[Impact of the Interdisciplinary Chronic Pain Rehabilitation Programme in patients with and without sleep disorders]. / Impacto del Programa de Rehabilitación Interdisciplinario de Dolor Crónico en pacientes sin y con trastornos del sueño.

INTRODUCTION: Sleep disorders and chronic pain are linked to each other bidirectionally. Both are related to affective disorders, fatigue, depression, anxiety and drug abuse, and have a significant effect on quality of life. The Interdisciplinary Pain Programme (IDP) aims to relieve the patients' pain and improve their functionality by incorporating healthy postural, sleep and nutritional habits, relaxation techniques, physical exercise and cognitive-behavioural mechanisms. PATIENTS AND METHODS: A retrospective, observational, cross-sectional study was conducted. A total of 323 patients with chronic pain who completed the IDP were examined. They were assessed at the beginning and at the end of the programme with pain, depression, quality of life and insomnia scales, and were then compared between groups with and without insomnia, that is, with an insomnia severity index (ISI) less than 15 versus greater than or equal to 15. Fifty-eight patients were studied by means of polysomnography. RESULTS: A significant improvement (p < 0.0001) in pain, depression and quality of life, as assessed by the visual analogue scale (VAS), the Beck inventory and the Short Form-36 (SF-36) questionnaire was observed in chronic pain patients with an ISI below 15 and in those with an ISI greater than or equal to 15. The results were superior in the group of patients with insomnia. The presence of a high apnoea and hypopnoea index and periodic lower limb movements in patients was not related to improvements on the Beck, SF-36, ISI and VAS scales. CONCLUSIONS: In conclusion, IDP benefits patients with chronic non-cancer-induced pain in several affected areas, in addition to pain, due to a comprehensive treatment. Polysomnography can help diagnose specific pathologies and individualise pharmacological treatment.

TITLE: Impacto del Programa de Rehabilitación Interdisciplinario de Dolor Crónico en pacientes sin y con trastornos del sueño.Introducción. Los trastornos del sueño y el dolor crónico están relacionados bidireccionalmente. Ambos están relacionados con trastornos afectivos, fatiga, depresión, ansiedad y abuso de fármacos, y afectan significativamente a la calidad de vida. El objetivo del Programa Interdisciplinario de Dolor (PRID) es aliviar el dolor del paciente y mejorar su funcionalidad a través de la incorporación de hábitos posturales, del sueño y nutricionales saludables, técnicas de relajación, ejercicio físico y mecanismos cognitivoconductuales. Pacientes y métodos. Se realizó un estudio retrospectivo, observacional y transversal. Se examinó a 323 pacientes con dolor crónico que completaron el PRID. Se les evaluó al principio y al final del programa con escalas de dolor, depresión, calidad de vida e insomnio, y se les comparó entre grupos con y sin insomnio ­índice de gravedad del insomnio (ISI) menor de 15 frente a mayor o igual a 15­. Se estudió a 58 pacientes con polisomnografía. Resultados. Se observó una mejoría significativa (p < 0,0001) del dolor, la depresión y la calidad de vida evaluados mediante la escala analógica visual (EVA), el inventario de Beck y el cuestionario Short Form-36 (SF-36), tanto en pacientes con dolor crónico con ISI menor de 15 como ISI mayor o igual a 15. Los resultados fueron superiores en el grupo de pacientes con insomnio. La presencia de un índice de apneas e hipopneas elevado y movimientos periódicos de los miembros inferiores en los pacientes no se relacionó con la mejoría de las escalas de Beck, SF-36, ISI y EVA. Conclusiones. En conclusión, el PRID beneficia a los pacientes con dolor crónico no oncológico en varias esferas afectadas, además del dolor, mediante un tratamiento integral. La polisomnografía puede ayudar a diagnosticar patologías específicas e individualizar el tratamiento farmacológico.

Simple variance reduction in Monte Carlo calculations of specific absorbed fractions: Russian roulette and splitting at the source organ.

