Auditory evoked potentials and tumor of the cerebellopontine angle]

The technique of auditory evoked potentials evaluates the auditory pathways along the vestibulocochlear nerve and in the brainstem. The authors stress the importance of this examination in the diagnosis of tumours of the cerebellopontine angle and they discuss its place in relation to radiological investigations.     

鼻咽癌病人放疗前后多种诱发电位的比较研究

目的：了解鼻咽癌（NPC）病人放疗,放疗后射线是否会引起多种诱发电位的改变。方法：对48例初次放疗的NPC病人在放疗前与放疗后各阶段进行脑干听觉诱发电位（BAEP）,短潜伏期体感诱发电位（SLSEP）,图形翻转视觉诱发电位（PRVEP）追踪研究。结果：与放疗前对比,本组病人放疗后不同的阶段BAEP、SLSEP、PRVEP某些波的伏期与波间潜伏期均值和放疗前的检测结果比较差异有显著性。结论：NPC病人接受放射治疗后,早期即可引起神经系统传导功能障碍,诱发电位技术可以反映这种传导功能障碍的存在,而BAEP、SLSEP、PRVEP3种诱发电位协同应用,可及时发现射线对听感觉、体感觉、视觉传导通路损伤。     

Central pontine myelinolysis: correlation between CT and electrophysiologic data

Because of the nature and location of the lesion in central pontine myelinolysis, considerable difficulties in diagnosis may arise. Computed tomography (CT) and brainstem auditory-evoked potentials are useful in following the spread and regression of the pontine lesion. The correlation between clinical evolution, serial CT scans, and brainstem auditory-evoked potentials is considered in a patient with central pontine myelinolysis and subsequent complete recovery with special emphasis on the evolution of the CT scan after recovery.     

椎基底动脉短暂缺血性眩晕脑干功能损害与经颅多普勒的相关性

目的　探讨椎基底动脉供血不足 (VBI)脑干功能与经颅多普勒 (TCD)的相关性。方法　对 6 8例临床诊断VBI的患者及 30例非VBI患者进行BR ,BAEP和TCD检测。结果　VBI组脑干功能损害 84 6 % ,TCD异常率为 83 1% ,χ2 检验差异无显著意义 ;非VBI组脑干功能损害 8 3% ,TCD异常率为 46 6 % ,χ2 检验差异有显著意义。VBI组脑干功能损害及TCD异常者为 98/136 ,皆正常者为 2 4/136 ,两者占 89 7% ;非VBI皆异常者为 4/6 0 ,皆正常者为 32 /6 0 ,两者占 6 0 %。结论　根据临床表现 ,结合BR ,BAEP及TCD检查结果可提高对VBI的诊断价值 ,而单独的TCD结果不足以作为诊断依据。     

Radiosensitivity and Biological Properties of Two Tumour-types Indigenous to the Same Host

Summary

A study was undertaken to provide information regarding the comparative effects of single and divided x-ray doses on the regression of experimental tumours. This is a first report. Two types of mammary tumours, a slower-growing, epithelial-cell type designated DBAH, and a faster-growing, spindle-cell type designated DBAG, both indigenous to the inbred DBA/212 strain of mice and propagated in parent hosts, were x-irradiated in vivo. A total dose of 10 000 r was employed in one exposure and in 2, 4 and 8 equal fractions delivered at 24-hour intervals to tumours ranging in size from 12–15 mm in diameter. The greatest effect on both types of tumours was obtained when 10 000 r was employed in two equal doses and the least effect when the dose was divided into eight equal fractions. Instances of local recurrences and distant metastases were more frequent in mice with the DBAG tumour treated with fractionated doses than in mice with the DBAH tumour. Quantitative data are recorded in tables 1 and 2. A contrasting pattern of cellular response to x-irradiation of these two types of tumour is demonstrated in the microphotographs.     

