Abstract To investigate the effect of estrogen deficiency on cognitive function in surgically menopausal women, a prospective study was conducted at the University Hospital in Assiut, Egypt, during the period of July 1997 to August 1999. The study included 35 women subjected to total abdominal hysterectomy and bilateral salpingo-oophorectomy for nonmalignant causes. They were subjected to cognitive assessment by Mini-Mental State Examination (MMSE), Wechsler Memory Scale (WMS) subtests, and measurement of auditory Event-Related Potentials (ERPs) and serial serum estradiol levels determination. Eighteen age- and education-, body-weight- and parity-matched control women were recruited for comparison. A significant decline in MMSE, WMS subtests (digit span, visual memory, logical memory and mental control) and prolongation of P300 of ERP latency was observed in the patient group at 3 and 6 months postoperatively. These changes were not observed in the control group. A significant correlation was found between serum estradiol level and mental control subtest score and P300 latency in patients preoperatively. Patients who had a drop of estrogen level >50% had more cognitive function decline. Rapid decline in estrogen level following surgical menopause was associated with a deleterious effect on cognitive function. Such observations may contribute to more understanding of the age-related cognitive decline in females.

Abstract To investigate the effect of estrogen deficiency on cognitive function in surgically menopausal women, a prospective study was conducted at the University Hospital in Assiut, Egypt, during the period of July 1997 to August 1999. The study included 35 women subjected to total abdominal hysterectomy and bilateral salpingo-oophorectomy for nonmalignant causes. They were subjected to cognitive assessment by Mini-Mental State Examination (MMSE), Wechsler Memory Scale (WMS) subtests, and measurement of auditory Event-Related Potentials (ERPs) and serial serum estradiol levels determination. Eighteen age- and education-, body-weight- and parity-matched control women were recruited for comparison. A significant decline in MMSE, WMS subtests (digit span, visual memory, logical memory and mental control) and prolongation of P300 of ERP latency was observed in the patient group at 3 and 6 months postoperatively. These changes were not observed in the control group. A significant correlation was found between serum estradiol level and mental control subtest score and P300 latency in patients preoperatively. Patients who had a drop of estrogen level >50% had more cognitive function decline. Rapid decline in estrogen level following surgical menopause was associated with a deleterious effect on cognitive function. Such observations may contribute to more understanding of the age-related cognitive decline in females.

Abstract In the field of neurolaryngology, there has been a great interest in neurophysiological studies, such as neurography, for the assessment of the integrity of the laryngeal neural pathway. Such tools provide an indication about the site and the nature of the nerve lesion. We have tried to use a magnetically evoked potential to assess the corticolaryngeal pathway in order to provide normative data on laryngeal nerve conductivity and to evaluate the integrity of the laryngeal neural system in patients with vocal-fold mobility disorders. This study was conducted on 26 subjects (10 normal volunteers and 16 patients with vocal-fold immobility) who were primarily selected on the basis of a comprehensive laryngeal evaluation including laryngo-videostroboscopy assessment. Transcranial (cortical) and mastoid (peripheral) magnetic stimulations were performed to evoke muscle action potentials of the thyro-arytenoid (TA) and cricothyroid muscles (CT). In normal volunteers, cortical stimulation leads to contralateral responses (cortical latency) after 10.9 and 11.3 ms and ipsilateral responses after 8.3 and 9.4 ms for right CT and TA muscles, respectively. There was a significant prolongation of cortical latency of the left TA compared with the right TA muscle, whilst no such significant difference was observed in the CT muscles. Peripheral stimulation evoked response (peripheral latency) after 2.8 and 2.7 ms in the right CT and TA, respectively, with the same significant prolongation of the left TA response compared with the right side. Amongst the patient groups, variable patterns of laryngeal muscle response latencies occurred, including normal response latency, lack of response of CT and TA muscles, prolonged peripheral latency with secondary prolonged cortical latency and prolonged cortical latency with normal peripheral latency. The results indicate that the magnetically evoked potential of laryngeal muscles offers an easy, non-invasive technique and could have a role in the assessment of the integrity of corticolaryngeal pathways.

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Abstract Recent studies report that some children with dyslexia have impaired visual processing, specifically in the fast-processing magnocellular pathway. The objective was to study the effect of varying luminance and temporal and spatial frequency on the latency and amplitude of the visual evoked potentials (VEPs) in normal and dyslexic Egyptian children who speak Arabic (a right-left reading and writing system). VEPs were recorded in 52 dyslexic and 41 normal children in the fourth grade using a black and white checkerboard pattern with different checkerboard sizes and different rates of stimuli at high- and low-contrast media. The peak of the major positive wave component (P100) of each waveform and the trough of the previous major negative wave component were identified, and the peak-to-trough amplitude was measured. The latency and amplitude of VEPs in response to different experimental conditions showed significant shortening of P100 latency under high-contrast media and under low spatial frequency in children with dyslexia compared with normal readers. Furthermore, dyslexia children showed prolonged P100 latency in response to high spatial frequency stimulation compared with the low spatial frequency (P=0.003) and significantly higher N1-P1 amplitude under high-contrast media compared with low-contrast media (P=0.02), whilst no such changes were observed in normal readers. These results are suggestive of deficiency within the parvocellular pathway rather than the magnocellular pathway. As reading apparently places demands primarily on the ability to discriminate fine details, which is to say, on the parvocellular system, we suggested that deficiency in this system, at least in Arabic speaking children, could be a predisposing factor in dyslexia.

