Mats Tullberg

White matter lesions impair frontal lobe function regardless of their location

Objective: To analyze the effect of white matter lesions in different brain regions on regional cortical glucose metabolism, regional cortical atrophy, and cognitive function in a sample with a broad range of cerebrovascular disease and cognitive function. Methods: Subjects (n = 78) were recruited for a study of subcortical ischemic vascular disease (SIVD) and Alzheimer disease (AD) contributions to dementia. A new method was developed to define volumes of interest from high-resolution three-dimensional T1-weighted MR images. Volumetric measures of MRI segmented white matter signal hyperintensities (WMH) in five different brain regions were related to regional PET glucose metabolism (rCMRglc) in cerebral cortex, MRI measures of regional cortical atrophy, and neuropsychological assessment of executive and memory function. Results: WMH was significantly higher in the prefrontal region compared to the other brain regions. In all subjects, higher frontal and parietal WMH were associated with reduced frontal rCMRglc, whereas occipitotemporal WMH was only marginally associated with frontal rCMRglc. These associations were stronger and more widely distributed in nondemented subjects where reduced frontal rCMRglc was correlated with WMH for all regions measured. In contrast, there was no relationship between WMH in any brain region and rCMRglc in either parietal or occipitotemporal regions. WMHs in all brain regions were associated with low executive scores in nondemented subjects. Conclusions: The frontal lobes are most severely affected by SIVD. WMHs are more abundant in the frontal region. Regardless of where in the brain these WMHs are located, they are associated with frontal hypometabolism and executive dysfunction.

Reduced frontotemporal perfusion in psychopathic personality

Several brain-imaging studies have found associations between aberrant functioning in the frontal and temporal lobes and violent offending. We have previously reported decreased frontotemporal perfusion unrelated to psychosis, substance abuse, or current medication in 21 violent offenders. In the present study, we compared the regional cerebral blood flow (rCBF) in a new group of 32 violent offenders to scores on the Psychopathy Checklist-Revised (PCL-R), which rates two aspects of psychopathy: disturbed interpersonal attitudes (Factor 1) and impulsive antisocial behavior (Factor 2). A recently proposed model has split Factor 1 into a new Factor 1 (deceitful interpersonal style), a new Factor 2 (affective unresponsiveness), and a Factor 3, which approximately corresponds to the old Factor 2. The rCBF was assessed by single-photon emission computed tomography (SPECT) with technetium-99m-d,l-hexamethylpropyleneamine oxime (HMPAO) in regions of interest (ROIs) placed in accordance with fusioned magnetic resonance images (MRI) and SPECT scans. Significant negative correlations were found between interpersonal features of psychopathy (the old and especially the new Factor 1) and the frontal and temporal perfusion. The two most clearly associated ROIs were the head of the caudate nuclei and the hippocampi. These findings in a group of violent offenders living under the same conditions, which reduced the number of state-related confounders, add to the evidence indicating that aberrant frontotemporal activity may be a factor in violent behavior.

White matter changes in normal pressure hydrocephalus and Binswanger disease: Specificity, predictive value and correlations to axonal degeneration and demyelination

Objectives– To analyse the diagnostic and prognostic value of periventricular hyperintensity (PVH) and deep white matter hyperintensity (DWMH) magnetic resonance imaging (MRI) changes and their relation to symptoms and cerebrospinal fluid (CSF) markers of demyelination (sulphatide) and axonal degeneration [neurofilament triplet protein (NFL)] in a large series of patients with normal pressure hydrocephalus (NPH) and Binswanger disease (BD). Materials and methods– PVH and DWMH were determined by a semi‐automatic segmentation method on T2‐weighted images in 29 patients with NPH and 17 patients with BD. CSF analyses, psychometric testing and quantification of balance, gait and continence were performed in all patients and also postoperatively in NPH patients. Results– No MRI variable could identify NPH or BD patients. Abundant PVH and DWMH preoperatively correlated with improvement in gait, balance and psychometric performance after shunt surgery (P < 0.05). CSF sulphatide correlated positively with the amount of DWMH (P < 0.05) while NFL was correlated to both PVH and DWMH (P < 0.05). Abundant PVH correlated with poor psychometric performance while DWMH correlated with gait disturbance (P < 0.05). Postoperative reduction in PVH correlated with improvement in gait, balance and psychometric performance. Conclusion– In spite of a refined quantification method, NPH and BD patients exhibited similar MRI changes. MRI had a predictive value in NPH patients. DWMH might relate to demyelination and PVH to neuronal axonal dysfunction. NPH and BD share the major part of symptoms and MRI changes, indicating a common pathophysiological pattern, and we raise the question of how to treat BD patients.

