Bilateral paramedian thalamic infarction with hypothalamic dysfunction

Unilateral thalamic lesions cause transient or permanent behavioral, sensory and oculomotor disturbances; bilateral lesions of thalamus result in more severe and longer lasting symptoms. We present an atypical case of bilateral paramedian thalamic infarct with concomitant hypothalamic dysfunction. The only risk factor of ischaemic stroke found in the patient was a short lasting episode of atrial fibrillation. Bilateral paramedian thalamic infarcts may result from occlusion of one paramedian thalamic artery, which arises from the posterior cerebral artery, either with separated or with a common trunk, thus supplying the thalamus bilaterally. Independently of anatomical variants of thalamus blood supply, the most probable cause of infarct in our patient was unilateral or bilateral occlusion of the posterior cerebral artery by cardioembolism, probably in the course of basilar artery occlusion. Hypothalamic dysfunction may accompany thalamic infarcts; thus hypothalamo-pituitary function should be routinely assessed in bithalamic infarcts.     

Bilateral paramedian thalamic infarction: a case with MRI and gamma-emission tomography

A 41-year-old woman presented with a history of sudden onset of a dementia with frontal signs and antero-retrograde amnesia. CT showed a bilateral paramedian thalamic infarct which was confirmed by MRI. The study of regional cerebral blood flow showed a decrease in both frontal regions. Results of imaging suggested lesions of the ventro-oral, latero-polar and intralaminar nuclei as well as of the mammillo-thalamic tract. The dorso-median nucleus appeared to be relatively spared.     

Bilateral thalamic lesions affect recollection- and familiarity-based recognition memory judgments

The contribution of the thalamus to different forms of explicit memory is poorly understood. In the current study, explicit memory performance was examined in a 40-year-old male (RG) with bilateral anterior and medial thalamic lesions. Standardized tests indicated that the patient exhibited more severe recall than recognition deficits and his performance was generally worse for verbal compared to nonverbal memory. Recognition memory tests using the remember-know (R/K) procedure and the confidence-based receiver operating characteristic (ROC) procedure were used to examine recollection-and familiarity-based recognition. These tests revealed that RG had deficits in recollection and smaller, but consistent deficits in familiarity. The results are in agreement with models indicating that the anteromedial thalamus is important for both recollection- and familiarity-based recognition memory.     

Long latency responses in pure sensory stroke due to thalamic infarction

Objectives – Our study was designed to clarify the role of the thalamus in the generation of the electrically elicited long-latency reflexes (LLR) in voluntarily activated hand muscles. Materials and methods – EMG responses of the thenar muscles were evoked by electrical stimulation of the median nerve at the wrist at motor threshold intensity in 10 patients with acute pure sensory stroke due to thalamic infarction. Concomitant recording of somatosensory evoked potentials (SEPs) was performed. The subjects were asked to steadily abduct the thumb at 20–30% of maximal force against a force transducer. Rectified and averaged EMG activities were recorded. Results – The LLR II was missing completely or significantly attenuated in the majority of the patients (9 of 10), of whom 3 also had delayed latency. Abnormal SEPs were documented in 7 patients (7 of 10). In the follow-up, 5 patients had partial reversal of LLR II. LLR II was still pathological in 1 fully recovered patient. Conclusion – Our results further confirm the transcortical generation of LLR II and imply that a thalamic relay is present in the afferent limb of the LLR.     

Bilateral ptosis and changes in state of alertness in thalamic infarction.

Uni- or bilateral supranuclear ptosis is known to be caused by cerebral lesion. The exact anatomical cortical and subcortical basis is still undefined. We report a case of a patient developing bilateral ptosis with a left thalamic lesion. The bilateral ptosis was associated with transient changes in the state of alertness. We postulate that the thalamus, especially the anterior region, may have an influential role on the pathway from the cortex via the posterior branch of the internal capsule to the levator palpebrae superioris nuclei.     

Bilateral medial medullary infarction

We present a case of bilateral medial medullary infarction demonstrated by magnetic resonance imaging (MRI) and review 12 previously reported cases. We classify these 13 cases (including the present case) into two groups according to the extent of the ischemic region: type 1, the ischemic lesion developed from the medullary pyramid to the medial longitudinal fasciculus; type 2, the lesion was confined to the medullary pyramid.A 71 year old man presented with slight disturbance of consciousness, dysarthria, disturbance of leftward gaze, no gag reflex and tetraparesis. He developed nearly complete horizontal ophthalmoplegia. MRI revealed upper medial medullary infarction bilaterally that extended to the pontomedullary junction. We propose that the prognosis of type 2 bilateral medial medullary infarction is better than that of type 1. Furthermore, the prognosis of bilateral medial medullary infarction itself may be better than previously indicated.     