Moderate cold exposure shortens evoked potential latencies in humans

Visual, auditory event-related potentials, and brainstem auditory-evoked responses were recorded in as many as six young male subjects in order to study the effects of moderate cold air exposure on central nervous system functioning. Evoked potentials were recorded during repeated 50-min exposures to air of 4 and 22 degrees C; these levels of exposure resulted in no change in rectal core temperature. Evoked potentials recorded during exposures to 4 degrees air displayed consistently shorter latencies compared to those recorded at 22 degrees, suggesting faster CNS processing of sensory stimuli in the cold. These results are consistent with recent investigations of cold-induced behavioral response changes which indicate that increased arousal may occur with moderate (nonhypothermic) cold exposure.     

Phaeochromocytoma and functioning paraganglioma in childhood and adolescence: role of iodine 131 metaiodobenzylguanidine.

Phaeochromocytomas and functioning paragangliomas are rare tumours in childhood and adolescence. We review our experience of 43 cases (24 men, 19 women) who were first diagnosed at the age of less than or equal to 18 years. All patients were evaluated at some point in their illness with iodine 131 metaiodobenzylguanidine (131I-mIBG) scintigraphy. Eight patients (19%) had bilateral adrenal tumours, 12 (28%) had solitary extra-adrenal tumours, and 8 (19%) had multiple tumours. In 10 patients (23%), the tumours were associated with a familial neurocristopathic syndrome. Thirteen of 24 (54%) unifocal tumours which were initially considered to be benign ultimately proved to be multi-focal and/or malignant. The final prevalence of malignancy was 60%--26 patients, of whom only 15 (57%) had obviously malignant tumours at the time of diagnosis. Primary tumour size greater than or equal to 5 cm was more commonly associated with a malignant course in adrenal but not extra-adrenal tumours. No other clinical, biochemical or morphological characteristic was significantly associated with malignancy. Although the high prevalence of malignancy in this series at least partly reflects referral bias, the need for lifelong follow-up of these patients is underscored. 131I-mIBG scintigraphy was positive in 36 patients (84%), with a somewhat lower false-negative rate (12%) than X-ray computed tomography (20%). Eight patients with malignant tumours received therapeutic doses of 131I-mIBG, with partial tumour responses in 3. Thus, 131I-mIBG is an efficacious, non-invasive, localising agent and may be considered as a palliative therapeutic agent when alternatives have failed.     

Evaluation of risk factors for lung tumour induction in rats exposed to either NpO 2 or PuO 2 aerosols

Purpose : To compare the incidence of each lung tumour type after inhalation exposure of rats to either NpO 2 or industrial PuO 2 aerosols, which have a similar size. Materials and methods : Male Sprague-Dawley rats were exposed once and followed during their whole life span. At the end of their life, the whole lungs were fixed, embedded and cut into thin sections for histological analysis. The presence of tumours was evaluated on three distinct levels of the lobes for phenotype determination to establish dose-effect relationships. Results : In the range of lung doses studied (0.05 to more than 50 Gy), the general trend was an increased frequency of all types of tumours after inhalation exposure to neptunium compared with plutonium. The linearity of the lower part of the dose-effect relationships for all malignant lung tumours leads to the conclusion that NpO 2 is 3.3-fold more carcinogenic than PuO 2. Conclusions : According to a linear extrapolation of the data on malignant lung tumour incidence collected among all studies reported on actinide oxide carcinogenesis, the risk of lung tumour appears to vary over a factor of about 10 depending on the nature and/or size of the aerosol. This variation has to be taken into account for a realistic assessment of tumour risk.     

