Accuracy and reproducibility of simple cross-sectional linear and area measurements of brain structures and their comparison with volume measurements

Communicating Hydrocephalus Following Treatment of Cerebellopontine Angle Tumors

OBJECTIVE

This study aimed to clarify the risk of communicating hydrocephalus in cerebellopontine angle tumors, focusing on distinct tumor types and treatment modalities, i.e., tumor resection and stereotactic radiosurgery (SRS).

METHODS

This study was a retrospective single-center cohort study. The cumulative incidences of symptomatic communicating hydrocephalus in schwannoma and meningioma patients were evaluated. A multivariate Cox model was used to assess the hazard ratios for the risk factors and odds ratios of distinct treatment subgroups.

RESULTS

A total of 405 cases, including 286 schwannomas and 119 meningiomas, were retrospectively reviewed. The risk of hydrocephalus was significantly higher in schwannomas than that in meningiomas (hazard ratio, 4.70 [95% confidence interval, 1.78-12.4, P = 0.002]). Patients with schwannomas who received SRS without tumor resection showed a significantly higher incidence than meningioma cases: 10.6% versus 1.4% (P = 0.037). We identified specific subgroups that were prone to increase the risk of hydrocephalus when treated with SRS alone. The result showed that patients with vestibular schwannoma of Koos grade III had a greater benefit from tumor resection than from SRS in preventing hydrocephalus (odds ratio, 0.089 [95% confidence interval, 0.011-0.743, P = 0.025]).

CONCLUSIONS

Symptomatic communicating hydrocephalus is more frequent in schwannoma than that in meningiomas. Primary treatment with tumor resection lowers the risk of hydrocephalus in specific subgroups of vestibular schwannoma.

Standard values for MRI brain biometry throughout the first year of life

BACKGROUND

Brain structures in the infant brain are investigated reliably using cranial magnetic resonance imaging. However, the lack of quantitative standard values for various brain regions results in data interpretation that is often subjective or based on small patient cohorts. The aim of this study was to create simple linear measurements to assess brain structures in infancy.

METHODS

We assessed cranial magnetic resonance imaging sessions of 131 children without intracerebral pathology retrospectively for size of various brain structures throughout the first year of life.

RESULTS

Standard values for the size and the growth rate of 14 brain structures including lateral ventricles, frontal subarachnoid space, pons, medulla oblongata, cerebellar vermis, pituitary gland, optical nerve, corpus callosum and the tegmentovermian angle were defined.

CONCLUSION

Our study offers reference values for the biometric assessment of the infant brain. Especially in children with multiple brain malformations, it is essential to know the normal absolute and relative size of brain structures.

Cognitive Control, Learning, and Clinical Motor Ratings Are Most Highly Associated with Basal Ganglia Brain Volumes in the Premanifest Huntington's Disease Phenotype

OBJECTIVES

Huntington's disease (HD) is a debilitating genetic disorder characterized by motor, cognitive and psychiatric abnormalities associated with neuropathological decline. HD pathology is the result of an extended chain of CAG (cytosine, adenine, guanine) trinucleotide repetitions in the HTT gene. Clinical diagnosis of HD requires the presence of an otherwise unexplained extrapyramidal movement disorder in a participant at risk for HD. Over the past 15 years, evidence has shown that cognitive, psychiatric, and subtle motor dysfunction is evident decades before traditional motor diagnosis. This study examines the relationships among subcortical brain volumes and measures of emerging disease phenotype in prodromal HD, before clinical diagnosis.

METHODS

The dataset includes 34 cognitive, motor, psychiatric, and functional variables and five subcortical brain volumes from 984 prodromal HD individuals enrolled in the PREDICT HD study. Using cluster analyses, seven distinct clusters encompassing cognitive, motor, psychiatric, and functional domains were identified. Individual cluster scores were then regressed against the subcortical brain volumetric measurements.

RESULTS

Accounting for site and genetic burden (the interaction of age and CAG repeat length) smaller caudate and putamen volumes were related to clusters reflecting motor symptom severity, cognitive control, and verbal learning.

CONCLUSIONS

Variable reduction of the HD phenotype using cluster analysis revealed biologically related domains of HD and are suitable for future research with this population. Our cognitive control cluster scores show sensitivity to changes in basal ganglia both within and outside the striatum that may not be captured by examining only motor scores. (JINS, 2017, 23, 159-170).

