Unilateral attention deficits and hemispheric asymmetries in the control of visual attention.

The present study sought to determine the roles of the two hemispheres in arousal and the selective components of attention. Ten patients with left and right parietal lesions and ten with left and right temporal lesions participated in the experiment. The hypothesis that posterior parietal lesions, whether left or right, cause two selective attentional deficits, namely, a reduced reactivity to stimuli in the visual field contralateral to the lesion, and a reduced reactivity to any stimulus which occupies a relative contralateral spatial position, was tested by asking the patient to tilt their head either to the left or to the right by 90 degrees and to respond to two stimuli displayed above and on either side of fixation mark. The arousal component of attention was studied by analysing the overall RT to visual stimuli independent of their spatial positions. The results showed that (1) patients with either left or right parietal damage are impaired in shifting attention from the ipsilateral to the contralateral visual field, and, within each visual field, in a direction contraversive to the lesion and (2) these two attentional deficits are more severe after right than after left parietal damage. Furthermore, the results show that the difficulty in maintaining a high level of alertness is a specific deficit of patients with right hemispheric lesion and not of patients with an extinction syndrome, insofar as there is no significant difference in overall RT between patients with parietal and temporal lesions.

Divided visuo-spatial attention systems with total and anterior callosotomy.

The role of the corpus callosum in the inter-hemispheric integration of the visuo-spatial attention system, was investigated in patients with a total callosotomy or with an anterior callosal section. Subjects produced simple reaction times (RTs) to visual targets shown to the left or right visual hemifield. Preceding the target by an interval of 500 ms, arrow cues predicting the target location were shown left and right of the point of ocular fixation. For a majority of total and anterior callosotomy patients, results with valid focused cues (both arrows pointing to the target location) and with divided-attention cues (arrows pointing away from fixation) did not differ and both conditions produced shorter RTs than with neutral cues (equal signs). In contrast, neurologically intact subjects showed equal RTs with divided-attention and neutral cues, whereas valid focused cues produced reduced RTs relative to neutral cues. These results indicate that most split-brains, in contrast to normal observers, are capable of directing their attention to left and right visual field locations simultaneously, and therefore that each cerebral hemisphere controls its own visuo-spatial attention mechanism.

Neuropsychological profile in myotonic dystrophy.

Twenty patients with myotonic dystrophy underwent neuropsychological evaluation. Performances were analysed with respect to general cognitive profile, family patterns of cognitive impairment, relation with sex, age, extent of muscular involvement, and sex of affected parent. Results showed severe intellectual deficit in 50% of patients and selective impairment of visuospatial and constructional functions. Female patients showed significantly worse global intellectual status than males. No difference in intellectual level was observed in patients with respect to age, extent of muscular involvement and sex of affected parent. No family pattern of cognitive impairment could be identified. Our results show that an extensive neuropsychological battery can reveal the existence of selective mental impairment. It may provide further data on cognitive impairment onset, progression and relation to muscular involvement.

Evolution of neuropsychological changes after partial callosotomy in intractable epilepsy.

Early neuropsychological changes following partial anterior callosotomy were evaluated in 15 patients with epilepsy (10 secondary generalized and 5 Lennox-Gastaut syndromes) by comparing their performances 1 month before surgery and then 15-20 and 90-100 days postoperatively without modifying the anticonvulsant treatment. The following neuropsychological and motor functions were tested: memory, attention, visuo-motor ability, posture, motor dexterity, language, praxis and gnosis. Social behaviour was also investigated. The main results are as follows: (i) most cognitive functions showed no significant variation; (ii) motor organization was still slightly impaired at the second check-up after the surgery; (iii) improvements in social behaviour and posture were frequently observed at the final evaluation. The analysis of individual cases highlights the influence of the extent of commissurotomy, lesions related to the surgical procedure and preoperative brain damage in determining the post-surgical profile. On this basis, the short-term neuropsychological cost of partial callosotomy appears to be low and seems to depend mostly on surgical parameters and brain conditions before the operation.