CSF neurofilament and glial fibrillary acidic protein in normal pressure hydrocephalus

We examined CSF levels of markers of neuronal degeneration and astrogliosis-the light subunit of the neurofilament triplet protein (NFL) and the glial fibrillary acidic protein (GFAP)-in 65 patients with normal pressure hydrocephalus (NPH). NFL was increased sixfold (864 ± 1,538[mean ± SD] versus 156 ± 81 ng/L; p ≤ 0.001) and GFAP twofold (1,116 ± 1,085 versus 637 ± 295 ng/L;p ≤ 0.01) in NPH patients compared with neurologically healthy age-matched controls. No correlation was found between any particular symptom or sign and GFAP levels in CSF. The levels of NFL, on the other hand, were higher in patients with severe symptoms compared with those with moderate or no symptoms. Furthermore, there was a correlation between a high level of NFL and gait disturbance, incontinence, psychometric incapability, and social dysfunction. A high preoperative NFL level was associated with favorable outcome after shunt surgery. This indicates that NFL is a marker of ongoing and possibly still-reversible axonal damage in NPH.

Influence of comorbidities in idiopathic normal pressure hydrocephalus — research and clinical care. A report of the ISHCSF task force on comorbidities in INPH

Idiopathic normal pressure hydrocephalus (INPH) is a syndrome of ventriculomegaly, gait impairment, cognitive decline and incontinence that occurs in an elderly population prone to many types of comorbidities. Identification of the comorbidities is thus an important part of the clinical management of INPH patients. In 2011, a task force was appointed by the International Society for Hydrocephalus and Cerebrospinal Fluid Disorders (ISHCSF) with the objective to compile an evidence-based expert analysis of what we know and what we need to know regarding comorbidities in INPH. This article is the final report of the task force. The expert panel conducted a comprehensive review of the literature. After weighing the evidence, the various proposals were discussed and the final document was approved by all the task force members and represents a consensus of expert opinions. Recommendations regarding the following topics are given: I. Musculoskeletal conditions; II. Urinary problems; III. Vascular disease including risk factors, Binswanger disease, and white matter hyperintensities; IV. Mild cognitive impairment and Alzheimer disease including biopsies; V. Other dementias (frontotemporal dementia, Lewy body, Parkinson); VI. Psychiatric and behavioral disorders; VII. Brain imaging; VIII. How to investigate and quantify. The task force concluded that comorbidity can be an important predictor of prognosis and post-operative outcome in INPH. Reported differences in outcomes among various INPH cohorts may be partly explained by variation in the rate and types of comorbidities at different hydrocephalus centers. Identification of comorbidities should thus be a central part of the clinical management of INPH where a detailed history, physical examination, and targeted investigations are the basis for diagnosis and grading. Future INPH research should focus on the contribution of comorbidity to overall morbidity, mortality and long-term outcomes.

Reduced regional cerebral blood flow in non-psychotic violent offenders

The present study was designed to replicate previously reported findings of abnormal frontal and/or temporal cerebral blood flow in violent offenders and to control for the influence of major mental disorder (MMD), substance abuse, and current medication. HMPAO-SPECT-CBF and MRI scans from pretrial forensic psychiatric investigations of 21 subjects convicted of impulsive violent crimes were retrospectively re-evaluated. In 16/21 subjects, visual assessment of SPECT scans showed some hypoperfusion in the temporal and/or frontal lobes. MRI showed no corresponding structural damage. Quantified regional cerebral blood flow (rCBF) in defined regions of interest was compared between index cases and 11 healthy control subjects. Index subjects had significant reductions in the right angular gyrus and the right medial temporal gyrus, bilaterally in the hippocampus, and in the left white frontal matter, but they had significantly increased rCBF in the parietal association cortex bilaterally. The aberrations were as frequent and severe among the subjects without MMD, substance abuse, and current medication (n=7) as in the entire group of index subjects.

