Cognitive function in patients with Parkinson's disease undergoing stereotaxic thalamotomy

Language profiles in Noonan Syndrome - A multiple case study

Noonan Syndrome (NS) is a genetic disorder associated with a diverse range of symptoms. This study aims to provide a comprehensive description of the linguistic profiles of children and adolescents with NS, focusing on vocabulary, grammar skills, phonological memory skills, working memory skills, and visuospatial skills. Sixteen participants aged 6-16 took part in the study. The findings reveal substantial variation in the affected linguistic areas, with some participants demonstrated normal findings, while inconsistent and overall weak language skills were observed in a large subgroup of participants.

Focused ultrasound thalamotomy in Parkinson disease: Nonmotor outcomes and quality of life

OBJECTIVE

To examine nonmotor outcomes and correlates of quality of life (QoL) 3 and 12 months after unilateral focused ultrasound thalamotomy in tremor-dominant Parkinson disease (TDPD).

METHODS

Twenty-seven patients with TDPD in a double-blind, sham-controlled, randomized clinical trial underwent comprehensive neuropsychological evaluations. These included assessment of mood, behavior, and QoL at baseline, 3 months, 3 months post crossover in the sham group, and 12 months after active treatment. We used Mann-Whitney U tests to assess differences between the active (n = 20) and sham (n = 7) groups at 3 months and Friedman tests to assess within-group changes after active treatment. We assessed correlations between disease variables and postoperative QoL using Kendall tau-b tests.

RESULTS

There were no differences in cognition, mood, or behavior between the active and sham groups at 3-month blinded assessment. After active treatment, there were no differences in mood or behavior. Only declines in Stroop Color Naming and phonemic fluency were observed. Patients experienced postoperative improvements in QoL and activities of daily living (ADL). Mood and behavioral symptoms, aspects of cognitive functioning, ADL, and overall motor symptom severity, but not tremor severity specifically, were associated with QoL.

CONCLUSIONS

In TDPD, unilateral focused ultrasound thalamotomy appears safe from a cognitive, mood, and behavioral perspective. QoL and ADL significantly improved following surgery. Nonmotor symptoms and ADL were more closely associated with QoL than tremor severity.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for patients with TDPD, unilateral focused ultrasound thalamotomy did not adversely change cognition, mood, or behavior at 3 months.

A longitudinal examination of the developmental executive function hierarchy in children with externalizing behavior problems

OBJECTIVE

Using a 4-year longitudinal design, we evaluated two hypotheses based on developmental executive function (EF) hierarchy accounts in a sample of children with externalizing problems.

METHOD

The participants performed EF tasks when they were between 8 and 12 years (M = 9.93), and again approximately 4 years later when they were between 12 and 15 years (M = 13.36).

RESULTS

Inhibition in middle childhood predicted working memory (WM) 4 years later. Further, deficits in inhibition and sustained attention were more prominent in middle rather than late childhood, whereas poor WM was salient throughout these periods.

CONCLUSIONS

These findings support the hypotheses that EFs develop hierarchically and that EF deficits in ADHD are more prominent in actively developing EFs. They also emphasize ADHD as a developmental disorder.

Emerging therapies for Parkinson's disease: from bench to bedside

The prevalence of Parkinson's disease (PD) increases with age and is projected to increase in parallel to the rising average age of the population. The disease can have significant health-related, social, and financial implications not only for the patient and the caregiver, but for the health care system as well. While the neuropathology of this neurodegenerative disorder is fairly well understood, its etiology remains a mystery, making it difficult to target therapy. The currently available drugs for treatment provide only symptomatic relief and do not control or prevent disease progression, and as a result patient compliance and satisfaction are low. Several emerging pharmacotherapies for PD are in different stages of clinical development. These therapies include adenosine A2A receptor antagonists, glutamate receptor antagonists, monoamine oxidase inhibitors, anti-apoptotic agents, and antioxidants such as coenzyme Q10, N-acetyl cysteine, and edaravone. Other emerging non-pharmacotherapies include viral vector gene therapy, microRNAs, transglutaminases, RTP801, stem cells and glial derived neurotrophic factor (GDNF). In addition, surgical procedures including deep brain stimulation, pallidotomy, thalamotomy and gamma knife surgery have emerged as alternative interventions for advanced PD patients who have completely utilized standard treatments and still suffer from persistent motor fluctuations. While several of these therapies hold much promise in delaying the onset of the disease and slowing its progression, more pharmacotherapies and surgical interventions need to be investigated in different stages of PD. It is hoped that these emerging therapies and surgical procedures will strengthen our clinical armamentarium for improved treatment of PD.