Physical training decreases susceptibility to pilocarpine-induced seizures in the injured rat brain

There is growing evidence that physical activity ameliorates the course of epilepsy in animal models as well as in clinical conditions. Since traumatic brain injury is one of the strongest determinants of epileptogenesis, the present study focuses on the question whether a moderate long-term physical training can decrease susceptibility to seizures evoked following brain damage. Wistar rats received a mechanical brain injury and were subjected to daily running sessions on a treadmill for 21 days. Thereafter, seizures were induced by pilocarpine injections in trained and non-trained, control groups. During the acute period of status epilepticus, the intensity of seizures was assessed within the six-hour observation period. The trained rats showed considerable amelioration of pilocarpine-induced motor symptoms when compared with their non-trained counterparts. Histological investigations of effects of the brain injury and of physical training detected significant quantitative changes in parvalbumin-, calretinin- and NPY-immunopositive neuronal populations. Some of the injury-induced changes, especially those shoved by parvalbumin-immunopositive neurons, were abolished by the subsequent physical training procedure and could, therefore, be considered as neuronal correlates of the observed functional amelioration of the injured brain.

Estimating intracranial volume using intracranial area in healthy children and those with childhood status epilepticus

BACKGROUND

Correcting volumetric measurements of brain structures for intracranial volume (ICV) is important in comparing volumes across subjects with different ICV. The aim of this study was to investigate whether intracranial area (ICA) reliably predicts actual ICV in a healthy pediatric cohort and in children with convulsive status epilepticus (CSE).

METHODS

T1-weighted volumetric MRI was performed on 20 healthy children (control group), 10 with CSE with structurally normal MRI (CSE/MR-), and 12 with CSE with structurally abnormal MRI (CSE/MR+). ICA, using a mid-sagittal slice, and the actual ICV were measured.

RESULTS

A high Spearman correlation was found between the ICA and ICV measurements in the control (r = 0.96; P < 0.0001), CSE/MR- (r = 0.93; P = 0.0003), and CSE/MR+ (r = 0.94; P < 0.0001) groups. On comparison of predicted and actual ICV, there was no significant difference in the CSE/MR- group (P = 0.77). However, the comparison between predicted and actual ICV was significantly different in the CSE/MR+ (P = 0.001) group. Our Bland-Altman plot showed that the ICA method consistently overestimated ICV in children in the CSE/MR+ group, especially in those with small ICV or widespread structural abnormalities.

CONCLUSIONS

After further validation, ICA measurement may be a reliable alternative to measuring actual ICV when correcting volume measurements for ICV, even in children with localized MRI abnormalities. Caution should be applied when the method is used in children with small ICV and those with multilobar brain pathology.

Brain dysplasia evoked by gamma irradiation at different stages of prenatal development leads to different tonic and clonic seizure reactivity

Rats with brain dysplasia evoked by interruption of different stages of prenatal neurogenesis show characteristic variations in susceptibility to seizures depending on the neurochemical specificity of pharmacological agents used to evoke seizures. To verify a discrepancy between the data obtained using different pharmacological models, neurochemically neutral electroshocks were applied here. To produce brain dysplasia of different degrees, pregnant Wistar rats were exposed to a single 1.0Gy dose of gamma rays on gestation days 13, 15, 17 or 19. From the postnatal day 60, their male offspring (E13s, E15s, E17s and E19s, respectively) were subjected to 21 daily electrical stimulations to evoke seizures. Profiles of tonic and clonic reactivity to electrical stimulation significantly differed from those observed following pilocarpine or kainic acid administration. E17s showed minimal intensity of tonic but maximal of clonic responses. On the contrary, very high tonic and low clonic reactivity was observed in E13s and E15s. Periventricular nodular heterotopias (PNHs) were observed exclusively in E15s and E17s. Generally, the size of PNHs was correlated positively with susceptibility to tonic seizures but negatively with susceptibility to clonic seizures. Analogous correlations with the size of the neocortex were opposite. E13s and E19s had brains devoid PNHs but showed high tonic seizure susceptibility similar to that in E15s. It can therefore be concluded that PNHs modified the type of seizure reactivity from tonic to clonic, depending of their size, but the presence of PNHs was not necessary for the development of seizure susceptibility itself.

