Topography of Cortical Microbleeds in Alzheimer's Disease with and without Cerebral Amyloid Angiopathy: A Post-Mortem 7.0-Tesla MRI Study

Cortical microbleeds (CMBs) detected on T2*-weighted gradient-echo (GRE) magnetic resonance imaging (MRI) are considered as a possible hallmark of cerebral amyloid angiopathy (CAA). The present post-mortem 7.0-tesla MRI study investigates whether topographic differences exist in Alzheimer's brains without (AD) and with CAA (AD-CAA). The distribution of CMBs in thirty-two post-mortem brains, consisting of 12 AD, 8 AD-CAA and 12 controls, was mutually compared on T2*-GRE MRI of six coronal sections of a cerebral hemisphere. The mean numbers of CMBs were determined in twenty-two different gyri. As a whole there was a trend of more CMBs on GRE MRI in the prefrontal section of the AD, the AD-CAA as well as of the control brains. Compared to controls AD brains had significantly more CMBs in the superior frontal, the inferior temporal, the rectus and the cinguli gyrus, and in the insular cortex. In AD-CAA brains CMBs were increased in all gyri with exception of the medial parietal gyrus and the hippocampus. AD-CAA brains showed a highly significant increase of CMBs in the inferior parietal gyrus (p value: 0.001) and a significant increase in the precuneus and the cuneus (p value: 0.01) compared to the AD brains. The differences in topographic distribution of CMBs between AD and AD-CAA brains should be further investigated on MRI in clinically suspected patients.

Hippocampal microbleed on a post-mortem t(2)∗-weighted gradient-echo 7.0-tesla magnetic resonance imaging?

The present post-mortem study of a brain from an Alzheimer patient showed on a T₂∗-weighted gradient-echo 7.0-T MRI of a coronal brain section a hyposignal in the hippocampus, suggesting a microbleed. On the corresponding histological examination, only iron deposits around the granular cellular layer and in blood vessel walls of the hippocampus were observed without evidence of a bleeding. This case report illustrates that the detection of microbleeds on MRI has to be interpreted with caution.

Comparison of 7.0-T T₂*-magnetic resonance imaging of cerebral bleeds in post-mortem brain sections of Alzheimer patients with their neuropathological correlates

BACKGROUND

In view of the increasing recognition of cerebral microbleeds (MCBs) with MRI, there is a need to validate their detection in post-mortem brains in patients with cerebrovascular diseases and dementia.

MATERIALS AND METHODS

Out of 20 post-mortem brains of patients with Alzheimer dementia and with different cerebrovascular lesions, 45 large sections of the cerebral hemispheres, brainstem and cerebellum were submitted to a 7.0-T T₂*-weighted MRI, and afterwards compared to the histological detection of haematomas, MCBs and mini-bleeds (MNBs).

RESULTS

The sensitivity, specificity, predictive positive value and predictive negative value of the T₂* imaging to detect MCBs and MNBs were excellent for those in the cortico-subcortical regions. There was a significant overestimation of MNBs in the striatum due to iron deposits unrelated to old haemorrhages. Also in the deep white matter, 42% of MNBs were not detected, while 31% of T₂* hyposignals were not due to MNBs but to vessels filled with post-mortem thrombi.

CONCLUSIONS

When evaluating the 'bleeding load' with 7.0-T T₂*-weighted MRI in post-mortem brain sections of patients with dementia and vascular risk factors, only quantification of small cerebral bleeds in the cortico-subcortical regions is reliable.

The impact of cerebral amyloid angiopathy on the occurrence of cerebrovascular lesions in demented patients with Alzheimer features: a neuropathological study

OBJECTIVE

The aim of this neuropathological study was to determine the prevalence of the different cerebrovascular lesions to be attributed to cerebral amyloid angiopathy (CAA) and of those associated with the severity of the Alzheimer dementia (AD) itself.

PATIENTS AND METHODS

The cerebrovascular lesions were compared separately in 40 brains of patients with mild and 50 with severe AD features. In the two groups, the number of lesions were compared between the brains with severe and those with mild of absent CAA.

RESULTS

The age of the patients, the vascular risk factors and antithrombotic treatment were similar in all the compared groups. The brains with mild and severe AD features and with CAA contained more haematomas, cortical micro-infarcts and micro-bleeds, and more severe white matter changes, and cortico-subcortical and white matter mini-bleeds. In the CAA brains with severe AD features, also more cortical territorial infarcts were observed, compared to those with mild AD features.

CONCLUSIONS

The increase in cortical infarcts cannot be attributed to the CAA alone, but also to the severity of the degenerative features, implying additional vascular factors in the pathogenesis of AD.

Vascular risk factors in patients with peripheral vestibular disorders

OBJECTIVES

The present observational retrospective study investigates whether there are differences in vascular risk factors between patients with spontaneous benign paroxysmal positional vertigo (BPPV) and those with Ménière's disease (MD).

PATIENTS AND METHODS

Out of a series of 1617 consecutive admitted patients, 36 presented isolated recurrent vertiginous events. Twenty patients with BPPV and 16 with MD were compared. In addition to extensive audiovestibular investigations, all patients had a complete cardio-vascular work-up. A computed tomography (CT) and a magnetic resonance imaging (MRI) of the brain were performed in all patients. The vascular risk factors and the CT/MRI findings were compared between the patients with BPPV and MD.

RESULTS

Small old cerebral infarcts were observed in 25% of the BPPV and 31.2% of the MD patients, although none of them had a prior history of stroke. All other vascular risk factors tended to be more frequent in the former group although only a statistically significant difference was found for coronary artery disease (P = 0.03).