Auditory Memory deficit in Elderly People with Hearing Loss

INTRODUCTION

Hearing loss is one of the most common problems in elderly people. Functional side effects of hearing loss are various. Due to the fact that hearing loss is the common impairment in elderly people; the importance of its possible effects on auditory memory is undeniable. This study aims to focus on the hearing loss effects on auditory memory.

MATERIALS AND METHODS

Dichotic Auditory Memory Test (DVMT) was performed on 47 elderly people, aged 60 to 80; that were divided in two groups, the first group consisted of elderly people with hearing range of 24 normal and the second one consisted of 23 elderly people with bilateral symmetrical ranged from mild to moderate Sensorineural hearing loss in the high frequency due to aging in both genders.

RESULTS

Significant difference was observed in DVMT between elderly people with normal hearing and those with hearing loss (P<0.22). According to the correlation test between Pure Tone Average (PTA) and the mean score of DVMT, increasing PTA resulted in reduction of DVMT score and this result was seen in both genders and all of the studied subjects.

CONCLUSION

Apart from aging, age-related hearing loss has shown significant effect on auditory verbal memory. This result depicts the importance of auditory intervention to make better communicational skills and therefore auditory memory in this population.

Neuropsychological function and past exposure to metallic mercury in female dental workers

The aim of this study was to see if dental personnel with previous exposure to metallic mercury have later developed disturbances in cognitive function. Ninety-one female participants who had been selected from a previous health survey of dental personnel were investigated neuropsychologically within the following domains: motor function, short-term memory, working memory, executive function, mental flexibility, and visual and verbal long-term memory. The scores were mainly within normal ranges. Relationships between an exposure score, the duration of employment before 1990, and previously measured mercury in urine as independent variables and the neuropsychological findings as dependent variables, were analyzed by multiple linear regression controlling for age, general ability, length of education, alcohol consumption, and previous head injuries. The only relationship that was statistically significant in the hypothesized direction was between the previously measured urine mercury values and visual long-term memory, where the urine values explained 30% of the variability. As the study had a low statistical power and also some other methodological limitations, the results have to be interpreted with caution. Even so, we think it is right to conclude that neuropsychological findings indicative of subsequent cognitive injuries are difficult to find in groups of otherwise healthy dental personnel with previous occupational exposure to mercury.

Is impairment in cognitive inhibition in the acute phase of major depression irreversible? Results from a 10-year follow-up study

OBJECTIVES

Even though many studies demonstrate cognitive impairment in the acute phase of depression and several studies indicate that this impairment might be long lasting despite symptom reduction and recovery, there is a lack of longitudinal studies on this field with considerable follow-up length. The aim of this study was to investigate whether the impairment observed in cognitive inhibition in the acute phase of depression is reversible or irreversible in a 10-year follow-up assessment.

DESIGN

A longitudinal study of 38 individuals, 19 with recurrent unipolar depression and 19 healthy controls matched for gender, age, and education were included in the study.

METHOD

Cognitive inhibition was investigated using the Stroop test at three different occasions: acute phase, short-term (6 months), and long-term (10 years) follow-up.

RESULTS

The results show that recurrent major depressive disorder patients have a long-lasting impairment in inhibition as measured by the Stroop test in 10-year follow-up. Further there is high consistency in inner group performance suggesting that severe impairment in the acute phase of illness is associated with severe impairment 10 years later despite recovery in the patient group.

CONCLUSIONS

The results show that impairment in cognitive inhibition is long lasting when present in the acute phase of recurrent depression. Impaired cognitive inhibition might be an irreversible vulnerability marker for recurrent depression.

An examination of shared variance in self-report and objective measures of attention in the incarcerated adult population

OBJECTIVE

The present study was designed to test some assumptions about screening procedures for ADHD in adults.

METHOD

Twenty-eight incarcerated male adults completed a self report scale of attention deficits as a part of an examination of attention and reading skills. Further assessment of attention included a battery of tests that assessed vigilance, attention shifts, and other aspects of cognitive control.

RESULTS

Fifty seven percent of the sample showed test performance indicating a high probability of ADHD. Correlation analyses yielded significant effects for self report scales and objective tests of attention.

CONCLUSION

The results support the assumption that the self report measures share a significant part of the variance with tests of attention commonly used in clinical assessment. However, the risk of making both false positive and false negative inferences about ADHD is present, as the specificity and the sensitivity of the rating scale needs to be further explored.

