The intracarotid amobarbital or Wada test: unilateral or bilateral?

OBJECTIVE

In the Netherlands, presurgical screening for temporal lobe epilepsy (TLE) includes the intracarotid amobarbital procedure (IAP), consisting of two consecutive injections of amobarbital, ipsilateral and contralateral to the epileptic focus. We studied whether a bilateral IAP has added value to a unilateral, ipsilateral IAP.

METHODS

This population-based study included 183 consecutive patients referred for screening for TLE surgery who underwent bilateral IAP. Using multivariable modeling, we assessed the added value of bilateral IAP on the decision for surgery, resection size, amygdalohippocampectomy, post-operative seizure freedom, memory performance, and IQ change.

RESULTS

Given the results from the unilateral IAP, the bilateral IAP had added prognostic value for postoperative change in verbal memory (P < 0.01) and verbal IQ (P < 0.01), especially if patients had a left-sided focus. In contrast, information provided by the contralateral IAP was not associated with decision-making or surgical strategy.

CONCLUSIONS

A bilateral IAP has added value in predicting post-operative verbal memory and IQ. A bilateral IAP is currently not used to guide surgical strategy, but may be used for this purpose when verbal capacity is of particular concern in patients with a left-sided focus. In other cases, IAP is best performed unilaterally.

Overlapping neurologic and cognitive phenotypes in patients with TSC1 or TSC2 mutations

OBJECTIVE

The purpose of this study was to systematically analyze the associations between different TSC1 and TSC2 mutations and the neurologic and cognitive phenotype in patients with tuberous sclerosis complex (TSC).

METHODS

Mutation analysis was performed in 58 patients with TSC. Epilepsy variables, including EEG, were classified. A cognition index was determined based on a comprehensive neuropsychological assessment. On three-dimensional fluid-attenuated inversion recovery MR images, an automated tuber segmentation program detected and calculated the number of tubers and the proportion of total brain volume occupied by tubers (tuber/brain proportion [TBP]).

RESULTS

As a group, patients with a TSC2 mutation had earlier age at seizure onset, lower cognition index, more tubers, and a greater TBP than those with a TSC1 mutation, but the ranges overlapped considerably. Familial cases were older at seizure onset and had a higher cognition index than nonfamilial cases. Patients with a mutation deleting or directly inactivating the tuberin GTPase activating protein (GAP) domain had more tubers and a greater TBP than those with an intact GAP domain. Patients with a truncating TSC1 or TSC2 mutation differed from those with nontruncating mutations in seizure types only.

CONCLUSIONS

Although patients with a TSC1 mutation are more likely to have a less severe neurologic and cognitive phenotype than those with a TSC2 mutation, the considerable overlap between both aspects of the phenotype implies that prediction of the neurologic and cognitive phenotypes in individuals with tuberous sclerosis complex should not be based on their particular TSC1 or TSC2 mutation.

Cognitive impairment in tuberous sclerosis complex is a multifactorial condition

OBJECTIVE

In patients with tuberous sclerosis complex (TSC), associations between tuber number, infantile spasms, and cognitive impairment have been proposed. We hypothesized that the tuber/brain proportion (TBP), the proportion of the total brain volume occupied by tubers, would be a better determinant of seizures and cognitive function than the number of tubers. We investigated tuber load, seizures, and cognitive function and their relationships.

METHODS

Tuber number and TBP were characterized on three-dimensional fluid-attenuated inversion recovery MRI with an automated tuber segmentation program. Seizure histories and EEG recordings were obtained. Intelligence equivalents were determined and an individual cognition index (a marker of cognition that incorporated multiple cognitive domains) was calculated.

RESULTS

In our sample of 61 patients with TSC, TBP was inversely related to the age at seizure onset and to the intelligence equivalent and tended to be inversely related to the cognition index. Further, a younger age at seizure onset or a history of infantile spasms was related to lower intelligence and lower cognition index. In a multivariable analysis, only age at seizure onset and cognition index were related.

CONCLUSIONS

Our systematic analysis confirms proposed relationships between tuber load, epilepsy and cognitive function in tuberous sclerosis complex (TSC), but also indicates that tuber/brain proportion is a better predictor of cognitive function than tuber number and that age at seizure onset is the only independent determinant of cognitive function. Seizure control should be the principal neurointervention in patients with TSC.

[Intracranial EEG monitoring for epilepsy surgery using electrode grids--results in the first 22 Dutch patients]

OBJECTIVE

Description of initial experiences with subdural electrode grids in patients with refractory focal epilepsy as additional diagnostic tool for epilepsy surgery. Using these electrodes, the attacks were recorded during a number of days and the cerebral cortex was electrically stimulated in order to map the functional areas.

DESIGN

Retrospective.

METHOD

Data were collected from patients in whom subdural electrode grids had been placed between 1 September 1999 and 31 August 2004. All patients underwent a neurological examination and a neuropsychological test before the implantation. At the follow-up examination, the results with regard to function and the frequency of attacks were noted, as well as the complications.

RESULTS

Electrodes were placed in 22 patients: 9 women and 13 men with an average age of 27 years (range: 5-42). The implantation lasted for an average of 7 days (range: 3-10). In 4 patients, increased seizures during implantation required intravenous anticonvulsant treatment. Severe but transitory complications were seen in 4 patients (meningitis, subdural haematoma and ischaemia). 19 patients underwent a therapeutic resection. A postoperative decline in language skills was noted in 1 patient, while another 2 scored poorer in verbal tests. A permanent decline in sensorimotor function was seen in 1 patient, but this had been foreseen. Of the 16 operated patients with a duration of follow-up of at least 1 year, so were (practically) free of attacks, and another 3 patients had significantly fewer attacks.

CONCLUSION

Registration with intracranial electrodes makes it possible to treat epileptic patients surgically by excision of brain tissue near critical areas. Such intensive monitoring is, however, not without risk and this must be weighed against the potential benefits.

Cerebrovascular Reserve Capacity Is Preserved in a Population-Based Sample of Patients with Type 2 Diabetes Mellitus

BACKGROUND AND PURPOSE

Type 2 diabetes mellitus (DM2) is associated with an increased risk of stroke. DM2 is also associated with cognitive impairments. Vascular dysfunction, such as impaired cerebrovascular reserve capacity (CVR), may be a determinant of these changes, but previous studies on CVR in DM2 have provided variable results in selected populations of patients. We aimed to examine CVR in a population-based sample of DM2 patients.

METHODS

The CO(2) reactivity of the middle cerebral artery was examined using transcranial Doppler ultrasonography in 81 DM2 patients and 38 controls. In DM2 patients CVR was correlated with diabetic parameters, vascular risk factors and cognitive functioning.

RESULTS

CVR was similar in patients and controls (51 vs. 49%). Within the DM2 group, there was no statistically significant relationship between CVR and DM duration, HbA(1c), albuminuria, blood pressure, intima-media thickness and cognition. CVR tended to be lower in diabetic patients with retinopathy [46 vs. 55%, mean difference: -7.9 (confidence interval -18.0, 2.2)].

CONCLUSION

We conclude that CVR is not impaired in unselected patients with DM2 and probably does not, therefore, play a major role in the aetiology of cognitive impairment.

Seizure Detection in Adult ICU Patients Based on Changes in EEG Synchronization Likelihood

INTRODUCTION

Seizures are common in Intensive Care Unit (ICU) patients, and may increase neuronal injury.

PURPOSE

To explore the possible value of synchronization likelihood (SL) for the automatic detection of seizures in adult ICU patients.

METHODS

We included EEGs from ICU patients with a variety of diagnoses. The gold standard for further analyses was the consensus judgment of three clinical neurophysiologists who classified 150 scalp EEG epochs as "definitely epileptiform," "definitely non epileptiform," or "uncertain." SL estimates the statistical interdependencies between two time series, such as two EEG channels. We computed the average synchronization by calculating the SL between one channel and every other channel, and taking the mean of these values.

RESULTS

The mean SL in the 38 "definitely epileptiform" epochs ranged from 0.095 to 0.386 (mean 0.189; SD 0.066). In the 34 "definitely nonepileptiform" epochs the mean SL ranged from 0.087 to 0.158 (mean 0.115; SD 0.016; p < 0.0005). The area under the ROC curve was 0.812 (95% Confidence Interval 0.725 to 0.898).

