Effects of carbamazepine and valproate on brainstem auditory evoked potentials in epileptic children

Brainstem auditory evoked potentials (BAEPs) were recorded in 18 epileptic children receiving carbamazepine and 10 epileptic children receiving valproate. BAEPs were recorded before the administration of antiepileptic drugs (AEDs) and 13 months later during which the children received AEDs. Statistical analysis of peak latencies and interpeak intervals of waves I–III–V were made. Carbamazepine treatment resulted in prolongation of peak latencies of waves I–III–V and interpeak intervals I–III and I–V. Valproate monotherapy, on the other hand, caused no consistent changes on BAEP. On the basis of these results we suggest that chronic carbamazepine therapy exerts a suppressive influence on the auditory pathways, both peripherally at the level of the cochlea and/or auditory nerve, and centrally at the brainstem.     

Effects of prenatal exposure to carbamazepine on brainstem auditory evoked potentials in infants of epileptic mothers

The purpose of this study was to determine if there are any correlations between carbamazepine serum levels of epileptic mothers during pregnancy and the brainstem auditory evoked potentials in their infants as an index of drug neurotoxicity in newborns exposed prenatally. We included 20 epileptic mothers with carbamazepine medication and their 20 otherwise healthy infants. The study was conducted from September 1, 1993, to December 15, 1999. Serum carbamazepine determinations were performed monthly by enzymatic immunoanalysis in the mothers, and the averages for each trimester during pregnancy were calculated. Brainstem auditory evoked potentials were performed at 10.2 +/- 4.6 weeks of postnatal life. Pearson's correlations were calculated between carbamazepine serum levels during pregnancy and waves and interwave intervals of brainstem auditory evoked potentials. Both examinations were performed without knowledge of the results of the other investigations. No alterations in the infants' brainstem auditory evoked potentials were evident, and carbamazepine determinations were within therapeutic levels. Significant Pearson's correlations between latencies of waves III and V and third trimester of carbamazepine serum concentration levels and I-V interwave intervals to third-trimester minimum serum levels of carbamazepine were found. The findings suggest that the higher carbamazepine levels in mothers are related to increased latencies in waves III and V and I-V interwave intervals in infants subclinically, which could be an early index of fetal neurotoxicity.     

Water intoxication in epileptic patients receiving carbamazepine.

Plasma sodium and osmolality were determined in 80 adult epileptic patients receiving chronic treatment with carbamazepine and in 50 control patients treated with other anticonvulsant drugs. Mean plasma osmolality was significantly lower in the carbamazepine-treated patients but mean plasma sodium did not differ in the two groups. Hyponatraemia was found in five of the carbamazine-treated patients and hypo-osmolality in six. None of the control patients had hyponatraemia and only one had a borderline low osmolality. Three of the 13 patients receiving carbamazepine alone were hyponatraemic. Plasma sodium concentration correlated negatively with both daily carbamazepine dose and serum carbamazepine level. Free water clearance after an oral water load was determined in six patients on carbamazepine alone and in six normal subjects not receiving drug therapy. The capacity of some of the patients to excrete the water load was found to be grossly impaired.     

卡马西平对诱发电位的影响及意义

目的研究长期口服卡马西平治疗癫对诱发电位的影响,并讨论其意义。方法选择尚未治疗的癫病人31例作为试验组;以性别、年龄与癫组相匹配的健康正常人26例作为对照组。两组先分别做脑干听觉诱发电位(BAEP)、事件相关电位P300、视觉诱发电位(VEP)和体感诱发电位(SEP),之后癫组开始卡马西平治疗,服药一年后再作上述各项检查。结果癫组病人治疗前各项电生理学指标与正常对照组相比无显著性差异;癫组卡马西平治疗后各项电生理指标与治疗前相比BAEP各波、P300以及VEP的P100波潜伏期均显著延长;SEP的潜伏期无显著变化。结论神经电生理学检查可以早期发现长期服用卡马西平导致的亚临床毒性。     

Limbic evoked potentials predict site of epileptic focus

Limbic evoked potentials (LEPs) were recorded from intracerebral electrodes in the hippocampi of seven preoperative epilepsy surgery patients. LEPs were evaluated using amplitude, form, and asymmetry by raters blinded as to the side of electrographically proven seizure onset. Raters correctly predicted the side of focus in all four patients with proven unilateral temporal lobe seizure onset. Further, LEP amplitudes in two patients with bilateral independent temporal lobe seizure onset were markedly diminished compared with one patient with a nontemporal lobe seizure onset. LEP recordings may assist in determination of the site of epileptogenic pathology.     

卡马西平对诱发电位的影响及意义

目的 研究长期口服卡马西平治疗癫癎对诱发电位的影响,并讨论其意义.方法选择尚未治疗的癫癎病人31例作为试验组;以性别、年龄与癫癎组相匹配的健康正常人26例作为对照组.两组先分别做脑干听觉诱发电位（BAEP）、事件相关电位P300、视觉诱发电位（VEP）和体感诱发电位（SEP）,之后癫癎组开始卡马西平治疗,服药一年后再作上述各项检查.结果 癫癎组病人治疗前各项电生理学指标与正常对照组相比无显著性差异;癫癎组卡马西平治疗后各项电生理指标与治疗前相比BAEP各波、P300以及VEP的P100波潜伏期均显著延长;SEP的潜伏期无显著变化.结论 神经电生理学检查可以早期发现长期服用卡马西平导致的亚临床毒性.     