Enduring cognitive dysfunction in unipolar major depression: a test-retest study using the Stroop paradigm

The aim of the study was to investigate automatic and effortful information processing with the Stroop paradigm in a long term perspective in patients with major depressive disorder (MDD). Patients were tested at two test occasions: at inclusion with a Hamilton Depression Rating Scale (HDRS) score >18, and after 6 months, when most patients had experienced symptom reduction. The Stroop paradigm is considered to measure aspects of attention and executive functioning and consists of three conditions/cards: naming the color of the patches (Color), reading of the color-words (Word) and naming the ink color of color-words (Color-Word). The Color-Word condition is proved to be the most cognitive demanding task and requires the proband to actively suppress interference and is therefore considered to require more effortful information processing, whereas naming the color of the patches and reading the color-words are expected to be more automatic and less cognitive demanding. A homogenous group of 19 patients with unipolar recurrent MDD according to DSM-IV and a HDRS score of >18 were included in the study. A control group was individually matched for age, gender and level of education. Depressed patients performed equal to the control group on the Color and Word cards at both test occasions. However, the patients were impaired compared with the control group on the Color-Word card task at both test occasions. Thus, the depressed patients showed no improvement of effortful attention/executive performance as a function of symptom reduction. The results indicate that the depressed patients showed impaired cognitive performance on cognitive demanding tasks when symptomatic and that this impairment prevailed after 6 months, despite significant improvement in their depressive symptoms.

A double blind evaluation of cognitive decline in a Norwegian cohort of asymptomatic carriers of Huntington's disease

Previous studies investigating subclinical signs of cognitive decline in presymptomatic carriers of Huntington's disease (HD) have shown conflicting results. The current study examines cognition in 105 at-risk individuals, using a broad neuropsychological test battery and adopting strict inclusion criteria for attaining a homogeneous sample. Results obtained by analyses of variance and effect size calculations indicate no clinical evidence of significant cognitive decline in asymptomatic HD carriers very far from onset of illness compared to noncarriers. Closeness to disease onset amongst gene carriers influenced cognition negatively whereas cytosine-adenine-guanine (CAG) repeat size did not. The findings call for longitudinal follow-up studies using a combination of clinical instruments and experimental paradigms to pinpoint when subtle cognitive deficits occur and within which of the cognitive domains.

Selective deficit in executive functioning among patients with borderline personality disorder

BACKGROUND

The aim of this study was to investigate the functioning of patients with borderline personality disorder (BPD) compared to healthy controls on five neuropsychological domains, with regard to the possible effect of differences in IQ.MethodOut-patients and in-patients with BPD (n=35) and healthy comparison subjects (n=35) were tested with an extensive neuropsychological battery, where most cognitive domains were covered by several tests.

RESULTS

When controlling for the effect of IQ, patients were found to have reduced executive functioning as compared to healthy controls. With regard to the other neuropsychological domains (working memory, attention, long-term verbal memory, and long-term non-verbal memory), no differences were found between the two groups. Within-subject analyses also identified executive functioning as a selective deficit among patients whereas long-term verbal memory was identified as a relative strength. An association was identified between the covariate general intellectual functioning and every neuropsychological domain. No statistically significant differences were found between the subgroups of patients with and without co-morbid post-traumatic stress disorder (PTSD) or between those with and without co-morbid major depression, or between the medicated and unmedicated subgroups on any of the neuropsychological domains.

CONCLUSIONS

Patients with BPD demonstrate a selective deficit in executive functioning. This corroborates studies that have identified frontal regions as potential neurobiological substrates of the BPD syndrome. The relative strength of the verbal long-term memory function raises pertinent questions regarding the presumed importance of hippocampal structures.

Left temporal lobe structural and functional abnormality underlying auditory hallucinations in schizophrenia

In this article, we have reviewed recent findings from our laboratory, originally presented in Hugdahl et al. (2008). These findings reveal that auditory hallucinations in schizophrenia should best be conceptualized as internally generated speech mis-representations lateralized to the left superior temporal gyrus and sulcus, not cognitively suppressed due to enhanced attention to the 'voices' and failure of fronto-parietal executive control functions. An overview of diagnostic questionnaires for scoring of symptoms is presented together with a review of behavioral, structural, and functional MRI data. Functional imaging data have either shown increased or decreased activation depending on whether patients have been presented an external stimulus during scanning. Structural imaging data have shown reduction of grey matter density and volume in the same areas in the temporal lobe. We have proposed a model for the understanding of auditory hallucinations that trace the origin of auditory hallucinations to neuronal abnormality in the speech areas in the left temporal lobe, which is not suppressed by volitional cognitive control processes, due to dysfunctional fronto-parietal executive cortical networks.

