Abstract The study was aimed at finding what factors in evoked potentials and EEG related to stuttering in subjects 6-25 years of age. Thirty-seven subjects who stuttered and 25 nonstuttering subjects, matched for age, sex and education, were evaluated employing visual evoked potentials, auditory evoked potentials, event-related potentials (P(300)), WISC-(IQ), and electroencephalography. A significant reduction of amplitude of P(100) of visual evoked potentials was found in stutterers with a significant prolongation of wave latencies I, III, V and interpeak latencies I-III and I-V in brainstem auditory evoked potentials. No significant abnormalities were recorded in P(200), N(200) and P(300) of event-related potentials in stutterers compared with the control group. The dominant EEG rhythm was slower in stutterers with a significant interhemispheric asymmetry compared with the control group. Fifty-four percent of the stutterers had pathological EEG. Epileptiform activities were recorded in 16.2% of stuttering subjects. Focal left temporal spike activity was recorded in 5.4% of stuttering subjects. The findings of this study point to a possible role of an organic etiopathogenesis of stuttering.

The aims of this study were to investigate the effect of stroke on the corticodiaphragmatic pathway and to clarify the relationships between neurophysiological data and degree of motor disability, site of infarction in CT scan, diaphragmatic excursion, blood gases and pulmonary function in stroke patients. The corticodiaphragmatic pathway was assessed using magnetic stimulation of the scalp sites and cervical roots. The study included 34 sequentially selected patients out of 250 patients with acute ischemic stroke. Twenty-five (age and sex matched) volunteers served as controls. Sixteen patients had cortical infarction, thirteen had subcortical infarction and five had both cortical and subcortical infarction. The mean Scandinavian Stroke Scale was 32.2. Decreased diaphragmatic excursion was observed in 41% of the patients. Twenty-four patients (70.5%) had abnormal magnetic evoked potentials (MEPs) of the affected hemisphere. In five patients MEPs were unelicitable from the affected hemisphere. The remaining nineteen patients had abnormal values of both cortical latency and central conduction time (CCT). Cortical latency, CCT, amplitude of compound muscle action potentials (CMAPs) and excitability threshold of the affected hemisphere were significantly altered compared to both the unaffected hemisphere and the control group. The patients with hemiplegia had a greater degree of hypoxia, hypocapnia and decreased serum bicarbonate level compared to the control group. Additionally, hemiplegic patients had a different degree of respiratory dysfunction. A statistically significant association was found between neurophysiological data and disability score, diaphragmatic excursion, site of infarction in CT scan and degree of respiratory dysfunction. Central diaphragmatic impairment may occur in acute stroke and could contribute to the occurrence of hypoxia in those patients.

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 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.