Laser evoked potentials in Carpal Tunnel Syndrome

ObjectivesThe aim of this study was to evaluate the function of Aδ fibers at the hand level in patients with clinical symptoms of Carpal Tunnel Syndrome (CTS) using CO₂ laser evoked potentials (LEPs), in light of the intensity and distribution of sensory symptoms and pain.MethodsThirty-four CTS outpatients (62 hands) were compared to 23 sex- and age-matched control subjects (46 hands). The periungueal skin of the first, second, third and fifth fingers, and the dorsum of the hands were stimulated in random order. The latency and amplitude of the N2, P2 and N1 components were evaluated with respect to the Nerve Conduction Study (NCS) data, clinical scales, pain intensity and glove-like symptoms distribution.ResultsThe amplitude of the N2–P2 complex was significantly reduced in CTS hands compared to normal hands after stimulation of the second and third fingers, even in patients with mild nerve conduction impairment. No significant fifth finger LEP abnormalities were found in patients with glove-like distribution symptoms. The N2–P2 amplitude at the second and third fingers was positively correlated with the severity of sensory symptoms.ConclusionsThe involvement of median nerve Aδ fibers in CTS seems to be an early phenomenon, which concurs with the impairment of large motor and sensory afferents and is linked to the severity of the disease.SignificanceThe finding of reduced sensory symptoms in patients with severe thin afferents damage, may suggest a slight expression of central sensitisation phenomena in the advanced stage of CTS syndrome.     

Laser evoked potentials in amyotrophic lateral sclerosis

The pathophysiological mechanism of the pain in ALS is still unclear. The aim of the study was to evaluate the laser evoked potentials (LEPs) in ALS patients in relation to their clinical features. Twenty-four ALS patients were selected. Pain features were assessed and their intensity was measured by a 0–10 VAS. LEPs were recorded in all patients and in 23 healthy subjects. The dorsum of both hands was stimulated, at laser stimuli intensity of 7.5 W, with 10 s inter-stimulus interval and 25 ms duration. Four electrodes were placed at Cz, T3, T4 and Fz positions, with the reference electrode at the nasion; T3 and T4 electrodes were referred off-line to Fz, in order to detect the N1 component. Latencies of N2, P2 and N1 waves were significantly higher in ALS than in controls. N1 amplitude was significantly increased in ALS patients compared to controls, with a similar trend for the N2–P2 complex. No correlation was found between LEP abnormalities, pain intensity and clinical features. A degeneration of subcortical structures may subtend a delay in the afferent input to the nociceptive cortex in ALS. On the other hand, an increase of pain processing at the cortical level may derive from a potential sensory compensation to motor cortex dysfunction.     

Effects of antiepileptic drugs on evoked potentials in epileptic children

To evaluate the visual and auditory function in children and adolescents who are undergoing monotherapy with sodium valproate, carbamazepine, and phenobarbital visual-evoked potentials and brainstem auditory-evoked potentials were measured in 58 epileptic patients (30 males and 28 females), ages 13.7 ± 6.9 years. Fifty healthy sex- and age-matched children served as controls. The measurements were performed before the beginning of therapy and after 12 months. Before the beginning of therapy, there were no significant differences in visual- and auditory-evoked potentials between the control group and the three groups of epileptic children. After 12 months of therapy, patients treated with carbamazepine demonstrated a significant (P < 0.001) increase of P100 latencies when compared with baseline data and control values; moreover, these patients exhibited a significant increase of peak latencies of waves I-III-V and interpeak interval I-V at auditory second evaluation. The patients treated with sodium valproate manifested a significant (P < 0.05) increase in VEP P100 latencies. On the contrary, children receiving phenobarbital did not manifest any significant abnormality at visual- and auditory-evoked potentials measurements. Our study demonstrates that for patients treated with carbamazepine and sodium valproate, an electrophysiologic dysfunction of visual and auditory sensory pathways can be present after 12 months of treatment.     