Pathological dissociation and neuropsychological functioning in borderline personality disorder

OBJECTIVE

Transient, stress-related severe dissociative symptoms or paranoid ideation is one of the criteria defining the borderline personality disorder (BPD). Examinations of the neuropsychological correlates of BPD reveal various findings. The purpose of this study was to investigate the association between dissociation and neuropsychological functioning in patients with BPD.

METHOD

The performance on an extensive neuropsychological battery of patients with BPD with (n=10) and without (n=20) pathological dissociation was compared with that of healthy controls (n=30).

RESULTS

Patients with pathological dissociation were found to have reduced functioning on every neuropsychological domain when compared with healthy controls. Patients without pathological dissociation were found to have reduced executive functioning, but no other differences were found.

CONCLUSION

Pathological dissociation is a clinical variable that differentiates patients with BPD with regard to cognitive functioning.

Attention and cognitive control: unfolding the dichotic listening story

In this article we present a theoretical approach to cognitive control and attention modulation, as well as review studies related to such a view, using an auditory task based on dichotic presentations of simple consonant-vowel syllables. The reviewed work comes out of joint research efforts by the 'Attention-node' at the 'Nordic Center of Excellence in Cognitive Control'. We suggest a new way of defining degrees of cognitive control based on systematically varying the stimulus intensity of the right or left ear dichotic stimulus, thus parametrically varying the degree of stimulus interference and conflict when assessing the amount of cognitive control necessary to resolve the interference. We first present an overview and review of previous studies using the so-called "forced-attention" dichotic listening paradigm. We then present behavioral and neuroimaging data to explore the suggested cognitive control model, with examples from normal adults, clinical and special ability groups.

Executive deficits in chronic PTSD related to political violence

Twenty-two subjects with chronic PTSD were compared to 23 subjects with no diagnoses (NPD) on tests of executive functioning (EF) that are assumed to have clinical significance after exposure to political violence.

METHOD

The three cognitive components of EF, intentionality, inhibition and executive memory [Burgess, P. W., Alderman, N., Evans, J., Emslie, H., Wilson, B. A. (1998). The ecological validity of tests of executive function. Journal of the International Neuropsychological Society, 4, 547-58], were measured using the Tower of London, Stroop Color-Word Test and Wisconsin Card Sorting Test (WCST), respectively.

RESULTS

The PTSD group was impaired on tasks measuring automatic processing and executive memory. Executive memory problems were related to elevated posttraumatic symptoms, but the executive components intentionality and inhibition did not differentiate the groups. Arousal and intrusive symptoms had no impact on intentionality.

CONCLUSION

Posttraumatic symptoms are related to automatic processing problems and impairment in executive memory. Observed dysfunctions in mental flexibility could have a negative impact on the cognitive processing of traumatic memory, thus preventing from recovery.

Neuropsychological function and symptoms in subjects with subclinical hypothyroidism and the effect of thyroxine treatment

OBJECTIVE

Our objective was to examine the relation between neuropsychological function and subclinical hypothyroidism (SHT), defined as serum TSH of 3.5-10.0 mIU/liter and normal serum free T4 and free T3 levels, and to study the effect of T4 supplementation.

SUBJECTS

A total of 89 subjects (45 males) with SHT and 154 control subjects (72 males) were recruited from a general health survey (the fifth Tromsø study). Sixty-nine of those with SHT were included in a placebo-controlled, double-blind intervention study with T4 medication for 1 yr.

MAIN OUTCOME MEASURES

We used fourteen tests of cognitive function, Beck Depression Inventory, General Health Questionnaire, and a questionnaire on hypothyroid symptoms.

RESULTS

The mean +/- sd serum TSH in the SHT and control group were 5.57 +/- 1.68 and 1.79 +/- 0.69 mIU/liter, respectively. There were no significant differences in cognitive function and hypothyroid symptoms between the two groups, but those with SHT scored significantly better than the controls on the GHQ-30. At the end of the intervention study, serum TSH in the T4 group (n = 36) and the placebo group (n = 33) were 1.52 +/- 1.51 and 5.42 +/- 1.96 mIU/liter, respectively. T4 substitution had no effect on any of the parameters measured.

CONCLUSION

In subjects with SHT where the serum TSH level is in the 3.5-10.0 mIU/liter range, there is no neuropsychological dysfunction, and compared with healthy controls, there is no difference in symptoms related to hypothyroidism.