CONCLUSIONS

In this pilot study BPPV does not appear to be such a benign condition but can indicate progression of general atherosclerotic disease.

Circulating intercellular adhesion molecule-1 and E-selectin in acute ischemic stroke

Exposure of endothelia to hypoxia followed by reperfusion, results in increased leukocyte activation and extravasation. These leukocytes potentiate ischemic neuronal damage. Extravasation of leukocytes is guided by adhesion molecule interactions on inflammatory and endothelial cells. Circulating adhesion molecules rapidly appear in peripheral blood. Commercially available ELISA kits were used to determine serum levels of E-selectin and intercellular adhesion molecule-1 (ICAM-1) in 36 patients at 1, 3, and 14 days after acute ischemic stroke. E-selectin levels were nonsignificantly increased at day 1, and decreased thereafter, reaching significantly lower values at day 14 in the stroke patients. ICAM-1 levels were similar in stroke patients at each sampling period, and did not differ from those of controls. Our data on ICAM-1 are in line with those of a recently published study. The decreasing circulating E-selectin may stem from endothelial cell damage, alterations in cytokine interactions, or unknown factors.

Cognitive impairment and seizures in patients with lacunar strokes

BACKGROUND

Lacunar infarcts and white matter changes have been linked to cognitive impairment. Patients with lacunar strokes can also develop seizures, although the relationship between the two remains unclear. The present study investigates whether seizures in patients with lacunar infarcts are related to the strokes or to an underlying neurodegenerative disorder leading to cognitive impairment.

METHODS

The demographic features, vascular risk factors and scores on the National Institutes of Health Stroke Scale (NIHSS) on admission for the stroke and on the modified Rankin scale on discharge, as well as on the Mini-Mental State Examination (MMSE), were determined in patients with a lacunar stroke. They were compared between 44 patients with and 248 without subsequent seizures.

RESULTS

Patients with seizures had a lower main NIHSS score (p = 0.00133) and a more severe MMSE score (p < 0.001). They remained significantly more dependent (p = 0.019) after hospital discharge. Smoking, as a vascular risk factor, appeared to occur less frequently in seizure patients (p = 0.039). On logistic regression analysis, only NIHSS and MMSE scores remained independent variables.

CONCLUSIONS

Seizure occurrence in patients with a lacunar infarct is not related to the severity of the stroke but rather to the degree of cognitive impairment. The present study suggests that the seizures are not due to lacunar infarcts but are more probably the expression of an underlying neurodegenerative process that is also responsible for the mental deterioration.

Stroke-related seizures in patients with a partial anterior circulation syndrome

BACKGROUND

Partial anterior circulation syndrome (PACS), due to cerebral infarction, is the most common stroke presentation of patients with seizures. This study investigates the characteristics of such patients according to their seizure onset time.

PATIENTS AND METHODS

The characteristics of 151 patients with a PACS and seizures were compared to 310 without seizures. The seizure groups were classified as those of early- (EO), of late- (LO) and of very late-onset (VLO) and those due to recurrent infarcts (RI).

RESULTS

Temporal lobe infarction is the main risk factor for developing seizures (P < 0.02). Seizures are responsible for increased dependency except in patients with those of VLO (P < 0.03). Patients with EO seizures have the worse outcome (P = 0.0111) with a trend of more status epilepticus (P = 0.066) but less recurrence (P = 0.003). A cardiac-embolic source is more common in patients with seizures due to RI (P = 0.015). Post-ictal EEG patterns are significantly different from those in the patients without seizures (P < 0.001) except for seizures of VLO.

CONCLUSIONS

There are significant differences in the seizure characteristics according to their time of onset.

Characteristics and outcomes of patients with seizures according to the time of onset in relation to stroke

BACKGROUND/AIM

Although most late-onset seizures (LS) appear within 2 years after stroke, some of them occur later and their characteristics are unknown. The aim of this study was to compare the characteristics of patients with very-late-onset seizures (VLS) to those with early-onset seizures (ES) and those with LS.

PATIENTS

The study group consisted of 204 patients with stroke-related seizures (29 ES, 128 LS and 47 VLS).

RESULTS

Intracranial haemorrhage was a more frequent cause of ES than of LS and no cause at all of VLS. On the other hand, 25% of the VLS were related to lacunar strokes. Status epilepticus occurred in 20.7% of the ES, in 11.7% of the LS and in 2.1% of the VLS patients. Seizure recurrences were 13.8% in the ES, 54.7% in the LS and 34.0% in the VLS group. Neurological impairment, at stroke onset, and the degree of disability were more severe in patients with ES compared to those with LS and were very mild in the VLS group. The EEG findings as a whole did not show significant differences between the three groups, although a normal EEG was more frequent in the VLS group.

CONCLUSION

VLS occur in patients with minor ischaemic strokes with good recovery and benign disease course.