PURPOSE: To investigate the capabilities of several variance reduction techniques in the calculation of specific absorbed fractions in cases where the source and the target organs are far away and/or the target organs have a small volume. METHODS: The specific absorbed fractions have been calculated by using the Monte Carlo code PENELOPE and by assuming the thyroid gland as the source organ and the testicles, the urinary bladder, the uterus, and the ovaries as the target ones. A mathematical anthropomorphic phantom, similar to the MIRD-type phantoms, has been considered. Photons with initial energies of 50, 100 and 500 keV were emitted isotropically from the volume of the source organ. Simulations have been carried out by implementing the variance reduction techniques of splitting and Russian roulette at the source organ only and the interaction forcing at the target organs. The influence of the implementation details of those techniques have been investigated and optimal parameters have been determined. All simulations were run with a CPU time of 1.5 · 105 s. RESULTS: Specific absorbed fractions with relative uncertainties well below 10% have been obtained in most cases, agreeing with those used as reference. The best value for the factor defining the application of the Russian roulette technique was r = 0.3. The best value for the splitting number was between s = 3 and s = 10, depending on the specific energies and target organs. CONCLUSIONS: The proposed strategy provides an effective method for computing specific absorbed fractions for the most unfavorable situations, with a computing effort that is considerably reduced with respect to other methodologies.

Detailed Monte Carlo Simulation of electron transport and electron energy loss spectra.

A computer program for detailed Monte Carlo simulation of the transport of electrons with kinetic energies in the range between about 0.1 and about 500 keV in bulk materials and in thin solid films is presented. Elastic scattering is described from differential cross sections calculated by the relativistic (Dirac) partial-wave expansion method with different models of the scattering potential. Inelastic interactions are simulated from an optical-data model based on an empirical optical oscillator strength that combines optical functions of the solid with atomic photoelectric data. The generalized oscillator strength is built from the adopted optical oscillator strength by using an extension algorithm derived from Lindhard's dielectric function for a free-electron gas. It is shown that simulated backscattering fractions of electron beams from bulk (semi-infinite) specimens are in good agreement with experimental data for beam energies from 0.1 keV up to about 100 keV. Simulations also yield transmitted and backscattered fractions of electron beams on thin solid films that agree closely with measurements for different film thicknesses and incidence angles. Simulated most probable deflection angles and depth-dose distributions also agree satisfactorily with measurements. Finally, electron energy loss spectra of several elemental solids are simulated and the effects of the beam energy and the foil thickness on the signal to background and signal to noise ratios are investigated. SCANNING 38:475-491, 2016. © 2015 Wiley Periodicals, Inc.

Monte Carlo calculation of specific absorbed fractions: variance reduction techniques.

The purpose of the present work is to calculate specific absorbed fractions using variance reduction techniques and assess the effectiveness of these techniques in improving the efficiency (i.e. reducing the statistical uncertainties) of simulation results in cases where the distance between the source and the target organs is large and/or the target organ is small. The variance reduction techniques of interaction forcing and an ant colony algorithm, which drives the application of splitting and Russian roulette, were applied in Monte Carlo calculations performed with the code penelope for photons with energies from 30 keV to 2 MeV. In the simulations we used a mathematical phantom derived from the well-known MIRD-type adult phantom. The thyroid gland was assumed to be the source organ and urinary bladder, testicles, uterus and ovaries were considered as target organs. Simulations were performed, for each target organ and for photons with different energies, using these variance reduction techniques, all run on the same processor and during a CPU time of 1.5 · 10(5) s. For energies above 100 keV both interaction forcing and the ant colony method allowed reaching relative uncertainties of the average absorbed dose in the target organs below 4% in all studied cases. When these two techniques were used together, the uncertainty was further reduced, by a factor of 0.5 or less. For photons with energies below 100 keV, an adapted initialization of the ant colony algorithm was required. By using interaction forcing and the ant colony algorithm, realistic values of the specific absorbed fractions can be obtained with relative uncertainties small enough to permit discriminating among simulations performed with different Monte Carlo codes and phantoms. The methodology described in the present work can be employed to calculate specific absorbed fractions for arbitrary arrangements, i.e. energy spectrum of primary radiation, phantom model and source and target organs.

Efficient Monte Carlo simulation of multileaf collimators using geometry-related variance-reduction techniques.