Neuropsychological function in relation to serum parathyroid hormone and serum 25-hydroxyvitamin D levels. The Tromsø study

There are receptors for parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D in the brain, and there are clinical and experimental data indicating that PTH and vitamin D may affect cerebral function. In the present study 21 subjects who both in the 5th Tromsø study and at a follow-up examination fulfilled criteria for secondary hyperparathyroidism (SHPT) without renal failure (serum calcium < 2.40 mmol/L, serum PTH > 6.4 pmol/L, and normal serum creatinine) and 63 control subjects were compared with tests for cognitive and emotional function. Those in the SHPT group had significantly impaired performance in 3 of 14 cognitive tests (Digit span forward, Stroop test part 1 and 2, and Word association test (FAS)) as compared with the controls, and also had a significantly higher depression score at the Beck Depression Inventory (BDI) (items 1-13). In a multiple linear regression model, a high serum PTH level was significantly associated with low performance at the Digit span forward, Stroop test part 1 and 2, and Digit Symbol tests. A low level of serum 25-hydroxyvitamin D was significantly associated with a high depression score. In conclusion, a deranged calcium metabolism appears to be associated with impaired function in several tests of neuropsychological function.

Neuropsychiatric disturbances in SLE are associated with antibodies against NMDA receptors

To determine whether neuropsychiatric manifestations in patients with systemic lupus erythematosus (SLE) are influenced by antibodies against the human N-methyl-D-aspartate (NMDA) receptor types NR2a or NR2b. A decapeptide was synthesized containing a sequence motif present in the extracellular ligand-binding domain of NMDA receptors NR2a and NR2b, bound by the monoclonal murine anti-DNA antibody R4A. In an ELISA with the murine monoclonal R4v as positive control, plasma samples of 57 patients with SLE were examined for the anti-peptide (anti-NR2) antibody after the patients had been subjected to comprehensive psychological and cognitive testing. Poor performance on the Visual Paired Associates test (immediate), the Grooved Pegboard test, as well as high scores on the Beck Depression Inventory, and scales D-2 (depression), Pd-4 (psychopathic deviate), Sc-8 (schizophrenia), and Ma-9 (hypomania) of the MMPI-2 were significantly associated with elevated levels of anti-NR2 antibodies. The findings in several domains indicate an association between anti-NR2 antibodies and depressed mood in addition to decreased short-time memory and learning. Antibodies to NMDA receptors thus may represent one of several mechanisms for cerebral dysfunction in patients with SLE.

Neuropsychiatric complications of medical and surgical therapies for Parkinson's disease

This review deals with the range of neuropsychiatric problems that may arise from the use of medical and surgical therapies in the treatment of Parkinson's disease. As new approaches emerge, these problems are diversifying. Well-recognized drug-related complications include hallucinations and psychosis and the so-called dopamine-dysregulation syndrome. The etiology of these problems has not been fully established and is not clearly dose related, while the management can be difficult and needs to be tailored to the individual patient. Cholinergic and dopaminergic drugs may both influence cognitive function. The development of pharmacogenetics could improve the therapeutic ratio of medical approaches to PD in the future. The literature relating to the neuropsychiatric issues complicating the surgical treatment of Parkinson's disease is more recent and frequently suffers from methodological problems, lack of a systematic approach, and adequate patient follow-up. The emergence of neuropsychiatric problems in association with surgery has shed new light upon the pathophysiological mechanisms underpinning these symptoms. Depression, hypomania, euphoria, mirth, and hypersexuality have all been described following deep brain stimulation procedures, although most studies have concentrated upon the depressive features. Anxiety has been described only rarely to date. Fortunately, permanent cognitive complications appear to be rare. The optimal management approach for surgically related neuropsychiatric problems is unknown at present. Prospective multicenter studies would contribute significantly to resolving this therapeutic uncertainty.

Vascular syndromes of the thalamus

BACKGROUND

This article reviews the anatomy, connections, and functions of the thalamic nuclei, their vascular supply, and the clinical syndromes that result from thalamic infarction.

SUMMARY OF REVIEW

Thalamic nuclei are composed of 5 major functional classes: reticular and intralaminar nuclei that subserve arousal and nociception; sensory nuclei in all major domains; effector nuclei concerned with motor function and aspects of language; associative nuclei that participate in high-level cognitive functions; and limbic nuclei concerned with mood and motivation. Vascular lesions destroy these nuclei in different combinations and produce sensorimotor and behavioral syndromes depending on which nuclei are involved. Tuberothalamic territory strokes produce impairments of arousal and orientation, learning and memory, personality, and executive function; superimposition of temporally unrelated information; and emotional facial paresis. Paramedian infarcts cause decreased arousal, particularly if the lesion is bilateral, and impaired learning and memory. Autobiographical memory impairment and executive failure result from lesions in either of these vascular territories. Language deficits result from left paramedian lesions and from left tuberothalamic lesions that include the ventrolateral nucleus. Right thalamic lesions in both these vascular territories produce visual-spatial deficits, including hemispatial neglect. Inferolateral territory strokes produce contralateral hemisensory loss, hemiparesis and hemiataxia, and pain syndromes that are more common after right thalamic lesions. Posterior choroidal lesions result in visual field deficits, variable sensory loss, weakness, dystonia, tremors, and occasionally amnesia and language impairment.