Verbal aggression in Alzheimer's disease. Clinical, functional and neuropsychological correlates

OBJECTIVES: To determine the clinical, functional and neuropsychological correlates of verbal aggression in Alzheimer's disease in a group of consecutive first attendees to a memory clinic. METHODS: 150 people were evaluated and diagnosed as suffering with probable Alzheimer's disease. These people were tested using the Behave-AD for the presence of verbal aggression, delusions, depression and agitation. They were also assessed with cognitive, functional and neuropsychological scales. RESULTS: Twenty-eight per cent of this group of Alzheimer patients had exhibited some verbal aggression in the preceding month. Male gender (p = 0.022), the presence of paranoid and delusional ideation (p = 0.003) and agitation (p = 0.042) were significantly associated with verbal aggression in a stepwise backward logistic regression analysis. CONCLUSION: The presence of verbal aggression should prompt the clinician to search for delusional ideation, which may respond to pharmacotherapy.     

Isolated lateral thalamic infarction: the role of posterior cerebral artery disease

Background and purpose: Lateral thalamic infarction (LTI) is usually caused by small vessel disease (SVD), i.e., occlusion of the deep perforator. However, focal atherosclerotic posterior cerebral artery disease (PCAD) may produce LTI via thrombotic occlusion of the perforator. We aimed to investigate the prevalence of PCAD in LTI and differences in clinical and imaging findings between LTIs associated with PCAD and SVD. Methods: We retrospectively evaluated 58 consecutive patients with isolated LTI who underwent diffusion‐weighted imaging (DWI) and MR angiography (MRA) within 7 days after stroke onset. Patients were divided into two groups: those with PCAD and those with SVD. Clinical syndromes were divided into pure sensory stroke (PSS) and sensory stroke plus (SS‐plus), i.e., the concomitant presence of motor dysfunction or ataxia. Clinical and imaging findings were compared between these two groups. Results: Of the 58 patients, 13 (22.4%) had PCAD. PSS was more frequently associated with SVD than with PCAD (57.8% vs. 23.1%, P = 0.032). Initial DWI lesion volume (cm³) was significantly larger in PCAD than in patients with SVD (0.38 ± 0.13 vs. 0.33 ± 0.22, P = 0.025). Among the 23 patients (39.7%) who underwent follow‐up DWI, patients with PCAD showed a significantly greater increase in subacute lesion volume than those with SVD (P = 0.019). Although National Institutes of Health Stroke Scale scores did not differ at admission (P = 0.185), they were significantly higher at discharge in PCAD than in patients with SVD (P = 0.012). Conclusions: Our data suggest that PCAD is an important cause of LTI, being related to SS‐plus, larger lesion volume, and worse clinical outcomes.     

Projection and innervation patterns of individual thalamic reticular axons in the thalamus of the adult rat: A three-dimensional,graphic, and morphometric analysis

The γ-aminobutyric acid-ergic thalamic reticular nucleus (Rt), which carries matching topographical maps of both the thalamus and cortex and in which constituent cells can synaptically communicate between each other, is the major extrinsic source of thalamic inhibitions and disinhibitions. Whether all the Rt axonal projections into the thalamus are similarly organized and have common projection and innervation patterns are questions of great interest to further our knowledge of the functioning of the Rt. The present study provides architectural and morphometric data of individual, anterogradely labeled axonal arbors that arose from distinct parts of the Rt. One hundred twenty-seven Rt neurons from all regions of Rt were marked juxtacellularly with biocytin or Neurobiotin in urethane-anesthetized adult rats. Eighteen two-dimensional and 14 three-dimensional reconstructions of single tracer-filled Rt neurons were made from serial, frontal, horizontal, or sagittal sections. Both the somatodendritic and axonal fields of tracer-filled Rt cells were mapped in three dimensions and illustrated to provide a complementary stereotaxic reference for future studies. Most marked units projected to a single nucleus of the anterior, dorsal, intralaminar, posterior, or ventral thalamus. Axons emerging from cells in distinct sectors of the Rt projected to distinct nuclei. Within a sector, neurons with separate dendritic fields innervated separate regions either in a single nucleus or into different but functionally related thalamic nuclei. Neurons with an overlap of their dendritic fields gave rise either to overlapping axonal arborizations or, more rarely, to distinct axonal arbors within two different thalamic nuclei implicated in the same function. In rare instances, an Rt axon could project within these two nuclei. Thalamic reticular axons commonly displayed a single well-circumscribed arbor containing a total of about 4,000 ± 1,000 boutons. Every arbor was composed of a dense central core, which encompassed a thalamic volume of 5–63 × 10⁶ μm³ and was made up of patches of maximal innervation density (10 ± 4 boutons/tissue cube of 25 μm each side), surrounded by a sparse component. The metric relationships between the Rt axonal arbors and the dendrites of their target thalamocortical neurons were determined. Both the size and maximal innervation density of the axonal patches were found to fit in with the somatodendritic architecture of the target cells. The Rt axonal projections of adult rats are thus characterized by their (1) well-focused terminal field with a patchy distribution of boutons and (2) parallel organization with a certain degree of divergence. The role of the Rt-mediated thalamic inhibition and disinhibition may be to contrast significant with nonrelevant ongoing thalamocortical information. J. Comp. Neurol. 391:180–203, 1998. © 1998 Wiley-Liss, Inc.     