The risk factors of symptomatic communicating hydrocephalus after stereotactic radiosurgery for unilateral vestibular schwannoma: the implication of brain atrophy

PURPOSE

To identify the effect of brain atrophy on the development of symptomatic communicating hydrocephalus (SCHCP) after stereotactic radiosurgery (SRS) for sporadic unilateral vestibular schwannomas (VS).

METHODS AND MATERIALS

A total of 444 patients with VS were treated with SRS as a primary treatment. One hundred eighty-one patients (40.8%) were male, and the mean age of the patients was 53±13 years (range, 11-81 years). The mean follow-up duration was 56.8±35.8 months (range, 12-160 months). The mean tumor volume was 2.78±3.33 cm3 (range, 0.03-23.30 cm3). The cross-sectional area of the lateral ventricles (CALV), defined as the combined area of the lateral ventricles at the level of the mammillary body, was measured on coronal T1-weighted magnetic resonance images as an indicator of brain atrophy.

RESULTS

At distant follow-up, a total of 25 (5.6%) patients had SCHCP. The median time to symptom development was 7 months (range, 1-48 months). The mean CALV was 334.0±194.0 mm2 (range, 44.70-1170 mm2). The intraclass correlation coefficient was 0.988 (95% confidence interval [CI], 0.976-0.994; p<0.001). In multivariate analysis, the CALV had a significant relationship with the development of SCHCP (p<0.001; odds ration [OR]=1.005; 95% CI, 1.002-1.007). Tumor volume and female sex also had a significant association (p<0.001; OR=1.246; 95% CI, 1.103-1.409; p<0.009; OR=7.256; 95% CI, 1.656-31.797, respectively). However, age failed to show any relationship with the development of SCHCP (p=0.364).

CONCLUSION

Brain atrophy may be related to de novo SCHCP after SRS, especially in female patients with a large VS. Follow-up surveillance should be individualized, considering the risk factors involved for each patient, for prompt diagnosis of SCHCP.

Evolution of olfaction in non-avian theropod dinosaurs and birds

Little is known about the olfactory capabilities of extinct basal (non-neornithine) birds or the evolutionary changes in olfaction that occurred from non-avian theropods through modern birds. Although modern birds are known to have diverse olfactory capabilities, olfaction is generally considered to have declined during avian evolution as visual and vestibular sensory enhancements occurred in association with flight. To test the hypothesis that olfaction diminished through avian evolution, we assessed relative olfactory bulb size, here used as a neuroanatomical proxy for olfactory capabilities, in 157 species of non-avian theropods, fossil birds and living birds. We show that relative olfactory bulb size increased during non-avian maniraptoriform evolution, remained stable across the non-avian theropod/bird transition, and increased during basal bird and early neornithine evolution. From early neornithines through a major part of neornithine evolution, the relative size of the olfactory bulbs remained stable before decreasing in derived neoavian clades. Our results show that, rather than decreasing, the importance of olfaction actually increased during early bird evolution, representing a previously unrecognized sensory enhancement. The relatively larger olfactory bulbs of earliest neornithines, compared with those of basal birds, may have endowed neornithines with improved olfaction for more effective foraging or navigation skills, which in turn may have been a factor allowing them to survive the end-Cretaceous mass extinction.

Influence of obstetric complication severity on brain morphology in schizophrenia: an MR study

INTRODUCTION

The purpose of this study was to determine if a causal relationship exists between obstetric complications (OCs) severity and linear magnetic resonance (MR) measurements of brain atrophy in patients with schizophrenia.

MATERIALS AND METHODS

Linear measurements of ventricular enlargement (bifrontal span, Evans ratio, and bicaudate ratio) and hippocampal atrophy (interuncal distance) were completed on MR images obtained in 47 patients with schizophrenia. Regression analysis was used to look at association with OCs severity, assessed by the "Midwife protocol" of Parnas and colleagues. The relationship between MR measurements and phenomenologic variables such as age at onset, illness duration, and exposure to antipsychotic medications was explored. The relationship between MR measurements, OCs severity, and symptom presentation was also investigated.