CONCLUSION

The mean SL may distinguish between seizure and nonseizure epochs, and may prove helpful to monitor epileptic activity in ICU patients.

Recovery of amplitude integrated electroencephalographic background patterns within 24 hours of perinatal asphyxia

OBJECTIVE

To assess the time course of recovery of severely abnormal initial amplitude integrated electroencephalographic (aEEG) patterns (flat trace (FT), continuous low voltage (CLV), or burst suppression (BS)) in full term asphyxiated neonates, in relation to other neurophysiological and neuroimaging findings and neurodevelopmental outcome.

METHODS

A total of 190 aEEGs of full term infants were reviewed. The neonates were admitted within 6 hours of birth to the neonatal intensive care unit because of perinatal asphyxia, and aEEG recording was started immediately. In all, 160 infants were included; 65 of these had an initial FT or CLV pattern and 25 an initial BS pattern. Neurodevelopmental outcome was assessed using a full neurological examination and the Griffiths' mental developmental scale.

RESULTS

In the FT/CLV group, the background pattern recovered to continuous normal voltage within 24 hours in six of the 65 infants (9%). All six infants survived the neonatal period; one had a severe disability, and five were normal at follow up. In the BS group, the background pattern improved to normal voltage in 12 of the 25 infants (48%) within 24 hours. Of these infants, one died, five survived with moderate to severe disability, two with mild disability, and four were normal. The patients who did not recover within 24 hours either died in the neonatal period or survived with a severe disability.

CONCLUSION

In this study there was a small group of infants who presented with a severely abnormal aEEG background pattern within six hours of birth, but who achieved recovery to a continuous normal background pattern within the first 24 hours. Sixty one percent of these infants survived without, or with a mild, disability.

Cortisol, depression and reduced cortico-cortical cross-talk in Cushing's syndrome

In the present report assumed relationships between hypercortisolism, depression and cortico-cortical cross-talk in Cushing's syndrome were investigated. Electroencephalographic (EEG) recordings and depression ratings from three patients diagnosed with mild, moderate and severe hypercortisolism were obtained. Reductions in cortico-cortical cross-talk as quantified by EEG coherence together with increases in depression were observed in the moderate and severe as compared to the mild hypercorticolism state. These findings provide preliminary evidence for the hypothesis that loss of cortico-cortical cross-talk might be linked to hypercortisolism and the severity of depressive symptoms.

Synaptosomal glutamate and GABA transport in patients with temporal lobe epilepsy

High-affinity glutamate and GABA transporters found in the plasma membrane of neurons and glial cells terminate neurotransmission by rapidly removing extracellular transmitter. Impairment of transporter function has been implicated in the pathophysiologic mechanisms underlying epileptogenesis. We characterized glutamate and gamma-aminobutyric acid (GABA) transport in synaptosomes, isolated from neocortical and hippocampal biopsies of patients with temporal lobe epilepsy (TLE). We analyzed K(+)-evoked release in the presence and absence of Ca(2+) to determine vesicular and transporter-mediated release, respectively. We also analyzed (3)H-glutamate and (3)H-GABA uptake, the effect of glutamate uptake inhibitors L-trans-pyrrolidine-2,4-dicarboxylic acid (tPDC) and DL-threo-beta-benzyloxyaspartate (TBOA), and GABA uptake inhibitor N-(4,4-diphenyl-3-butenyl)-3-piperidinecarboxylic acid (SK&F 89976-A). Neocortical synaptosomes from TLE patients did not show vesicular glutamate release, strongly reduced transporter-mediated release, and an increased basal release compared to that in rat synaptosomes. Furthermore, basal release was less sensitive to tPDC, and (3)H-glutamate uptake was reduced compared to that in rat synaptosomes. Vesicular GABA release from neocortical synaptosomes of TLE patients was reduced compared to that in rat synaptosomes, whereas transporter-mediated release was hardly affected. Furthermore, basal GABA release was more than doubled, but neither basal nor stimulated release were increased by SK&F 89976-A, which did significantly increase both types of GABA release in rat synaptosomes. Finally, (3)H-GABA uptake by synaptosomes from TLE patients was reduced significantly in hippocampus (0.19 +/- 0.04%), compared to that in neocortex (0.32 +/- 0.04%). Control experiments with human peritumoral cortical tissue suggest that impaired uptake of glutamate, but not of GABA, was caused in part by the hypoxic state of the biopsy. Our findings provide evidence for impaired function of glutamate and GABA transporters in human TLE.

Measurement of the conductivity of skull, temporarily removed during epilepsy surgery

The conductivity of the human skull plays an important role in source localization of brain activity, because it is low as compared to other tissues in the head. The value usually taken for the conductivity of skull is questionable. In a carefully chosen procedure, in which sterility, a stable temperature, and relative humidity were guaranteed, we measured the (lumped, homogeneous) conductivity of the skull in five patients undergoing epilepsy surgery, using an extended four-point method. Twenty-eight current configurations were used, in each of which the potential due to an applied current was measured. A finite difference model, incorporating the geometry of the skull and the electrode locations, derived from CT data, was used to mimic the measurements. The conductivity values found were ranging from 32 mS/m to 80 mS/m, which is much higher than the values reported in other studies. Causes for these higher conductivity values are discussed.

Collateral flow and ischemic brain lesions in patients with unilateral carotid artery occlusion

OBJECTIVE

To investigate the association between ischemic brain lesions and intracranial collateral blood flow in patients with unilateral occlusion of the internal carotid artery (ICA).

METHODS

Sixty-eight consecutive patients were included. Ischemic lesions on MRI were identified on hard copies, and volume measurements of the lesions were performed on an MR workstation. Intracranial collateral pathways were studied with MR angiography, digital subtraction angiography, and transcranial Doppler sonography.

RESULTS

The presence of collateral flow via the anterior communicating artery (ACoA) was associated with a reduction in prevalence (p = 0.01) and volume (p = 0.008) of internal border zone infarcts in the hemisphere ipsilateral to the occluded ICA. Absence of collateral blood flow via the circle of Willis was associated with an increase in prevalence (p = 0.007) and volume (p = 0.005) of internal border zone infarcts. No association between any collateral flow pattern in the circle of Willis and periventricular lesions or lacunar, territorial, or external border zone infarcts was found. No association between collateral flow via the ophthalmic artery or leptomeningeal vessels with any type of ischemic lesion was found.

CONCLUSION

Collateral flow via the ACoA is associated with a reduction of the prevalence and volume of internal border zone lesions but not with any other type of ischemic lesion. The presence of a functional posterior communicating artery or secondary collateral pathways is not associated with the prevalence of any type of ischemic lesion.

Quantitative cerebral perfusion MRI and CO2 reactivity measurements in patients with symptomatic internal carotid artery occlusion

Quantitative perfusion MRI is a promising new technique capable of offering information on cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). However, it is still unclear how these perfusion parameters relate to the underlying physiological indicators and how they compare to conventional techniques. The purpose of this study was to investigate how quantitative perfusion MRI is related to the cerebrovascular reactivity as measured by transcranial Doppler ultrasonography (TCD) in combination with a CO2 stimulus in patients with a symptomatic occlusion of the internal carotid artery (ICA). Thirty-nine patients with transient or minor disabling retinal or hemispheric ischemic symptoms and an occlusion of the ICA underwent quantitative perfusion MRI and CO2 reactivity measurements by TCD. Perfusion parameters were correlated with cerebrovascular reactivity measurements and compared with measurements of control subjects. The results of this study show a negative correlation between the cerebrovascular reactivity and the time to bolus peak (TBP) both for gray (r = -0.26, P = 0.035) and white matter (r = -0.28, P = 0.026). No correlation between resting CBV, CBF, or MTT and cerebrovascular reactivity was found. Our results indicate that an increase in TBP reflects a poor development of collateral flow, which is supported by a relatively low CO2 reactivity in these patients.

Diazepam-enhanced beta activity in Sturge Weber syndrome: its diagnostic significance in comparison with MRI

OBJECTIVES

This study was performed to assess the extent of functional involvement of the affected hemisphere in Sturge Weber syndrome in comparison with the uninvolved hemisphere. To this end beta activity in the electroencephalogram (EEG) was measured, both before and after administration of diazepam intravenously (i.v.).

