Impaired attention mechanisms in confabulating patients: A VLSM and DWI study

Attention is one of the most studied cognitive functions in brain-damaged populations or neurological syndromes, as its malfunction can be related to deficits in other higher cognitive functions. In the present study, we aimed at delimiting the attention deficits of a sample of brain-injured patients presenting confabulations by assessing their performance on alertness, spatial orienting, and executive control tasks. Confabulating patients, who present false memories or beliefs without intention to deceive, usually show memory deficits and/or executive dysfunction. However, it is also likely that attention processes may be impaired in patients showing confabulations. Here, we compared confabulating patients' attention performance to a lesion control group and a healthy control group. Confabulating patients' mean overall accuracy was lower than the one of healthy and lesion controls along the three experimental tasks. Importantly, confabulators presented a greater Simon congruency effect than both lesion controls and healthy controls in the presence of predictive spatial cues, besides a lower percentage of hits and longer RTs in the Go-NoGo task, demonstrating deficits in executive control. They also showed a higher reliance on alerting and spatially predictive orienting cues in the context of a deficient performance. Grey and white matter analyses showed that patients' percentage of hits in the Go-NoGo task was related to damage to the right inferior frontal gyrus (pars triangularis and pars opercularis), whereas the integrity of the right inferior fronto-occipital fasciculus was negatively correlated with their alertness effect. These results are consistent with previous literature highlighting an executive dysfunction in confabulating patients, and suggest that some additional forms of attention, such as alertness and spatial orienting, could be selectively impaired in this clinical syndrome.

Complete resection of hypervascularised extraventricular neurocytoma after preoperative embolisation

A 13-year-old female arrived at the Emergency Department with a two-week history of headache, and bilateral papilloedema on examination. The initial study with CT and MRI showed a large multicystic left frontal mass with calcification surrounded by peripheral oedema, subacute intralesional bleeding and association of multiple large vessels. She was initially operated on in another centre where a subacute haematoma was found, evacuating to multiple vessels and arteriolised veins. Despite the earlier neuroimaging findings, arteriovenous malformation (AVM) was suspected, so she was referred to our centre for further treatment. We performed angiography, MR angiography and MRI with advanced sequences, diagnosing a highly vascularised intra-axial tumour which was embolised. The patient was then definitively operated on, with the resulting finding of extraventricular neurocytoma (EVN). EVN are extremely rare lesions, not previously described in the literature as hypervascularised lesions, which in our case required prior angiography and embolisation for proper diagnosis and adequate management.

[Idiopathic intracranial hypertension and spontaneous cerebrospinal fluid fistula. Usefulness of intracranial pressure monitoring]

Spontaneous cerebrospinal fluid (CSF) fistulas are rather common in daily practice. The aim of the surgical treatment is closure of the leak, but recurrences are quite frequent. The association between spontaneous CSF fistulas and idiopathic intracranial hypertension (IIH) is not uncommon, and this is probably the cause of the low rate of success of the surgical treatment. Symptoms of IIH associated with spontaneous CSF fistula are atypical, and diagnosis is often missed. Continuous intracranial pressure monitoring is very useful in the diagnosis of chronic IIH and in patients with spontaneous CSF fistula, as it helps in making decisions on the treatment of these patients.

CNK/T-cell brain lymphoma associated with Epstein-Barr virus in a patient with AIDS

We report a case of extranodal NK/T-cell lymphoma, nasal type, with exclusive cerebral localization in a patient with AIDS. The patient presented with neurological alterations, fever and convulsions, so the initial presumptive diagnosis was an opportunistic brain infection. MRI showed a left parietal necrotic lesion and a stereotactic brain biopsy was performed for pathological, microbiological and molecular studies. Histological sections showed an angiocentric and angiodestructive growth pattern and the immunophenotype of this tumor was CD56+, CD45+, CD3+ (cytoplasmic), Granzyme B+ and Perforin+. All the microbiological studies such as bacterial, fungi, micobacteria, Toxoplasma gondii and Cryptococcus determination were negatives. A PCR study with primer specific for EBV viral genome of Bam-Hi-w system was positive. Also, a rearrangement study showed T-cell gene rearrangement with monoclonal appearance. A diagnosis of extranodal NK/T-cell lymphoma was made and the patient died a few days later. This case represents a very rare example of NK/T-cell lymphoma of the brain in a patient with AIDS. The diagnosis of this kind of lymphomas requires a multimodality approach correlating clinical, morphological, immunophenotypic and molecular data.

Linear accelerator radiosurgery in treatment of central neurocytomas

OBJECTIVES

The purpose of this report was to review our experience with stereotactic radiosurgery in the management of patients with residual neurocytomas after initial surgery.

METHODS

Between October 1996 and December 2001, four patients with central neurocytoma were treated by surgery and subsequently underwent linear accelerator (LINAC) radiosurgery.

RESULTS

Two of the patients were cured, one exhibited a significant reduction in tumour size and the fourth remains stable. All four patients are alive and well.

CONCLUSIONS

In cases of small residual tumours or recurrences radiosurgery allows open surgery to be avoided and is a safe and potentially effective approach.

[Diagnosis of mesial temporal sclerosis with magnetic resonance imaging]

INTRODUCTION

Mesial temporal sclerosis (MTS) is a progressive drug-resistant epileptic syndrome which requires rapid, effective diagnosis and treatment. Histologically there is atrophy and gliosis of the hippocampus.

OBJECTIVE

To establish magnetic resonance (MR) imaging guidelines for correct diagnosis.

PATIENTS AND METHODS

We made a prospective study of 78 patients with drug-resistant temporal lobe epilepsy (44 women and 34 men; age 6-66 years, mean 31 years). Using a magnet of 1.5 Teslas paracoronal sections were made of the hippocampus with T1 volumetric with inversion-recovery, FLAIR (fluid-attenuated inversion-recovery) and T2 relaxometry. A control group of 30 healthy volunteers was established. The reduction in volume and hippocampal T2 hyperintensity were considered to be MTS diagnosed on MR.

RESULTS

No hippocampal differences were observed among the healthy volunteers. The confidence intervals (mean +/- 1.96 SD) were: right volume: 4.169-5.911 mm3; left volume: 4.097-5.940 mm3; time of T2 relaxation: 98-113 ms. MTS was observed in 42 patients (54%): 24 left, 14 right and four asymmetrical bilateral. The results of the diagnostic validity (sensitivity/specificity) were: T1 volumetric 91/92%, FLAIR 93.5/98% and T2 relaxometry 91/92%. There was atrophy of other extrahippocampal structures in five cases of MTS; 10 patients with MTS (23.5%) had another extrahippocampal lesion associated (dual pathology), particularly migration disorders; 21 patients (27%) had lesions without MTS (tumors, alterations of migration, nonspecific gliosis) and in 15 cases (19%) there were no abnormal findings. A total of 27 patients were operated on: 22 with MTS (21 had diagnostic MR, one case had no abnormal findings), four cases had tumors and one had cortical dysplasia.

CONCLUSION

The combination of quantitative techniques (T1 volumetric with inversion-recovery and T2 relaxometry) and FLAIR optimize MTS diagnosis using MR.