A technique for accelerating the simulation of multileaf collimators with Monte Carlo methods is presented. This technique, which will be referred to as the movable-skin method, is based on geometrical modifications that do not alter the physical shape of the leaves, but that affect the logical way in which the Monte Carlo code processes the geometry. Zones of the geometry from which secondary radiation can emerge are defined as skins and the radiation transport throughout these zones is simulated accurately, while transport in non-skin zones is modelled approximately. The skins method is general and can be applied to most of the radiation transport Monte Carlo codes used in radiotherapy. The code AUTOLINAC for the automatic generation of the geometry file and the physical parameters required in a simulation of a linac with the Monte Carlo code PENELOPE is also introduced. This code has a modularized library of all Varian Clinac machines with their multileaf collimators and electron applicators. AUTOLINAC automatically determines the position of skins and the parameter values employed for other variance-reduction techniques that are adequate for the simulation of a linac. Using the adaptive variance-reduction techniques presented here it is possible to simulate with PENELOPE an entire linac with a fully closed multileaf collimator in two hours. For this benchmark a single core of a 2.8 GHz processor was used and 2% statistical uncertainty (1sigma) of the absorbed dose in water was reached with a voxel size of 2 x 2 x 2 mm(3). Several configurations of the multileaf collimator were simulated and the results were found to be in excellent agreement with experimental measurements.

Monte Carlo evaluation of the convolution/superposition algorithm of Hi-Art tomotherapy in heterogeneous phantoms and clinical cases.

The reliability of the convolution/superposition (C/S) algorithm of the Hi-Art tomotherapy system is evaluated by using the Monte Carlo model TomoPen, which has been already validated for homogeneous phantoms. The study was performed in three stages. First, measurements with EBT Gafchromic film for a 1.25 x 2.5 cm2 field in a heterogeneous phantom consisting of two slabs of polystyrene separated with Styrofoam were compared to simulation results from TomoPen. The excellent agreement found in this comparison justifies the use of TomoPen as the reference for the remaining parts of this work. Second, to allow analysis and interpretation of the results in clinical cases, dose distributions calculated with TomoPen and C/S were compared for a similar phantom geometry, with multiple slabs of various densities. Even in conditions of lack of lateral electronic equilibrium, overall good agreement was obtained between C/S and TomoPen results, with deviations within 3%/2 mm, showing that the C/S algorithm accounts for modifications in secondary electron transport due to the presence of a low density medium. Finally, calculations were performed with TomoPen and C/S of dose distributions in various clinical cases, from large bilateral head and neck tumors to small lung tumors with diameter of < 3 cm. To ensure a "fair" comparison, identical dose calculation grid and dose-volume histogram calculator were used. Very good agreement was obtained for most of the cases, with no significant differences between the DVHs obtained from both calculations. However, deviations of up to 4% for the dose received by 95% of the target volume were found for the small lung tumors. Therefore, the approximations in the C/S algorithm slightly influence the accuracy in small lung tumors even though the C/S algorithm of the tomotherapy system shows very good overall behavior.

Monte Carlo simulation of helical tomotherapy with PENELOPE.

Helical tomotherapy (HT) delivers intensity-modulated radiation therapy (IMRT) using the simultaneous movement of the couch, the gantry and the binary multileaf collimator (MLC), a procedure that differs from conventional dynamic or step-and-shoot IMRT. A Monte Carlo (MC) simulation of HT in the helical mode therefore requires a new approach. Using validated phase-space files (PSFs) obtained through the MC simulation of the static mode with PENELOPE, an analytical model of the binary MLC, called the 'transfer function' (TF), was first devised to perform the transport of particles through the MLC much faster than time-consuming MC simulation and with no significant loss of accuracy. Second, a new tool, called TomoPen, was designed to simulate the helical mode by rotating and translating the initial coordinates and directions of the particles in the PSF according to the instantaneous position of the machine, transporting the particles through the MLC (in the instantaneous configuration defined by the sinogram), and computing the dose distribution in the CT structure using PENELOPE. Good agreement with measurements and with the treatment planning system of tomotherapy was obtained, with deviations generally well within 2%/1 mm, for the simulation of the helical mode for two commissioning procedures and a clinical plan calculated and measured in homogeneous conditions.

Spectrum of cutaneous hyperalgesias/allodynias in neuropathic pain patients.

OBJECTIVES: The aim of this study was to discern the pathophysio-logical bases for neuropathic hyperalgesias. METHODS: In this study, neurological and neurophysiological evaluation of 132 consecutive hyperalgesia patients using rigorous clinical and laboratory protocols were carried out. RESULTS: Two discrete semeiologic entities emerged: classic neurological vs atypical, fulfilling taxonomically complex regional pain syndrome (CRPS) II and I, respectively. The classic group (34.9%) exhibited sensorimotor patterns restricted to nerve distribution and documented nerve fiber dysfunction. Among them four (3.03%) had sensitization of C-nociceptors, seven (5.3%) had central release of nociceptive input, and 35 (26.52%) probable ectopic nerve impulse generation. The atypical group (65.1%) displayed weakness with interrupted effort; non-anatomical hypoesthesia and hyperalgesia; hypoesthesia or paresis reversed by placebo, or atypical abnormal movements, and physiological normality of motor and sensory pathways. CONCLUSIONS: Spatiotemporal features of neuropathic hyperalgesia constitute key criteria for differential diagnosis between CRPS II and I and, together with other behavioral sensorimotor features, signal psychogenic pseudoneurological dysfunction vs structural neuropathology. 'Neuropathic' hyperalgesias may reflect neuropathological or psychopathological disorders.