RESULTS

OCs severity was significantly associated with MR measurements of ventricular enlargement (bifrontal span, Evans ratio). As the severity of OCs increased, bifrontal span and Evans ratio increased. This effect was independent of age at onset, illness duration, or even antipsychotic treatment. Interestingly, bifrontal span, Evans ratio, and OCs severity score all showed a significant positive correlation with hallucinatory symptomatology.

CONCLUSION

Although confirmatory studies are needed, our findings would support the idea that environmental factors, in this case severe OCs, might partly contribute to ventricular abnormalities in schizophrenia.

Corpus callosum size in relation to motor performance in 9- to 10-year-old children with neonatal encephalopathy

Magnetic resonance imaging studies have contributed to recognize the patterns of cerebral injury related to neonatal encephalopathy (NE). We assessed whether a smaller corpus callosum (CC) explained the difference in motor performance between school-age children with NE and controls. Frontal, middle, and posterior areas of the CC were measured in 61 9-10-y-old children with NE and in 47 controls. Motor performance was determined using the Movement Assessment Battery for Children (M-ABC). Linear regression was used to assess whether differences in M-ABC between NE children and controls could be explained by CC size. The CC of 11/30 children with NE type I according to Sarnat (NE I) and 19/36 children with NE type II according to Sarnat (NE II) showed generalized or focal thinning, compared with 8/49 controls. Children with NE II had significantly smaller middle and posterior parts and total areas of the CC. Children with NE scored significantly worse on the M-ABC than controls. The reduction in size of the posterior part of the CC partly explained the mean differences on the M-ABC. Children with NE have poorer motor skills than controls, which is partly explained by a smaller size of the CC.

Three-dimensional volumetric analysis and reconstruction of amygdala and hippocampal head, body and tail

Volumetric changes in the amygdala and hippocampus are relevant to many disorders, but their close proximity makes it difficult to separate these structures by magnetic resonance imaging, leading many volumetric protocols to exclude problematic slices from analysis, or to analyze the amygdalo-hippocampal complex conjointly. The hippocampus tail is also often excluded, because of the difficulty in separating it from the thalamus. We have developed a reliable protocol for volumetric analysis and 3-D reconstruction of the amygdala and hippocampus (as a whole and in its anatomical parts). Twenty volunteers from clinical and healthy populations were recruited. T1-weighted images were acquired at 1.5 Tesla with native spatial resolution of 1.5 mm x 1.0 mm x 1.0 mm. Volumetric analyses were performed blind to diagnosis, using the interactive software package DISPLAY. Inter-rater (intrarater) intraclass correlations for the method were: 0.95 (0.88) for hippocampus tail, 0.83 (0.93) for hippocampus body, 0.95 (0.92) for hippocampus head, 0.96 (0.86) for total hippocampus and 0.86 (0.94) for amygdala. Volumes (mean+/-S.D.) corrected for intracranial volume for this mixed group were for the hippocampal tail: 0.325+/-0.087 cm(3); hippocampal body: 0.662+/-0.120 cm(3); hippocampal head: 1.23+/-0.174 cm(3); total hippocampus: 2.218+/-0.217 cm(3), and amygdala: 0.808+/-0.185 cm(3). In conclusion, the study demonstrates that the amygdala and hippocampal parts can be quantified reliably.

Distribution of Brain Metastases in Relation to the Hippocampus: Implications for Neurocognitive Functional Preservation

PURPOSE

With the advent of intensity-modulated radiotherapy, the ability to limit the radiation dose to normal tissue offers an avenue to limit side effects. This study attempted to delineate the distribution of brain metastases with relation to the hippocampus for the purpose of exploring the viability of tomotherapy-guided hippocampal sparing therapy potentially to reduce neurocognitive deficits from radiation.

METHODS AND MATERIALS

The pre-radiotherapy T1-weighted, postcontrast axial MR images of 100 patients who received whole brain radiotherapy, stereotactic radiosurgery, or a radiosurgical boost following whole brain radiotherapy between 2002 and 2006 were examined. We contoured brain metastases as well as hippocampi with 5-, 10-, and 15-mm expansion envelopes.

RESULTS

Of the 272 identified metastases, 3.3% (n = 9) were within 5 mm of the hippocampus, and 86.4% of metastases were greater than 15 mm from the hippocampus (n = 235). The most common location for metastatic disease was the frontal lobe (31.6%, n = 86). This was followed by the cerebellum (24.3%, n = 66), parietal lobe (16.9%, n = 46), temporal lobe (12.9%, n = 35), occipital lobe (7.7%, n = 21), deep brain nuclei (4.0%, n = 11), and brainstem (2.6%, n = 7).

