Thalamic Lesions and Aphasia or Neglect.

PURPOSE OF REVIEW: When the thalamus is damaged, not only are there neurological symptoms such as sensory impairment, hemianopia, or motor control disorders, but there are also various neuropsychological symptoms. We discuss the basic anatomy and function of the thalamus followed by a discussion of thalamic aphasia and hemineglect. RECENT FINDINGS: Subcortical lesions in patients with hemineglect involved the anatomical network directly linked to the superior temporal gyrus. Furthermore, the pulvinar, part of the thalamus, may be associated with hemineglect. General linguistic tasks activated the thalami, depending on the difficulty, as well as the frontal and temporal lobes. The thalamus may play a role in language and be involved in the activation of cortical language areas, and in the linguistic integration function via verbal memory and semantic mechanisms. Thalamic lesions are associated with aphasia and hemineglect. It is possible the mechanisms and such neuropsychological may be different depending on the size and site of the thalamic lesion.

Lucid dreams, an atypical sleep disturbance in anterior and mediodorsal thalamic strokes.

BACKGROUND: Cognitive, affective, and behavioural disturbances are commonly reported following thalamic strokes. Conversely, sleep disorders are rarely reported in this context. OBSERVATIONS: Herein, we report the cases of two young patients admitted for an ischemic stroke located in the territories of the left pre-mammillary and paramedian arteries. Together with aphasia, memory complaint, impaired attention and executive functions, they reported lucid dreams with catastrophic content or conflicting situations. CONCLUSION: Lucid dreams are an atypical presentation in thalamic strokes. These cases enlarge the clinical spectrum of sleep-wake disturbances potentially observed after an acute cerebrovascular event.

Neonatal thalamic hemorrhage is strongly associated with electrical status epilepticus in slow wave sleep.

PURPOSE: Thalamic hemorrhage has been associated with neonatal cerebral sinovenous thrombosis (CSVT), especially when the straight sinus is involved, and often presents with neonatal seizures. Early thalamic injury has previously been shown to predispose to epilepsy and electrical status epilepticus in slow wave sleep (ESES). The objective of this study was to assess the prevalence of sleep-induced epileptic electroencephalography (EEG) abnormalities and postneonatal epilepsy after neonatal thalamic hemorrhage associated with CSVT, in the absence of more widespread cerebral damage. METHODS: Between 2003 and 2008 15 neonates were diagnosed with a thalamic hemorrhage due to suspected or proven CSVT. Neurodevelopment and the history of seizures were assessed at follow-up in the outpatient clinic in all 14 survivors (age 2-9 years). Whole-night or sleep-deprived EEG recordings were obtained to assess the prevalence of interictal epileptiform activity (EA) and calculate a sleep-induced spike and wave index (SWI). KEY FINDINGS: Three children were diagnosed with classic ESES (SWI >85%). Two children had ESES spectrum disorder (SWI between 50% and 85%), and in two children significant sleep-induced epileptiform activity (SIEA) was noted (SWI between 25% and 50%). Two other children were diagnosed with focal epilepsy, in the absence of sleep-induced epileptiform EEG abnormalities. Five children (age 2-7 years) had normal EEG recordings at follow-up. Deficits in neurodevelopment were seen significantly more often in children with ESES, ESES spectrum, or SIEA. SIGNIFICANCE: Neonates with thalamic hemorrhage associated with straight sinus thrombosis, without evidence of more widespread cerebral damage, are at high risk of developing ESES (spectrum) disorder (35%), SIEA (14%), or focal epilepsy (14%). Electrographic abnormalities may already be present prior to recognition of cognitive deficits. Early diagnosis may guide parents and caregivers, and subsequent treatment may improve neurodevelopmental outcome. Routine annual sleep EEG recordings in children with neonatal thalamic injury following CSVT may improve recognition of ESES.

When solving 22-7 is much more difficult than 99-12.

We describe the case of a 69-year-old professor of mathematics (GV) who was examined 2 years after left-hemispheric capsular-thalamic haemorrhage. GV showed disproportionate impairment in subtractions requiring borrowing (22 - 7). For large subtraction problems without borrowing (99 - 12) performance was almost flawless. Subtractions with borrowing mostly relied on inadequate attempts to invert subtractions into the corresponding additions (22 - 7 = x as 7 + x = 22). The hypothesis is advanced that difficulty in the inhibitory components of attention tasks (Stroop test, go-no-go task) might be the responsible factor of his calculation impairment. A deficit in subtractions with borrowing might be related to left-hemispheric damage involving thalamo-cortical connections.