Brain metabolism in adult chronic hydrocephalus

Normal pressure hydrocephalus (NPH) is the most frequent form of chronic hydrocephalus in adults. NPH remains underdiagnosed although between 5% and 10% of all demented patients may suffer from this disorder. As dementia is an increasing demographic problem, treatable forms such as in NPH have become a central issue in neurology. Despite the traditional perception of hydrocephalus being a disorder of disturbed CSF dynamics, in NPH metabolic impairment seems at least as important. So far, the only valid animal model of NPH is chronic adult kaolin hydrocephalus. In this model, opening of alternative CSF outflow pathways leads to normal or near‐normal intracranial pressure and CSF outflow resistance. Yet, various metabolic disturbances cause ongoing ventricular enlargement and characteristic symptoms including cognitive decline and gait ataxia. Delayed hippocampal neuronal death, accumulation of beta‐amyloid and disturbed cholinergic neurotransmission may contribute to memory dysfunction. Compromised periventricular blood flow, decreased dopamine levels in the substantia nigra and damaged striatal GABAergic interneurons may reflect basal ganglia symptoms. At least in human hydrocephalus cerebrovascular co‐morbidity of the white matter plays an important role as well. It seems that in hydrocephalus from a certain ‘point of no return’ metabolic impairment becomes decoupled from CSF dynamics and, at least partly, self‐sustained. This is probably the reason why despite restored CSF circulation by shunting many patients with chronic hydrocephalus still suffer from severe neurological deficits. The present paper offers a comprehensive review of the experimental and clinical data suggesting metabolic disturbances in chronic hydrocephalus.

THE NEUROPSYCHOLOGY OF PATIENTS WITH CLINICALLY DIAGNOSED IDIOPATHIC NORMAL PRESSURE HYDROCEPHALUS

OBJECTIVETo compare the neuropsychological performance of patients with idiopathic normal pressure hydrocephalus (INPH) with that of healthy individuals and to examine its relation to neurological signs, vascular comorbidity, and background factors. METHODSA consecutive series of 58 patients with INPH underwent neurological, neuroradiological, and neuropsychological examinations. The neuropsychological tests, measuring vigilance, fine movements of the hands, learning, working memory, and aspects of executive functioning, were also administered to 108 healthy individuals. RESULTSPatients performed worse than healthy individuals on all included tests. Significant correlations between test results were more frequent and stronger among patients and the degree of neuropsychological impairment was related to the severity of other signs of INPH. Patients with vascular risk factors performed worse than those without. CONCLUSIONThe neuropsychological deficits in INPH are widely distributed, interrelated, associated with neurological signs, and aggravated by vascular comorbidity.

Postural disturbance in patients with normal pressure hydrocephalus.

The postural function in 52 patients with normal pressure hydrocephalus (NPH) and in 19 patients with subcortical arteriosclerotic encephalopathy (SAE) was analysed bedside and in 17 of the NPH, 10 of the SAE and 23 healthy individuals (HI) also examined with a force platform. At the bedside examination, no differences in postural functions between NPH and SAE patients were found. The NPH patients improved more in the postural than in motor functions after shunt surgery. The NPH patients had a larger sway area and a higher backward directed velocity of centre of pressure than HI. The direction of the inclination in the sagittal plane was neutral or forward in the NPH and the SAE patients while it was backward in HI. The postural function was better in positions with open eyes in all 3 groups, but significantly less in the NPH patients, indicating a misinterpretation of afferent visual stimuli in the brainstem postural centre.

NEUROPSYCHOLOGICAL EFFECTS OF SHUNT TREATMENT IN IDIOPATHIC NORMAL PRESSURE HYDROCEPHALUS

OBJECTIVETo prospectively evaluate the effects of shunting on the neuropsychological performance of patients with idiopathic normal pressure hydrocephalus (INPH), to compare their performance with that of healthy individuals, and to estimate the predictive utility of putatively important factors. METHODSA consecutive series of 47 patients with INPH underwent neurological, radiological, and neuropsychological examinations before and 3 months after shunt surgery. The same neuropsychological tests, measuring simple and target reaction times, dexterity, memory and learning, working memory, and aspects of executive functioning, were also administered to 159 healthy individuals. RESULTSPerformance on all neuropsychological tests, except Simple Reaction Time and Digit Span, significantly improved after surgery, with more severe functional deficits showing greatest improvement. Age, education, duration, vascular comorbidity, sex, and onset symptom all failed to predict the neuropsychological effects of treatment. Despite improvement 3 months after shunt surgery, INPH patients were still outperformed by healthy individuals. CONCLUSIONMost of the wide range of neuropsychological functions that are affected by INPH are markedly improved by shunt treatment, but not completely restored.