Chronic obstructive pulmonary disease as a risk factor for stroke-related seizures

Chronic obstructive pulmonary disease (COPD) is a risk factor for cardiovascular disorders and different types of stroke. The present retrospective study investigates whether COPD is also a risk factor for the development of seizures in stroke patients. The study population consisted of 237 patients with stroke-related seizures. The control population was composed of 939 patients, admitted for a stroke between 2002 and 2004 and who did not develop epileptic spells on a follow up of 2 years. The stroke type and aetiology, and the vascular risk factors, including COPD, were compared. The seizure patients were older (P = 0.009) and had more arterial hypertension (P = 0.046) and cardiac-embolic strokes (P = 0.045) than the control group. On logistic regression only partial anterior circulation syndrome/infarct (PACS/I) and COPD (P < 0.001) emerged as independent risk factors for the development of seizures in stroke patients. The occurrence of seizures was not related to the severity of the COPD or to its type of treatment. The present study confirms that seizures occur most frequently in patients with a PACS/I. Although we were unable to demonstrate why COPD is a risk factor for seizures in stroke patients, its frequent associated nocturnal oxygen desaturation seems to be the most plausible explanation. Further prospective are needed to assess the role of COPD as a possible independent risk factor for stroke-related seizures.

Seizures and epilepsy in patients with lacunar strokes

BACKGROUND

The relation between seizures and small subcortical infarcts is uncertain. The present retrospective study investigates whether differences are observed between patients with and without seizures following a lacunar stroke.

PATIENTS AND METHODS

Thirty-seven patients with seizures and a prior history of a lacunar stroke were admitted to the Ghent University Hospital during 2000 and 2005. They were compared to 205 patients, admitted between 2002 and 2004, with an acute lacunar stroke and without epileptic spells on follow-up. Nine out of the 37 patients with seizures and 48 out of the 205 without seizures had a history of recurrent strokes.

RESULTS

No differences in vascular risk factors, distribution and frequency of the lacunes, degree of severity of the white matter changes and outcome were observed. On the Mini-Mental State Examination moderate to severe cognitive disturbances were observed in the seizure group and in some patients of the non-seizure group.

CONCLUSIONS

In the present study we found no evidence that seizures are directly induced by lacunar infarcts. The seizures appear to be part of a more global ongoing cerebral disorder probably leading to cognitive impairment.

Magnetic Resonance Imaging after Seizures in Patients with an Ischemic Stroke

BACKGROUND

Seizures related to ischemic strokes are harmful. Their pathogenesis is not very well understood. The present study investigates whether diffusion-weighted imaging (DWI) can detect if those seizures are due to recurrent infarction or responsible for secondary ischemic changes.

PATIENTS AND METHODS

DWI was obtained within 8 days in 60 patients with seizures (7 early and 53 late onset) related to an ischemic stroke.

RESULTS

In 30 patients, positive DWI with decreased apparent diffusion coefficient was found. In 11 patients with late-onset seizures, the DWI showed a positive rim, surrounding the old infarct, while in 12 patients a large positive zone corresponding to a new infarct was observed. All 7 patients with early-onset seizures had positive DWI corresponding to the establishing infarct. A large positive zone on DWI was mainly observed in cardioembolic stroke.

CONCLUSIONS

The positive rim around the old infarct can be considered as cytotoxic edema. Recurrent acute infarction, mainly of cardioembolic origin, seems to be a significant cause of so-called late-onset seizures, making the subdivision into early- and late-onset seizures arbitrary.

EEG Findings after a Cerebral Territorial Infarct in Patients Who Develop Early- and Late-Onset Seizures

BACKGROUND

EEG findings are generally not considered to be very helpful for the diagnosis of poststroke seizures.

PURPOSE

This retrospective study investigates the EEG characteristics in patients who develop seizures after a cerebral territorial infarct.

PATIENTS AND METHODS

The study population consisted of 110 patients with seizures after a cerebral territorial infarct (12 with early- and 98 with late-onset seizures) and 275 without. All 110 patients had an interictal EEG after their first seizure. The EEG patterns after the stroke were compared between those available from 69 patients who developed seizures and those from 275 who did not. Also the EEG patterns after the seizure (n = 110) were compared to those in the poststroke group without subsequent seizures.

RESULTS

Periodic lateralized epileptic discharges (PLEDs) on the EEG after stroke were only found in 5.8% of the patients with early- and late-onset seizures. They were absent in the stroke group without seizures. Frontal intermittent rhythmic delta activities (FIRDAs) were observed in 24.6% of the seizure group, compared to 1.1% in the control group. Diffuse slowing occurred also significantly more often in the former (21.7%) compared to the latter group (5.1%). Normal EEG findings were seen in 53.8% of the stroke patients without seizures, compared to 8.5% in those with seizures. The incidence of focal slowing was the same in both groups. Similar findings were observed when comparing the EEG patterns of the patients after the first poststroke seizure to those of the stroke group without subsequent seizures. In patients with early-onset seizures, PLEDs or FIRDAs were present in 25% each. FIRDAs and diffuse slowing were significantly more frequently observed on the poststroke EEGs of patients who developed late-onset seizures.

CONCLUSIONS

FIRDAs, PLEDs and diffuse slowing are the most frequent EEG findings in patients with early-onset seizures. Patients with FIRDAs and diffuse slowing on the poststroke EEG have a high risk to develop late-onset seizures, while the chance is reduced in those with normal EEG findings.

