The neuro-behavioural syndrome of brainstem disease.

We describe two patients with isolated brainstem lesions who exhibited behavioural and cognitive changes that are commonly associated with frontal lobe pathology, as leading clinical features. These cases illustrate the role of distributed neural networks in cognitive and behavioural processes. The brainstem, frontal-subcortical and limbic systems are extensively and reciprocally linked via neurotransmitter projection pathways. We argue that cognitive and behavioural features in patients with brainstem lesions reflect remote effects of brainstem structures on frontal lobe and limbic regions, as a consequence of disruption to ascending neurotransmitter pathways.

Clinical-anatomical correlation in a selective phonemic speech production impairment.

Although phonemic paraphasias are common in aphasic disorders, including Broca's aphasia, conduction aphasia and transcortical motor aphasia, selective phonemic speech production impairment, or phonemic disintegration, is unusual. A patient with a selective phonemic speech production disorder underwent clinical, neuropsychological and structural neuroradiological assessment over a period of 6 years. The disorder was characterised by phonemic paraphasias (phonemic disintegration) with preserved comprehension and naming. Imaging showed a focal lesion in the white matter of the left precentral gyrus and, to a lesser extent, the posterior part of the left middle frontal gyrus, with overlying cortical atrophy. Biopsy of the lesion, after several years of observation, showed a calcified haemangioma. Clinical-anatomical correlation in this case suggests the importance of primary motor cortex of the inferior precentral (pre-Rolandic) gyrus and subjacent white matter in phoneme production, with sparing of the posterior inferior frontal gyrus (Broca's area).

Retrograde amnesia: clinical and methodological caveats.

Several clinical and methodological caveats are outlined as they pertain to retrograde amnesia research, and data relevant to these caveats are presented. Three caveats in particular are noted in relation to recently published cases of marked retrograde amnesia; (i) temporal lobe epilepsy may influence memory for news events; (ii) there may be additional, unsuspected pathology in cases of amnesia, such as those with cerebral hypoxia; (iii) degree of media exposure is closely related to performance on the types of news events memory tests that are commonly used in retrograde amnesia research.

Executive function in multiple sclerosis. The role of frontal lobe pathology.

Deficits in executive function and the relationship to frontal lesion load as detected on MRI were investigated in 42 multiple sclerosis patients. A battery of neuropsychological test examining executive skills including computerized tests of planning and spatial working memory was administered to all subjects. Performance on these tests was impaired in the patient group when compared with a group of matched controls, but not all executive skills were affected to the same extent. Although a number of executive test scores correlated with the severity of frontal lesion load, it was difficult to disentangle the specific contribution of frontal lobe pathology to the impairment on executive tasks. This study highlights the difficulties in attempting to attribute specific cognitive abnormalities to focal brain pathology in the presence of widespread disease such as in multiple sclerosis.

Modality specific semantic knowledge loss for unique items.

We report the case of a man who, following a major myocardial infarction, suffered anoxia followed by significant event memory impairment. Investigations indicated that his semantic memory for word concepts and object meanings was well preserved. However, he had great difficulty in identifying in the visual (but not verbal) modality historically known people, such as Queen Elizabeth I and Napoleon, and well known world and London landmarks, such as the Parthenon and Buckingham Palace. This selective impairment could not be accounted for in terms of prosopagnosia or high level visual perceptual deficits and we interpret it as a modality specific semantic memory loss for unique objects.

The pattern of cognitive impairments in neuroacanthocytosis. A frontosubcortical dementia.

OBJECTIVE: To identify the neuropsychological profiles of patients with neuroacanthocytosis. PATIENTS: The medical files of 19 previously reported cases of neuroacanthocytosis were reviewed. Ten of the patients involved had undergone comprehensive cognitive assessments, and their neuropsychological records formed the basis of the present study. DATA EXTRACTION: Data on discrepancies between estimated optimal and obtained measures of general intelligence and scores on focal cognitive tests of memory, language, visual perception, and frontal lobe executive skills were tabulated and interpreted. RESULTS: Eight of the patients had evidence of general intellectual deterioration. Five patients presented with memory impairment, two of whom showed visuoperceptual deficits. None of the patients showed any significant high-level language deficits. The most consistent findings across cases was evidence of impairment in frontal lobe executive skills and psychiatric morbidity. CONCLUSION: The cognitive and psychiatric features of the patients suggests that neuroacanthocytosis is a frontosubcortical type of dementia.

