Clinical Neuroscience

[CHANGES IN EEG-COMPLEXITY AFTER SUBCORTICAL ISCHEMIC BRAIN DAMAGE]

MOLNÁR Márk1, CSUHAJ Roland1, HORVÁTH Szabolcs2, VASTAGH Ildikó3, GAÁL Zsófia Anna1, CZIGLER Balázs4, BÁLINT Andrea4, NAGY Zoltán5

MAY 30, 2006

Clinical Neuroscience - 2006;59(05-06)

[Introduction - Complexity analysis of the EEG is a relatively new field in theoretical and cinical electrophysiology. The authors present results of EEG-analysis in a patient with stroke, utilizing the sensitivity of the new procedures with respect to linear and nonlinear synchronization. Participants and methods - The EEG (19 channels) was recorded in a patient with subcortical unilateral ischaemic completed stroke involving the frontoparietal white matter while leaving the cortex intact and in 12 healthy controls in eyes open and in eyes closed conditions. Results - In the patient, increased Omega-complexity was found in slow (delta, theta) and lower alpha frequencies in the side of the stroke and in high frequencies (beta2 in eyes closed, alpha2, beta1 and beta2 in eyes open conditions) in the intact side. Synchronization likelihood was higher in the ischaemic side in the beta2 (eyes closed) and both in the beta1 and beta2 (eyes open) frequencies. Increasing Omega-complexity caused by eyes opening was markedly reduced in the patient in the beta frequencies compared to that seen in the controls. The difference was more conspicuous in the side of the infarct and involved not only the beta but also the alpha frequencies as well. Opening the eyes decreased synchronization likelihood in all frequency bands in the controls and also in the patient except the alpha2, beta1 and beta2 bands in the side of the lesion. Conclusions - The increased Omega-complexity and decreased synchronization likelihood in the slow frequencies in the infarcted side is probably the result of lesioned interneuronal connections lowering the level of cooperation of neuronal systems involved in this type of activity. The increased Omega-complexity and decreased synchronization likelihood caused by eyes opening could not be observed in the beta and alpha frequencies in the side of the lesion, possibly caused by damaged thalamocortical connections.]

AFFILIATIONS

  1. Magyar Tudományos Akadémia, Pszichológiai Kutatóintézet, Budapest
  2. Szent Rókus Kórház, Neurológiai Osztály, Budapest
  3. Semmelweis Egyetem, Általános Orvostudományi Kar, Neurológiai Klinika, Budapest
  4. Eötvös Loránd Tudományegyetem–Magyar Tudományos Akadémia, Pszichofiziológiai Központ, Budapest
  5. Agyérbetegségek Országos Központja, Budapest

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[EPILEPSY AND MALE SEXUAL DYSFUNCTION: ETIOLOGY, DIAGNOSIS AND THERAPY]

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[While 10% of healthy men had sexual dysfunctions, male epilepsy patients experience sexual problems in 40-70%. The cause of sexual dysfunction in epilepsy is multifactorial, but there are three main factors: the epilepsy itself, antiepileptic treatment and psychiatrical/psychic problems. Antiepileptics with hepatic enzyme induction potential (carbamazepine, phenytoin) enhance the metabolism of sexual steroids. Valproic acid as an enzyme inhibitor and drug with high protein binding affinity elevates the free serum levels of androgenes. Certain antiepileptic drugs may have negative cognitive side effects, some of them can induce psychiatric disorders. These drugs can facilitate male sexual dysfunctions through these psychic side effects. The metabolic and endocrine alterations caused by carbamazepin may return to normal level after replacement of carbamazepin with oxcarbazepine. After an oxcarbazepin-carbamazepin replacement, carbamazepin-induced impotency can be cured. According some new data lamotrigine can also help in sexual dysfunction. The therapy of sexual dysfunction in epilepsy depends on its cause. In cases of hormonal alterations, the fist step is a change of antiepileptic regimen. Instead of enzymeinductor antiepileptics and valproate, new antiepileptic drugs should be prescribed. At present, the most investigated antiepileptic drug is the oxcarbazepine with positive effect on antiepileptic-induced male sexual dysfunction, however, lamotrigine seems to be also beneficial. If the hormonal and sexual dysfunctions cannot be eliminated by drug changes, androgenic therapy or bromocriptin may be required. Testosteron may not only be beneficial on sexual functions, but can reduce also the seizure frequency. Independent of etiology, erectile dysfunctions can be successfully treated by sildenafil.]

Clinical Neuroscience

[ABSTRACTS OF THE 8TH CONGRESS OF THE HUNGARIAN EPILEPSY LEAGUE Pécs, 25-27 May, 2006.]

