[Mechanisms of myofascial pain]. / Mécanismes des douleurs myofasciales.

The aim of this paper is to review available data and current hypotheses concerning myofascial pain syndrome pathophysiology and implications for clinical practice. A muscular hypothesis has been proposed for episodic and chronic tension headache as well as for myofascial syndrome and fibromyalgia. These different syndromes may be compared as, besides their frequent combination, they have common features characterized by spontaneous pain, painful points, and lack of objective findings. They must be distinguished because each has its own diagnostic criteria. Pressure algometry appears to be a reliable method for assessing pressure sensitivity in myofascial pain. Pressure pain is not specific to tension headache and can be observed in other chronic headaches. It has not been demonstrated that the trigger points of fibromyalgia are specific in idiopathic cases. It is difficult to find an electrophysiological investigation which is specific for myofascial pain. For daily practice, the clinical approach with interview and examination remain the advisable attitude. Pathophysiological hypotheses help in better understanding of referred pain by sensitization of nociceptive central pathways according to the Ruch convergence projection theory (1965), modified by Mense in 1994. These theories do not however provide an explanation of the primary muscular mechanisms. Implications for myofascial pain patient management is discussed.

[Principles of organization of a center for pain evaluation and treatment]. / Principes d'organisation d'un centre d'évaluation et de traitement de la douleur.

Since the development during the sixties of the pioneer pain clinics in the United-States, the need of a pluridisciplinary approach of the chronic pain patient has progressively compelled recognition. The principles of organization of this new care units--the pin center--are now clearly determined. It has become classic to compare acute pain as a warning symptom with chronic pain as an illness in itself with its constellation of psychosocial factors. Chronic pain refers to a daily pain persisting for 3 to 6 months. Neurophysiological, neuropsychological and behavioral differences legitimate the acute/chronic distinction. We will consider the following items: the types of patient, the multidisciplinary model, the team functioning, the initial consultation, the multidisciplinary synthesis discussion, the somatician role, the psychiatrist role and the possible disadvantages. Beside the care mission, multidisciplinary pain centers also have a key role in clinical research and teaching.

[Clinical approach in patients with chronic pain]. / Abord clinique du patient douloureux chronique.

In the case of a patient having persistent pain for 3 to 6 months, the physician needs to structure the various data obtained over that time. We propose an approach which analyzes pain according to various independent axes, in particular somatic and psychosocial. Correct diagnosis of the pathophysiological mechanism of pain (excess nociception, neurogenous, maintenance by the sympathetic nervous system, or muscular) is required in order to direct appropriate symptomatic treatment. In parallel with this somatic approach to the aetiology of chronic pain, certain individual variables must be taken into account such as anxiety level, depression, personality, and reinforcement factors (secondary benefits) that can amplify pain or maintain the chronicity of pain in such patients.

[Need of risk reevaluation in morphine dependence in pain patients]. / Nécessité de réévaluation du risque de dépendance avec les analgésiques morphiniques chez le malade douloureux.

It is commonly recognized than opioids analgesics have an major place in the treatment of pain. In spite of guidelines, opioids drugs remain underutilized in chronic cancer pain and acute severe pain. Among the possible factors, involved in the insufficient use of opioids drugs, is the fear (opiophoby) of physicians, nurses, patients and family to induce or to maintain an addiction. This review examines the potential of iatrogenic addiction. We will examined the place of morphine-like drugs in the treatment of severe acute pain and chronic cancer pain, the definition of dependency in pain patients, the assessment of the dependency potential in patients treated for pain. Available studies indicate that iatrogenic addiction is quite scarce and that the risk for a major tolerance is very small. Further studies will be necessary, since opioids analgesics may also be useful in some non-cancer chronic pain.

Study of experimental pain measures and nociceptive reflex in chronic pain patients and normal subjects.

This study evaluates (i) the effect of heterotopic chronic pain on various experimental pain measures, (ii) the relationship between experimental pain measures and chronic pain symptomatology assessment, and (iii) the influence of the various pain aetiologies on experimental pain measures. Fifty-three chronic pain patients were compared to 17 pain-free subjects with the following psychophysical and physiological indices: pain threshold (PTh), pain tolerance (PTol), verbal estimation of intensity and unpleasantness (intensity scale, IS; unpleasantness scale, US), threshold for intensity and unpleasantness (ITh and UTh), lower limb RIII nociceptive reflex (RIIITh and RIII frequency of occurrence). Chronic pain syndromes included neuropathic pain (n = 12), iodopathic pain (n = 12), myofascial syndromes (n = 9), headache (n = 9), and miscellaneous pain (n = 11). Chronic pain symptomatology was assessed with a visual analogue scale (VAS), a French MPQ adaptation (QDSA), Beck Depression Inventory (BDI), Spielberger State Trait Inventory (STAI) and Eysenck Personality Inventory (EPI). No significant difference was observed between chronic pain patients and pain-free control groups and between patient subgroups for PTh, PTol and RIIITh. No significant correlation was found between experimental pain measures and clinical pain, anxiety or depression scores. However, the chronic pain patients had a higher threshold for unpleasantness and judged the suprathreshold stimuli significantly less intense and less unpleasant than the control group. These results are discussed in relation to diffuse noxious inhibitory controls and the adaptation level theory of chronic pain experience.

[The chronically painful hand. A consecutive series of 60 cases]. / La main douloureuse chronique. A propos d'une série consécutive de soixante cas.