Computed tomographic changes of the brain and clinical outcome of patients with seizures and epilepsy after an ischaemic hemispheric stroke

It is not well established whether seizures and epilepsy after an ischaemic stroke increase the disability of patients. Seventy-two patients with delayed seizures after a hemispheric infarct (37 with a single seizure and 35 with epilepsy) were included in the study. The modified Rankin scale was used to compare disability of the patients at 1 month after stroke and at 2 weeks after single or the last seizure, in case of epilepsy. The size of the X-ray hypoattenuation zone was compared on computed tomographic (CT) scans, performed in the weeks after the stroke and 1 week after single or repeated seizures. Lesion size was determined by superimposing the CT slices on digital cerebral vascular maps, on which the contours of the infarct area were delineated. The extent of the infarcts was expressed as the percentage fraction of the total surface area of the cerebral hemisphere. Groups with a single seizure and with epilepsy were mutually compared. Infarcts predominated in the parieto-temporal cortical regions. In the overall group the median Rankin score worsened significantly after seizures. The average size of the X-ray hypoattenuation zone was also significantly increased on the CT scans after the seizures, compared with those after stroke, without clear evidence of recent infarction. Mutual comparison of patients with a single seizure episode and of those with epilepsy showed only a trend of more severe disability and of increase in lesion size in the post-stroke epilepsy group. Delayed seizures and epilepsy after ischaemic stroke are accompanied by an increase in lesion size on CT and by worsening of the disability of the patients. This study does not allow to determine whether this is due to stroke recurrence or due to additional damage as a result of the seizures themselves.

Delayed transient worsening of neurological deficits after ischaemic stroke

BACKGROUND

Although the causes of stroke recurrence are well known, no particular study deals with the specific issue of late-onset transient worsening of the neurological deficit (TWND) after an ischaemic stroke.

PATIENTS AND METHODS

In this retrospective study the aetiology of the TWNDs in 101 patients was compared to the causes of transient ischaemic attacks (TIAs) in 115 patients. All patients had a full cardiovascular and neuroimaging examination according to current guidelines. An electroencephalogram (EEG) was performed when necessary. The diagnosis of inhibitory seizures was retained when the EEG showed periodic lateralized epileptiform discharges or intermittent rhythmic delta activities, or when the patient developed typical seizures afterwards.

RESULTS

Arterial hypertension and diabetes were more prevalent vascular risk factors in TWND patients. Small-vessel disease and inhibitory seizures were a more frequent cause of TWNDs than of TIAs. Extracranial large-vessel disease predominates in TIA patients. The global prevalence of cardiac diseases as cause of TIAs and TWNDs was the same, although severe ulcerous plaques of the aortic arch and patent foramen ovale with atrial septum aneurysm occurred more frequently in TWND patients.

CONCLUSIONS

The most frequent causes of late-onset TWNDs were different from those of TIAs. Apart from repeated neuroimaging of the brain, exhaustive cardiac investigations and EEG are mandatory in TWND patients.

Cerebral blood flow and oxygen metabolism in symptomatic internal carotid artery occlusion by (traumatic) cervical artery dissection

The present study investigates whether cerebral infarction resulting from internal carotid artery occlusion by cervical dissection is due to emboli, released from a superimposed luminal thrombus, or is due to haemodynamic failure and hypoperfusion. Ten patients with a history of stroke and with a visible cerebral infarct on computed tomographic scan, due to cervical dissection and thrombosis of the internal carotid artery, were studied with positron emission tomography in order to assess the regional cerebral blood flow (rCBF), the regional cerebral metabolic rate of oxygen (rCMRO2) and the regional oxygen extraction fraction (rOEF) in different regions of the brain. rCBF and rCMRO2 were only decreased in the infarct area but not in the peri-infarct zone or elsewhere in the brain. As rOEF was not increased in the affected cerebral hemisphere, the present study suggests artery-to-artery embolism rather than a haemodynamic event as the cause of the stroke. Use of anticoagulants thus appears to be the appropriate treatment in the acute stage.

Clinical predictors of late-onset seizures and epilepsy in patients with cerebrovascular disease

BACKGROUND

Seizures and epilepsy are harmful and worsen the disability of stroke patients. There are currently no good clinical predictors of late-onset seizures and epilepsy in patients with cerebrovascular disease (CVD).

PATIENTS AND METHODS

110 patients with delayed seizures after an ischaemic or a haemorrhagic stroke, a transient ischaemic attack or a subarachnoid haemorrhage (60 with a single seizure and 50 with epilepsy) and 366 without seizures were included in this retrospective study. The clinical syndrome, the stroke aetiology and the vascular risk factors were compared. The groups with a single seizure and with epilepsy were also analysed separately.

RESULTS

There were no differences in age, gender, aetiology and vascular risk factors between the groups with and without seizures. When comparing the incidence of the clinical syndromes, ischaemic partial anterior circulation syndrome (PACS) was significantly more and transient ischaemic attack less frequent in the group with seizures compared to the control group. The severity of the neurological impairment on admission and the degree of disability on discharge after a PACS was similar in those who developed late-onset seizures compared with those who did not. Also on the Cox proportional hazards analysis, PACS appeared to be the only clinical risk factor for development of seizures and epilepsy in patients with CVD. No differences were observed in clinical predictors between patients with a single seizure and those with epilepsy.

CONCLUSION

PACS is the only independent predictor for the occurrence of late-onset seizures in patients with CVD.

Comparison of age of onset and development of motor complications between smokers and non-smokers in Parkinson's disease

BACKGROUND

There is growing evidence from case-control and from cohort studies that smoking is inversely related to the risk of developing Parkinson's disease (PD). However, it is still controversial if PD starts at an older age in ever-smoking patients compared to never-smoking ones.

PATIENTS AND METHODS

The present retrospective study compares in a large series of 512 out-patients, collected over the last 24 years, the age of onset of the complaints, the age at which PD was diagnosed and the start of levodopa treatment between ever- and never-smokers. Also, the occurrence of long-term side-effects of the drug was evaluated. 184 PD patients with a history of smoking were compared with 328 who had never smoked. The subgroups with and without a family history of PD were analysed separately.