Monte Carlo simulation of electron beams from an accelerator head using PENELOPE.

The Monte Carlo code PENELOPE has been used to simulate electron beams from a Siemens Mevatron KDS linac with nominal energies of 6, 12 and 18 MeV. Owing to its accuracy, which stems from that of the underlying physical interaction models, PENELOPE is suitable for simulating problems of interest to the medical physics community. It includes a geometry package that allows the definition of complex quadric geometries, such as those of irradiation instruments, in a straightforward manner. Dose distributions in water simulated with PENELOPE agree well with experimental measurements using a silicon detector and a monitoring ionization chamber. Insertion of a lead slab in the incident beam at the surface of the water phantom produces sharp variations in the dose distributions, which are correctly reproduced by the simulation code. Results from PENELOPE are also compared with those of equivalent simulations with the EGS4-based user codes BEAM and DOSXYZ. Angular and energy distributions of electrons and photons in the phase-space plane (at the downstream end of the applicator) obtained from both simulation codes are similar, although significant differences do appear in some cases. These differences, however, are shown to have a negligible effect on the calculated dose distributions. Various practical aspects of the simulations, such as the calculation of statistical uncertainties and the effect of the 'latent' variance in the phase-space file, are discussed in detail.

Practical aspects of Monte Carlo simulation of charged particle transport: mixed algorithms and variance reduction techniques.

This paper is concerned with the practical implementation of Monte Carlo simulation methods for charged particle transport. The emphasis is on light particles (electrons and positrons) because of the larger scattering and energy straggling effects. Differential cross sections (DCS) for the various interaction mechanisms are described. As the average number of interactions along the particle track increases with the initial energy, detailed simulation becomes unfeasible at high energies. We can then rely on mixed simulation algorithms: hard events (i.e. individual interactions with angular deflection or energy loss larger than given cutoff values) are sampled from the DCS whereas soft events are simulated by means of a multiple scattering approach. Too frequently, the statistical uncertainty of analogue simulation (i.e. strict simulation of the physical interaction process) is found to be so large that results are meaningless. This problem can be partially solved by applying simple variance reduction techniques.

Involuntary movements and abnormal spontaneous EMG activity in syringomyelia and syringobulbia.

OBJECTIVE: To describe different types of involuntary movements and abnormal spontaneous electromyographic (EMG) activity in patients with syringomyelia. BACKGROUND: A comprehensive study on involuntary movements in patients with syringomyelia has not yet been undertaken, to these authors' knowledge. METHODS: One hundred adult patients with syringomyelia were examined over the last 15 years. Involuntary movements were videotaped and evaluated by two independent observers. Electromyographic recordings were made using bipolar surface electrodes. The H-reflex recovery curve was obtained after stimulation of the median nerve at the elbow and recording from the flexor carpi radialis. RESULTS: Involuntary movements or abnormal postures were observed in 22 patients. Three patients showed segmental spinal myoclonus, nine minipolymyoclonus, and four propriospinal myoclonus. Five patients had unilateral or bilateral hand postural tremor (8-10 Hz). Focal or segmental dystonia was observed in three patients. Electromyography showed spontaneous bursts of grouped action potentials synchronous in muscles innervated by the same spinal segment, synchronous firing of neurogenic motor unit potentials, or continuous motor unit activity. Increased H-reflex responses to conditioning stimuli were found in patients with spinal myoclonus. Long latency responses were obtained during peripheral nerve stimulation in four patients. Four patients had rigidity and abnormal upper limb posture. Respiratory synkinesis was observed in three patients. One patient developed inverse masticatory muscle activity. CONCLUSIONS: Patients with syringomyelia showed a wide spectrum of involuntary movements. An increased excitability of spinal motor neurons was probably the basic underlying mechanism.

Monte Carlo calculation of the dose distributions of two 106Ru eye applicators.