METHODS

In 9 patients asymmetry in beta band activity was studied before and after diazepam administration. Several beta bands and asymmetry parameters were calculated. beta band asymmetries were compared with structural abnormalities (magnetic resonance imaging, MRI).

RESULTS

Total beta activity was reduced in the involved hemisphere in all patients after diazepam administration. In 3 patients functional abnormalities were found in brain regions that were structurally intact.

CONCLUSIONS

Decreased diazepam-enhanced beta activity in the EEG is a sensitive criterion of functional abnormality. In patients with subtle structural abnormalities diazepam-enhanced EEG may have added value in diagnosing functional involvement and in monitoring disease progression in patients.

The existence of two sources in rolandic epilepsy: confirmation with high resolution EEG, MEG and fMRI

In benign rolandic epilepsy seizure semiology suggests that the epileptic focus resides in the lower sensorimotor cortex. Previous studies involving dipole modeling based on 32 channel EEG have confirmed this localization. These studies have also suggested that two distinct dipole sources are required to adequately describe the typical interictal spikes. Since in benign epilepsy invasive validation is prohibited, this study tries to further establish these results using a multi-modal approach, involving 32 channel EEG, high resolution 84 channel EEG, 151 channel MEG and fMRI. From one patient interictal spikes were recorded and analyzed using the MUSIC algorithm in a realistic volume conductor model. In an fMRI experiment the same patient performed voluntary tongue movements, thus mimicking a typical seizure. Results show that EEC, MEG and fMRI localization converge on the same area in the lower part of the sensorimotor cortex, and that high resolution EEG clearly reveals two distinct sources, one in the post- and one in the pre-central cortex.

EEG evidence for shunt requirement during carotid endarterectomy: optimal EEG derivations with respect to frequency bands and anesthetic regimen

Currently there is no consensus on the derivations that should be used for EEG monitoring during carotid endarterectomy (CEA). The aim of this study was to determine which derivations distinguish the best between patients requiring a shunt and patients who do not need a shunt. Four predefined frequency bands and two regimens for general anesthesia (isoflurane versus propofol) were used. EEG data (16 channels) were obtained from 152 EEGs recorded during carotid endarterectomy. Analog EEG signals of preclamp and clamp periods of 100 seconds were digitized to compute power spectra. Changes in power during clamping were calculated for all possible derivations in four predefined frequency bands and were expressed as Z-scores. For each derivation, the area under the receiver operating characteristics curve was calculated. Derivations with the greatest area under the receiver operating characteristics curve were considered to distinguish the best between the shunt and the nonshunt groups formed in retrospect on the basis of consensus between three independent and experienced board-certified electroencephalographers. The two different anesthetic regimens resulted in different patterns of EEG changes because of clamping. The optimal derivations to differentiate between the shunt and the nonshunt groups also differed for the two anesthetic regimens, although for both conditions, anterior head regions were especially preferred. The optimal derivations are given for each anesthetic regimen.

Activation of interictal spiking in mesiotemporal lobe epilepsy by propofol-induced sleep

The objective of this study was to test whether low-dose propofol increases the number of interictal spikes in patients with mesiotemporal lobe epilepsy, and to determine whether this is the result of intrinsic properties and is restricted to the primary epileptogenic focus. Controlled infusion of propofol in step-up/-down target concentrations of 0, 0.3, 0.6, and 0.8 mg/L was administered to 10 patients during a 3.5-hour daytime EEG registration. The number of spikes were counted and related to propofol concentration and sleep level. Results were compared with a spontaneous, nocturnal first sleep cycle in 9 of 10 patients. All patients entered nonrapid eye movement 1 sleep during propofol administration, and 8 reached nonrapid eye movement 2 sleep. In 7 patients who showed spikes, spikes were related to sleep (P < 0.05) and not to increasing (P = 0.1) or decreasing (P = 0.5) propofol concentration. Six of nine patients showed more spikes during spontaneous (nocturnal) sleep than during propofol-induced sleep. Contralateral spiking was not suppressed selectively. Low-dose propofol is a safe means of increasing spiking in these patients because it induces sleep. There were no signs of an intrinsic epileptogenicity of propofol or a selective effect on ipsilateral spikes. Controlled sleep induction will increase the yield of interictal spikes during short interictal recordings such as in magnetoencephalography.

Sustained bilateral hemodynamic benefit of contralateral carotid endarterectomy in patients with symptomatic internal carotid artery occlusion

BACKGROUND AND PURPOSE

We sought to investigate whether in patients with a symptomatic internal carotid artery (ICA) occlusion, endarterectomy of a severe stenosis of the contralateral carotid artery can establish long-term cerebral hemodynamic improvement.

METHODS

Nineteen patients were studied on average 1 month before and 6 months after contralateral carotid endarterectomy (CEA). Volume flow in the main extracranial and intracranial arteries was measured with MR angiography. Collateral flow via the circle of Willis and the ophthalmic arteries was studied with MR angiography and transcranial Doppler sonography, respectively. Cerebral metabolism and CO(2) vasoreactivity were investigated with MR spectroscopy and transcranial Doppler sonography, respectively. Twelve nonoperated patients with a symptomatic ICA occlusion and contralateral ICA stenosis, who were matched for age and sex, served as control patients.

RESULTS

In patients who underwent surgery, flow in the operated ICA increased significantly (P:<0.05) and flow in the basilar artery decreased significantly (P:<0.01) after CEA. On the occlusion side, mean flow in the middle cerebral artery increased significantly from 71 to 85 mL/min (P:<0.05) after CEA. The prevalence of collateral flow via the anterior communicating artery to the occlusion side increased significantly (47% before and 84% after CEA; P:<0.05), while the prevalence of reversed ophthalmic artery flow on the operation side decreased significantly (42% before and 5% after CEA; P:<0.05). In the hemisphere on the side of the ICA occlusion, lactate was no longer detected after CEA in 80% of operated patients, whereas it was no longer detected over time in 14% of nonoperated patients (P:<0.05). CO(2) reactivity increased significantly in operated patients in both hemispheres (P:<0.01).

CONCLUSIONS

Contralateral CEA in patients with a symptomatic ICA occlusion induces cerebral hemodynamic improvement not only on the side of surgery but also on the side of the ICA occlusion.

Recurrent ischemia in symptomatic carotid occlusion: prognostic value of hemodynamic factors

OBJECTIVE

To identify hemodynamic factors that predict recurrence of ipsilateral cerebral ischemic events in patients with symptomatic carotid artery occlusion (CAO).

PATIENTS AND METHODS

The authors studied 117 consecutive patients with CAO and corresponding recent (</=6 months) ischemic symptoms of the brain or eye that were transient or at most mildly disabling. They determined, using Cox proportional hazards analysis, the prognostic value for recurrence of ipsilateral cerebral ischemic events of 1) clinical features believed to indicate hemodynamic compromise, 2) collateral blood flow pattern, and 3) transcranial Doppler CO(2)-reactivity.

RESULTS

None of the 24 patients with symptoms of retinal ischemia alone had a recurrent cerebral ischemic event. In the 93 patients with cerebral ischemic symptoms on entry, recurrence of these symptoms was independently predicted by 1) the nature of the initial symptoms being of purported hemodynamic origin (limb-shaking, precipitation of symptoms by rising, exercise or low blood pressure, retinal claudication) (hazard ratio [HR] 3.8, 95% CI 1.5 to 9.5), 2) continuing symptoms after the CAO had been documented, but before inclusion in the study (HR 5.9, 95% CI 2.2 to 16.1), and 3) the presence of collateral blood flow via leptomeningeal vessels (HR 4.1, 95% CI 1.3 to 13.1). CO(2)-reactivity did not predict recurrence of cerebral ischemic events.

CONCLUSIONS

Having cerebral in contrast to retinal ischemia, clinical features suggestive of hemodynamic compromise, continuing symptoms after demonstration of the CAO, and presence of leptomeningeal collaterals may help to identify patients with symptomatic CAO at high risk of future cerebral ischemia.

A longitudinal study of collateral flow patterns in the circle of Willis and the ophthalmic artery in patients with a symptomatic internal carotid artery occlusion

BACKGROUND AND PURPOSE

The purpose of the present study was to assess whether the direction of flow via the circle of Willis and the ophthalmic artery (OphA) changed over time in patients with a symptomatic occlusion of the internal carotid artery (ICA) who did not experience recurrent cerebral ischemic symptoms.