RESULTS

In the overall ever-smoking group, as well as in the subgroup without a family history, the onset of the disease and the time of the diagnosis of PD and the time at which levodopa was started occurred at an older age than in the never-smoking group. This difference could not be demonstrated in the patients with a family history, due to the low number of cases and the lack of statistical power. Although the follow-up period was the same in both study groups, motor fluctuations and dyskinesia were more frequent and appeared earlier after levodopa treatment in the non-smoking compared to the ever-smoking PD patients. Only for cognitive impairment there was a non-significant trend in the smoking group.

CONCLUSION

The present study confirms the protective action of smoking on PD and also suggests some modulating effect of smoking on the dopaminergic system.

Cerebral bloodflow and oxygen metabolism in borderzone and territorial infarcts due to symptomatic carotid artery occlusion

It remains controversial whether borderzone infarcts are due to compromised cerebral perfusion and whether territorial infarcts are caused by artery-to-artery emboli in case of occlusion of the internal carotid artery. The present positron emission tomography study compares with normal controls, the average regional cerebral bloodflow (rCBF), regional oxygen extraction fraction (rOEF) and regional cerebral metabolic rate for oxygen (rCMRO(2)) in the infarct area, the peri-infarct zone, the remaining homolateral hemisphere and in the contralateral hemisphere of 10 patients with borderzone and 17 patients with territorial infarcts, due to internal carotid artery occlusion by atherosclerosis and by cervical dissection. The steady-state technique with oxygen-15 was used. A nearly significant increase of rOEF with lowered rCBF and rCMRO(2) was observed in the peri-infarct zone of patients with territorial infarcts. In patients with borderzone infarcts rCMRO(2) was decreased in the peri-infarct zone, in the remaining homolateral hemisphere and in the contralateral hemisphere without changes in rCBF and rOEF. The present study finds no arguments that impaired cerebral perfusion is a more frequent cause of borderzone than of territorial infarcts.

The prognostic significance of changes in lesion size of established cerebral infarcts on computed tomography of the brain

BACKGROUND

As a second part of our prospective study, we assessed the size of the infarct lesion on computed tomography (CT) of the brain at two fixed time points after stroke in order to investigate its influence on the clinical outcome.

METHODS

From 220 consecutive stroke patients, admitted within 24 h after onset with symptoms lasting more than 24 h, we selected 150 displaying an anterior circulation infarct or syndrome. All included patients had CT scans without contrast enhancement on day 3 (+/- 8 h) and on day 10 (+/- 8 h) after stroke onset. The size of the X-ray hypoattenuation zone was determined by superimposing the CT slices on digital cerebral vascular maps, on which the contours of the infarct area were delineated. The lesion size was expressed as the fraction of the total surface area of these digital cerebral maps. The patients were divided into four groups according to their degree of disability at 3 months on the modified Rankin (R) scale as follows : R 0-1, R 2-3, R 4-5, R 6.

RESULTS

There was a clear association between lesion size on CT, on day 3 and on day 10, and the clinical outcome. Lesion size decreased between day 3 and day 10 in the groups R 0-1 and R 2-3, remained unchanged in the group R 4-5 and further increased in group R 6.

CONCLUSION

Lesion size on CT is a significant predictor of stroke outcome. It decreases from day 3 to day 10 in patients with no or low disability at 3 months, but increases in those who do not survive their stroke.

A pure sensorimotor stroke due to cervical vertebral artery occlusion

We reviewed the case history of a 45 year-old women, who presented a pure right sensorimotor stroke, due to a left paramedial medullary infarct as result of a left cervical vertebral artery occlusion. The unusual location of the infarct could be explained by the combination of an anatomical variant of the left branch of the anterior spinal artery and the presence of a deep cervical artery, issued from the costo-cervical trunck. This collateral circulation allowed that the lateral and upper medulla was not infarcted.

The prognostic significance of changes in X-ray attenuation on CT in established cerebral infarcts

BACKGROUND

X-ray hypoattenuation on computed tomography (CT) reflects the severity of ischaemic damage after stroke. However, the clinical syndrome and the effect of time influence the visibility of infarcts. This prospective study analyses whether the degree of hypoattenuation on CT at two time intervals after stroke has a predictive value for the clinical outcome.

METHODS

220 consecutive stroke patients were admitted within 24 h after onset with symptoms lasting more than 24 h. The study was restricted to 150 patients displaying an anterior circulation infarct or syndrome. All patients had CT scans without contrast enhancement on day 3 (+/-8 h) and day 10 (+/-8 h) after stroke onset. The degree of X-ray attenuation expressed in Hounsfield units was determined in the centre of the infarct area and compared to that in the corresponding zone of the contralateral hemisphere. The patients were divided into four groups according to their degree of disability at 3 months on the modified Rankin scale as follows: R 0-1, R 2-3, R 4-5 and R 6.

RESULTS

Patients in groups R 4-5 and R 6 had the most severe impairment on admission. The average decrease of X-ray attenuation on CT on day 3 was less in patients in group R 0-1, but was not different between the three other groups, while it was significantly correlated with the severity of the disability on day 10. CT X-ray attenuation increased between days 3 and 10 in group R 0-1, was unchanged in group R 2-3 and further decreased in groups R 4-5 and R 6.

CONCLUSION

The degree of X-ray attenuation on CT on day 3 allows us to distinguish those patients who will recover more or less completely from those with definite disability, while the CT findings on day 10 allow a more precise prediction of outcome. Increase of X-ray attenuation on day 10 is known as the fogging effect and appears to be a favourable prognostic factor. Fogging is generally considered to be due to macrophage invasion and proliferation of capillaries within the infarct area, but probably also represents partial restoration of some viable tissue.