Metabolic syndrome and three of its components as risk factors for recurrent ischaemic stroke presenting as large-vessel infarction

Background and purpose:  Although a clear protocol for reduction of recurrent ischaemic stroke (RIS) has been established, few studies have compared the stroke subtype distribution and risk factors between RIS and first-ever stroke (FES).
Methods:  This one-year hospital-based study enrolled 587 FES and 475 RIS patients. Patients were categorized into four stroke subtypes according to a modified TOAST stroke subtype classification system. Risk factor profiles were compared between the two major stroke groups and between the corresponding four subtypes to discriminate the significant risk factors for RIS.
Results:  A multivariate regression analysis identified hypertension (OR, 1.87; 95% CI, 1.34–2.62), diabetes mellitus (DM) (OR, 1.57; 95% CI, 1.22–2.02), low high-density lipoprotein (LHDL) (OR, 1.43; 95% CI, 1.08–1.88) and older age as significant RIS risk factors. The significance of the former three RIS factors was further recognized in its large-vessel subtype. Moreover, metabolic syndrome was significantly more common in the recurrent stroke group ( P  = 0.01), including its large-vessel subtype ( P  = 0.04). Progressively increasing odds ratios from 1.49 to 2.02, in accordance with increased number of diagnostic components of metabolic syndrome for recurrent large-vessel ischaemic stroke, were noted.
Conclusions:  Metabolic syndrome likely plays a crucial role in the development of RIS, including large-vessel infarction in modern-day Taiwan.     

A child with mutism after bilateral thalamic infarction

The occurence of mutism after thalamic lesions has rarely been observed before adulthood. We report a 6.5-year-old girl who presented with sudden mutism with a decreased level of alertness. Her MRI revealed a T2-fluid attenuated inversion recovery hyperintensity in both thalami, which suggested bithalamic infarction in the territory of the thalamo-perforating arteries and, more specifically, the para-median territories. Mutism was followed by a deficit of speech initiation with slow and slurred speech. Her speech returned to normal at 3 months after the onset of symptoms. Thus mutism could be the equivalent of akinetic mutism limited to the speech sphere.     

Late-onset thermal hypersensitivity after focal ischemic thalamic infarcts as a model for central post-stroke pain in rats

Central post-stroke pain (CPSP) is a neuropathic pain syndrome that often develops in a delayed manner after thalamic stroke. Here, we describe a new model of CPSP by stereotaxic thalamic injection of endothelin-1. Stroke rats (n=12), but not saline-injected controls (n=12), developed a progressive, contralateral cutaneous thermal hyperalgesia over 4 weeks, without motor deficits. Lesions were highly focal and mainly affected the ventral posterior thalamic complex. Tchis model reproduces the infarct location and delayed hypersensitivity typical of CPSP, and may be useful to investigate its pathophysiology and test therapies targeting recovery and pain after thalamic stroke.     