METHODS

Sixty-two patients with a symptomatic ICA occlusion were investigated within 6 months after symptoms occurred. The investigations were repeated after 6 and 12 months. The directions of flow in the A1 segment and the posterior communicating artery (PCoA), both on the side of the symptomatic ICA occlusion, were assessed with the use of magnetic resonance angiography. The pattern of collateral flow via the circle of Willis was categorized as via the A1 segment only, via the PCoA only, via the A1 segment plus the PCoA, or no collateral flow via the circle of Willis. The direction of flow in the OphA was investigated with transcranial Doppler sonography. CO(2) reactivity was determined with transcranial Doppler sonography to investigate whether changes in flow patterns were accompanied by changes in cerebrovascular reactivity.

RESULTS

There were no statistically significant changes over time in the direction of blood flow in the A1 segment and the PCoA or in the pattern of collateral flow via the circle of Willis. On average, 72% of patients with a unilateral ICA occlusion (n=41) had willisian collateral flow compared with 37% of patients with a bilateral ICA occlusion (n=21; P<0.05). Patients with a unilateral ICA occlusion tended to a lower prevalence of reversed flow via the OphA over time. CO(2) reactivity did not change significantly in any patient group. In patients with a unilateral ICA occlusion, decreased CO(2) reactivity was associated with a higher prevalence of absent willisian collateral flow and a lower prevalence of collateral flow via the A1 segment plus the PCoA.

CONCLUSIONS

The absence of recurrent cerebral ischemic symptoms in patients with a symptomatic ICA occlusion is not associated with an improvement in collateral flow via the circle of Willis or the OphA during 1.5-year follow-up.

Glutamate and gamma-aminobutyric acid content and release of synaptosomes from temporal lobe epilepsy patients

During surgical intervention in medically refractory temporal lobe epilepsy (TLE) patients, diagnosed with either mesial temporal lobe sclerosis (MTS)- or tumor (T)-associated TLE, biopsies were taken from the anterior temporal neocortex and the hippocampal region. Synaptosomes, isolated from these biopsies were used to study intrasynaptosomal Ca(2+) levels ([Ca(2+)](i)), and glutamate and gamma-aminobutyric acid (GABA) contents and release. All synaptosomal preparations demonstrated a basal [Ca(2+)](i) of about 200 nM, except neocortical synaptosomes from MTS-associated TLE patients (420 nM). K(+)-induced depolarization resulted in a robust increase of the basal [Ca(2+)](i) in all preparations. Neocortical synaptosomes from TLE patients contained 22.9 +/- 3.0 nmol glutamate and 4.6 +/- 0.5 nmol GABA per milligram synaptosomal protein, whereas rat cortical synaptosomes contained twice as much glutamate and four times as much GABA. Hippocampal synaptosomes from MTS-associated TLE patients, unlike those from T-associated TLE patients, contained about 70% less glutamate and 55% less GABA than neocortical synaptosomes. Expressed as percentage of total synaptosomal content, synaptosomes from MTS-associated TLE patients exhibited an increased basal and a reduced K(+)-induced glutamate and GABA release compared to rat cortical synaptosomes. In MTS-associated TLE patients, only GABA release from neocortical synaptosomes was partially Ca(2+)-dependent. Control experiments in rat synaptosomes demonstrated that at least part of the reduction in K(+)-induced release can be ascribed to resection-induced hypoxia in biopsies. Thus, synaptosomes from MTS-associated TLE patients exhibit a significant K(+)-induced increase in [Ca(2+)](i), but the consequent release of glutamate and GABA is severely impaired. Our data show that at least part of the differences in glutamate and GABA content and release between human biopsy material and fresh rat tissue is due to the resection time.

The use of preoperative transcranial Doppler variables to predict which patients do not need a shunt during carotid endarterectomy

OBJECTIVES

to analyse whether preoperative transcranial Doppler (TCD) variables can predict intraoperative shunt requirement.

DESIGN AND METHODS

the blood-flow velocity (BFV) in the major basal cerebral arteries was measured preoperatively with TCD, in 178 patients scheduled for CEA. Carotid artery compression and CO2 reactivity tests were also performed. Intraoperative electroencephalography was used to decide whether a shunt was needed. Differences in the probability of shunt requirement between the categories of variables were assessed with crosstabs statistics.

RESULTS

preoperative TCD criteria clearly identified a subgroup of 59 patients (33%) who did not require a shunt. In general, these patients appeared to have adequate collateral flow through the anterior communicating artery. In contrast, prediction of the need for a shunt was less reliable. TCD variables could predict the need for a shunt with a probability of only 60%.

CONCLUSIONS

preoperative TCD can be used to identify patients who do not require a shunt during carotid endarterectomy.

The need for correct realistic geometry in the inverse EEG problem

For accurate electroencephalogram-based localization of mesial temporal and frontal sources correct modeling of skull shape and thickness is required. In a simulation study in which results for matched sets of computed tomography and magnetic resonance (MR) images are compared, it is found that errors arising from skull models based on smooth and inflated segmented MR images of the cortex are of the order of 1 cm. These errors are comparable to those found when overestimating or underestimating skull conductivity by a factor of two.

Characterization of neocortical and hippocampal synaptosomes from temporal lobe epilepsy patients

To investigate epilepsy-associated changes in the presynaptic terminal, we isolated and characterized synaptosomes from biopsies resected during surgical treatment of drug-resistant temporal lobe epilepsy (TLE) patients. Our main findings are: (1) The yield of synaptosomal protein from biopsies of epilepsy patients was about 25% of that from rat brain. Synaptosomal preparations were essentially free of glial contaminations. (2) Synaptosomes from TLE patients and naive rat brain, quickly responded to K(+)-depolarization with a 70% increase in intrasynaptosomal Ca(2+) ([Ca(2+)](i)), and a 40% increase in B-50/GAP-43 phosphorylation. (3) Neocortical and hippocampal synaptosomes from TLE patients contained 20-50% of the glutamate and gamma-aminobutyric acid (GABA) contents of rat cortical synaptosomes. (4) Although the absolute amount of glutamate and GABA released under basal conditions from neocortical synaptosomes of TLE patients was lower than from rat synaptosomes, basal release expressed as percentage of total content was higher (16.4% and 17.3%, respectively) than in rat (11.5% and 9. 9%, respectively). (5) Depolarization-induced glutamate and GABA release from neocortical synaptosomes from TLE patients was smaller than from rat synaptosomes (3.9% and 13.0% vs. 21.9% and 25.0%, respectively). (6) Analysis of breakdown of glial fibrillary acid protein (GFAP) indicates that resection time (anoxic period during the operation) is a critical parameter for the quality of the synaptosomes. We conclude that highly pure and viable synaptosomes can be isolated even from highly sclerotic human epileptic tissue. Our data show that in studies on human synaptosomes it is of critical importance to distinguish methodological (i.e., resection time) from pathology-related abnormalities.

Decreased transcranial Doppler carbon dioxide reactivity is associated with disordered cerebral metabolism in patients with internal carotid artery stenosis

PURPOSE

The hemodynamic effect of stenosis of the internal carotid artery (ICA) can be assessed by measuring, with transcranial Doppler (TCD), the carbon dioxide (CO(2)) reactivity of the cerebral vessels. The aim of this study was to determine whether a decreased CO(2) reactivity is associated with a compromised cerebral metabolism, as evaluated with (1)H magnetic resonance spectroscopy (MRS).

METHODS

Sixty-six patients with unilateral or bilateral stenosis of the ICA, who were scheduled for carotid endarterectomy (CEA) and who had undergone both a TCD CO(2) reactivity test and a MRS examination, were included in this study. The ICA stenosis on one side (CEA side) was always more than 70%, and the extent of the stenosis on the contralateral side varied.

RESULTS

The CO(2) reactivity and the N-acetyl aspartate (NAA)/choline ratio were correlated in both hemispheres (r =.43; P <.001). Patients with an ICA occlusion contralateral to the CEA side are especially at risk for disordered cerebral hemodynamics and metabolism; in the contralateral hemisphere, the mean CO(2) reactivity and NAA/choline ratio were abnormal (18% and 1.52, respectively), and lactate was present in 85% of the patients. Changes indicative of disordered hemodynamics were found more often in symptomatic than in asymptomatic patients.