Glycohistochemical characterization of vascular muscle cell destruction in CADASIL subjects by lectins, neoglycoconjugates and galectin-specific antibodies

CADASIL (Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) is a type of small-artery stroke and vascular dementia-inducing pathology of the brain. In order to explain the molecular mechanisms behind the alterations to the blood vessels in CADASIL subjects, we scrutinized the expression of glycan and glycan-binding sites in the wall of vessels taken from five such subjects (vs. five control subjects matched for age and sex). Specimens were taken from the brain, heart, kidney, liver and lung. Although the main vessel lesions were observed in the tissues depending on the blood-brain barrier, alterations to systemic vessels were also observed despite the absence of any symptoms. The histochemical expression of a panel of 10 biotinylated neoglycoconjugates [Gal-beta(1-4)-D-Glc, Galbeta(1-3)GalNAc, alpha-D-GalNAc, beta-D-GalNAc, GalNAcalpha(1-3)-D-GalNAcalpha, GalNAcalpha(1-3)-D-GalNAcbeta, beta-D-Glc, alpha-D-Man, l-Fucose and D-Glcalpha(1-4)-D-Glc], eight plant lectins (PNA, MAA, SNA, DBA, WGA, ConA, GNA and UEA-1) and two antigalectin antibodies was monitored by means of semiquantitative and quantitative computer-assisted microscopy. The data show the altered histochemical binding of plant lectins, such as UEA-1 and ConA, in the vessel walls of CADASIL subjects. The present work, based upon staining by a panel of neoglycoconjugates, provides a biochemical characterization of the alteration of vessel walls in the brain compared to other organs including the heart, kidney, lung and liver in CADASIL as opposed to control subjects. These glycohistochemical results suggest a functional relevance of protein-carbohydrate interactions in this disease.

Regional cerebral blood flow and episodic memory in Parkinson's disease: a single photon emission tomography study

In this paper we examined 46 nondemented Parkinson's disease (PD) patients by means of perfusion single photon emission computed tomography (SPECT) and neuropsychological testing. The aim was to detect correlations of regional cerebral blood flow with episodic memory performance, using an operator-independent technique for the analysis of SPECT data. A significant positive correlation was found between prefrontal blood flow and episodic memory performances. However, age was the most important determinant of memory scores. Age also correlated significantly negatively with prefrontal perfusion. Our methodology also allowed detection of an inverse correlation of left medial temporal lobe perfusion with the memory score. This had not been found in previous studies and might indicate compensatory mechanisms in the brain of PD patients. It is concluded that episodic memory in nondemented PD patients is most dependent on the effects of aging and that the aging effects on cerebral perfusion in the PD brain parallel to a large extent the findings in normal controls.

Predictors of cognitive impairment in advanced Parkinson's disease

OBJECTIVE

To investigate the cognitive profile of patients with idiopathic Parkinson's disease and to determine the demographic and medical variables that contribute to the cognitive outcome.

DESIGN

Retrospective cohort analysis.

METHODS

100 patients with idiopathic Parkinson's disease were given a neuropsychological test battery investigating attention, memory, and visuospatial and executive functions. Test performance was compared against normative data, and linear regression determined significant predictors of cognitive impairment from a set of demographic and disease course variables.

RESULTS

Frontal-type cognitive dysfunction was widespread in patients with advanced Parkinson's disease. Attention and memory were mildly to moderately impaired, whereas visuospatial function showed only subtle impairment. Older age and tremor at onset were significant predictors of poor cognitive performance.

CONCLUSIONS

The observed cognitive impairment in patients with advanced Parkinson's disease is more than expected for normal aging. Although in apparent contrast with most previous research, reporting a greater risk of cognitive dysfunction in Parkinson's disease patients with predominant akinesia/rigidity, tremor at onset may be a marker for more widespread brain pathology that contributes to an increased risk of cognitive impairment.

Positron emission tomographic study of post-ischaemic-hypoxic amnesia

BACKGROUND

Despite extensive research, it still remains controversial as to what the precise location of the critical lesions underlying amnesia actually is. The amnesic syndrome is believed to be heterogeneous and due to several distinct functional deficits.

PATIENTS AND METHODS

Two patients, a 45-year-old woman and a 56-year-old man, with sudden cardiopulmonary arrest and successful resuscitation, were left with a clear amnesic syndrome as main neurological sequela. During their revalidation period, they underwent a positron emission tomographic (PET) examination, utilizing the (13)NH(3) bolus technique at rest and after intravenous acetazolamide administration.

RESULTS

Both PET studies showed more or less similar features with a decrease in regional cerebral blood flow (rCBF) in the frontal, temporal and parietal lobes. In addition, the rCBF was increased in both thalami of the 45-year-old woman and in the striata of the 56-year-old man. Acetazolamide vasoreactivity was most lost in the frontal lobes.

CONCLUSIONS

In the present PET study, we demonstrated that destruction of the inhibitory pathways to the thalamus and basal ganglia by ischaemic-hypoxic frontal lesions could be one of the mechanisms leading to amnesia.

Dorsal thalamic haemorrhage complicating polyarteritis nodosa: a clinico-pathologic case report

Intracerebral haemorrhage is a rare complication of polyarteritis nodosa (PAN). We present the clinico-pathologic findings of a 62 year-old patient with systemic involvement by PAN, who developed temporary decrease of consciousness and a mild left hemisyndrome due to a small right dorsal thalamic haemorrhage. No clear cause for the haemorrhage was found on postmortem examination.