This study was based on 60 patients presenting with hand pain refractory to usual treatment. The aim of this study was to assess the pathophysiological and neuropsychological factors involved in a population of patients recruited in a hand surgery unit. Analysis of this series revealed the frequency of desafferentation mechanisms. These symptoms can be treated by means of antidepressants, antiepileptics and peripheral neurostimulation. Anxio-depressive factors were of limited importance in this series, at least in comparison with the population usually examined in a pain treatment centre. However, their presence in a subgroup of patients (26% of cases) and the limitations of symptomatic analgesic treatment justifie a global approach to chronic pain in order to establish the participation of the various factors in each particular case. It is useful to combine aetiological treatments with psychological treatments (antidepressants, relaxation therapy, for example) to increase the patient's tolerance of their persistent painful symptoms.

[Problems posed by the evaluation of pain and its psychological aspects]. / Problèmes posés par l'évaluation de la douleur et de ses aspects psychologiques.

Pain is a complex, multidimensional and multifactorial neuropsychological phenomenon with sensory-discriminative, affective, cognitive and behavioral components. Issues on pain assessment are related to the objective evaluation of a subjective phenomenon. Different levels of evaluation are to be considered. Some methods such as visual analog scale, numerical scale and verbal permit a global pain estimation. The aim of other methods such as the McGill Pain Questionnaire is a quantitative and qualitative evaluation of the sensory and affective pain components. The measure of objective behavioral changes is an interesting approach, but at the present time there is no valid, simple and commonly used method. There is also a need for methods permitting better exploration of pain, and in particular a selective evaluation of organic and functional factors. The limits of psychological factor evaluation are reported.

Study of verbal description in neuropathic pain.

The aim of this paper is to study the quality of verbal description and its diagnostic value in neuropathic pain. The verbal description of pain as assessed by a French adjective list questionnaire (QDSA) is compared between a group of 100 patients with neuropathic pain and a mixed group of 97 chronic benign and cancer non-neuropathic pain patients. Seventeen descriptors of the 61 QDSA descriptors have a significant intergroup frequency difference. By principal component analysis and Varimax rotation of the intercorrelation matrix of descriptors in the neuropathic group. 7 factors accounting for 66.0% of the total variance are derived. Six factors reflect purely sensory or affective aspects of the pain experience. Seven descriptors from the discriminant analysis function correctly assign 77% of neuropathic pain patients and 81% of the non-neuropathic pain patients. In a second neuropathic pain group of 32 patients, the discriminant function coefficient permits correct diagnostic categorization in 66% of the cases. Implications for clinical practice and trials are discussed.

[Oculomotor forms of myasthenia]. / Les formes oculo-motrices de la myasthénie.

The diagnostic difficulty in purely oculo-motor forms of myasthenia can be due to the lack of fluctuation in symptoms, the occurrence of complete spontaneous remissions, lasting several months or years, the absence of a decremental response in muscle potentials as evidenced by classical repetitive stimulation of the motor nerve, and negative responses to pharmacological testing. Thus, several investigative procedures have been developed to aid in the diagnosis of questionable cases. These include electromyography of proximal muscles and single fiber recordings, the dosage of acetylcholine receptors antibodies (specificity of nearly 100 %), and histological examination of neuro-muscular junction (invariably finding specific lesions of motor end plates). In spite of the diffuse pathological process and the possible overlapping with other types of myasthenia, many oculo-motor forms remain strictly localized throughout their course. Furthermore the prognosis of oculo-motor myasthenia is far better than other forms. Several hypotheses exist to explain the peculiarities of ocular myasthenia. Among these explanations are the theories that there are structural factors specific to oculo-motor muscles and that there exist a heterogeneity of acetylcholine receptor antibodies. On the therapeutic grounds, the frequent failure of anticholinesterase agents has been established. Corticosteroids are often very efficacious, but require high maintenance doses. The adverse side effects of such therapy have led some authors to suggest thymectomy as an alternative therapeutic modality.

[Association of ankylosing spondylarthritis, cauda equina syndrome and dilatation of the lumbar cul-de-sac with voluminous arachnoid diverticulum. Clinical, radiological and tomodensitometric study of a case]. / Sur l'association spondylarthrite ankylosante, syndrome de la queue de cheval et dilatation du cul-de-sac lombaire avec volumineux diverticule arachnoïdien. Etude clinique, radiologique et tomodensitométrique d'un cas.

The authors report a clinical and radiological observation of cauda equina syndrome associated with ankylosing spondylitis. Although only 32 cases have been reported in the literature over the last twenty years, such an association is probably not exceptional. The mode of onset and the course of the neurological symptoms is quite similar from case to case: ankylosing spondylitis preexisting for many years, and inactive when neurological signs develop, the latter usually being very slowly progressive. The usual radiological features, demonstrated by saccoradiculography in the supine position, are posterior diverticulas of the lumbar theca, contiguous to bony erosions of the laminae, well visualized by computed tomography. Pathogenesis remains obscure, and none of the attempted therapies, including surgical procedures, have proved effective.

[Syncope and transitory amaurosis during mastocytosis]. / Syncope et amaurose transitoire au cours d'une mastocytose.

In a 70-year old man who has been suffering for 20 years from mastocytosis, a syncope followed by a transitory amaurosis occured. Neurological complications of mastocytosis are exceptionnal. Syncope is the most frequent, secondary to a drop in arterial pressure due to an inappropriate discharge of histamin.