, both of these kinds of qualities may occur together, making differential diagnosis difficult [LOI. Dubuisson and Melzack [3] found that the McGill Pain Questionnaire (MPQ) can be used to discriminate among different kinds of pain. Using the MPQ, a discriminant analysis was 77% correct in making a prediction of the patients’ clinical pain problem on the basis of verbal descriptors alone. Several other studies have confirmed the discriminative capacity of the MPQ [1,5,6,12,15], while a few have found that severe pain may obscure the MPQ’s discriminative ability [7,14]. The purpose of this study was to see whether the MPQ is capable of discriminating between patients with trigeminal neuralgia and those with atypical facial pain, and whether it can further serve as a predictive aid in the differential diagnosis between the two syndromes.
Methods
The subjects were 74 patients who were admitted to the Presbyterian University Hospital or attended the Hospital Pam Clinic for treatment of facial pain. Forty-three patients (9 M, 34 F) were diagnosed as having trigeminal neuralgia, and 31 patients (5 M, 26 F) were diagnosed as having atypical facial pain. McGill Pain Questionnaire The McGill Pain Questionnaire [ll] consists of 20 sets of words describing sensory, affective, evaluative and miscellaneous dimensions of the experience of pain. Recent studies have shown the questionnaire to be reliable, to be sensitive to
299
the effects of different therapies on chronic pain, and to discriminate between different pain syndromes [14]. The questionnaire was given to the patients as part of the standard informationgathering procedure at the hospital or clinic. The patients were told to read the instructions carefully and were reminded to choose only those words that best described a typical episode of pain. In the present study, two additional words ‘diffuse’ and ‘localized’ - were added to the list of descriptors. Two major indexes can be obtained from the questionnaire. The first is the pain rating index (PRI), which is the sum of the rank values of the words chosen, which are based on the positions of the words in each category. The PRI can be computed separately for the sensory (categories l-lo), affective (categories ll-15) evaluative (category 16) and miscellaneous (categories 17-20) words or as a total score for categories l-20. The second is an index of present pain intensity (PPI), a measure of the overall pain intensity on a scale of O-5: 0 represents no pain, 1 mild, 2 discomforting, 3 distressing, 4 horrible and 5 excruciating pain. Procedure
Each patient received a thorough neurological examination which led to a diagnosis of trigeminal neuralgia or atypical facial pain. In addition, each patient was given the McGill Pain Questionnaire (MPQ) together with instructions on the procedure for choosing the appropriate verbal descriptors. The patient then filled in the MPQ. Photocopies of the MPQs for the first 53 patients were sent to Melzack and Amsel, and the data were entered into the computer for statistical analysis. This group consisted of 28 patients with trigeminal neuralgia (7 M, 21 F) and 25 with atypical facial pain (3 M, 22 F). A second group of patients filled out the MPQ in a similar way, and copies were sent to Melzack and Amsel without indication of the diagnosis. This group comprised 21 patients: 15 with trigeminal neuralgia (2 M, 13 F); 6 with atypical facial pain (2 M, 4 F). Statistical analyses were carried out to predict the diagnosis. After the prediction was made, Terrence and Fromm provided the code that permitted a comparison of the predictions and diagnoses.
Results The data of group I were analyzed by using a discriminant analysis to determine the pattern of descriptors that best discriminated between the patients with trigeminal neuralgia and those with atypical facial pain. Table I provides the key words and their weights which comprised the equation used to discriminate between the two sets of patients. Relatively higher weights indicate that a higher proportion of patients in that group chose that particular descriptor. Thus, patients with trigeminal neuralgia tended to choose flashing, terrifying, blinding and torturing, while patients with atypical facial pain tended to choose vicious, diffuse and excruciating, In the analysis of group I, 91% of the patients were correctly classified using the 7 descriptors and the constants in Table I.
TABLE
I
CLASSIFICATION Descriptors
Flashing Terrifying Vicious Blinding Torturing Diffuse Excruciating Constant (c)
FUNCTION
COEFFICIENTS Trigeminal neuralgia 0.67
I .99 2.53 -0.14 1.53 11.63 2.41 -X.66
Atypical facial pain
-_I____
- 1.91 0.61 6.19 - 2.98 0.03 21.44 5.10 -21.X6
To determine whether the key descriptors were able to predict the diagnosis of group II, the discriminant function derived from the analysis of group I was applied to the patients of group II. The results showed a correct prediction for 90% of the patients. One patient in each group was misclassified.