Cingulate cortical and anterior thalamic neuronal correlates of the overtraining reversal effect in rabbits

Multiple-unit activity of the cingulate cortex and the anteroventral (AV) nucleus of the thalamus in rabbits was recorded during reversal training, following differential conditioning of a locomotory (wheel rotation) avoidance response. The CS+ and CS? were pure tones (1 or 8 kHz) and the UCS was a footshock delivered through the grid floor of the wheel. One group of the rabbits received original training to a criterion followed immediately by reversal training. A second group received training to criterion followed by additional training sessions (overtraining), prior to reversal training. The results indicated that the overtraining reversal effect (ORE) occurred. That is, the overtrained subjects acquired the reverse discrimination in significantly fewer sessions than the non-overtrained subjects. The overall (non-discriminative) neuronal reactivity in all cingulate cortical laminae was reduced by overtraining, whereas the overall reactivity of the AV thalamus was enhanced. In addition, the non-overtrained subjects manifested a discriminative neuronal response appropriate to the original task (i.e. a greater response to the CS? than to the CS+ for reversal training), throughout the precriterial sessions of reversal training. This persistent ‘original habit effect’ occurred only at brief latencies (20–30 msec) after CS onset, and only in the deep cortical laminae (V–VI). The neuronal activity of the superficial laminae (I–IV) in non-overtrained subjects underwent a transition, in parallel with the behavior, from a discriminative response appropriate to the original task to one appropriate to the reversal task. No significant training-related changes were seen at any cortical depth in the overtrained subjects. Presentation of non-contingent footshocks during two sessions of reversal training following criterion re-enhanced the overall reactivity and the brief-latency discriminative neuronal response appropriate to the original task, which had undergone decline during reversal training, in the deep cortical laminae of the non-overtrained subjects. The enhanced overall reactivity and the discriminative activity in the superficial laminae of non-overtrained subjects had not declined during reversal training and were not altered by the non-contingent footshocks. The implications of these data are discussed in regard to the neural causation of the ORE.     

The reticular thalamic nucleus (RTN) of the rat: cytoarchitectural, Golgi, immunocytochemical, and horseradish peroxidase study.

Experiments have been performed on adult albino rats in order to study the cellular organization of the thalamic reticular nucleus. For this purpose four approaches have been used: Nissl stain, Golgi impregnation, retrograde transport of horseradish peroxidase after injection in different thalamic nuclei, and immunocytochemistry with antibodies against GABA and glutamic acid decarboxylase. In sections through the horizontal plane, three morphologically different neurons have been observed. Cells with round perikarya and with multipolar dendrites were found predominantly in the rostral pole of the nucleus. Neurons with large fusiform cell body and with dendrites arborizing mainly on the horizontal plane were detected through the whole extent of the nucleus. Small fusiform neurons were observed almost exclusively in the medial third of the dorso-ventral extent of the nucleus. The Golgi impregnation method demonstrated that dendrites of small fusiform neurons develop in the vertical plane perpendicular to the dendritic arborization of large fusiform neurons. In coronal sections neurons with round perikarya and with large fusiform cell bodies are detectable while small fusiform neurons are only rarely visible. These data have been confirmed by statistical form factor analysis. Moreover, by means of the horseradish peroxidase and the immunocytochemical study, it has been confirmed that all three groups of neurons project within the thalamus and that they are GABAergic. The data concerning the distribution within the nucleus of the three morphologically different neurons are discussed in relation to the topographic distribution of cortical sensory afferents and to the topographic maps within different sectors of the reticular nucleus.     

Basal ganglia ischaemic infarction after thrombectomy: cognitive impairment at acute stage

Background and purpose

After successful mechanical thrombectomy for middle cerebral artery occlusion, basal ganglia infarction is commonly detectable. Whilst the functional outcome of these patients is often good, less knowledge is available about the cognitive outcome. The aim of our study was to assess the presence of cognitive impairment within 1 week after thrombectomy.

Methods

In all, 43 subjects underwent a general cognitive assessment using the Montreal Cognitive Assessment and an extensive battery of tests. Patients were classified as cognitively impaired (CImp) or not (noCImp) according to a Montreal Cognitive Assessment score below 18.

Results

Cognitively impaired and noCImp subjects did not differ either in their National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) at admittance, or in their Fazekas score and Alberta Stroke Program Early Computed Tomography Score. At discharge, CImp subjects showed higher scores than noCImp subjects on NIHSS (p = 0.002) and mRS (p < 0.001). The percentage of pathological performances on each neuropsychological test in the whole sample and in CImp and noCImp patients shows a similar cognitive profile between the groups.

Conclusions

Some patients who underwent thrombectomy experienced a detectable cognitive impairment that probably led to worse NIHSS and mRS. The neuropsychological profile of such cognitive impairment at the acute stage consists of wide deficits in numerous cognitive domains, suggesting that basal ganglia damage may lead to complex functional impairments.     