老年慢性精神分裂症的脑电地形图和多项诱发电位研究

为了解老年慢性精神分裂症患者与正常老人在脑电图（ＥＥＧ）、脑电地形图（ＢＥＡＭ）、视觉和听觉诱发电位（ＶＥＰ、ＡＥＰ）、脑干听觉反应（ＡＢＲ）和认知电位Ｐ３００（Ｐ３００）检测中的不同表现，对４０例正常老人及３４例老年慢性精神分裂症患者作６项电生理检测。结果发现，患者ＥＥＧ异常率达６６．７％，其ＢＥＡＭ趋向凹字形低密度带，ＶＥＰ（潜伏期Ｐ１、Ｐ２）、Ｐ３００（靶潜伏期Ｎ１—Ｐ２—Ｎ２—Ｐ３）均前移，ＡＥＰ（潜伏期Ｎ２、Ｐ３）延迟，ＡＥＰ、ＶＥＰ和Ｐ３００的Ｐ２、Ｐ３波幅均减低，均有显著性差异（Ｐ＜０．０５或Ｐ＜０．０１）。患者的ＡＢＲ于中央区左右侧不对称，绝对波幅波Ⅰ降低（Ｐ＜０．０１），这与本组对象ＣＴ结果吻合。采用多项诱发电位检测技术能较可靠反映精神分裂症患者脑的功能，可辅助患者的认知功能评定     

Long-term treatment with carbamazepine affects CSF somatostatin immunoreactivity in epileptic patients.

A number of pharmacological evidence supports the view that somatostatin (SS) may be importantly involved in the seizure susceptibility both in humans and in laboratory animals. In a previous report the Authors have provided the finding that a short-term carbamazepine (CBZ) administration is able to reduce SS-CSF-IR in epileptic patients. The present study has been carried out to investigate whether a long-term treatment with CBZ affects in a similar way SS-IR content in CSF from temporal lobe epileptics (CPS). The results confirm and expand previous evidence suggesting that CBZ lowering effect on CSF-SS-IR may be relevant to its anticonvulsivant action.     

Increased bone turnover in epileptic patients treated with carbamazepine

Bone turnover has been investigated in 12 epileptic patients before and after treatment with carbamazepine and in 15 sex- and age-matched control subjects. We found higher values of markers of bone formation (serum bone alkaline phosphatase, osteocalcin, and propeptides of types I and III procollagen) and of bone resorption (serum telopeptide of type I collagen and urine N-telopeptides of type I collagen) in patients than in controls. Our study demonstrates that carbamazepine induces an increase of bone turnover.     

Withdrawal of phenobarbital and carbamazepine in epileptic patients: a preliminary neuropsychological report.

We systematically investigated the neuropsychological effects of controlled withdrawal of antiepileptic therapy with a battery of tests exploring intelligence, vigilance, attention, memory and sensori-motor performance. 16 patients without seizures for at least 2 years, 9 on therapy with phenobarbital (PB) and 7 with carbamazepine (CBZ), were examined 4 times over a period of 21 months. No significant correlation was found between drug levels and performance in the tests. The slight differences found between the PB and CBZ groups at full doses disappeared completely one year after withdrawal.     

Vestibular evoked myogenic potentials in multiple sclerosis patients.

OBJECTIVES: Vestibular evoked myogenic potentials (VEMPs) are saccular responses to loud acoustic stimuli and are recordable from the sterno-cleido-mastoid muscle ipsilaterally to the stimulated ear. This study aimed to investigate VEMPs in patients suffering from multiple sclerosis (MS), and to compare these findings with both clinical and instrumental data. METHODS: We recorded VEMPs from 70 MS patients, whose clinical data were retrospectively evaluated for the possible occurrence of: past and current (with respect to VEMP recording) brainstem and/or cerebellar symptoms; current brainstem and/or cerebellar signs. Sixty-five patients underwent brainstem auditory evoked potentials (BAEPs) recording; 63 of the same patients underwent saccadic eye movement recording and subjective visual vertical (SVV) evaluation. RESULTS: VEMPs were abnormal in 31%, BAEPs in 38% and SVV in 21% of the patients. Saccadic eye movements showed a possible brainstem dysfunction in 44.4% of the patients. There was no correlation between the occurrence of abnormalities and the technical means of detection. The same held true for correlations with clinical data, with the exception of the BAEPs; these proved to be more frequently abnormal in patients presenting at neurological examination with brainstem and/or cerebellar signs that were possibly related to the complaint of dizziness. CONCLUSIONS: VEMPs should be considered a useful complementary neurophysiological tool for the evaluation of brainstem dysfunction.     

Early evoked potentials in patients with acoustic neuroma.

Using clicks with varying interstimulus intervals and coherent tone-bursts, early components of the auditory evoked potential (brain stem responses) were studied in four patients with confirmed acoustic neuroma. Abnormalities in responses appeared with shorter interstimulus intervals and with tone-bursts delivered monaurally to the involved ear; bilateral alterations occurred in one patient with brain stem displacement. The results indicate that BSR can provide a stable, independent, noninvasive measure of auditory nerve function useful in the early detection of acoustic neuroma. The results contribute to the understanding of the so-called human FFR.     

Impaired visual contrast sensitivity in epileptic patients treated with carbamazepine

Critical flicker fusion frequencies and visual contrast sensitivity were determined in 27 adult epileptic patients receiving carbamazepine monotherapy and in 24 healthy, drug-free control subjects. Flicker fusion thresholds were the same in patients and control subjects, whereas the contrast sensitivity was significantly reduced in the patient group at all spatial frequencies. There was a significant negative correlation between the plasma concentration of carbamazepine and the contrast sensitivity at 11.4 and 22.8 cycles per degree, indicating that the reduced contrast sensitivity was due to the drug therapy.