Vagus nerve stimulation for epilepsy, clinical efficacy of programmed and magnet stimulation

RATIONALE

Vagus nerve stimulation (VNS) by intermittent and programmed electrical stimulation of the left vagus nerve in the neck, has become widely available. It is an effective treatment for patients with refractory epilepsy. Patients can be provided with a magnet that allows to deliver additional stimulation trains. Since earlier studies have demonstrated the persistence of a stimulation effect after discontinuation of the stimulation train, we evaluated the clinical efficacy of VNS both in the programmed intermittent stimulation mode and magnet stimulation mode.

METHODS

A group of 30 patients (16 F, 14 M) with medically refractory partial epilepsy, who were unsuitable candidates for resective surgery, were included in the study. The patients, their companions and caregivers were instructed on how to administer additional stimulation trains using a hand-held magnet when an aura or a seizure onset occurred. Patients or caregivers could recognize habitual seizures and were able to evaluate sudden interruption of these seizures. Using seizure diaries, detailed accounts of magnet use and regular clinic follow-up visits, data on seizure frequency and severity and number of magnet applications were collected. Patients who provided unreliable information were excluded from the analysis.

RESULTS

Forty-seven percent of all patients had an improvement in seizure control with a reduction in seizure frequency of more than 50% during a mean follow-up of 33 months (range: 4-67 months). More than half of the patients used the magnet and provided reliable information. In 63% of patients who were able to self-administer or receive additional magnet stimulation, seizures could be interrupted, be it consistently or occasionally. More than half of the patients who reported a positive effect of magnet stimulation became responders. In most cases the magnet was applied by a caregiver.

CONCLUSIONS

To our knowledge, this study is the first to explore the efficacy of magnet-induced vagus nerve stimulation. Results suggest that the magnet is a useful tool that provides patients and mainly caregivers with an additional means of controlling refractory seizures. Additional controlled studies comparing programmed stimulation and magnet-induced stimulation in monitoring conditions are warranted.

Direct medical costs of refractory epilepsy incurred by three different treatment modalities: a prospective assessment

PURPOSE

More than 20% of epilepsy patients have refractory seizures. Treatment options for these patients include continued polytherapy with/without novel antiepileptic drugs (AEDs), epilepsy surgery (ES), or vagus nerve stimulation (VNS). The purpose of this study was prospectively to compare epilepsy-related direct medical costs (ERDMCs) incurred by these different treatment modalities.

METHODS

Eighty-four patients underwent a complete presurgical evaluation protocol at our institution. As a result, 24 (29%) patients were treated with continued AED polytherapy only; 35 (40%) underwent ES; and 25 (30%) had VNS. In each patient, annual costs in the 2 years preceding the therapeutic decision (ERDMC-pre) and during the follow-up afterward (ERDMC-post) were prospectively calculated. Furthermore, frequency of complex partial seizures with/without secondary generalization (CPS+/-SG), dosage and number of AEDs, number of hospital admission days, clinic visits, and laboratory tests before and after the therapeutic decision also were prospectively assessed. ERDMC-pre and ERDMC-post were compared in and among the three treatment groups.

RESULTS

In patients conservatively treated with AEDs, mean frequency of CPSs decreased from 12 per month to nine per month, whereas mean ERDMCs decreased from $2,525 U.S. to $2,421 U.S. In surgical patients, mean seizure frequency decreased from six to fewer than one per month; mean ERDMCs per year decreased from $1,465 U.S. preoperatively to $1,186 U.S. postoperatively. In the VNS group, mean seizure frequency decreased from 21 per month to seven per month. ERDMCs in this subgroup decreased from $4,826 U.S. to $2,496 U.S. Mean seizure frequency changes were significant when conservatively treated patients were compared with surgically treated and VNS patient groups (chi2 test, p<0.001 and p=0.0019, respectively). ERDMC changes in conservatively treated patients also were statistically significant when compared with surgically treated and VNS patients (chi2 test, p=0.0007 and p=0.0036, respectively). No statistically significant differences were found in ERDMC changes between the surgical and VNS groups (chi2 test, p=0.387).

CONCLUSIONS

Ongoing daily treatment of patients who underwent resective surgery costs significantly less than conservative treatment. For patients in whom resective surgery is not an option, ERDMC show a significant decrease in VNS-treated patients compared with conservatively treated patients.

Cobalt-55 positron emission tomography in vascular dementia: significance of white matter changes

BACKGROUND

Vascular dementia (VaD) is still used as a covering term to indicate the relationship between cerebrovascular disease and the progressive cognitive disorder. The contribution of white matter changes (WMCs), seen with computed tomography (CT) and magnetic resonance imaging (MRI) of the brain, to dementia had not been fully elucidated. Cobalt-55 (55Co) positron emission tomography (PET) allows us to distinguish between recent and old infarcts.

PURPOSE

The present study investigates whether 55Co PET can detect the lesions responsible for the progression of the cognitive disorder in VaD patients.

PATIENTS AND METHODS

20 consecutive patients with a previous history of repeated strokes occurring more than 6 months before and with multiple cortical infarcts, lacunes and WMCs on CT and 5 age-matched controls were investigated with 55Co PET. The stroke patients were divided in two groups: 8 with and 12 without VaD. Average 55Co counts in cerebral cortex, deep gray nuclei and white matter were compared to the value in the cerebellum used as reference.