Efficacy and safety of ginsenoside-Rd for acute ischaemic stroke: a randomized, double-blind, placebo-controlled, phase II multicenter trial

Background and purpose:  Ginsenoside-Rd is a selective competitive Ca²⁺ receptor antagonist. A phase II randomized, double-blind, placebo-controlled, multicenter study was conducted to examine the efficacy and safety of ginsenoside-Rd in patients with acute ischaemic stroke.
Methods:  A total of 199 patients were randomized equally to receive a 14-day infusion of placebo (group B), ginsenoside-Rd 10 mg (group A) or ginsenoside-Rd 20 mg (group C). Primary end-points were National Institutes of Health Stroke Scale (NIHSS) scores at 15 days. Secondary end-points were NIHSS scores and the Barthel Index at 8 days, the Barthel Index and the modified Rankin scale at 15 days and 90 days. The safety end-points included serious and non-serious adverse events, laboratory values and vital signs. Analysis was by intention to treat.
Results:  For the primary study outcome, there is significant difference amongst the three groups at 15 days in NIHSS scores ( P  = 0.0003). Comparing group A with B and group B with C, the difference in the mean for NIHSS was significant in statistics ( P  = 0.0004, P  = 0.0009 respectively). This is no significant difference between group A and C ( P  = 0.9640). For the secondary study outcome, ginsenoside-Rd did not improve neurological functioning. Incidence of serious and non-serious adverse events was similar amongst the three groups.
Conclusions:  Ginsenoside-Rd may be of some benefit in acute ischaemic stroke.     

Cortical,thalamic, and amygdaloid connections of the anterior and posterior insular cortices

Cortical, thalamic, and amygdaloid projections of the rat anterior and posterior insular cortices were examined using the anterograde transport of biocytin. Granular and dysgranular posterior insular areas between bregma and 2 mm anterior to bregma projected to the gustatory thalamic nucleus. Granular cortex projected to the subjacent dysgranular cortex which in turn projected to the agranular (all layers) and granular cortices (layers I and VI). Both granular and dysgranular posterior areas projected heavily to the dysgranular anterior insular cortex. Agranular posterior insular cortex projected to medial mediodorsal nucleus, agranular anterior insular and infralimbic cortices as well as granular and dysgranular posterior insula. No projections to the amygdala were observed from posterior granular cortex, although dysgranular cortex projected to the lateral central nucleus, dorsolateral lateral nucleus, and posterior basolateral nucleus. Agranular projections were similar, although they included medial and lateral central nucleus and the ventral lateral nucleus. Dysgranular anterior insular cortex projected to lateral agranular frontal cortex and granular and dysgranular posterior insular regions. Agranular anterior insular cortex projected to the dysgranular anterior and prelimbic cortices. Anterior insuloamygdaloid projections targeted the rostral lateral and anterior basolateral nuclei with sparse projections to the rostral central nucleus. The data suggest that the anterior insula is an interface between the posterior insular cortex and motor cortex and is connected with motor-related amygdala regions. Amygdaloid projections from the posterior insular cortex appear to be organized in a feedforward parallel fashion targeting all levels of the intraamygdaloid connections linking the lateral, basolateral, and central nuclei . J. Comp. Neurol. 399:440–468, 1998. © 1998 Wiley-Liss, Inc.     

Diaschisis after thalamic stroke: a comparison of metabolic and structural changes in a patient with amnesic syndrome

Introduction –  We present a patient with a left anteromedial thalamic lesion with an amnesic syndrome. The patient underwent neuropsychological testing, cerebrospinal fluid (CSF) analyses, magnetic resonance imaging (MRI) [T2, flair, and diffusion tensor imaging (DTI)] and [18F]-2-fluoro-deoxy- d -glucose positron emission tomography (FDG-PET) to assess indirect effects of thalamic lesions on cortical function.
Case report –  A 67-year-old right-handed woman was admitted to a university-based memory unit because of memory and concentration problems. Neuropsychological testing revealed dysfunction of episodic memory, semantic memory and working memory. General intellectual function and attention capacity were preserved. MRI revealed an anteromedial thalamic lesion in the left hemisphere. FDG-PET showed decreased uptake in the frontal, parietal and temporal lobes of the left hemisphere. Regions of interest (ROI) in white matter were selected and left and right hemispheres were compared. Fractional anisotropy (FA) in ROI representing thalamo-cortical connections were decreased in the left hemisphere when compared with the right.
Conclusion –  The results show the importance of a network that include the anterior and dorsomedian nuclei, which influence the activity in areas of the cortex responsible for memory processes. The imaging findings suggest that areas of cortical diaschisis after thalamic infarction correspond to areas affected by thalamo-cortical fibre loss as measured with FA.