Proton magnetic resonance spectroscopy of systemic lupus erythematosus involving the central nervous system.

We examined 13 patients with neurological manifestations of systemic lupus erythematosus (SLE) based on previous and/or current neurological or psychotic episodes by magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (MRS) together with psychiatric and cognitive assessment. MRI was abnormal in 7 patients, showing high signal lesions in the white matter and/or cerebral atrophy. Proton MRS centred on white matter lesions in 5 patients showed a reduction in the N-acetyl aspartate creatine ratio compared with normal appearing white matter in the SLE group and in 10 healthy controls. This pattern of abnormality does not allow differentiation of SLE lesions from the chronic plaques occurring in multiple sclerosis. There was a very high incidence of current psychiatric morbidity in the SLE group, namely in 12 of the 13 patients. There was no correlation between the presence of current psychiatric involvement and/or cognitive dysfunction and abnormalities detected with MRI or MRS.

Bilateral lesions of CA1 and CA2 fields of the hippocampus are sufficient to cause a severe amnesic syndrome in humans.

A patient is reported in whom a classic amnesic syndrome developed as a result of repeated episodes of cerebral ischaemia, accompanied by seizures. The amnesia was very severe for both old and newly acquired memories and the critical lesions defined by MRI were circumscribed areas confined to CA1 and CA2 fields of both hippocampi.

A prospective clinical study of stereotactic subcaudate tractotomy.

This study describes a cohort of 23 patients undergoing stereotactic subcaudate tractotomy. Research Diagnostic Criteria indicated that 70% suffered major depressive disorder; the remainder mostly had a bipolar affective disorder. There were serial assessments pre-operatively and at 2 weeks and 6 months post-operatively using the Hamilton Rating Scale for depression, the Present State Examination (PSE), Newcastle Scale, the Beck Depression Inventory, and the Taylor Manifest Anxiety Scale. Neuropsychological assessment included tests thought to be sensitive to frontal lobe dysfunction, as well as tests of general intelligence, attention, memory, language and visuo-spatial function. Post-operatively, depression rating scale scores decreased significantly but most patients continued to exhibit a number of PSE syndromes. Depression rating scale scores were correlated with 1 year global outcome: there was no significant correlation except for the 6 month assessment when lower Hamilton scores were found to be associated with better global outcome. Correlations between the neuropsychological tests and the Hamilton and Beck depression scales at 2 weeks post-operatively suggested that an improvement in psychiatric condition was associated with greater efficiency on some tests of attention and verbal recall, as well as faster performance on a sorting task. By contrast, the changes at 6 months suggested an association between improvement in psychiatric condition and less efficient performance on certain neuropsychological tests including verbal recognition memory, attention and two tests of frontal lobe dysfunction.

Task specific visuospatial neglect related to density and salience of stimuli.

We report the case of a male patient with a right parietal tumour. On examination he presented with marked visuospatial neglect and anosognosia for his deficits. Experimental analysis of his visuospatial neglect revealed that his ability to identify simple stimuli in the contralateral to the lesion space was significantly influenced by the degree of density of stimuli in the ipsilateral space. Similarly his performance was found to be affected significantly by the complexity or salience of a stimulus in the ipsilateral space. An attempt is made to interpret these observations in the context of current major theories of neglect.

Selective impairment of retrieving people's names: a category specific disorder?

