Subcortical aphasia from a thalamic abscess

Navigating the Complexity of Thalamic Abscess: A Systematic Review of Case Studies and Evidence-Based Management

Thalamic abscesses are rare, life-threatening conditions and represent only a few percent of the total cases of brain abscesses. Due to their deep location and critical involvement of sensory and motor pathways, they remain one of the most challenging entities to diagnose and manage. Despite advances in neuro-imaging and neurosurgical techniques, thalamic abscess continues to be a challenge or question in clinical practice regarding optimum treatment modality. Given the nature of the description, a systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Case reports were retrieved after extensive searches in PubMed and Scopus with specified inclusion criteria: isolated thalamic abscesses that needed surgical interventions. The reporting quality was assessed according to CARE (CAse REports) guidelines, while data on clinical presentation and diagnostic approach were extracted. Thirty-three cases with the diagnosis of thalamic abscess were reviewed. The most common presentations included headache, hemiparesis, and altered sensorium. CT and MRI were the common diagnostic tools for these patients; stereotactic aspiration was the most common surgical intervention performed. Streptococcus species were the most common causative organisms. At follow-up, the majority of patients had a good outcome with complete or near-complete recovery. There were rare complications, such as hydrocephalus and recurrence, and mortality was low. Thalamic abscesses are infrequent but have a good prognosis in case of appropriate diagnosis and treatment with stereotactic aspiration and appropriate antibiotic therapy. The present systematic review points out the need for adopting an individual approach to treatment and for further studies that could provide better information on diagnostic and therapeutic strategies regarding this severe disease.

Cognitive and everyday functioning after bacterial brain abscess: a prospective study of functional recovery from 8 weeks to 1 year post-treatment

OBJECTIVE

A bacterial brain abscess may damage surrounding brain tissue by mass effect, inflammatory processes, and bacterial toxins. The aim of this study was to examine cognitive and functional outcomes at 8 weeks and 1 year following acute treatment.

METHODS

Prospective study of 20 patients with bacterial brain abscess (aged 17-73 years; 45% females) with neuropsychological assessment at 8 weeks and 1 year post-treatment. Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A) and Patient Competence Rating Scale (PCRS) were used to assess everyday functioning and administered to patients and informants.

RESULTS

Cognitive impairment was found in 30% of patients at 8 weeks and 22% at 1 year. Significant improvements were seen on tests of perceptual reasoning, attention, verbal fluency, and motor abilities (p < 0.05). At 1 year, 45% had returned to full-time employment. Nevertheless, patients and their informants obtained scores within the normal range on measures of everyday functioning (PCRS and BRIEF-A) at 8 weeks and 1 year. No significant improvements on these measures emerged over time.

CONCLUSION

Residual long-term cognitive impairment and diminished work ability affected 22% and 45% of patients one year after BA. Persistent cognitive impairment emphasizes the importance of prompt acute treatment and cognitive rehabilitation.

Thalamic bacterial abscess presenting with hemiparesis and expressive aphasia

Brain abscesses are relative rare in the developing world, with an incidence of 2% of all space occupying lesions. Deep-seated abscesses such as thalamic and basal ganglia abscesses are much rarer than abscesses in other locations of the brain, comprising 1.3-6% of all brain abscesses. These abscesses may present with hemiparesis, and subcortical aphasia has only been reported in a few cases throughout the literature. Here we present and discuss a case of thalamic brain abscess caused by S. anginosus that presented with subcortical aphasia.

Streptococcus pneumoniae meningoencephalitis with bilateral basal ganglia necrosis: an unusual complication due to vasculitis

Streptococcus pneumoniae (S pneumoniae) is a common cause of bacterial meningitis, frequently leading to death or severe neurological impairment. We report an exceptional case of a 4-month-old boy with meningitis caused by S pneumoniae. Computed tomography (CT) and magnetic resonance imaging (MRI) examinations of the brain showed bilateral symmetrical necrosis involving the lentiform and caudate nuclei, as well as the thalamus. T1-weighted MR images showed patchy areas of increased signal intensity, consistent with hemorrhagic transformation of the lesions. Autopsy revealed widespread necrosis of the basal ganglia with clear signs of vasculitis. Severe complications of S pneumoniae meningoencephalitis are known in infants but to our knowledge, such lesions in the basal ganglia have only been reported thrice in adults and never in children.

Transient Broca's aphasia as feature of an extradural abscess

Diagnosis of extradural abscesses can be difficult and is often delayed. The case is presented of a 13-year-old girl who was afebrile and had episodes of expressive aphasia, with maintenance of awareness and understanding, lasting for 2-3 minutes and with normal neurologic examination in between. She was found to have a left frontal extradural abscess overlying the region of Broca's area (Brodmann area 44/45) on magnetic resonance imaging. An electroencephalogram showed continuous delta activity in the left frontotemporal region. She made a full recovery after surgical evacuation of pus, which upon culture grew Streptococcus milleri. The possible cause of transient aphasia in this condition is pressure-induced or inflammatory mediator-induced ischemia, with or without associated focal seizures.