Discussion
The results show convincingly that verbal descriptors can aid in the diagnosis of trigeminal neuralgia and atypical facial pain. Each of these disorders is characterized by a constellation of descriptors that differs from the other. It was noted in the introduction that most patients with these two syndromes can be accurately diagnosed on the basis of several criteria, which are outlined in traditional neurological texts [2,8,16]. However, in that small group that defies easy characterization, and in which the usual criteria may be obscured by exceptional presenting symptoms, the MPQ provides an additional aid that may lead to a correct diagnosis (and, therefore, appropriate treatment). It is interesting that only a single sensory word - flashing - is included in the key descriptors of the discriminant analysis. The remaining words are predominantly affective, with different subsets being characteristic of either trigeminal neuralgia or atypical facial pain. It is evident that the two syndromes are not discriminated by any simple sensory/affective dichotomy but, rather, each appears to have a different emotional impact on the patient which is characterized by different subsets of words. The differences are sufficiently large that they were 91% correct in discriminating between the two types of patients in group I, and 90% correct in predicting the diagnosis of the patients in group II. The results lend further support to the discriminant capacity of the MPQ. This capacity has been demonstrated in several studies involving a variety of clinical pain syndromes [3,5,6,12,15] as well as in a recent study of acute laboratory pains [l]. It is evident, however, that this discrirninant capacity has limits. High levels of anxiety and other psychological disturbance, which may produce high affective scores, may
301
obscure the discriminative capacity [7]. Moreover, certain key words that discriminate among specific syndromes may be absent [13]. In the present study, for example, it was important to add the words localized and diffuse. Other syndromes may require the addition of other words such as the temporal descriptors intermittent and continuous. Experimenters are encouraged to modify the questionnaire to suit the needs of the particular syndromes being studied. The most important requirement of a measuring instrument is its utility. It is possible to tailor the MPQ to meet particular needs - thus, we now have the Low-Back Pain Scale [9] and the Headache Scale [6]. The present study provides a Facial Pain Scale to help in the diagnosis of difficult cases of trigeminal neuralgia and atypical facial pain.
Acknowledgements It is a pleasure to thank Dr. Ruben Tenicela and Dr. Peter Jannetta for allowing us to test their patients, and Ms. Darlene Lovasika and Mrs. Myriam Edelman for their help in acquiring and analyzing the data. This study was supported by Grant A7891 from the Natural Sciences and Engineering Research Council of Canada. References 1 Chen, A.C.N. and Treede, R.-D., The McGill Pain Questionnaire in the assessment of phasic and tonic experimental pain: behavioral evaluation of the ‘pain inhibiting pain’ effect, Pain, 22 (1985) 67-79. 2 Diamond, S. and Friedman, A.P., Headache, Medical Examination Publishing Co., New York, 1983. 3 Dubuisson, D. and Melzack, R., Classification of clinical pain descriptions by multiple group discriminant analysis, Exp. Neurol., 51 (1976) 480-487. 4 Friedman, A.P., Atypical facial pain, Headache, 9 (1969) 27-30. 5 Grushka, M. and Sessle, B.J., Applicability of the McGill Pain Questionnaire to the differentiation of ‘toothache’ pain, Pain, 19 (1984) 49-57. 6 Hunter, M., The headache scale: a new approach to the assessment of headache pain based on pain descriptions, Pain, 16 (1983) 361-373. 7 Kremer, E.F. and Atkinson, J.H., Pain language as a measure of affect in chronic pain patients. In: R. Melzack (Ed.), Pain Me~urement and Assessment, Raven Press, New York, 1983, pp. 119-127. 8 Lance, J.W., M~h~srn and Management of Headache, 4th edn., Bntte~orth, London, 1982. 9 Leavitt, F., Detecting psychological disturbance using verbal pain measurement: the back pain classification scale. In: R. Melzack (Ed.), Pain Measurement and Assessment, Raven Press, New York, 1985, pp. 79-84. 10 Loeser, J.D., Tic douloureux and atypical facial pain. In: P.D. Wall and R. Melzack (Eds.), Textbook of Pain, Churchill Livingstone, Edinburgh, 1984, pp. 426-434. 11 Melzack, R., The McGill Pain Questionnaire: major properties and scoring methods, Pain, 1 (1975) 277-299. 12 Melzack, R., Discriminative capacity of the McGill Pain Questionnaire (Letter to the Editor), Pain, 23 (1985) 201-203. 13 Reading, A.E., An analysis of the language of pain in chronic and acute patient groups, Pain, 13 (1982) 185-192. 14 Reading, A.E., Testing pain mechanisms in persons in pain. In: P.D. Wall and R. Melzack (Eds.), Textbook of Pain, Churchill Livingstone, Edinburgh, 1984, pp. 195-204.
15 Wagstaff. S.. Smith. O.V. and Wood, P.H.N.. Verbal pain descriptors used by patlenta with arthrltls. Ann. rheum. Dis., 44 (1985) 262-265. 16 Wartenberg, R., Neuritis, Sensory Neuritis, Neuralgia, Oxford University Press, New York, 19.58. 17 Weddington, W.W. and Blazer, D., Atypical facial pain and trigeminal neuralgia: a comparison study. Psychosomatics. 20 (1979) 348-356.