Modifications in morphology of epileptic seizures after callosotomy.

The callosotomy on drug-resistant epileptic seizures may abolish or reduce their frequency and may modified the morphology of different kind of seizures. Our series is composed of 36 patients. Drop-attacks and complex partial seizures (CP) were present in all patients, generalized tonic-clonic seizures (GTC) in 16 (44.4%) and simple partial seizures (SP) and myoclonic attacks (MY) in 6 patients each. We found two kinds of modifications: a) lateralization of hypotonia which becomes hemisomatic, with lateral bending to the hypotonic side; b) different way of falling, due not only to the lateralization of hypotonia but also to the gradual impairment of muscle tone. Modifications in CP mainly concerned automatisms, which disappeared in 39.1% of patients, while 34.8% of them had a significant reduction in automatisms; this reduction consisted in simplification of automatic movements and in shorter duration of seizures.

Predictive factors of callosotomy in drug-resistant epileptic patients with a long follow-up.

Some possible factors to predict outcome after callosotomy were investigated in a personal series composed of 36 patients. Twenty-seven of them were submitted to anterior callosotomy, 1 to posterior callosotomy and the remaining 8 patients to two stage complete division of corpus callosum. All factors, either positive or negative, do not appear completely reliable; they can be envisaged only in relative terms and do not seem to be relevant to make surgical decision or to discard surgery. In author's series, dealing specifically with drop-attacks, it clearly appeared that abrupt falls to the ground unpreceded by other epileptic features did definitely better. This was the only statistically significant datum.

EEG Patterns after callosotomy.

In 36 patients with drug-resistant epilepsy submitted to anterior callosotomy (27 cases), to two-stage total callosotomy (8 cases) and to posterior callosotomy (1 case) the EEG variations concerning background activity, focal activity and sharp-waves (SW) bisynchronous activity were evaluated. EEG modifications observed after callosotomy are the following: background rhythm tends to be better organised as spectral analysis demonstrated, this finding usually coincide with reduction of bisynchronous discharges. It appears that improvement in background activity cannot be correlated with outcome, but it seems to be to some extent since at the same time cognitive functions also seem to improve; however, this last aspect need to be checked in much larger series. The number and location of EEG foci do not change, but they appear to be more active; this is likely to depend only on the concomitant reduction of bisynchronous activity. No correlation seems to exist between the number and the location of foci, which are generally multiple. Lateralization of bisynchronous discharges as well as the reduction of their frequency and duration were observed. However, the clinical course is quite different: in some patients we have achieved good clinical responses in others postoperative results were poor. Lateralization of bisynchronous discharges is never absolute, on the grounds that in prolonged recordings bisynchronous discharges are nearly always present. Bisynchronous discharges in some cases are alternatively predominant in both hemispheres even within minutes or seconds. It was observed that after certain time, generally some months, lateralized discharges tend to generalize again, confirming that corpus callosum is replaced in discharge diffusion by other structures (brain-stem, diencephalon).

Mutism in 36 patients who underwent callosotomy for drug-resistant epilepsy.

Thirty-six drug-resistant epileptic patients submitted to callosotomy were studied. Anterior callosotomy was performed in 27 patients, total two-stage callosotomy was performed in 8 patients and 1 patient had only posterior callosotomy. We found mutism in 10 patients (2 after complete callosotomy and 8 after anterior section). The patients did not speak, but the comprehension was present: they were able to carry out orders and to write. Their attitude to the environment was characterized by complete indifference. The mutism was always transient, lasting from 4 to 25 days (mean 7 days). Regression of mutism was always complete. We think that this complication should be chiefly attributed mainly to surgical manipulation, even if it is impossible to completely exclude a multi-factorial etiology.

Peripheral neuropathy in myotonic dystrophy: electrophysiological and clinical features.