CONCLUSIONS

Of the 100 patients, 8 had metastases within 5 mm of the hippocampus. Hence, a 5-mm margin around the hippocampus for conformal avoidance whole brain radiotherapy represents an acceptable risk, especially because these patients in the absence of any other intracranial disease could be salvaged using stereotactic radiosurgery. Moreover, we developed a hippocampal sparing tomotherapy plan as proof of principle to verify the feasibility of this therapy in the setting of brain metastases.

In vivo basal ganglia volumetry through application of NURBS models to MR images

Volumetry of basal ganglia (BG) based on magnetic resonance imaging (MRI) provides a sensitive marker in differential diagnosis of BG disorders. The non-uniform rational B-spline (NURBS) surfaces are mathematical representations of three-dimensional structures which have recently been applied in volumetric studies. In this study, a volumetric evaluation of BG based on NURBS was performed in 35 right-handed volunteers. We aimed to compare and validate this technique with respect to manual MRI volumetry and evaluate possible side differences between these structures. Intra- and interobserver biases less than 1.5% demonstrated the method's stability. The mean percentage differences between NURBS and manual methods were less than 1% for all the structures considered; however, the internal segments of the globus pallidus showed a mean percentage difference of about 1.7%. Rightward asymmetry was found for the caudate nucleus (mean+/-SD 3.20+/-0.20 cm(3) vs. 3.10+/-0.19 cm(3), P<0.001) for both its head (1.44+/-0.10 cm(3) vs. 1.41+/-0.09 cm(3), P<0.01) and its body/tail (1.73+/-0.11 cm(3) and 1.68+/-0.12 cm(3), P<0.01), and for the globus pallidus (1.23+/-0.08 cm(3) and 1.18+/-0.09 cm(3), P<0.001) for both the internal (0.33+/-0.05 cm(3) vs. 0.31+/-0.05 cm(3), P<0.01) and external (0.90+/-0.05 cm(3) vs. 0.86+/-0.05 cm(3), P<0.001) segments. No volumetric side differences were found for the putamen (3.43+/-0.14 cm(3) vs. 3.39+/-0.17 cm(3), P>0.05). The rightward asymmetry of the BG may be ascribed to the predominant use of the right hand. In conclusion, NURBS is an accurate and reliable method for quantitative volumetry of nervous structures. It offers the advantage of giving a three-dimensional representation of the structures examined.

MRI parameters of Alzheimer's disease in an Arab population of Wadi Ara, Israel

Magnetic resonance imaging (MRI) findings are reported from 15 individuals in an Arab-Israeli community who were diagnosed with Alzheimer's disease (AD). The quantitative parameters that were used for MRI analyses included gradings (0-3) and linear measurements of different brain structures. Generalized tissue loss was assessed by combined measurements of the ventricles (ventricular score, VS) and sulcal grading and width (SG, SW, respectively). Loss of brain tissue in specific regions of interest, eg, temporal lobes, basal ganglia, and midbrain, was evaluated by precise measurements. We observed abnormal tissue characteristics, expressed as high intensity foci in white matter on T2W sequences, as well as tissue loss, both generalized and focal. Most notable were changes involving the head of the caudate nuclei, the midbrain, and to a lesser degree, medial temporal structures.

Size of the neocerebellar vermis is associated with cognition in healthy elderly men

Cerebellar volumes show small positive correlations with cognitive ability in young adults, but no studies have examined this relationship in older adults. Furthermore, no studies have examined relationships between sizes of subareas of the cerebellum and cognitive ability. We hypothesized that size of the two areas of the neocerebellar vermis would correlate with a battery of eight cognitive tests in 50 men aged 65-70. Size of the neocerebellar areas of the vermis correlated positively with several cognitive tests (r's=.29-.37, p<.05), whilst sizes of other parts of the vermis did not correlate with any cognitive tests. Total cerebellar volumes correlated significantly with a test of nonverbal reasoning (r=.030, p=.42). These findings suggest a specific association of neocerebellar vermis size with variations in cognitive ability in older adults.