Aphasia following striatocapsular infarction may be explained by concomitant small cortical infarct on diffusion-weighted imaging

BACKGROUND

The underlying mechanism of aphasia following striatocapsular infarction (SCI) remains controversial. We hypothesized that aphasia resulting from SCI might be associated with concomitant cortical lesions, which can be demonstrated by diffusion-weighted imaging (DWI).

METHODS

We analyzed 24 patients with left SCI who underwent DWI and MR angiography within 2 days after the onset. Aphasia was assessed by the modified Korean version of the Boston Diagnostic Aphasia Examination test.

RESULTS

DWI showed the presence of additional ischemic lesions involving the cortical areas in 13 of 24 SCI patients (54%). Ten patients (42%) showed aphasia. All 10 patients with aphasia had cortical lesions in addition to SCI (p = 0.0002), whereas 21% (3/14) of the nonaphasic patients had additional cortical lesions. Conventional MRI did not reveal the presence of corresponding acute cortical lesions in any of the aphasic patients. There was no difference between the patients with and without aphasia in terms of their stroke etiology.

CONCLUSIONS

Our data suggest that aphasia due to SCI in the acute stage may be attributed to direct cortical injury, whose presence can be demonstrated by DWI, even though it might be invisible on conventional imaging.

Subcortical aphasia: three different language disorder syndromes?

The study analyses clinical presentation of language functions of 32 patients with subcortical aphasia induced by stroke. The patients have been divided into three groups according to neuroanatomic localization of the lesion, defined by CT and MRI examination (striato-capsular aphasia, aphasia associated with white matter paraventricular lesions and thalamic aphasia). The following batteries and tests were used: the neurologic examination, CT scan, MRI, Doppler ultrasound, Mini Mental State Examination, Boston Diagnostic Aphasia Examination (BDAE), Boston Naming Test (BNT), Token Test and Verbal Fluency Test. Clinical presentation of subcortical aphasias is characterized with preserved repetition, however, some groups differ by certain specific features of language impairment. Striato-capsular aphasia and aphasia associated with white matter paraventricular lesions are characterized with lack of speech fluency, occurrence of literary paraphasias, mainly preserved comprehension and naming. Thalamic aphasia, however, is characterized with fluent output, impaired comprehension and naming with predominant verbal paraphasias. The specific features of language impairment suggest that subcortical structures contribute to language organization. Considering the results of language tests we presume that the most prominent feature in striato-capsular aphasia is phonetic impairment of language, opposite to thalamic aphasia where lexical-sematic processing seems to be affected.

Subcortical aphasia and neglect in acute stroke: the role of cortical hypoperfusion

We have hypothesized that most cases of aphasia or hemispatial neglect due to acute, subcortical infarct can be accounted for by concurrent cortical hypoperfusion. To test this hypothesis, we demonstrate: (i) that pure subcortical infarctions are associated with cortical hypoperfusion in subjects with aphasia/neglect; (ii) that reversal of cortical hypoperfusion is associated with resolution of the aphasia; and (iii) that aphasia/neglect strongly predicts cortical ischaemia and/or hypoperfusion. We prospectively evaluated a consecutive series of 115 patients who presented within 24 h of onset or progression of stroke symptoms, with MRI sequences including diffusion weighted imaging (DWI) and perfusion weighted imaging (PWI), and detailed testing for aphasia or hemispatial neglect. The association between aphasia or neglect and cortical infarct (or dense ischaemia) on DWI and cortical hypoperfusion indicated by PWI, was evaluated with chi-squared analyses. Fisher exact tests were used for analyses with small samples. Cases of DWI lesion restricted to subcortical white matter and/or grey matter structures (n = 44) were examined for the presence of aphasia or neglect, and for the presence of cortical hypoperfusion. In addition, subjects who received intervention to restore perfusion were evaluated with DWI, PWI, and cognitive tests before and after intervention. Finally, the positive predictive value of the cognitive deficits for identifying cortical abnormalities on DWI and PWI were calculated from all patients. Of the subjects with only subcortical lesions on DWI in this study (n = 44), all those who had aphasia or neglect showed concurrent cortical hypoperfusion. Among the patients who received intervention that successfully restored cortical perfusion, 100% (six out of six) showed immediate resolution of aphasia. In the 115 patients, aphasia and neglect were much more strongly associated with cortical hypoperfusion (chi(2) = 57.3 for aphasia; chi(2) = 28.7 for neglect; d.f. = 1; P < 0.000001 for each), than with cortical infarct/ischaemia on DWI (chi(2) = 8.5 for aphasia; chi(2) = 9.7 for neglect; d.f. = 1; P < 0.005 for each). Aphasia showed a much higher positive predictive value for cortical abnormality on PWI (95%) than on DWI (62%), as did neglect (100% positive predictive value for PWI versus 74% for DWI). From these data we conclude that aphasia and neglect due to acute subcortical stroke can be largely explained by cortical hypoperfusion.