CONCLUSIONS

These vascular syndromes reflect the reciprocal cerebral cortical-thalamic connections that have been interrupted and provide insights into the functional properties of the thalamus.

Task switching deficits associated with Parkinson's disease reflect depleted attentional resources

Using a Stroop task switching paradigm, Brown and Marsden [Brain 111 (1988) 323; Brain 114 (1991) 215] proposed that set shifting deficits in Parkinson's disease (PD) reflect limited attentional resources rather than deficits in internal control, as was previously supposed. In the present study, we tested this claim using a more recently developed Stroop task switching paradigm for which the internal control and attentional resources accounts made contrasting predictions. A PD group (N=30) was compared with an age-matched control group (N=34) on vocal response time (RT) for color naming and word reading in response to neutral and incongruent Stroop stimuli. Participants carried out four blocks of task repetition trials, and eight blocks of task switching trials. The results revealed that a deficit due to PD was absent for two conditions necessitating internal control, but was present in the condition which placed the highest demand on attentional resources. This selective deficit is congruent with Brown and Marsden's conclusions that depleted attentional resources, not an impairment in internal control per se, is the basis of the set shifting deficits associated with PD.

Postmortem analysis of bilateral subthalamic electrode implants in Parkinson's disease

This is the second neuropathological report detailing bilateral electrodes targeting the subthalamic nucleus (STN) in idiopathic Parkinson's disease (PD). The patient presented with unilateral tremor-dominant parkinsonism. Bilateral STN stimulation was carried out 7 years later due to significant disease progression and severe motor fluctuations. The patient exhibited bilateral improvements in rigidity and bradykinesia both intraoperatively and postoperatively. The patient died 2 months later from aspiration pneumonia. Neuropathological examination confirmed both the diagnosis of PD and the electrode placements. The tip of the left electrode was located medially and posteriorly in the left STN and the tip of the right electrode entered the base of the thalamus/zona incerta immediately above the right STN. Tissue changes associated with the subthalamic electrode tracts included mild cell loss, astrogliosis, and some tissue vacuolation. Our postmortem analysis indicates little tissue damage associated with STN stimulation for PD.

Neuropsychiatry of the basal ganglia

This review aims to relate recent findings describing the role and neural connectivity of the basal ganglia to the clinical neuropsychiatry of basal ganglia movement disorders and to the role of basal ganglia disturbances in "psychiatric"' states. Articles relating to the relevant topics were initially collected through MEDLINE and papers relating to the clinical conditions discussed were also reviewed. The anatomy and connections of the basal ganglia indicate that these structures are important links between parts of the brain that have classically been considered to be related to emotional functioning and brain regions previously considered to have largely motor functions. The basal ganglia have a role in the development and integration of psychomotor behaviours, involving motor functions, memory and attentional mechanisms, and reward processes.

Prophylactic hyperdynamic postoperative fluid therapy after aneurysmal subarachnoid hemorrhage: a clinical, prospective, randomized, controlled study

OBJECTIVE

To investigate the role of prophylactic hyperdynamic postoperative fluid therapy in preventing delayed ischemic neurological deficits attributable to cerebral vasospasm.

METHODS

We designed a prospected, randomized, controlled study and included 32 patients with subarachnoid hemorrhage. Sixteen patients received hypervolemic hypertensive hemodilution fluid therapy; the other 16 patients received normovolemic fluid therapy. All patients were monitored for at least 12 days, with clinical assessments, transcranial Doppler recordings, single-photon emission computed tomographic (SPECT) scanning, and routine computed tomographic scanning. For fluid balance monitoring, a number of blood samples were obtained on a daily basis and continuous central venous pressure and mean arterial blood pressure measurements were performed for both groups. All patients received intravenous nimodipine infusions between Day 1 and Day 12. End points of this study were clinical outcomes, clinically evident and transcranial Doppler sonography-evident vasospasm, SPECT findings, complications, and costs. Clinical examinations (using the Glasgow Outcome Scale) performed 1 year after discharge, together with neuropsychological assessments and SPECT scanning, were the basis for the evaluation of clinical outcomes.