Schizophrenia-like psychosis associated with right lacunar thalamic infarct.

Thalamic dysfunction has been associated with schizophrenia and other psychotic disorders. We describe an adult patient with a lacunar infarct in the posterior region of the right thalamus exhibiting a paranoid schizophrenia-like psychosis as the only clinical manifestation. Neuropsychological assessment showed alterations in visuospatial memory and executive functions at follow up. This case highlights the role of information processing by the thalamus in the development of delusions. We suggest that dysfunction of the right mediodorsal and pulvinar thalamic nuclei disrupts both thalamic sensory processing and thalamo-prefrontal circuits mediating belief evaluation, leading to delusional beliefs.

The effect of thalamic hemorrhage on the fornix.

OBJECTIVES: The fornix is indirectly connected to the anterior thalamus via the mamilothalamic tract. There has been no diffusion tensor tractography (DTT) study on the effect of thalamic hemorrhage on the fornix. Using DTT, we attempted to investigate the effect of thalamic hemorrhage on the fornix in patients with thalamic hemorrhage. SUBJECTS AND METHODS: Twenty-one consecutive patients with thalamic hemorrhage and 21 age-matched normal healthy control subjects were recruited. DTT data were acquired at an average of 21 days after onset. We measured fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the three parts of the fornix (column, body, and crus) respectively. RESULTS: FA values of the affected and unaffected hemispheres in the patient group were lower than those of the control group in all three parts of the fornix (p < .05). By contrast, compared with the control group, the ADC value was found to be increased only in the body (p < .05). CONCLUSIONS: According to our results, the FA value decrement with increased or normal ADC value in the patient group seems to indicate neuronal loss in the fornix, which appeared to be ascribed to secondary degeneration following thalamic hemorrhage.

Combining shape and connectivity analysis: an MRI study of thalamic degeneration in Alzheimer's disease.

Alzheimer's disease (AD) is associated with neuronal loss not only in the hippocampus and amygdala but also in the thalamus. Anterodorsal, centromedial, and pulvinar nuclei are the main sites of degeneration in AD. Here we combined shape analysis and diffusion tensor imaging (DTI) tractography to study degeneration in AD in the thalamus and its connections. Structural and diffusion tensor MRI scans were obtained from 16 AD patients and 22 demographically similar healthy volunteers. The thalamus, hippocampus, and amygdala were automatically segmented using our locally developed algorithm, and group comparisons were carried out for each surface vertex. We also employed probabilistic diffusion tractography to obtain connectivity measures between individual thalamic voxels and hippocampus/amygdala voxels and to segment the internal medullary lamina (IML). Shape analysis showed significant bilateral regional atrophy in the dorsal-medial part of the thalamus in AD patients compared to controls. Probabilistic tractography demonstrated that these regions are mainly connected with the hippocampus, temporal, and prefrontal cortex. Intrathalamic FA comparisons showed reductions in the anterodorsal region of thalamus. Intrathalamic tractography from this region revealed that the IML was significantly smaller in AD patients than in controls. We suggest that these changes can be attributed to the degeneration of the anterodorsal and intralaminar nuclei, respectively. In addition, based on previous neuropathological reports, ventral and dorsal-medial shape change in the thalamus in AD patients is likely to be driven by IML atrophy. This combined shape and connectivity analysis provides MRI evidence of regional thalamic degeneration in AD.

[Neuropsychological disturbances in thalamic hemorrhage--clinical study]. / Tulburari neuropsihologice în hemoragia talamica. Studiu clinic.

UNLABELLED: Neuropsychological disturbances are frequently associated with hemorrhagic stroke of the thalamus. MATERIAL AND METHOD: We present our personal findings on 117 patients admitted in the Ist Neurological Clinic, lasi with hemorrhagic stroke of the thalamus. RESULTS: Transcortical aphasia for the left-sided strokes and anosognosia or hemi-neglect were among the most prominent clinical features, especially for large thalamic hemorrhage. Visual or tactile extinction, memory disturbances, agitation and hallucinosis were also exhibited in various proportions.