CONCLUSION

A decreased CO(2) reactivity appears to be associated with a disordered cerebral metabolism. Patients with severe bilateral ICA stenosis are at risk for disordered cerebral metabolism and hemodynamics. Therefore, the indication for CEA based on the degree of ICA stenosis and clinical grounds might be refined with an additional test, such as the TCD CO(2) reactivity test.

Reduction of sympathetic hyperactivity by enalapril in patients with chronic renal failure

BACKGROUND

Inhibition of angiotensin-converting enzyme (ACE) reduces the risk of cardiovascular problems in patients with chronic renal failure. This effect may be due in part to a decrease in sympathetic nervous activity, but no direct evidence of such an action is available.

METHODS

We studied muscle sympathetic-nerve activity in 14 patients with hypertension, chronic renal failure, and increased plasma renin activity before, during, and after administration of the ACE inhibitor enalapril. Ten other patients with similar clinical characteristics were studied before and during treatment with the calcium-channel blocker amlodipine. Normal subjects matched for age and weight were included in both studies.

RESULTS

At base line, mean (+/-SD) muscle sympathetic-nerve activity was higher in the group of patients who received enalapril than in the control subjects (35+/-17 vs. 19+/-9 bursts per minute, P=0.004). The baroreflex curve, which reflects changes in muscle sympathetic-nerve activity caused by manipulations of blood pressure with sodium nitroprusside and phenylephrine, was shifted to the right in the patients, but baroreflex sensitivity was similar to that in the control subjects (-2.1+/-1.9 and -2.7+/-1.3 bursts per minute per mm Hg, respectively; P=0.36). A single dose of the sympatholytic drug clonidine caused a greater fall in blood pressure in the patients than in the control subjects. Treatment with enalapril normalized blood pressure and muscle sympathetic-nerve activity (at 23+/-10 bursts per minute) in the patients and shifted the baroreflex curve to the left, reflecting normal blood-pressure levels, without significantly changing sensitivity (-2.3+/-1.8 bursts per minute per mm Hg, P=0.96). In the patients who received amlodipine, treatment also lowered blood pressure but increased muscle sympathetic-nerve activity, from 41+/-19 to 56+/-14 bursts per minute (P=0.02).

CONCLUSIONS

Increased sympathetic activity contributes to hypertension in patients with chronic renal disease. ACE inhibition controls hypertension and decreases sympathetic hyperactivity.

Carotid endarterectomy monitoring: patterns of spectral EEG changes due to carotid artery clamping

OBJECTIVE

The purpose of the study was to make an objective and quantitative analysis of the EEG changes caused by carotid artery clamping during carotid endarterectomy (CEA) monitoring.

METHODS

Factor analysis was used to study the intraoperative spectral EEG changes in 94 patients during clamping of the carotid artery. In addition, the relation between the extracted factors and the changes in blood pressure and blood flow velocity in the middle cerebral artery during clamping was studied.

RESULTS

Two factors were extracted with factor analysis. The first factor represented a change in power in the alpha and beta frequency ranges in combination with a less pronounced opposite change in power in the delta frequency range. The second factor represented a change in power restricted to the delta and theta frequencies. With the first factor, two types of spectral EEG changes could be distinguished: changes indicative of cerebral ischemia (decrease in fast activity and increase in slow activity) and the opposite changes suggesting cerebral activation (arousal). With the two factors combined, the changes indicative of minor ischemia (decrease in fast activity only) could also be distinguished.

CONCLUSION

Further study is required to test whether patients showing the EEG changes indicative of activation or minor ischemia actually require shunting.

Relevance of temporal lobe white matter changes in hippocampal sclerosis. Magnetic resonance imaging and histology

RATIONALE AND OBJECTIVES

To evaluate the diagnostic relevance of ipsilateral atrophy of the collateral white matter in the parahippocampal gyrus (ACWMp) and temporal lobe gray/white matter demarcation loss (GWDL) on magnetic resonance imaging in patients with histologically confirmed hippocampal sclerosis. In the second part of this investigation, histologic specimens were analyzed to find an explanation for GWDL.

METHODS

Retrospective visual assessment of hippocampal signal intensity and size and of ACWMp and GWDL was performed using 4- to 5-mm coronal T2-weighted spin-echo magnetic resonance images of 80 patients with histologically proven hippocampal sclerosis and of 30 age-matched controls without epilepsy. Frequency of occurrence and likelihood ratios of ACWMp and GWDL were calculated and their contribution to the diagnosis of hippocampal sclerosis was assessed, particularly in patients with no or restricted hippocampal abnormalities (either high signal or smaller size) on magnetic resonance imaging. The second part of the study involved the morphologic histologic assessment of neocortical temporal lobe specimens of all patients. Myelin density was evaluated in specimens of a subgroup of six patients with hippocampal sclerosis and GWDL on MRI and six patients with hippocampal sclerosis without GWDL.

RESULTS

ACWMp was found in 68% and GWDL in 65% of patients with hippocampal sclerosis on magnetic resonance imaging. Both features had an infinite positive likelihood ratio. Sixty-two patients (77.5%) had concomitant hippocampal signal increase and smaller size. Eighteen patients (22.5%) had no or restricted hippocampal abnormalities on magnetic resonance imaging. When using ACWMp and GWDL as additional diagnostic parameters, 13 of these 18 patients were more unambiguously diagnosed as having hippocampal sclerosis. No significant morphologic differences were found between GWDL-positive and GWDL-negative specimens. A significantly lower average myelin stain was found in the white matter of the GWDL-positive group compared to the GWDL-negative group.

CONCLUSIONS

ACWMp and GWDL can improve the visual diagnosis of hippocampal sclerosis, particularly in patients with no or restricted hippocampal abnormalities. These results suggest that loss of myelin may be the underlying cause of GWDL in association with hippocampal sclerosis.

Changes in health-related quality of life after carotid endarterectomy

OBJECTIVES

Carotid endarterectomy (CEA) is intended to prevent stroke and therefore to extend lifespan. Whether CEA also influences health-related quality of life (HRQOL) is largely unknown. This study aimed to assess HRQOL-changes after CEA.

DESIGN

Prospective study, data assessment within 1 week before and 3 months after CEA.

MATERIALS

Patient classification (n = 70) was based on presenting neurological symptoms (none (24), transient (26), or permanent (20)), patency or occlusion (27%) of the contralateral internal carotid artery and intraoperative shunt requirement (28%).

METHODS

HRQOL was investigated with the Sickness Impact Profile (SIP). Analysis of variance was used to adjust for the influence of preoperative differences in functional impairment and comorbidity on the changes found.

RESULTS

Preoperative findings showed that the SIP scores of stroke patients and shunted patients were significantly higher (indicating poorer HRQOL) than those of the other patients. No adverse effect of CEA was observed. Analysis of variance revealed that neurological classification was not reflected to HRQOL changes. However, patients with contralateral occlusion showed a significant postoperative improvement (f = 4.99, p < 0.05).

CONCLUSIONS

HRQOL improvement after CEA is restricted to patients with occlusion of the contralateral carotid artery. Assessment of outcome of CEA should be related not only to neurological classification, but also to haemodynamic factors such as contralateral occlusion.

Changes in cerebral oxygen uptake and cerebral electrical activity during defibrillation threshold testing

During cardioverter-defibrillator implantation, repeated episodes of ventricular fibrillation (VF) are induced. Insufficient recovery of oxygen metabolism may cause neurological sequelae. In this prospective clinical study, we monitored the electroencephalogram (EEG), middle cerebral artery blood flow velocity (Vmca), and jugular bulb oxygen saturation and estimated cerebral oxygen uptake. Results were analyzed for tests requiring a single shock (Group 1) and tests requiring multiple shocks for defibrillation (Group 2). Immediately after the induction of VF, the mean arterial blood pressure (MAP) decreased to < 30 mm Hg, and the Vmca decreased to 0 cm/s. The EEG showed ischemic changes consisting of a decrease of fast, and an increase of slow, activity, progressively declining to isoelectricity within 11 +/- 2 s. After defibrillation, the MAP recovered rapidly regardless of the arrest duration (3 +/- 2 s). The EEG recovered within 17 +/- 9 and 22 +/- 12 s, respectively, for Groups 1 and 2 (P < 0.05) and did not reveal ischemic changes until induction of a subsequent arrest. In Group 1, the cerebral oxygen uptake increased to 191% +/- 31% of baseline values and returned to baseline in 16 +/- 7 s, whereas in Group 2, it increased to 229% +/- 38% (P < 0.05), followed by a significant decrease to less than baseline (85% +/- 18%; P < 0.005), and returned to baseline simultaneously with the Vmca. We conclude that, although restoration to normal of the EEG and cerebral oxygen uptake coincide in short arrests, EEG recovery underestimates metabolic recovery after tests requiring multiple shocks.