Evaluation of risk factors for lung tumour induction in rats exposed to either NpO(2) or PuO(2) aerosols

PURPOSE: To compare the incidence of each lung tumour type after inhalation exposure of rats to either NpO(2) or industrial PuO(2) aerosols, which have a similar size. MATERIALS AND METHODS: Male Sprague-Dawley rats were exposed once and followed during their whole life span. At the end of their life, the whole lungs were fixed, embedded and cut into thin sections for histological analysis. The presence of tumours was evaluated on three distinct levels of the lobes for phenotype determination to establish dose-effect relationships. RESULTS: In the range of lung doses studied (0.05 to more than 50 Gy), the general trend was an increased frequency of all types of tumours after inhalation exposure to neptunium compared with plutonium. The linearity of the lower part of the dose-effect relationships for all malignant lung tumours leads to the conclusion that NpO(2) is 3.3-fold more carcinogenic than PuO(2). CONCLUSIONS: According to a linear extrapolation of the data on malignant lung tumour incidence collected among all studies reported on actinide oxide carcinogenesis, the risk of lung tumour appears to vary over a factor of about 10 depending on the nature and/or size of the aerosol. This variation has to be taken into account for a realistic assessment of tumour risk.     

Cranial MR in spinal cord MS: diagnosing patients with isolated spinal cord symptoms

MR brain scans, spinal fluid electrophoresis, and evoked responses were obtained in 10 adult patients with isolated spinal cord symptoms diagnosed as possible multiple sclerosis (MS) according to the McAlpine criteria. Typical lesions of MS were found on T2-weighted MR images in six patients. Spinal fluid abnormalities were found in four. Visual-evoked responses or brainstem auditory-evoked responses were abnormal in three. MR in conjunction with spinal fluid analysis supported the diagnosis of MS in eight of 10 patients. Evoked responses appeared less sensitive than MR in identifying subclinical lesions in this population.     

Comparison of clinical, magnetic resonance and evoked potentials data in a case of valproic-acid-related hyperammonemic coma

Magnetic resonance (MR) multimodality evoked potentials (MEPs) and clinical findings were correlated in a 47-year-old epileptic man in whom parenteral valproic acid (VPA) therapy induced severe comatose hyperammonemic encephalopathy without biological signs of hepatotoxicity (or hepatocytic dysfunction). Although the plasma VPA level remained within a normal therapeutic range, the ammoniemia increased to a toxic peak level at 411 mol/l 24 h after symptom onset, requiring VPA therapy discontinuation. Brain MR monitoring demonstrated early cytotoxic edema evolving into delayed vasogenic edema and final brain atrophy. Concomitantly to abnormalities within the brainstem on MR images, an increase in brainstem conduction at MEPs and clinical disturbance of brainstem reflexes were observed at the initial phase of the disease course. Later, the resolution of the MR and MEPs abnormalities paralleled the clinical recovery of the reflexes.     

Cryotherapy of breast cancer under ultrasound guidance: initial results and limitations

The aim of this study was to investigate the potential and feasibility of ultrasound-guided cryotherapy in breast cancer. Fifteen female patients with 16 breast cancers (mean tumour diameter 21±7.8 mm) were treated. A 3-mm cryo probe was placed in the tumour under ultrasound guidance. Two freeze/thaw cycles with durations of 7–10 min and 5 min, respectively, were performed. The size of the iceballs was measured sonographically in 1-min intervals. The patients underwent surgery within 5 days and the specimens were evaluated histologically. The mean diameter of the iceball was 28±2.7 mm after the second freezing cycle. No severe side effects were observed. Five tumours with a diameter below 16 mm did not show any remaining invasive cancer after treatment. Two of these had ductal carcinoma in situ (DCIS) in the surrounding tissue. In 11 patients cryotherapy of tumours reaching diameters of 23 mm or more resulted in incomplete necrosis. This study shows that the invasive components of small tumours can be treated using cryotherapy. Remnant DCIS components which may not be detected preinterventionally represent a challenging problem for complete ablation. In tumours larger than 15 mm two or more cryo probes should be used to achieve larger iceballs. Electronic Publication     