Peripheral neuropathy was investigated in thirty-one patients with myotonic dystrophy (MyD) and sixteen relatives. Using standard electrophysiological criteria, a sensorimotor axonal peripheral neuropathy was found in 14 MyD cases (45%) and not in unaffected first-degree relatives. The whole group of the MyD patients showed significant impairment of mean motor and sensory conduction values, compared with controls. The presence of polyneuropathy was correlated with the patients' age and the severity and duration of the clinical manifestations of MyD.

[Remarks on callosotomy in the treatment of drug-resistant epilepsy]. / Remarques sur la callosotomie dans le traitement de l'épilepsie pharmaco-résistante.

In this report 17 patients with long-standing non-focal epilepsy underwent callosotomy (this was total in two patients and performed in two stages, and anterior-subtotal in the remaining patients). In all patients the atonic-hypertonic seizures with sudden falls were the most disabling epileptic fits. Callosotomy proved efficient in controlling atonic fits in 10 out of 15 patients in whom surgical results are evaluated. In 3 additional patients the frequency of atonic fits was reduced by more than 50%. In the remaining two patients, no therapeutic effect was observed. Callosotomy was less effective on seizures which were not atonic. Therefore, this procedure appears to be indicated in patients in whom atonic fits are predominant. The main effect of callosotomy is to transform drug-resistant seizures into drug-sensitive ones. Neuropsychological sequels are insignificant unless the splenium is severed. However, considerable psychic and behavioral improvement was nearly always observed after surgery. Despite the fact that on a therapeutic level results were often satisfactory, a number of practical problems still remain. These concern the full spectrum of indications for callosotomy, the extent of corpus callosum section, choice of methods in severely mentally retarded patients and, finally, the age at which the operation should be carried out.

Reversible multifocal encephalopathy following tuberculous infection.

Tuberculous encephalic infection is commonly reported as confined to Asians or Africans or people living in poor hygienic conditions; very often it follows meningitis in patients with lung TB infection. We describe three western patients coming from good social environment and suffering from multifocal tuberculous encephalopathy. Two of them showed neither meningitis or lung TB when CNS involvement appeared. Complete recovery after therapy is described, together with the evolution of brain CT and, in 1 case, MRI features. The instrumental findings accompanying the complete recovery suggest that the lesions described in these cases are a localized form of encephalitis responsive to medical treatment, unlike tuberculomas, which often need surgical treatment. The occurrence of tuberculous encephalic infection in western, middle-class patients with or without meningitis emphasizes that tuberculous encephalopathy must be considered in the differential diagnosis of multifocal brain lesions.

Recognition impairment correlated with short bisynchronous epileptic discharges.

The occurrence of transitory cognitive impairment during diffuse subclinical electroencephalographic (EEG) discharges has been widely documented but the role of the parameters influencing the cognitive performance and the involvement of motor or verbal response in the tasks used is still under debate. Fifteen patients suffering from primary generalized epilepsy with frequent bisynchronous EEG epileptic bursts underwent a shape recognition task during EEG monitoring. The test sequence was as follows: memorandum, pause, and multiple choice set. After pressing the response button, the patient was asked to confirm the choice verbally. The following parameters were considered: geometrical complexity of the shape, chronological position of the burst occurring during the single test, and the duration of discharge ranging from 1 to 3 s. Results showed a significant increase in incorrect responses during the test when discharges occurred, with more errors occurring for difficult than for easy shapes. Neither the discharge position nor the duration of the epileptic burst influenced the performance. Diffuse epileptic activity of short duration produced selective effects on the cognitive process regardless of the motor component of the response.

Neuropsychological changes after callosotomy in drug-resistant epilepsy: a study of the short-term evolution.