IMPLICATIONS

Short test intervals have been mentioned as a cause of neurological sequelae after cardioverter-defibrillator implantation. This study demonstrates that although all systemic hemodynamic variables and the electrocardiogram may have returned to normal, cerebral oxygen uptake may still be depressed for a considerable time, especially after tests requiring two or more shocks.

Cold stress provokes sympathoinhibitory presyncope in healthy subjects and hemodialysis patients with low cardiac output

BACKGROUND

Sudden hypotension in progressive hypovolemia or during hemodialysis is attributed to sudden inhibition of sympathetic activity. Critical ventricular underfilling seems responsible for this paradox, but it is unknown why the transition from sympathoactivation accompanying hypovolemia to sympathoinhibition is so abrupt. We studied whether brief fluctuation of sympathetic activity induced by cold pressor test (CPT) evokes sympathoinhibition if applied during low cardiac output.

METHODS AND RESULTS

Fourteen healthy subjects underwent CPT, lower-body negative pressure (LBNP; -45 mm Hg for 60 minutes), or the combination thereof. CPT alone caused vasoconstriction and increased muscle sympathetic nerve activity, followed by uneventful relaxation. When applied during reduced cardiac output, tachycardia, and vasoconstriction induced by prior LBNP for 6 minutes, CPT again caused vasoconstriction, now followed by acute hypotension in 10 subjects, and was associated with vasorelaxation, relative bradycardia, and fall in muscle sympathetic nerve activity. Eight subjects also experienced acute LBNP-induced hypotension in the absence of CPT, but not until 17 +/- 6 minutes of LBNP. We also performed CPT before and in the final phase of hemodialysis in 8 patients. Before dialysis, the patients tolerated CPT uneventfully, but during hemodialysis, CPT provoked acute hypotension in 5 cases, showing similar withdrawal of vasoconstriction.

CONCLUSIONS

This is the first study showing that brief cold stress, tolerated well in normal circulatory conditions, can provoke sudden sympathoinhibition and hypotension when applied during decreased cardiac output induced by LBNP or hemodialysis. We suggest that during conditions of a decreased cardiac output, subtle sympathetic relaxation such as follows cold stress triggers self-enhancing relaxation that cannot be controlled.

Bilateral increase in CO2 reactivity after unilateral carotid endarterectomy

BACKGROUND AND PURPOSE

A low or absent CO2 reactivity is considered indicative of a compromised hemodynamic compensatory capacity in patients with internal carotid artery (ICA) stenosis or occlusion. The aim of the present study was to investigate whether patients with preoperatively decreased or absent CO2 reactivity show an improvement of CO2 reactivity 3 months after carotid endarterectomy (CEA) and whether the preoperative CO2 reactivity is correlated with clinical classification and hemodynamic factors.

METHODS

A group of 65 patients with > 70% ICA stenosis was studied. CO2 reactivity was measured by bilateral transcranial Doppler sonography before and 3 months after CEA.

RESULTS

The preoperative CO2 reactivity was not significantly different in subgroups formed according to the presenting clinical symptoms. Patients with severe ICA stenosis with contralateral ICA occlusion had mean low preoperative CO2 reactivity on both sides. Furthermore, patients with reversed flow in the ophthalmic artery had low mean preoperative CO2 reactivity on the same side. The CO2 reactivity was not significantly different in the subgroups of patients with signs of collateral blood flow through the anterior or posterior communicating artery. In particular, patients with low preoperative CO2 reactivity (approximately < 30%) showed an evident increase after the operation. Such an inverse correlation was found bilaterally, although it was more pronounced on the CEA side.

CONCLUSIONS

CEA can increase CO2 reactivity in both hemispheres. This effect is most pronounced in patients with low (< 30%) preoperative CO2 reactivity. If this group represents patients who would be at risk from low-flow stroke, then testing of CO2 reactivity might help select a subset of patients with an especially high probability of benefit from CEA.

Assessment of the preferred plane and sequence in the depiction of mesial temporal sclerosis using magnetic resonance imaging

RATIONALE AND OBJECTIVES

Definition of optimal magnetic resonance (MR) scanning plane and conventional MR sequence for the detection of mesial temporal sclerosis (MTS).

METHODS

Coronal and axial T2-weighted images and axial T2-weighted images parallel to the long axis of the hippocampus (APLAH) and coronal inversion recovery (IR) images were obtained in patients with medically intractable temporal lobe epilepsy in their phase 1 preoperative evaluation. Thirty-three consecutive MR scans were reviewed by a panel of three radiologists. Twenty-three patients had MR abnormalities consistent with MTS, and ten scans were normal. To assess the best single scanning technique, another group of three radiologists, who were masked to all patient data, individually assessed the different planes and sequences of the 33 studies presented separately in a random fashion. For each plane and sequence, the likelihood (L) ratio for the correct diagnosis was determined separately.

RESULTS

For all planes considered separately, a likelihood ratio of 4.4 was optimal for the coronal T2-weighted images. The likelihood ratio of APLAH T2 was 2.2; of axial T2, 3.9; of coronal IR, indefinite because of 100% specificity.

CONCLUSIONS

For the assessment of MTS, coronal T2-weighted images were considered the best single scanning technique.

Acute increase of myocardial workload, hemodynamic instability, and myocardial histological changes induced by brain death in the cat

Brain death-related hemodynamic instability may preclude donor heart procurement. The relationships between the initial changes of myocardial workload, hemodynamic deterioration, and myocardial histological changes caused by acute induction of brain death are unclear. Cats (n = 15) were submitted to brain death by rapid inflation of an intracranial balloon. A further 12 cats served as a sham-operated control group. The changes in heart rate, mean arterial blood pressure, systolic and diastolic arterial blood pressure, left ventricular developed pressure, LV dP/dtmax, rate-pressure product (RPP), and circulating noradrenaline and adrenaline were studied during 240 min after the induction of brain death. Central venous pressure was kept constant. The hearts were histologically examined afterward. Electrocerebral activity disappeared within 30 sec after balloon inflation. At 3 min, noradrenaline and adrenaline levels had increased 75- and 40-fold, respectively, compared to pre-induction levels. The hemodynamic response was characterized by an early and rapid increase of hemodynamic variables at 2.9 +/- 0.2 min. This was followed by a second phase of normalization or deterioration. Two distinct subgroups (n = 9) became hemodynamically unstable (HDU), characterized by a systolic arterial blood pressure < 90 mm Hg, at 108 +/- 29 min, and progressively deteriorated to 67 +/- 8 mm Hg at 240 min after inflation of the balloon. The hemodynamic variables of the other, hemodynamically stable (HDS), subgroup (n = 6) normalized at 60 min after inflation. Hemodynamic deterioration of the HDU subgroup compared to the HDS subgroup was significant at 10 min after induction of brain death. The maximum values of RPP were similar in the two subgroups. Respiratory and metabolic variables at the end of the experiment were not different in both subgroups. Histological evidence of myocardial damage was present in 73% (11/15) of the brain dead cats and absent in the control group. The histological changes were identified both in hearts of HDU (6/9) and HDS (5/6) cats. In the cat, no relationships were demonstrated between the acute increase of myocardial workload, the occurrence of hemodynamic deterioration, and myocardial histological changes after rapid induction of brain death. These results may contribute to the discussion whether hemodynamic instability of the donor is an appropriate exclusion criterion for heart transplantation.