Magnetic resonance in multiple sclerosis

Summary Magnetic Resonance Imaging was performed in more than 200 patients with clinical suspicion or knowledge of Multiple Sclerosis. One hundred and forty-seven (60 males and 87 females) had MR evidence of multiple sclerosis lesions. The MR signal of demyelinating plaques characteristically has prolonged T1 and T2 relaxation times and the T2-weighted spin-echo sequences are generally superior to the T1-weighted images because the lesions are better visualized as areas of increased signal intensity. MR is also able to detect plaques in the brainstem, cerebellum and within the cervical spinal cord. MR appears to be an important, non-invasive method for the diagnosis of Multiple Sclerosis and has proven to be diagnostically superior to CT, evoked potentials (EP) and CSF examination. In a selected group of 30 patients, with the whole battery of the relevant MS studies, MR was positive in 100%, CT in 33,3%, EP in 56% and CSF examination in 60%. In patients clinically presenting only with signs of spinal cord involvement or optic neuritis or when the clinical presentation is uncertain MR has proven to be a very useful diagnostic tool for diagnosis of MS by demonstrating unsuspected lesions in the cerebral hemispheres.     

The effect of iohexol on brainstem auditory evoked potentials

Summary A prospective study was made to evaluate the effect of intrathecal injection of iohexol on brainstem auditory evoked potentials (BAEP) following myeloradiculography, in order to assess its neurotoxicity. Thirty patients who received contrast medium via the lumbar route for myeloradiculography (cervical level=25 patients, lumbar level=5 patients) had BAEP examinations before, 2 h and 24 h after myelography. No statistically significant prolongation of absolute and interpeak latencies was found between premyelographic and postmyelographic records. Low incidence (20%) of insignificant clinical adverse effect following myelography was also noted in the same group of patient.     

Changes in acoustically evoked brain potentials during oxygen breathing at normal and increased pressures]

Acoustically evoked potentials of the human brain were studied when breathing pure oxygen at a normal and positive pressure. An exposure to pure oxygen at a normal pressure reduced the amplitude of evoked potentials. This effect was more pronounced at a positive oxygen pressure. The after-effect was prolonged due to the influence of an increased oxygen concentration. During an exposure to the air at a positive pressure the reduction of the amplitude was smaller and reached the pretest level as soon as the pressure returned to normal. Evoked potentials are a sensitive indicator of the effect of an altered atmosphere on the central nervous system and the sensory system.     

Evoked potential and other CNS reactions during a heliox dive to 360 msw

Six divers were compressed to 360 msw on heliox. Visual and cognitive evoked responses were performed repeatedly predive, during the dive, and postdive. The evoked response changes were compared with other neuropsychological and neurophysiological results from the dive. The individual diver analysis revealed normal visual evoked responses (P100) for 5 out of 6 divers. The diver with significant increase in P100-latency had more marked HPNS than the others. On the cognitive evoked responses, the P300-waves were not obtainable at the deepest depths (for 4 out of 6 divers) even if the shorter wave forms were normal. The P300-wave was obtainable at 354 msw and 215 msw for 4 divers, and 3 of them had increase in the P300-latency compared with their predive average. There was a significant correlation between P100 change and the sign-index on the other CNS-tests. In conclusion, valid results on the visual and cognitive evoked responses were obtained at pressure. Mild symptoms and signs of HPNS led to normal visual evoked responses, while more marked effects gave significant increases in the visual evoked latency. The more major changes in cognitive evoked responses at pressure, even on minor HPNS-affected divers, indicated that higher cortical functions are affected at high pressures (greater than 300 msw).     

Suppression of cerebral evoked potentials preceding rapid reaction movement

In this study we examined the gating of the cerebral evoked potentials during warning-imperative stimulus intervals and preceding the rapid movement. We also examined the possibility of the gating phenomenon occurring in the precentral cortex. The experiment showed that the amplitudes of cerebral evoked potentials increase at all C3 and CZ during the warning-imperative stimulus intervals. Therefore, it seems that gating does not occur within the central nervous system during warning-imperative stimulus intervals. Furthermore, we observed that preceding rapid movement, the amplitudes of the cerebral evoked potentials decreased at all C3 and CZ. In the present experiment, it does not seem that a peripheral mechanism plays a role in the rapid movement. Therefore, it can be concluded that the decrease in amplitude of the cerebral evoked potentials preceding rapid movement may be due to a central mechanism irrespective of afferent information. In addition, we confirmed that the amplitude of cerebral evoked potentials decreases considerably at the precentral cortex and that the attenuation in amplitude of cerebral evoked potentials is more pronounced over the CZ than over the C3.     