Neuropsychological deficits after bithalamic hemorrhages.

Strategic lesions of the thalamus interfere with cognitive functions and produce complex neuropsychological symptoms. Bilateral, simultaneous thalamic hemorrhages are unusual causes of thalamic dementia. We present clinical, neuropsychological and structural neuroimaging data of a 12-month follow-up period of a patient with bilateral thalamic hemorrhages. After the operation of pancreatitis acuta hemorrhagico-necroticans, the patient developed coma. Computed tomography (CT) and magnetic resonance (MR) of the brain showed medially situated bithalamic hematomas. During the follow-up period, patient's level of consciousness has improved. Moderate dementia (MMSE 20/30) was found with severe temporal and spatial disorientation. Neuropsychological tests showed that attention and concentration were prominently impaired; there were severe verbal and less prominent, visual memory deficits, with anterograde and retrograde amnesia, accompanied by confabulations. Loss of cognitive flexibility and dysexecutive syndrome were also demonstrated. Dynamic apraxia, visual organization and visual construction deficit and impairment of categorial and phonemic fluency were noted. Language was only moderately impaired (anomia). A year later, neuropsychological profile was similar with moderate improvement of retrograde amnesia, whereas anterograde deficits persisted. Neuropsychological syndrome in our patient with bilateral thalamic hemorrhages was characteristic for subcortico-cortical cognitive deficit and was caused by disruption of the cortico-thalamic circuitry.

Dysexecutive syndrome following anterior thalamic ischemia in the dominant hemisphere.

In the article, we describe a rare case: a 52-year-old male patient with an isolated lesion of the anterior thalamic nuclei in the dominant hemisphere due to an ischemic stroke. The patient's syndrome of disordered verbal fluency, working memory, learning and executive functions is seen as a part of a lesion in the dorsolateral complex circuit. During the following 6 months, we observed significant improvement in visual learning, recent memory and categorisation of subjects, while verbal learning and visuospatial planning remained insufficient. In this context, the preservation of thalamic structures in different types of cognitive deterioration is discussed.

Hypersexuality and dysexecutive syndrome after a thalamic infarct.

Hypersexuality can result from insults to several neuroanatomical structures that regulate sexual behavior. A case is presented of an adult male with a thalamic infarct resulting in a paramedian thalamic syndrome, consisting of hypersomnolence, confabulatory anterograde amnesia (including reduplicative paramnesia), vertical gaze deficits, and hypophonic speech. A dysexecutive syndrome also manifested, consisting of social disinhibition, apathy, witzelsucht, motor inhibition deficits, and environmental dependence. Hypersexuality uncharacteristic of his premorbid behavior was evident in instances of exhibitionism, public masturbation, and verbal sexual obscenities. In contrast to the few previous reports of hypersexuality following thalamic infarct, this case neither involved mania nor hemichorea. The relevance of the mediodorsal thalamic nucleus in limbic and prefrontal circuits is discussed.

Language disorder in a child with early left thalamic lesion.

In this paper we present the case of a child with early left thalamic vascular damage who subsequently developed a language disorder. At 3 years and 8 months, her language was poor and unintelligible and showed phonetic, phonological and morpho-syntactic disorders. She did not exhibit any signs of mental retardation. After specific speech therapy, she improved in all linguistic skills. Given the lack of reports on thalamic lesions in children, this paper describes the effect of a thalamic injury in the earliest phases of language acquisition in a child who showed consistent phonological disorders. This case seems to confirm early hemispheric specialisation and the importance of a timely therapy.

Development of selective verbal memory impairment secondary to a left thalamic infarct: a longitudinal case study.

A 68 year old man suffered an acute dysphasic episode with persistent memory disturbance while taking part as a control in a longitudinal magnetic resonance imaging (MRI) study. A small new left thalamic infarct involving the mamillo-thalamic tract could be demonstrated on volumetric MRI, coinciding with the development of a selective verbal memory impairment. This suggests that lateralisation of cognitive processing of visual and verbal material exists at the thalamic as well as the cortical level. High resolution volumetric MRI may be helpful in demonstrating small subcortical infarcts that may not be seen using computed tomography or conventional MRI.