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Clinical Neuroscience

[COMPLEX GAZE DISTURBANCE CAUSED BY THALAMIC AND MESENCEPHALIC INFARCTS]

GULYÁS Szilvia, NAGY Ferenc, SZIRMAI Imre

[A 36 year-old male patient developed sudden double vision and gait imbalance. Neurological examination revealed gaze paresis upward and on the left side downward (vertical “oneand- a-half”-syndrome), horizontal gaze nystagmus on the left bulbus directed to left. The MRI revealed bilateral thalamic and left midbrain ischemic lesions. The brainstem auditory and visual evoked responses were normally configured. Optokinetic nystagmus test found rightward, upward and downward hypometric saccades, convergence-retraction nystagmus - which was not visible at physical neurological examination - saccadic smooth pursuit eye movement and pseudoabducent palsy on both sides. The complex gaze disturbance was attributed to the lesions in the intralaminar nuclei of the thalamus and in the pretectal and rostromedial tegmentum of the mesencephalon. Infarcts may have been due to a variant artery: i.e. the thalamoperforant and the superior paramedian mesencephalic arteries originate with common branch from one of the communicant basilar artery. The authors discuss the mechanism of complex gaze palsy and call attention to the diagnostic value of optokinetic nystagmus examination.]

Clinical Neuroscience

[CONGRESS CALENDAR]

[Congress calendar 2006;59(05-06)]

Clinical Neuroscience

[Tünde Csépány-Zsolt Illés: Clinical neuroimmunology]

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[Spectral, phase-synchronization, and graph theoretical EEG changes related to mental arithmetics]

BOHA Roland, TÓTH Brigitta, GAÁL Zsófia Anna, KARDOS Zsófia, FILE Bálint, MOLNÁR Márk

[During mental arithmetic operations working memory playsan important role, but there are only few studies in which anattempt was made to separate this effect from the process ofarithmetics per se. In this study the effects of arithmetic onthe EEG of young adults (14 participants, six of themwomen, mean age 21.57 years, SD: 2.62) was investigatedduring a subtraction task in the θ(4-8 Hz) frequency band.Besides the power density spectrum analysis phasesynchrony based on recently developed graph theoreticalmethods were used and strength of local connections (clustercoefficient; C) and global interconnectedness of network(characteristic path length; L) were determined. Before thearithmetic task passive viewing (control situation) and anumber recognition paradigms were used. During the arith-metic task compared to the control situation significantlyincreasing phase synchrony and C values were found. L wassignificantly shorter (F(2, 26)=818.77, p<0.0001) only dur-ing the arithmetic task: this fact and the former two resultsimply that the network topology shifted towards the “smallworld” direction. Our findings concerning regionaldifferences confirm those reported earlier in the literature:compared to the control condition significant task-relatedincrease was found in C values in the parietal areas [moreexplicitly in the left side, (F(1, 13)=7.2020, p=0.0188)],which probably corresponds to stronger local connectionsand more synchronized (sub)networks. During the task con-dition significantly increased θband power; (F(1,13)=7.9708, p=0.0144) and decreased L values werefound in the left frontal region compared to the right side(F(1, 13)=6.0734, p=0.0284), which can also be interpret-ed as an indicator of optimized network topology ofinformation processing.]

Clinical Neuroscience

[SPECTRAL EEG-CHARACTERISTICS OF SUBCORTICAL ISCHEMIC BRAIN LESION- A CASE STUDY]

MOLNÁR Márk, CSUHAJ Roland, HORVÁTH Szabolcs, VASTAGH Ildikó, GAÁL Zsófia Anna, CZIGLER Balázs, BÁLINT Andrea, NAGY Zoltán

[Introduction - Although the EEG-changes caused by ischemic stroke are well known, data of the literature are rather ambiguous. The EEGfindings recorded in a patient with a unilateral subcortical ischemic lesion are evaluated with special emphasis related to the effect of the dynamics caused by eyes opening. Participants and methods - Data recorded from a patient (54 years old male with a completed stroke involving the frontal and parietal subcortical region in the left side) were compared to those of a control group (12 healthy age matched subjects). Absolute and relative frequency spectra, theta/beta quotients, the interaction index characterizing the effect of eyes opening and the symmetry index were calculated from the EEG recorded in eyes closed and eyes open conditions. Data of the patient were compared to those recorded in the control group on the basis of 95% confidance intervals. Results - Irrespective of the recording conditions the predominance of slow activity and the increase of theta/beta quotients were found in the absolute frequency spectra. The increase of beta1 and beta2 frequency bands following eyes opening on the side of the lesion were found to be less obvious than that seen on the intact side and that observed in the control group. With respect to the interaction index related to the side differences caused by eyes opening the change of the beta2 frequency band was found to be the most conspicuous. The symmetry index underscored the predominance of slow (delta, theta, alpha1) frequencies on the lesion side, and that of the fast (beta1, beta2) frequencies on the intact side in both recording conditions. Conclusions - Localized lesion of the white matter without cortical damage can cause the predominance of slow activity and decrease of the fast frequency bands on the side of the lesion which can be shown by the absolute frequency spectra and is revealed by the symmetry index. The lack of functional reactivity of the fast frequencies in the side of the lesion can clearly be seen in the change of relative spectra following eyes opening and on the basis of the calculation of the interaction index reflecting the dynamics of side differences.]

Clinical Neuroscience

Electrophysiological investigation for autonomic dysfunction in patients with myasthenia gravis: A prospective study

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