[Brain death criteria; guidelines by the Public Health Council]

The Committee on brain death criteria of the Health Council of the Netherlands has formulated guidelines for diagnosing brain death according to prevailing medical opinion. The guidelines are based on the relevant scientific literature and consultation of the professional groups involved and take into consideration that various views on death, or brain death, are existent in the community. The Committee has attempted to phrase the guidelines in clear and specific terms, in order to minimize interpretational differences. It endorses the most stringent definition of brain death, as given in the Organ Donation Act, the so-called 'whole brain death' concept. It must be established that the potential donor has irreparable and complete loss of brain and brain stem function. Three diagnostic phases are needed. In one of these an isoelectric electroencephalogram is required. This does not preclude that certain neurons in certain areas may still be active, but these phenomena are no indication of higher brain function or its intermediary or supportive functions. If electroencephalography cannot be performed, or if the apnoea test is not possible, cerebral arterial angiography is required. In children, the investigations must be repeated. A written codicil by the donor will be respected, but it is unlikely that organs or tissues are removed against the will of the family.

Prospective study of the prevalence of Alzheimer-type dementia in institutionalized individuals with Down syndrome

Institutionalized patients with Down syndrome (n = 307) were monitored for 5 to 10 years prospectively to determine prevalence of Alzheimer-type dementia. Clinical signs, cognitive functioning, and EEGs were assessed. When possible, postmortem neuropathological examinations were conducted. Progressive mental and physical deterioration was found for 56 of the residents. Mean age at onset of dementia was 56 years. Prevalence increased from 11% between ages 40 and 49 to 77% between 60 and 69. All patients 70 and over had dementia. Neuropathological findings were consistent with clinical diagnosis. Use of a dementia checklist, cognitive skills inventory, and EEG reliably detected Alzheimer-type dementia at an early stage.

Use of electroencephalography to detect Alzheimer's disease in Down's syndrome

We studied the role of electroencephalography (EEG) in the diagnosis of Alzheimer-type dementia in patients with Down's syndrome. 197 patients with Down's syndrome were monitored for 5 to 8 years. Aspects of cognitive functioning were assessed twice yearly. EEGs were scored in a blind fashion, and changes in the EEG were compared to changes in cognitive functioning. When possible, a neuropathological post-mortem examination was performed. Cognitive functioning was drastically reduced in 29 patients. The dominant occipital rhythm became slower at the onset of the cognitive deterioration, and eventually disappeared. In 11 of these patients neuropathological examination showed a severe form of Alzheimer's disease. Changes in the frequency of the dominant occipital rhythm could distinguish between Alzheimer's disease or other causes as underlying the cognitive decline. Slowing of the dominant occipital rhythm seems to be related to Alzheimer's disease in patients with Down's syndrome, and the frequency of the dominant occipital activity decreases at the onset of cognitive deterioration. The EEG is thus an important tool in the clinical diagnosis of Alzheimer-type dementia in patients with Down's syndrome.

The contribution of conventional and quantitative electroencephalography during monitoring of exposure to hyperbaric oxygen

In the present study, experimental exposures to hyperbaric oxygen (HBO) were performed (30-min exposure to 2.8 bar pure oxygen). During all phases of the experiment the electroencephalogram (EEG) was recorded continuously for on-line visual monitoring and off-line quantitative analysis. Conventional and quantitative EEG findings are described for a group of 23 subjects during an uncomplicated HBO exposure and for one subject who had a generalized tonic-clinic seizure when exposed to HBO. In the group of subjects who did not show signs of toxicity, EEG changes were minor and were not considered indicative of an adverse effect of HBO on the brain during the HBO exposure. Pre-convulsive EEG changes were detected in the subject with the seizure but were too insignificant for practical monitoring purposes and did not clearly herald clinical signs.

Fast spin-echo MR of contact points on implanted intracerebral stainless steel multicontact electrodes

A three-dimensional fast spin-echo MR technique is proposed for locating contact points on implanted intracerebral multicontact electrode bundles, Coronal or sagittal reformatting shows the entire trajectory of the electrode bundles. The contract points are clearly visible owing to the absence of coating material associated with a slightly larger susceptibility artifact. Potentially, this technique may preclude postimplantation thin-section CT, with its associated high radiation dose.

Value of transcranial Doppler indices in predicting raised ICP in infantile hydrocephalus. A study with review of the literature

Cerebral hemodynamic changes in infants with progressive hydrocephalus have been studied with the transcranial Doppler (TCD) technique. Several authors have referred to the correlation between the hemodynamic changes and increased intracranial pressure (ICP). Despite conflicting conclusions on the value of pulsatility index (PI) and resistance index (RI) measurements for monitoring infantile hydrocephalus, these pulsatility indices are the most commonly used for this purpose. Although clinical signs of raised ICP are highly variable and unreliable in infants, assumptions have been made in most of the studies about the presence of elevated ICP on the basis of the patient's clinical state. Few studies have reported on actual ICP values, however, and a direct relationship between ICP and TCD changes has never been adequately demonstrated. In the present study, this relationship was investigated in long-term simultaneous TCD/ICP measurements, in an attempt to develop a noninvasive method of monitoring the effect of ICP on intracranial hemodynamics. Two groups of data sets were established. Group I consisted of pre- and postoperative (shunt implantation) TCD/ICP measurements. Group II were long-term simultaneous TCD/ICP recordings showing significant ICP variations. In most of the postoperative measurements there was a decrease in the average PI and RI values. The correlation between PI or RI and ICP in the long-term simultaneous recordings, however, was generally poor. The risk of obtaining false positive or false negative PI or RI values in short-term measurements was also demonstrated. It can be concluded from our results, besides the wide range of reference values for the Doppler indices and extracranial influences upon them, that the present Doppler indices are inadequate for monitoring the complex intracranial dynamic responses in patients with raised ICP.

Monitoring intracranial dynamics by transcranial Doppler--a new Doppler index: trans systolic time

Since the introduction of transcranial Doppler sonography (TCD) several investigators have described the relationship between raised intracranial pressure (ICP) and Doppler waveform. This waveform has been expressed by several indices, such as the pulsatility index (PI) and the resistance index (RI). These indices are used to demonstrate the presence of raised ICP. In childhood hydrocephalus this information can be used to indicate the need for shunt implantation. However, PI and RI do prove to have certain disadvantages as both are strongly influenced by the heart rate. Moreover, both indices have a broad range of reference values, especially in children. Therefore, they are not very reliable for detecting insidious changes in the ICP. These drawbacks are due to the fact that these indices are composed of blood flow velocity measurements and do not embody the slope of the TCD waveform itself. An ideal TCD waveform analysis should be performed concerning the time-related changes of the velocities. We present a hydrodynamic model, with its electrical analogue, which shows the effects of raised ICP on the intracranial hemodynamic system. Based on these physical findings we define a new Doppler index, the Trans Systolic Time, reflecting specific changes in the TCD waveform induced by changes in the mean ICP. The applicability of this index, compared with PI and RI, is illustrated by consecutive simultaneous TCD and AFP measurements in three children with hydrocephalus.

Electroencephalography improves the prediction of functional outcome in the acute stage of cerebral ischemia

BACKGROUND AND PURPOSE

We studied the value of clinical and electroencephalographic assessment in patients with acute first-ever supratentorial ischemia in predicting functional outcome after 1 year.

METHODS

In 55 consecutive patients admitted after a median interval of less than 24 hours, the degree of handicap was dichotomized as moderate (Rankin grade 1, 2, or 3) or severe (Rankin grade 4 or 5). Clinical deficits were categorized according to signs of a lacunar or a cortical syndrome. Without knowledge of clinical data, electroencephalograms (EEGs) were classified according to findings predicting good or poor prognosis. The outcome after 1 year was assessed as good (Rankin grade 3 or less) or poor (Rankin grade 4 or 5 or death from stroke) and was correlated to clinical data and to EEG findings in the acute stage.