Larger corpus callosum size with better motor performance in prematurely born children

The objective of this study is to determine the relation between the size of the corpus callosum (CC) and motor performance in a population-based cohort of preterm children. Preterm born children (n = 221) with a gestational age less than or equal to 32 weeks and/or a birth weight below 1500 g were eligible for this study. At the age of 7 or 8 years, frontal, middle, posterior, and total areas (mm2) of the corpus callosum were measured on true midsagittal MRI. Due to anxiety of 10 children and motion artifacts in 7 other children, 204 MRIs could be assessed in the preterm group (mean GA 29.4 weeks, sd 2.0,mean BW 1200 g, sd 323). The preterm group consisted of 15 children with cerebral palsy (CP) and 189 children without CP. Motor function was established by using the Movement Assessment Battery for Children, and the Developmental Test of Visual Motor Integration was obtained. The same examinations were performed in 21 term born children. The mean total cross-sectional CC area was significantly smaller in preterm born infants compared with their term born controls (338 mm2 versus 422 mm2, P < 0.0001). The preterm children with CP had significantly smaller mean CC areas compared with the preterms who did not develop CP (P < 0.0001-P < 0.002). However, the preterms born without CP also had significantly smaller body, posterior, and total CC areas compared with term born controls (P < 0.0001-P < 0.002). Only the difference in frontal area measurements dilrc) -3.3 mm2/score point (95% CI -4.5, -2.1). The association existed in all parts of the CC but increased in the direction of the posterior part: frontal: lrc -0.8 mm2/score point (-1.2, -0.4), middle: lrc -1.1 mm2/score point (-1.7, -0.5) and posterior: lrc -1.4 mm2/score point (-1.8, -0.9). An association between CC area and its subareas and the standard scores of the VMI was also found. A larger CC was strongly related t o better scores onthe VMI test total area CC: lrc 0.05 score/mm2 (95% CI 0.03, 0.07), frontal: lrc 0.12 score/mm2 (0.05,0.19), middle: lrc 0.10 score/mm2 (0.05, 0.15) and posterior: lrc 0.12 score/mm2 (0.06, 0.18). After adjustment for gestational age, birth weight, and total cerebral area, these associations were still significant. There is a strong association between the size of the corpus callosum (total midsagittal cross area as well as frontal, middle, and posterior area) and motor function in preterm children, investigated at school age. A poorer score on the Movement ABC was related to a smaller CC. A larger CC was strongly associated with better VMI standard scores.

Apparent diffusion coefficient (ADC) measurements may be more reliable and reproducible than lesion volume on diffusion-weighted images from patients with acute ischaemic stroke-implications for study design

Early ischemic change after stroke can be demonstrated with diffusion-weighted imaging (DWI) and quantified by measuring the apparent diffusion coefficient (ADC) and/or lesion volume. We examined the reliability and reproducibility of lesion volume and ADC measurement on DWI images, and discuss the implications for clinical studies. Using 38 DWI scans from 15 stroke patients, two observers (a physicist and a neuroscience graduate) blind to each other, recorded the lesion volume on DWI sequences, measured the ADC values in this volume and calculated the ratio of ischemic: control ADC (ADCr). One observer repeated his measurements blind to his first, and also examined the effect on lesion volume and ADC of deliberately varying by only one pixel, the outline of the visible boundary of the lesion. The inter and intra-rater reliability were worse for lesion volume than ADC or ADCr measurements: lesion volume, inter-rater coefficient of variation (CoV) 85 +/- 130%, intra-rater CoV 20+/-SD80% (p < 0.05); ADC inter-rater CoV 7.7 +/- SD 19%, intra-rater CoV 0.2 +/- SD 12% (p = NS); and ADCr inter-rater CoV 8 +/- SD27%, intra-rater CoV 0.8 +/- SD73% (p = NS). Altering the position of the outline tracing of the lesion boundary by one pixel altered the measured volumes by 22 +/- SD25% (p < 0.05), but ADC values were altered by only 2.9 +/- SD4.9% and ADCr by 2.7 +/- SD4.8% (p = NS). ADC and ADCr values are more reliable and reproducible than DWI lesion size in acute ischemic stroke because altering where the lesion boundary is measured has a much greater impact on lesion volume than on the ADC or ADCr. This effect is greatest in large lesions.