Abstract Recent studies report that some children with dyslexia have impaired visual processing, specifically in the fast-processing magnocellular pathway. The objective was to study the effect of varying luminance and temporal and spatial frequency on the latency and amplitude of the visual evoked potentials (VEPs) in normal and dyslexic Egyptian children who speak Arabic (a right-left reading and writing system). VEPs were recorded in 52 dyslexic and 41 normal children in the fourth grade using a black and white checkerboard pattern with different checkerboard sizes and different rates of stimuli at high- and low-contrast media. The peak of the major positive wave component (P100) of each waveform and the trough of the previous major negative wave component were identified, and the peak-to-trough amplitude was measured. The latency and amplitude of VEPs in response to different experimental conditions showed significant shortening of P100 latency under high-contrast media and under low spatial frequency in children with dyslexia compared with normal readers. Furthermore, dyslexia children showed prolonged P100 latency in response to high spatial frequency stimulation compared with the low spatial frequency (P=0.003) and significantly higher N1-P1 amplitude under high-contrast media compared with low-contrast media (P=0.02), whilst no such changes were observed in normal readers. These results are suggestive of deficiency within the parvocellular pathway rather than the magnocellular pathway. As reading apparently places demands primarily on the ability to discriminate fine details, which is to say, on the parvocellular system, we suggested that deficiency in this system, at least in Arabic speaking children, could be a predisposing factor in dyslexia.

Abstract Repetitive transcranial magnetic stimulation (rTMS) induces lateralized speech arrest consistent with cerebral dominance for language. Studies of language cerebral dominance in differently handed healthy subjects have been limited. Using a focal magnetic coil, we examined the degree of consistency between handedness as evaluated by the Stanley Coren Score and hemispheric dominance for language as determined by rTMS in 25 right- and 25 left-handed medical students. They were categorized according to the score into 24 strongly right-handed, 1 moderately right-handed, 19 strongly left-handed, 3 moderately left-handed and 3 ambidextrous (equally-handed). In the strongly right-handed subjects, left-sided language cerebral dominance was recorded in 87.5% of the subjects, and bilateral cerebral representation in 8.2%, and right-sided language cerebral dominance in 4.2%. In the strongly left-handed subjects, 73.7% had left-side language cerebral dominance, 15.8% had bilateral cerebral representation and 10.5% had right-side cerebral language dominance. In mixed handed subjects (moderately right, left and ambidextrous), bilateral cerebral representation was observed in 57% and left-side cerebral language dominance in 43%. There were 27 subjects who developed speech arrest at 140% of motor threshold, the others developed speech arrest at lower intensities. Speech lateralized to the left-side cerebral dominance in strongly right- and left-handed subjects, but bilateral cerebral representation was frequent in mixed handedness and right-sided cerebral

Abstract Cortical excitability of the primary motor cortex is altered in patients with Parkinson's disease (PD). Therefore, modulation of cortical excitability by high frequency repetitive transcranial magnetic stimulation (rTMS) of the motor cortex might result in beneficial effects on motor functions in PD. The present study aims to evaluate the effect of rTMS of the motor cortex on motor functions in patients with PD. Thirty-six unmedicated PD patients were included consecutively in this study. The patients were assigned in a randomized pattern to one of two groups, one group receiving real-rTMS (suprathreshold 5-Hz, 2000 pulses once a day for 10 consecutive days) and the second group receiving sham-rTMS using closed envelopes. Total motor section of Unified Parkinson's Disease Rating Scale (UPDRS), walking speed, and self-assessment scale were performed for each patient before rTMS and after the first, fifth, 10th sessions, and then after 1 month. Evaluation of these measures was performed blindly without knowing the type of rTMS. anova for repeated measurements revealed a significant time effect for the total motor UPDRS, walking speed and self-assessment scale during the course of the study in the group of patients receiving real-rTMS (P = 0.0001, 0.001, and 0.002), while no significant changes were observed in the group receiving sham-rTMS except in self-assessment scale (P = 0.019). A 10-day course of real-rTMS resulted in statistically significant long-term improvement of the motor functions in comparison with the sham-rTMS. The rTMS could have a therapeutic role of for PD patients.

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