With the increasing interest in callosotomy as treatment for intractable epilepsy, it seems to be important to define the neuropsychological consequences of the related surgical operation. 8 patients suffering from drug-resistant seizures underwent section of the corpus callosum, 6 in the anterior part only and 2 undergoing complete two-stage commissurotomy including the posterior part. Before the callosotomy the patients were studied using a cognitive, affective and behavioural battery which was repeated 15 and 90-100 days after the operation. The patients with sufficient I.Q. were described in more detail using the cognitive parameters; the social and motor behaviour of Lennox-Gastaut subjects are accurately reported. No disconnection syndrome was ever observed after the partial commissurotomy while it occurred in one of the two complete callosotomies. The patients showed longer reaction times and a mild impairment of linguistic, praxic, memory and motor functions in the former evaluation (15 days), but there was consistent improvement in the latter check up. At the 90-100 day follow-up the Lennox-Gastaut patients responded more readily to the environmental stimulations and their postural, motor and behavioural functions were unchanged or improved, with respect to presurgical performances. The social and emotional behaviour of all the patients had always improved by the time the long-term evaluation (90 days) was performed. Finally, by limiting the callosotomy to the anterior part only, the neurological and psychological consequences seem to be limited.(ABSTRACT TRUNCATED AT 250 WORDS)

Commissurotomy in intractable epilepsy: clinical and surgical comment.

Two patients suffering from seizures unresponsive to medical treatment underwent two-stage "central" commissurotomy. In one patient anterior callostomy was carried out first; in the other the surgical procedure was performed in the reverse order. The clinical, EEG, and neuropsychological features of the two patients are reported before the operation, between stage 1 and stage 2 of the procedure, and after completion of the commissurotomy. The surgical aspects of the two different procedures and the related clinical pictures are described in detail.

May preclinical markers of brain infection by HIV be detected? A cognitive, CSF and neuroradiological investigation.

A group of patients with HIV infection in various stages of the disease was studied with regard to CSF, neuroradiological and neuropsychological aspects. A considerable number of them showed signs of CNS involvement, as revealed by abnormalities in all the three fields investigated, despite a frequently unremarkable neurological examination. The findings of CSF alterations, neuroradiological abnormalities and selective cognitive impairment in the absence of opportunistic infections of the CNS support the hypothesis of an early and direct action of HIV on the nervous system.

Influence of vigabatrin on cognitive performances and behaviour in patients with drug-resistant epilepsy.

INTRODUCTION: The aim of this research was to evaluate changes in cognitive performances, mood and quality of life in drug-resistant epileptic patients, after the introduction of Vigabatrin (VGB) as additional treatment. MATERIAL AND METHODS: A four-step evaluation was carried out in two groups of 20 patients each, randomly assigned to VGB or placebo treatment. A battery of neuropsychological tests investigating attention, memory and adaptive abilities, associated with inventories concerning depression, quality of life and the concern of families upon patient behaviour, were utilised. For each subject, four evaluations were performed, two before and two after VGB/placebo administration. RESULTS: No relevant side-effects regarding cognition and behavior were detected in the VGB group. The intra-group comparison between pre- and post-treatment phases showed a slight improvement in cognitive performances of VGB patients and a positive change in their overall psychological status. The inter-group comparison confirmed the selective improvement occurring in the trend of a few neuropsychological test scores in the VGB group. CONCLUSION: Such results help to reject the hypothesis that the addition of VGB to the current antiepileptic treatment may affect cognitive performances and behaviour.

Trail making test: normative values from 287 normal adult controls.

The Trail Making Test (TMT), which explores visual-conceptual and visual-motor tracking, is a frequently used neuropsychological test because of its ease of administration and sensitivity to brain damage. In this paper, norms are provided for the time scores derived from parts A and B, and for the (B-A) difference. The data were collected from 287 adult Italian subjects stratified by gender, schooling and age (from 20 to 79 years). The test scores were affected by age, education and general intelligence (as expressed by Raven's Coloured Progressive Matrices). Only for part A did females have longer time scores than males. Test-retest reliability was high for each score.

[Bromocriptine in Parkinsonian syndromes. Results obtained in a group of patients treated for 8 months]. / La bromocriptina nelle sindromi parkinsoniane. Risultati ottenuti in un gruppo di pazienti trattati per 8 mesi.