Percutaneous radiofrequency ablation for unresectable large hepatic tumours during hepatic blood flow occlusion in four patients

AIM: To evaluate percutaneous radiofrequency (RF) ablation therapy for unresectable large hepatic tumours combined with regional interruption of hepatic blood flow, and to assess the safety and efficacy of this procedure. MATERIALS AND METHODS: Four patients with hepatic tumours were enrolled in this study. Patients were treated by a single session of RF ablation during occlusion of both hepatic artery and hepatic vein. Tumour size ranged from 45-57 mm (mean 50.2 mm). Initial therapeutic efficacy was evaluated with helical computed tomography (CT) performed within 9 days after the treatment. CT or magnetic resonance imaging (MRI) was performed every 2-3 months thereafter. RESULTS: The largest axis of coagulated lesions after the ablation was 50-60 mm (mean 56.5 mm) in diameter. The ablation therapy was considered complete in three patients; after a mean follow-up of 12.7 months, CT and MRI revealed complete destruction of their tumours. One patient required further treatment. No severe complications occurred. CONCLUSION: Although further studies are needed, in this limited clinical trial a local ablation area exceeding 50 mm in diameter was achieved safely.     

Phaeochromocytoma and functioning paraganglioma in childhood and adolescence: role of iodine 131 metaiodobenzylguanidine

Phaeochromocytomas and functioning paragangliomas are rare tumours in childhood and adolescence. We review our experience of 43 cases (24 men, 19 women) who were first diagnosed at the age of 18 years. All patients were evaluated at some point in their illness with iodine 131 metaiodobenzylguanidine (¹³¹I-mIBG) scintigraphy. Eight patients (19%) had bilateral adrenal tumours, 12 (28%) had solitary extra-adrenal tumours, and 8 (19%) had multiple tumours. In 10 patients (23%), the tumours were associated with a familial neurocristopathic syndrome. Thirteen of 24 (54%) unifocal tumours which were initially considered to be benign ultimately proved to be multi-focal and/or malignant. The final prevalence of malignancy was 60% – 26 patients, of whom only 15 (57%) had obviously malignant tumours at the time of diagnosis. Primary tumour size 5 cm was more commonly associated with a malignant course in adrenal but not extra-adrenal tumours. No other clinical, biochemical or morphological characteristic was significantly associated with malignancy. Although the high prevalence of malignancy in this series at least partly reflects referral bias, the need for lifelong follow-up of these patients is underscored.¹³¹I-mIBG scintigraphy was positive in 36 patients (84%), with a somewhat lower false-negative rate (12%) than X-ray computed tomography (20%). Eight patients with malignant tumours received therapeutic doses of¹³¹I-mIBG, with partial tumour responses in 3. Thus,¹³¹I-mIBG is an efficacious, non-invasive, localising agent and may be considered as a palliative therapeutic agent when alternatives have failed.     

Human brainstem auditory evoked potentials (BAEP) before and after MR examinations

Recently significant changes of human brainstem auditory evoked potentials (BAEP) after exposure to static magnetic fields were reported (L. von Klitzing, Clin. Physiol. Meas. 7(2), 157 (1986); L. Stojan, D. Sperber, and K. Dransfeld, Naturwissenschaften 75, 622 (1988]. We recorded BAEPs of 11 subjects before and after a routine MRI examination at 1.5 T. In addition the BAEP of a healthy volunteer was measured in five different static magnetic fields (0-2.0 T). Our results indicate that routine MRI investigations do not significantly alter the interpeak latencies of the BAEPs.