RESULTS

No differences were observed between the two groups with respect to cerebral vasospasm (as observed clinically or on transcranial Doppler recordings). When regional cerebral blood flow was evaluated by means of SPECT analysis performed on Day 12 after subarachnoid hemorrhage, no differences were revealed. One-year clinical follow-up assessments (with the Glasgow Outcome Scale), including SPECT findings and neuropsychological function results, did not demonstrate any significant group differences. Costs were higher and complications were more frequent for the hyperdynamic therapy group.

CONCLUSION

Neither early nor late outcome measures revealed any significant differences between the two subarachnoid hemorrhage treatment models.

Open interconnected model of basal ganglia-thalamocortical circuitry and its relevance to the clinical syndrome of Huntington's disease

The early stages of Huntington's disease (HD) present with motor, cognitive, and emotional symptoms. Correspondingly, current models implicate dysfunction of the motor, associative, and limbic basal ganglia-thalamocortical circuits. Available data, however, indicate that in the early stages of the disease, striatal damage is mainly restricted to the associative striatum. Based on an open interconnected model of basal ganglia-thalamocortical organization, we provide a detailed account of the mechanisms by which associative striatal pathology may lead to the complex pattern of motor, cognitive, and emotional symptoms of early HD. According to this account, the degeneration of a direct and several indirect pathways arising from the associative striatum leads to impaired functioning of: (1) the motor circuit, resulting in chorea and bradykinesia, (2) the associative circuit, resulting in abnormal eye movements, "frontal-like" cognitive deficits and "cognitive disinhibition," and (3) the limbic circuit, resulting in affective and psychiatric symptoms. When relevant, this analysis is aided by comparing the symptomatology of HD patients to that of patients with mild to moderate Parkinson's disease, since in the latter there is similar dysfunction of direct pathways but opposite dysfunction of indirect pathways. Finally, we suggest a potential novel treatment of HD and provide supportive evidence from a rat model of the disease.

Cognitive functioning after subthalamic nucleotomy for refractory Parkinson's disease

OBJECTIVE

To evaluate whether subthalamic nucleotomy produces adverse cognitive effects in patients with Parkinson's disease.

METHOD

Twelve patients with Parkinson's disease underwent stereotactic surgery to the subthalamic nucleus. Presurgical and postsurgical neuropsychological assessment of attention, memory, executive function, language, and verbal intellect were undertaken with a battery of tests designed to minimise potential contamination of cognitive effects by motor symptoms.

RESULTS

There was no statistically significant difference in the cognitive tests results after operation for the group as a whole. Reliable change indexes were generated for the cognitive tests. Reliable change postoperatively was found on specific tests of verbal memory, attention, and planning. Left sided operations were associated with greater incidence of deterioration postsurgery.

CONCLUSIONS

Preliminary data on the first reported cognitive changes after subthalamic nucleotomy suggested few adverse cognitive effects of the surgery although discrete neuropsychological changes were seen in some patients. These effects were consistent with current theories on the cognitive functions of the basal ganglia.

Neurocognitive correlates of stereotactic thalamotomy and thalamic stimulation in Parkinsonian patients

In the present paper we have reviewed five different studies that relate to neuropsychological consequences of stereotactic thalamotomy and thalamic stimulation in patients with Parkinson's disease. The neuropsychological results are in a strict sense confined to thalamotomy and thalamic stimulation, although the more general message of the importance of investigating cognitive functions before and after surgery applies to other stereotactic techniques for surgical treatment of movement disorders as well. It is argued in the paper that stereotactic thalamotomy provides a unique model for basic research on the neuropsychology of the thalamus, while in return, neuropsychological tests for cognitive dysfunction after surgery may be the most important clinical follow-up. Three general conclusions seem warranted from the data. (1) Parkinsonian patients are impaired on a range of cognitive functions, including language processing, memory, and executive functions. (2) Stereotactic thalamotomy does not further impair the patient; instead, we observed improvement on some tests, particularly verbal memory. (3) In general, there does not seem to be a laterality effect, depending on which side the thalamotomy lesion is applied. An exception to this are dichotically presented simple speech sounds and autonomic responses. In both instances, left-sided brain stimulation produced enhanced performance, while lesioning the left thalamus impaired dichotic listening performance. Finally, we present a new hypothesis for a mechanism behind the thalamotomy effect, based in part on changes in arousal thresholds.