RESULTS

In the control group, the 55Co uptake was identical in the cerebral cortex and in the cerebellum, but lower in the deep gray nuclei and the cerebral white matter. When comparing the stroke groups with the control, the 55Co uptake was similar for the cerebral cortex and deep gray nuclei, but significantly increased in the cerebral white matter. The 55Co uptake was also more increased in the stroke group with VaD compared to the non-demented group.

CONCLUSION

55Co PET shows that the WMCs are due to the ongoing damage of probably ischaemic origin which is more prominent in stroke patients with progressive cognitive decline.

Programmed and magnet-induced vagus nerve stimulation for refractory epilepsy

Vagus nerve stimulation (VNS) is an effective alternative treatment for patients with refractory epilepsy. The generator produces intermittent stimulation trains and does not require patient intervention. Using currently available technology, continuous stimulation is incompatible with a reasonable battery life. Because earlier studies have demonstrated the persistence of a stimulation effect after discontinuation of the stimulation train, we intended to evaluate the clinical efficacy of VNS in both the programmed intermittent stimulation mode and the magnet stimulation mode. Patients, companions, and caregivers were instructed on how to administer additional stimulation trains when an aura or a seizure onset occurred. We assumed that patients or caregivers could recognize habitual seizures and were able to evaluate sudden interruption of these seizures. During a mean follow-up of 35 months, 46% of patients became responders, with a reduction in seizure frequency of more than 50%. Twenty-nine percent of patients stopped having convulsive seizures. In two thirds of patients who were able to self-administer or receive additional magnet stimulation, seizures could be interrupted consistently or occasionally. More than half of the patients who reported a positive effect of magnet stimulation became responders. Only three patients were able to use the magnet themselves. In most cases, support from caregivers was necessary. This study is the first to document the efficacy of magnet-induced VNS in a larger patient population during long-term follow-up. The magnet is a useful tool that provides patients who are treated with VNS and mainly caregivers of such patients with an additional means of controlling seizures. To further confirm the self-reported results from our patients, additional studies comparing programmed stimulation and magnet-induced stimulation during monitoring conditions are needed.

Vagus nerve stimulation for refractory epilepsy

Vagus nerve stimulation (VNS) is a neurophysiological treatment for patients with medically or surgically refractory epilepsy. Since the first human implant in 1989, more than 10 000 patients have been treated with VNS. Two randomized controlled studies have shown a statistically significant decrease in seizure frequency during a 12-week treatment period versus a baseline period when 'high stimulation' mode was compared with 'low stimulation' mode. The efficacy appears to increase over time. In general, one third of the patients show a >50% reduction of seizure frequency; one third show a 30-50% seizure reduction, and one third of patients show no response. Few patients become seizure-free. Side effects during stimulation are mainly voice alteration, coughing, throat paraesthesia and discomfort. When studied on a long-term basis, VNS is an efficacious, safe and cost-effective treatment not only in adults but also in children and the elderly. The precise mechanism of action remains to be elucidated. In recent years much progress has been made through neurophysiological, neuroanatomical, neurochemical and cerebral blood flow studies in animals and patients treated with VNS. Further elucidation of the mechanism of action of VNS may increase its clinical efficacy and our general understanding of some physiopathological aspects of epilepsy. Finally, VNS may become an alternative treatment for other conditions such as depression and pain.

The mechanism of action of vagus nerve stimulation for refractory epilepsy: the current status

Vagus nerve stimulation (VNS) is a neurophysiologic treatment for patients with medically or surgically refractory epilepsy. Since the first human implant in 1989, more than 10,000 patients have been treated with VNS. The precise mechanism of action remains to be elucidated. Animal experiments with VNS were initially performed to demonstrate efficacy and safety preceding the clinical trials in human patients. Mechanism of action research involving animal experiments can provide essential clues. Animal experiments are often labor-intensive even in the hands of experienced researchers, however, and the results remain only a reflection of the complicated pathophysiologic systems of the human brain. Mechanism of action research in human patients treated with VNS is particularly challenging because of safety concerns, the large number of patients required, and the heterogeneous nature of various small patient series. This study provides an overview of the progress that has been made in the past 10 years through neurophysiologic, neuroanatomic, neurochemical, and cerebral blood flow studies in animals and patients treated with VNS. Further elucidation of the mechanism of action of VNS may increase its clinical efficacy. It may also provide inspiration for the development of new therapeutic modalities for refractory epilepsy.

Parkinsonism in patients with vascular dementia: clinical, computed- and positron emission-tomographic findings

PURPOSE

The present study investigates the vascular nature of parkinsonian features in patients with 'probable' vascular dementia.

PATIENTS AND METHODS

Forty patients with vascular dementia were studied with positron emission tomography (PET) using the steady state technique with (15)O in order to assess regional cerebral blood flow (rCBF), regional oxygen extraction rate (rOER) and regional metabolic rate for oxygen (rCMRO(2)) in different brain regions. The findings in 10 patients with (VaDP) were compared to 30 without parkinsonism (VaD).

RESULTS

The clinical and computed tomographic findings in the parkinsonian patients were similar to those described in the literature as probable vascular parkinsonism. The PET results showed decreased rCBF and rCMRO(2) in the frontal and parietal cortices and in the striatum of the VaDP compared to the VaD group. The decrease of rCBF and rCMRO(2) in frontal and parietal cortices is due to the more severe mental changes in the VaDP group. In the VaDP patients rCBF and rCMRO(2) were more decreased and rOER increased in the striatum contralateral to the most affected parkinsonian side.

CONCLUSION

Our PET findings show that local ischemic changes in the striatum contribute to parkinsonism in vascular dementia patients.