MR perfusion imaging reveals regions of hypoperfusion associated with aphasia and neglect

OBJECTIVE

To evaluate diffusion-weighted imaging (DWI) and MR perfusion imaging (MRPI) as tools for identifying regions of infarct and hypoperfusion associated with aphasia and neglect in hyperacute stroke. Secondary goal: to establish a functional correlate of a radiologically defined "ischemic penumbra."

METHODS

Forty subjects underwent DWI, MRPI, and standardized tests for lexical deficits or hemispatial neglect within 24 hours of stroke onset or progression. Ten patients had repeat DWI, MRPI, and cognitive testing after 3 days (in some cases after reperfusion therapy). Pearson correlations between error rate on cognitive testing and volume of abnormality on DWI versus MRPI were determined at each time period, and regions of hypoperfusion corresponding to specific cognitive deficits were identified.

RESULTS

Error rate was more strongly correlated with volume of hypoperfused tissue on MRPI (r = 0.65 to 0.93; p < 0.01 to p < 0.0003) than with volume of lesion on DWI (r = 0.54 to 0.75; p = 0.14 to p < 0.01) for dominant and nondominant hemisphere stroke, at each time point. Forty-eight percent of aphasic patients and 67% of those with hemispatial neglect had either no infarct or only small subcortical infarct on DWI, but had focal cortical hypoperfusion. Patients who had successful reperfusion therapy showed resolution of the hypoperfused territory beyond the infarction on repeat MRPI and showed resolution of corresponding deficits.

CONCLUSIONS

MRPI shows regions of hypoperfused cortex associated with lexical deficits or hemispatial neglect, even when DWI shows no infarct or only small subcortical infarct. MRPI-DWI mismatch indicates regions of functionally salvageable tissue.

Loss of psychic self-activation after paramedian bithalamic infarction

BACKGROUND AND PURPOSE

Loss of psychic self-activation has been described after bilateral lesions to the globus pallidus, striatum, and white matter of the frontal lobes, but it is a very rare sign of bithalamic lesions. The exact functional-anatomic mechanism underlying loss of psychic self-activation following bithalamic lesions remains to be elucidated.

CASE DESCRIPTION

We present clinical, neuropsychological, structural, and functional neuroimaging data of an 18-month follow-up period of a man with prominent loss of psychic self-activation after coronary arteriography. Except for memory decline, accompanying symptoms remained restricted to the acute phase. The neurobehavioral syndrome consisted mainly of apathy, indifference, poor motivation, and flattened affect, and this remained unchanged during the entire follow-up period. MRI showed a bithalamic infarction involving the nucleus medialis thalami bilaterally. Single-photon emission CT revealed a severe relative hypoperfusion of both thalami, a relative hypoperfusion of both nuclei caudati, and a relative hypoperfusion mesiofrontally.

CONCLUSIONS

Single-photon emission CT data support the hypothesis that the neurobehavioral manifestations after bithalamic paramedian infarction are caused by disruption of the striatal-ventral pallidal-thalamic-frontomesial limbic loop. Probably, bilateral disruption at different levels of the striatal-ventral pallidal-thalamic-frontomesial loop may lead to a similar clinical picture consisting of loss of psychic self-activation.

Global aphasia due to thalamic hemorrhage: a case report and review of the literature

A 55-year-old patient was admitted with weakness in the right extremities and with significant language deficits. Both computed tomography (CT) and positron-emission tomography (PET) using 2-fluoro-2-deoxy-D-glucose were done within 1 month and repeated at 10 months after onset. Language evaluation was done using parts of the Western Aphasia Battery (WAB) and the Boston Diagnostic Aphasia Examination (BDAE) at 1 month after admission, at 3 months, and at 10 months. The initial CT scan revealed hemorrhage in the left thalamus with edema surrounding the hemorrhage. A follow-up CT scan after 10 months showed an old hemorrhage in the left thalamus with no new lesions. The initial PET scan revealed hypometabolism in the left thalamus, and a repeat PET scan at 10 months showed reduced uptake in the left frontal, left parietal, and left temporal cortex. An initial language evaluation showed impaired auditory and reading comprehension, poor verbal expression, impaired repetition, and difficulty with naming and with sentence completion. The patient was diagnosed with global aphasia. Follow-up language evaluation at 3 months and 10 months showed only minimal improvement in his communication. Global aphasia due to lesions in the thalamic region is rare and the prognosis is poor.