Cognitive outcomes after deep brain stimulation for Parkinson's disease: a review of initial studies and recommendations for future research

Modern ablative surgery for movement disorders probably results in less frequent and severe cognitive morbidity than seen in early surgical series. Nonetheless, recent studies indicate that neurobehavioral functions commonly compromised in Parkinson's disease (PD) (e.g., executive functions, verbal fluency, and memory) are negatively impacted in some patients by lesion placement. The potential reversibility of cognitive dysfunction after chronic electrical deep brain stimulation (DBS) for PD has lead some to favor this treatment modality over ablation. This paper reviews the initial studies of the cognitive effects of thalamic, pallidal, and subthalamic DBS. These studies suggest that DBS is relatively safe from a cognitive standpoint and that the benefits of motor improvements probably outweigh the cost of minimal cognitive morbidity. This conclusion must be offered with caution, however, given the small numbers of studies to date and their methodological limitations. Neurobehavioral research has yet to adequately address (1) outcome relative to appropriate control groups; (2) effects of electrode placement versus stimulation; (3) laterality- and site-specific effects of DBS; (4) long-term effects of DBS; (5) effects of stimulation parameters; (6) risk factors for cognitive dysfunction with DBS; (7) whether cognitive dysfunction associated with DBS is reversible; and (8) comparative neurobehavioral outcome after DBS and ablation. DBS affords an exciting opportunity to clarify the neurobehavioral role of the basal ganglia.

Neuropsychological functioning in a patient with essential tremor with and without bilateral VIM stimulation

The effects of deep brain stimulation on motor functions, cognitive abilities, and mood were assessed in an 80-year-old, right-handed male with a chronic history of essential tremor. Electrodes were implanted bilaterally in the ventral intermediate nucleus of the thalamus during a single operation. Upon evaluation at 3 months postsurgery, bilateral stimulation was associated with a clinically significant reduction in tremor ratings and improvement in manual dexterity. At that time, a battery of neuropsychological measures was administered with and without bilateral stimulation. The patient demonstrated comparable performances on measures of visuospatial perception, attention, mental tracking, verbal learning, and verbal recognition memory in both the "on" and "off" conditions. Without stimulation, the patient demonstrated declines of greater than 1 SD on measures of verbal fluency and verbal recall compared to when the stimulators were active. Responses to mood rating scales also indicated greater subjective distress without stimulation. Results are discussed in the context of previous studies of the effects of thalamic stimulation on neurocognitive functioning.

Physiological localisation in functional neurosurgery for movement disorders: a simple approach

Controversy exists between anatomical methods and single cell recording as the preferred approach in target localisation in functional neurosurgery for movement disorders. The controversy centres on accuracy as compared to practicality. We describe a mapping technique of semi-microstimulation utilising threshold measurements which has been used in 66 procedures in 50 subjects. We compared the accuracy of anatomical localisation with the final chosen target using the above technique. We also compared the benefit, the side effects and the surgical complication rate with published data on single cell recording and anatomical localisation. The mean difference in 3-dimensional space between the anatomical target and the physiological target was 6.85 mm (P < 0.0001). A good response was obtained in 80% of procedures. Mortality was 1.5%. The surgical complication rate was 1.5%. Mild side effects, serious side effects, transient side effects and permanent side effects were evident in 4.5%, 10.6%, 6.1% and 9.1% of procedures. These figures compared better than anatomical studies and similar to single cell recording studies. It is concluded that this approach provides both accuracy and simplicity and is recommended as a compromise to the currently available methods.

Chronic electrical stimulation of the left ventrointermediate (Vim) thalamic nucleus for the treatment of pharmacotherapy-resistant Parkinson's disease: a differential impact on access to semantic and episodic memory?

Thalamotomy for medically refractory Parkinson's disease (PD) is considered to be efficacious and relatively safe. Because a minority of patients experience decrements in language and memory (often mild and transient) after thalamotomy, chronic thalamic deep brain stimulation (DBS) might be a safer treatment given its reversibility and the modifiability of stimulation parameters. Two preliminary studies support the relative cognitive safety of unilateral DBS of the ventral intermediate (Vim) thalamic nucleus, but it is unclear whether possibly subtle changes in language and memory represent effects of "microthalamotomy" or of stimulation per se. This report provides preliminary data concerning effects of left thalamic stimulation on information processing speed, semantic memory (verbal fluency and visual confrontation naming), and verbal episodic memory in a patient with PD. In addition to being evaluated before and 3 and 6 months after surgery, the patient was tested 18 months after surgery either on or off medications and with the stimulator turned either on or off (order counterbalanced across medication conditions). Test performance differences between the stimulation conditions were attenuated "off" as compared to "on" medication. Vim stimulation consistently, albeit subtly, improved semantic verbal fluency but interfered with immediate recall of word lists. Parallels to findings from acute, intraoperative thalamic stimulation studies are explored. The hypothesis is offered that left Vim stimulation might facilitate access to semantic memory, but interfere with episodic memory processes.