A patient with an extremely long-standing low grade glioma affecting the left temporal lobe is described. The patient was almost entirely unable to retrieve the names of current personalities, although in other respects identification was unimpaired and nominal functions were only mildly inefficient. In particular geographical features and historical figures were generally appropriately named. The problem was equally severe whether naming was to confrontation, from description or by generation. A similarly severe impairment was also found for the retrieval of new words that had come into the language in the last twenty years (eg. aids). The impairment of retrieving people's names was interpreted in terms of a long-standing inability to form new associations between meaning and phonological word-forms.

Confabulations related to tacit awareness in visual neglect.

The case of a man with left-sided visuospatial neglect is reported. His performance on a test for neglect, the "burning house test", is analysed and compared with that of other patients referred to in the literature. We suggest that the confabulations neglect patients may produce when confronted with this test reflect the degree of preconscious awareness for left-sided features.

Clinically isolated lesions of the type seen in multiple sclerosis: a cognitive, psychiatric, and MRI follow up study.

There is a dearth of longitudinal studies on psychometric and psychiatric change in multiple sclerosis (MS) particularly on the evolution of these abnormalities early in the disease process. A 4 1/2 year follow up study documenting magnetic resonance imaging (MRI), psychometric, and psychiatric abnormalities was undertaken in a group of 48 patients with clinically isolated lesions--for example, optic neuritis--which are frequently the harbinger of MS. At follow up about half the subjects had developed clinically definite MS, with memory deficits becoming apparent. Deficits in attention documented at initial assessment were present but unchanged in those subjects who still had a clinically isolated lesion status. However, after MS was categorised into a relapsing-remitting or chronic progressive course, patients with a chronic progressive course were found to have significantly deteriorated with regard to auditory attention tasks. T1 relaxation times in apparently normal white matter correlated with certain indices of cognitive impairment. In developing a model to explain the pathogenesis of intellectual and emotional change in MS, the interaction of organic, psychological, and social factors needs to be emphasised.

Selective lower-case letter ideational dysgraphia.

A case study of a man with a selective ideational dysgraphia for lower-case letters is described. His spelling skills were only very mildly impaired and there was no evidence of other praxic or visuoconstructional impairments. The findings are discussed in the context of information processing models. It is suggested that the representation of upper- and lower-case letters must be fairly independent.

The neuropsychological features of mitochondrial myopathies and encephalomyopathies.

Detailed testing of higher cerebral function was performed in 36 patients with mitochondrial myopathies and encephalomyopathies. Fourteen of these patients were thought to be cognitively impaired on clinical grounds. The assessments included tests of general intellectual ability and focal tests of memory, language, and perception. Twenty-one (58%) of the 36 patients who were tested had evidence of general intellectual deterioration, with focal cognitive deficits of variable degree. Of the remaining 15 patients in whom there was no evidence of general intellectual decline, five displayed focal cognitive deficits. In only 10 patients was there evidence of cerebral dysfunction. The range and extent of cognitive deficits in mitochondrial myopathies are greater than predicted by their clinical presentations.

Neuropsychological correlates of stereotactic subcaudate tractotomy. A prospective study.

Stereotactic subcaudate tractotomy is a surgical procedure performed for the alleviation of intractable affective disorders. It involves the destruction of bifrontal pathways located beneath and in front of the head of the caudate nucleus. We report the first prospective study of the neuropsychological correlates of this operation in 23 patients. Tests of general intelligence, speed and attention, as well as a wide range of focal cognitive tests, including tasks which have been reported in the literature to be sensitive to frontal lobe dysfunction, were administered 1 wk before the operation, 2 wks after the operation and approximately 6 mths after the operation. The results indicated that this operation does not cause any significant, long-term adverse, cognitive deficits. In the post-operative assessment, however, patients show a significant deterioration in their performance on recognition memory tests and a large proportion of them present with a marked tendency to confabulate on recall tasks. In addition, their performance on some of the tasks which are considered to be sensitive to frontal lobe dysfunction is found to be significantly impaired. These deficits are interpreted to reflect frontal lobe dysfunction due to widespread post-operative oedema rather than damage to the subcaudate pathways. The potential for research on these transient effects of the operation for the advancement of our understanding of frontal lobe functions is discussed.