Antiparkinsonian treatment with L-Dopa gives rise to a number of problems: I) lack of initial response in a few cases; II) side-effects; III) becoming less effective after the first few years of treatment. Consequently, various drugs have been tried to replace, or combine with, L-Dopa. Among those drugs bromocriptine has been described the most effective. Twelve patients suffering from severe parkinsonism, all being intolerant to L-Dopa, have been treated with Bromocriptine. They fell into stage V of the Hoehn and Yahr's scale after 8 days of complete withdrawal of therapy with L-Dopa. Benefit and side-effects have been assessed as follows: a) L-Dopa alone; b) bromocriptine alone; c) combination of a and b. A daily dose of 30 mg of bromocriptine was given for 4 months. This was then reduced to 15 mg with the addition of L-Dopa for another 4 months. The results were: I) bromocriptine scored higher in all patients except one; II) bromocriptine has been consistently less effective than L-Dopa; III) side-effects were similar to those of L-Dopa but less frequent; IV) the combined effect of the two drugs was superior to each drug given alone.

Neuropsychological performances in patients treated with different antiepileptic drugs.

Twenty-six patients, suffering from various forms of epilepsy (2 with simple partial, 14 with complex partial, and 10 with generalized seizures) and treated with different drugs (10 with DPH, 10 with PB, and 6 with CBZ), underwent neuropsychological tests in order to evaluate: 1) Vigilance; 2) attention; 3) motor, sensory and adaptive (visuomotor) performances; 4) memory span, short-term and long-term memory, considering verbal as well as spatial aspects. The battery of tests was administered prior to treatment and when the drug plasmatic levels were within the ranges considered therapeutic. The results show that in the case of DPH there is an improvement of vigilance and adaptive performances but a worsening of attention and memory functions. With PB, only motor and adaptive performances improve; all other functions worsen. Finally, with CBZ, vigilance, attention, sensory performances and memory functions are unmodified while only motor and adaptive performances appear to improve.

Callosal and cortical contribution to procedural learning.

Acallosal and callosotomized subjects usually show impairments on tasks requiring bilateral interdependent motor control. However, few studies have assessed the ability of these subjects to learn a skill that requires the simultaneous contribution of each hemisphere in its acquisition. The present study examined whether acallosal and callosotomized subjects could learn a visuomotor skill that involved a motor control from either both or a single hemisphere. Eleven adult patients, six acallosal and five callosotomized, participated in this study. Seven of these patients had epileptic foci located in the frontal and/or temporal areas and one of the acallosal patients showed bilateral prefrontal atrophy following surgical removal of an orbitofrontal cyst. The performance of the experimental subjects was compared with that of 11 matched control subjects, on a modified version of a serial reaction time task developed by Nissen and Bullemer (Cogn Psychol 1987; 19: 1-32). This skill acquisition task involved bimanual or unimanual key-pressing responses to a sequence of 10 visual stimuli that was repeated 160 times. A declarative memory task was then performed to assess explicit knowledge of the sequence. None of the experimental subjects learned the task in the bimanual condition. Patients with frontal epileptic foci or orbitofrontal damage also failed to learn the task in the unimanual condition when they were using the hand contralateral to the damaged hemisphere. All other subjects, including the acallosal and callosotomized patients with temporal foci, learned the visuomotor skill as well as their controls in the unimanual condition. In spite of the absence of transfer and interhemispheric integration of procedural learning, some of the acallosal and callosotomized patients were able to learn the sequence explicitly. These findings indicate that the corpus callosum and the frontal cortical areas are important for procedural learning of a visuomotor skill. They also confirm the dissociation described by Squire (Science 1986; 232: 1612-9 and J Cogn Neurosci 1992; 4: 232-43) between the declarative and procedural memory systems and extend this dissociation to processes involving simultaneous bihemispheric co-operation.