Management of refractory complex partial seizures: current state of the art

Diagnosis of complex partial epilepsy is based on the clinical history, and laboratory tests, including EEG and neuroimaging studies, corroborate the diagnosis. The goal of epilepsy management is to make the patient completely seizure-free without drug-induced side effects, even in the patient with refractory complex partial seizures. Frequently this can be accomplished by choice of the optimal antiepileptic drug (AED) or a combination of drugs, the use of strategies to maximize the effectiveness of drug treatment, or by surgical removal of the seizure focus. Currently there are five “classical” first-line AEDs and 11 new AEDs available in the US and in many other countries for the treatment of localization-related epilepsy. The current state of the evidence is that no AED is clearly superior to other AEDs in the management of refractory complex partial seizures. Therefore the choice of which drug to use in an individual patient has to be based on other considerations, including the potential adverse reactions that may occur in that patient. There are a number of strategies for optimal use of AEDs in the management of refractory complex partial seizures. These include verification of the diagnosis of epilepsy and classification of specific seizure types, use of monotherapy if possible but polytherapy if necessary, starting with a low dose and raising it slowly but, until complete seizure control is achieved, pushing to the maximum tolerated dose, changing timing of dosing to reduce toxicity, using pharmacokinetic principles to fine-tune AED doses, adjusting dose for drug–drug interactions, and never giving up in the pursuit of better seizure control. Resection of the seizure focus can be curative in the majority of patients with seizures localized to one mesial temporal lobe. Success rates for resection of extratemporal seizure foci are lower. Vagus nerve stimulation (VNS) devices result in a significant reduction of seizure frequency in many patients, but patients rarely become completely seizure-free as a result of VNS device implantation. Management of refractory complex partial seizures continues to improve with the identification of new drugs and the development of new approaches to their control and cure

Singularities of Scattering Amplitudes on Unphysical Sheets and Their Interpretation

The analytic structure of two-particle scattering amplitudes on the unphysical sheet of the Riemann surface reached by crossing the two-particle cut is discussed. The singularities of the amplitudes there are shown to be poles and their physical interpretation is studied. The way in which bound states appear on the physical sheet in the Mandelstam representation, both as isolated poles and as cuts, is traced in detail. The properties of partial wave amplitudes and of the full amplitude as a function of energy and angle and of energy and momentum transfer are discussed. Finally, a few remarks are made in connection with unstable states

Effects of an extra U(1) axial condensate on the strong decays of pseudoscalar mesons

We consider a scenario (supported by some lattice results) in which a U(1)-breaking condensate survives across the chiral transition in QCD. This scenario has important consequences for the pseudoscalar-meson sector, which can be studied using an effective Lagrangian model. In particular, generalizing the results obtained in two previous papers, where the effects on the radiative decays eta,eta' --> gamma gamma were studied, in this paper we study the effects of the U(1) chiral condensate on the strong decays of the "light" pseudoscalar mesons, i.e., eta,eta' --> 3pi^0; eta,eta' --> pi^+ pi^- pi^0; eta' --> eta pi^0 pi^0; eta' --> eta pi^+ pi^-; and also on the strong decays of an exotic ("heavy") SU(3)-singlet pseudoscalar state eta_X, predicted by the model.Comment: One misprint in Eq. (2.10) has been eliminated; Eqs. (B.8) and (B.9) in Appendix B have been corrected; 46 pages, 1 tabl

A soluble problem in dispersion theory

The Lee model is modified by addition of a new field θ′ and a weak coupling N+θ→N+θ′, which leads to instability of the V particle: V→N+θ→N+θ′. The decay amplitude is calculated to lowest order in the weak coupling by dispersion relation methods. In effect we are required to study a set of simultaneous dispersion relations. The problem is completely soluble and serves to clarify the essential structure of dispersion methods. The results agree with what one obtains, more easily in the present case, by direct methods

Form factors in β decay and μ capture

We suppose that β decay and μ capture are described by a universal vector and axial vector Lagrangian and we consider, via dispersion relation techniques, the properties of the corresponding S-matrix elements. Owing to the strong interactions of the nucleons, the structure of the S matrix is expected to be more complicated than that of the Lagrangian. In the former, vector and axial vector terms appear, but with coefficients which in general depend on the invariant nucleon momentum transfer; they can be thought of as Fermi interaction form factors. Moreover, two additional kinds of terms can appear in the S-matrix elements: one which simulates a direct pseudoscalar coupling and one which simulates a direct coupling involving derivatives of the nucleon wave functions. The latter is probably too small to have any experimental significance. The former, though negligible in β decay, may be appreciable in μ capture. We estimate the effective pseudoscalar coupling coefficient there to be about eight times as large as the axial vector coefficient. More generally, we investigate the structure of the various form factors; and we also reconsider, in further refinement, a recent quantitative discussion which we have given of π→μ+ν decay

Decay of the pi meson

A quantitative study of π→μ+ν decay is presented using the techniques of dispersion theory. The discussion is based on a model in which the decay occurs through pion disintegration into a nucleon-antinucleon pair, the latter annihilating via a Fermi interaction to produce the leptons. The weak vertex contains effectively both axial vector and pseudoscalar couplings even if one adopts the point of view of a universal axial vector and vector Fermi interaction. The pion-nucleon vertex which enters our model is also calculated using dispersion techniques. Under the assumption that this vertex is damped for large momentum transfers, we obtain a result for the pion lifetime largely independent of the detailed properties of the vertex and one which is in very close agreement with experiment. The precise prediction of our theory depends on the energy dependence of the complex phase shift for nucleon-antinucleon scattering in the 1S0 isotopic triplet state

Lunar Meteorite NWA 11421: X-Ray Tomogrpahy & Preliminary Petrology

Lunar meteorite NWA 11421 is provisionally placed with the "NWA 8046 clan" of similar stones (the "Algerian Megafind") of which at least 33 kg has been recovered. NWA 11421 and pairs are feldspathic regolith breccias, with angular fragments of plagioclase-rich clasts in a dark glassy matrix. Most members of this clan contain < 5.5% FeO and < 0.3 ppm Th. To date, there have been no petrographic studies reported of these lunar meteorites. An 11.7 gm sample of NWA 11421 was purchased from Marcin Cimala, holder of the main mass - this sample is consistent in all respects with the formal meteorite description. This particular sample was selected because it appeared to contain a fragment of dunite

Elementary Derivation of the Chiral Anomaly

An elementary derivation of the chiral gauge anomaly in all even dimensions is given in terms of noncommutative traces of pseudo-differential operators.Comment: Minor errors and misprints corrected, a reference added. AmsTex file, 12 output pages. If you do not have preloaded AmsTex you have to \input amstex.te