Primary medical therapy for acromegaly: an open, prospective, multicenter study of the effects of subcutaneous and intramuscular slow-release octreotide on growth hormone, insulin-like growth factor-I, and tumor size

Conventional surgery and radiotherapy for acromegaly have limitations. There are few data on the use of the somatostatin analog octreotide (Oct) as primary medical therapy. An open prospective study of 27 patients with newly diagnosed acromegaly was conducted in nine endocrine centers in the United Kingdom. Twenty patients had macroadenomas, and 7 had microadenomas. For the first 24 wk (phase 1), patients received sc Oct in an initial dose of 100 microg, 3 times daily, increased to 200 micro g three times daily after 4 wk in the 13 patients whose mean serum GH remained greater than 5 mU/liter (2 microg/liter). Five-point GH profiles were performed at 0, 4, 12, and 24 wk, and high resolution pituitary imaging using a standard protocol was performed at 0, 12, and 24 wk (magnetic resonance imaging in 25 patients and computed tomography in 2). Tumor dimensions and volumes were calculated by a central, reporting neuroradiologist, and the results were audited by a second, independent neuroradiologist. After 24 wk, 15 patients proceeded to phase 2 of the study with a direct switch to monthly injections of the depot formulation of Oct, Sandostatin long-acting release (Oct-LAR). Further GH profiles were performed at 36 and 48 wk, and pituitary imaging was performed at 48 wk. The median pretreatment serum GH concentration was 30.7 mU/liter (range, 6.7-141.4). During sc Oct, serum GH fell to less than 5 mU/liter in 9 patients (38%), and IGF-I fell to normal in 8 patients (33%). All 27 tumors shrank during sc Oct; for microadenomas the median tumor volume reduction was 49% (range, 12-73), and for macroadenomas it was 43% (range, 6-92). After 24 wk of Oct-LAR (end of phase 2), the GH level was less than 5 mU/liter in 11 of 14 patients (79%), and IGF-I was normal in 8 of 15 patients (53%). In the 15 patients given Oct-LAR (10 macroadenomas), wk 48 scans showed a further overall median tumor volume reduction of 24%. At the end of the study 79% of patients had mean serum GH levels below 5 mU/liter, 53% had normal IGF-I levels, and 73% showed greater than 30% tumor shrinkage. Twenty-nine percent of patients achieved all 3 targets, but no patient with pretreatment GH levels above 50 mU/liter did so at any stage of the study. Primary medical therapy with Oct offers the prospect of normalization of GH/IGF-I levels together with substantial tumor shrinkage in a significant subset of acromegalic patients. This is most likely to occur in patients with pretreatment GH levels less than 50 mU/liter (20 microg/liter).

Intracranial capacity and brain volumes are associated with cognition in healthy elderly men

BACKGROUND

Brain size and intracranial capacity are correlated with cognitive performance in young healthy adults, but data are lacking on these relationships in older healthy adults.

OBJECTIVE

To test the hypotheses that intracranial capacity, volumes of specific brain regions, and a measure of the shared variance between brain regions are positively associated with cognitive function in a sample of healthy, unmedicated elderly men (n = 97; mean age 67.8, SD 1.3).

METHODS

Individuals underwent MRI, with measurements of intracranial area and volumetric measurements of hippocampi, temporal lobes, and frontal lobes. Cognitive testing included measures of premorbid intelligence, fluid intelligence, verbal memory, visuospatial memory, verbal fluency, and attention and processing speed.

RESULTS

Cognitive tests showed significant positive intercorrelations throughout, and regional brain volumes were also universally, significantly, and positively intercorrelated. Intracranial area and several regional brain volumes correlated with tests of premorbid and fluid intelligence and tests of visuospatial memory. Tests of verbal memory and verbal fluency did not correlate significantly with brain volumes. Structural equation modeling demonstrated that the relationships between specific cognitive tests and regional brain volumes could best be summarized by a significant positive relationship between a general brain size factor and a general cognitive factor, and not by associations between individual tests and particular brain regions.

CONCLUSIONS

In healthy elderly men, there are significant relationships between multiple cognitive tests and both intracranial capacity and regional brain volumes. These relationships may be largely due to longstanding associations between general cognitive ability and overall brain size.