RESULTS

Thirty patients with a moderate handicap on admission all had a good outcome (predictive value [PV] of the initial handicap, 1.00; 95% confidence interval [CI], 0.88 to 1.00). Of the 25 patients with severe handicap on admission a poor outcome occurred in 13 (PV, 0.52; 95% CI, 0.31 to 0.72). If these patients with severe handicap at baseline were subdivided according to clinical features, a lacunar syndrome predicted good outcome in 4 of 5 patients (PV, 0.80; 95% CI, 0.28 to 1.00), but a cortical syndrome predicted poor outcome in only 12 of 20 patients (PV, 0.60; 95% CI, 0.36 to 0.81). Of the 20 patients with severe handicap and a cortical syndrome at baseline, an EEG with features predicting a good prognosis correctly predicted good outcome in 6 of 7 patients (PV, 0.86; 95% CI, 0.42 to 1.00). An EEG with features predicting poor prognosis correctly predicted poor outcome in 11 of 13 patients (PV, 0.85; 95% CI, 0.55 to 0.98).

CONCLUSIONS

Electroencephalography improves the prediction of functional outcome in patients with a severe neurological deficit in the acute stage of cerebral ischemia. This may have implications for the design of future intervention trials in acute stroke.

Temporal lobe epilepsy: the various MR appearances of histologically proven mesial temporal sclerosis

PURPOSE

To determine the frequency of appearance of various MR signs in mesial temporal sclerosis, to determine the optimal scanning planes for their visualization, and to propose a histologic explanation for the diminished demarcation between gray and white matter in the temporal lobe, a frequent MR finding in patients with mesial temporal sclerosis.

METHODS

MR scans of 14 surgically treated patients with epilepsy and histologically proven mesial temporal sclerosis were assessed for the presence of six features: feature 1, high signal intensity in the hippocampus; 2, reduced hippocampal size; 3, ipsilateral atrophy of the hippocampal collateral white matter; 4, enlarged temporal horn; 5, reduced gray-white matter demarcation in the temporal lobe; and 6, decreased temporal lobe size.

RESULTS

Feature 1 was present in 14 patients and was best appreciated on the T2-weighted images in planes parallel to the long axes of the hippocampi. Feature 2, present in 12 patients, and feature 6, present in 9 patients, were optimally seen in the coronal planes and on the inversion-recovery sequences in particular. Feature 3, present in 12 patients, was optimally seen on the coronal T2-weighted images. Feature 4, seen in 11 patients, was equally well seen in all planes (transverse, coronal, and parallel to the long axes of the hippocampi). Feature 5, seen in 10 patients, was best appreciated on the T2-weighted images in the planes of the long axes of the hippocampi. Histologic investigation of the temporal lobe white matter in the 10 patients with feature 5 demonstrated on the MR scan showed abnormalities in 7 cases. Oligodendroglia cell clusters were found in 6, with concomitant corpora amylacea in 1 case and perivascular macrophages with pigment a sole finding in another case.

CONCLUSION

Of the six features found in cases of mesial temporal sclerosis on MR, increased hippocampal signal intensity is the most consistent. A decreased gray-white matter demarcation in the temporal lobe parenchyma is also a frequent feature of this disease. A combination of multiple scanning planes results in an optimal demonstration of lesions.

Randomized double-blind placebo-controlled trial to evaluate the effect of the ACTH4-9 analogue ORG 2766 in IDDM patients with neuropathy

In this study we report a randomized double-blind, placebo-controlled trial to evaluate the effect of ORG 2766 in IDDM patients with peripheral neuropathy. Sixty-two patients were selected based on the following criteria: abnormal vibration perception threshold above the 95th-percentile adjusted for age and/or abnormal warm temperature threshold, both measured in the right hand. The patients were randomized into two treatment groups after baseline studies: Group 1 was treated with placebo and Group 2 was treated with 3 mg of the ACTH4-9 analogue ORG 2766 every 24 h. The total study period was 1 year. After 1 year of treatment there was a significant improvement in vibration threshold in Group 1 compared to Group 2. No other parameters improved in the study period. The number of patients selected may have been too small to detect a more important treatment effect. We conclude from this study that ORG 2766 can improve vibration threshold, indicating large myelinated fibre function, but does not affect any of the other neurophysiological function tests.

The effect of non-depot ACTH(1-24) on infantile spasms

However, side-effects such as severe infections, hypertension and electrolyte imbalance have been found, assumed to be related to hypercortisolism induced by chronic ACTH treatment. The authors treated 18 patients with infantile spasms with non-depot ACTH(1-24). The therapeutic effect of non-depot ACTH was comparable to that of depot ACTH, with no severe bacterial infection or sepsis. The incidence of hypertension was significantly lower in the non-depot ACTH group, and persistent hypercortisolaemia was not found. Non-depot ACTH(1-24) appears to be as effective as ACTH(1-24) depot therapy in the treatment of infantile spasms, and its side-effects are mild. It would appear that the effect of non-depot ACTH is not mediated by hypercortisolism, but by a direct neurotropic effect on the brain.

Is the corrected QT interval a reliable indicator of the severity of diabetic autonomic neuropathy?

OBJECTIVE

We investigated whether the corrected QT interval correlated with two other tests for diagnosing autonomic dysfunction in 60 type I diabetic patients with proven peripheral neuropathy. The mean age +/- SD was 48.3 +/- 11.2 yr, the mean duration of diabetes was 24.9 +/- 11.4 yr, and the mean HbA1 was 9.3 +/- 2.4%.

RESEARCH DESIGN AND METHODS

All patients underwent three autonomic function tests: 1) the standard five cardiovascular Ewing tests, each scored 0 (normal), 0.5 (borderline), or 1.0 (abnormal). We used the sum of the abnormal findings for the analysis, the cardiovascular autonomic score; 2) measurement of the corrected QT interval taken from a routine electrocardiogram recording; and 3) static and dynamic pupillometry: measurement of dark adapted pupil diameter as percentage of total iris diameter and of pupil constriction latency using an infrared light reflex technique.

RESULTS

No significant correlation was found between age, duration of diabetes, or HbA1 and any of the autonomic function tests, except for one between age and cardiovascular autonomic score (r = 0.3202, P = 0.0126). Corrected QT interval did not correlate with cardiovascular autonomic score, pupil diameter, or constriction latency. A significant inverse correlation was found between cardiovascular autonomic score and pupil diameter (r = -0.4861, P < 0.001) and constriction latency (r = 0.3783, P < 0.001). Pupil diameter and constriction latency correlated well (r = -0.4276, P < 0.001).

CONCLUSIONS

The corrected QT interval did not correlate with cardiovascular autonomic tests nor pupillometry results. The corrected QT interval therefore should not be used for the diagnosis of the severity of diabetic autonomic neuropathy.

Subclinical diabetic polyneuropathy: early detection of involvement of different nerve fibre types

Nerve conduction studies, tests of autonomic function and terminal nerve branches, and soleus muscle H reflexes were applied to 60 patients with insulin dependent diabetes mellitus who had no clinical symptoms but abnormal vibratory or temperature perception thresholds indicating subclinical neuropathy. In most patients neurophysiological examination yielded a broad spectrum of neural dysfunction. The perception threshold for cold stimuli was sometimes selectively impaired and abnormal pupillometry results were common, suggesting that small fibres are vulnerable in the early stage of diabetic neuropathy. The arms were less frequently and less severely affected than the legs, an effect that may be related to nerve length. The neurophysiological test results did not change in 30 patients followed up for one year.

Identical morphology of the rolandic spike-and-wave complex in different clinical entities

The morphology of the rolandic spike, the trough between the rolandic spike and the following slow wave, and of the slow wave itself was quantitatively studied in 43 children, classified into five clinical groups: (a) functional with epilepsy benign focal epilepsy of childhood with centrotemporal spikes (BECT) with oropharyngeal seizures or (b) BECT with unilateral or generalized seizures or (c) functional without epilepsy, and (d) organic with or (e) without epilepsy. The morphologic features of the rolandic spike-and-wave complex were identical in the five clinical categories. Thus, a quantitative description of the rolandic spike-and-wave complex can be given that is valid for the 43 children of the present study, although they represent a heterogeneity of associated clinical syndromes. The rolandic spike appeared to be not a spike but a sharp wave with a mean duration of 88 ms. In contrast to the opinion of several investigators, the morphology of the rolandic spike does not provide a clue to its "epileptogenicity" or to the presence or absence of an organic cerebral lesion in the individual child. In clinical practice, additional information (background activity of the EEG, computed tomography (CT) scan, or magnetic resonance imaging (MRI) of the brain) is needed to determine the significance of rolandic spikes occurring in the EEG of a child with respect to the probability of a cerebral lesion and the prognosis in relation to epileptic seizures.