BACKGROUND AND PURPOSE: Beta emitting 106Ru applicators are widely used to treat choroidal melanoma. In view of the importance of clinical applications of this radioisotope and the relative lack of knowledge of the dose distributions, three-dimensional dose maps of two concave applicators were calculated by means of Monte Carlo simulation. MATERIALS AND METHODS: Simulations of small CCA and CCB concave applicators manufactured by Bebig were performed using the Monte Carlo code PENELOPE, which allows the description of the structure (geometry and materials) of the applicator in detail. Electrons are emitted from the 106Ru nuclei isotropically, with initial energy randomly sampled from the corresponding Fermi spectra and with initial positions uniformly distributed on the radioactive layer. Primary electrons, as well as the produced delta-rays, are assumed to be absorbed in the medium when they slow down to an energy of 70 keV. Bremsstrahlung photons with energies larger than 7 keV are also simulated. The simulation code has been run on a 166 MHz PENTIUM PC. RESULTS: Three-dimensional dose distributions produced by the CCA and CCB applicators in a water sphere, concentric with the applicator, were evaluated. To minimize the magnitude of statistical uncertainties, advantage has been taken of the cylindrical symmetry of the problem. The relative depth-dose (along the symmetry axis of the applicator) was also evaluated from the applicator surface up to distances larger than I cm, with statistical uncertainties of a few percent. Results compare well with data supplied by the manufacturer. CONCLUSIONS: We have performed accurate Monte Carlo calculations of three-dimensional dose distributions from CCA and CCB 106Ru applicators. The results, presented in the form of two-dimensional maps, depth-dose distributions along the symmetry axis and lateral dose profiles, provide a detailed description of the dose delivered in treatments of choroidal melanoma.

Use of antiepileptic drugs in nontraumatic neurosurgical procedures. Is there any best route and time of administration?

We assessed in 15 consecutive patients the best route and time of administration for phenytoin (PHT) prophylaxis in neurosurgical procedures. We also correlated PHT levels in serum and cerebrospinal fluid after oral and parenteral loading doses. The mean PHT level was 13.9 micrograms/ml in serum and 2.03 micrograms/ml in cerebrospinal fluid (CSF), with a significant correlation between levels in both compartments (r = 0.73, p < 0.01). Mean PHT levels among the different groups were not statistically significant. We conclude that therapeutic levels of PHT in CSF can be achieved independently of the route of administration, as long as accepted loading doses are used.

[Monitoring cervical dilatation by impedance]. / Partogramme enregistré par impédancemétrie.

Several different physics procedures have been tried to mechanize the recording of partograms. Can a measure of impedance of tissue Z using potential difference V, according to Ohm's law V = Z1, and 1 is a constant, be correlated with a measure of cervical dilatation using vaginal examination? This was our hypothesis. The tissue impedance meter was made to our design and applied according to a bipolar procedure. Our work was carried out on 28 patients. 10 patients were registered before labour started in order to test the apparatus and to record the impedance variations without labour taking place, and 18 patients were registered in labour to see whether there was any correlation. The level of impedance in the cervix without labour was 302.7 Ohms with a deviation of 8.2. Using student's t tests it was found that there was a significant correlation (p less than 0.001) in four measurements between the impedance measure and measures obtained by extrapolating the degrees of dilatation calculated from vaginal examination. This is a preliminary study in which we have defined the conditions that are necessary to confirm these first results and to further develop the method.

[Congenital arteriovenous fistula of the kidney. Report on a further case (author's transl)]. / Fistule artério-veineuse congénitale du rein. Un nouveau cas.

A congenital arteriovenous fistula of the kidney was discovered in a 75-year-old man presenting with hematuria and a silent kidney on I.V.U. The diagnosis had been suggested from the results of pre-operative arteriography examination. Treatment consisted of a total nephrectomy, because of the age of the patient and the hilar site of the "angioma". Reports in the published literature confirm the rare nature of this type of lesion and the difficulties encountered when trying to classify them in precise nosological groups.

[Post-traumatic extrahepatic arterioportal fistula. A case with a spontaneously favourable course]. / Fistule artério-portale extra-hépatique, post-traumatique. Un nouveau cas d'évolution spontanément favorable.

The authors describe a case of post-traumatic arterio-portal fistula (APF), discovered on the 12th day after coeliomesenteric arteriography performed because of a postoperative complication, and emphasize the rare nature of this lesion, as shown by a review of the published literature. They stress the value of coeliomesenteric arteriography after urgent laparatomy for hepatic trauma for investigation of any possible lesions.