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PubMed1990

Do the skull and dura exert influence on brain volume regulation following hypo- and hyperosmolar fluid treatment?

The present studies were performed to determine the response of the brain water and electrolytes to acute hypoosmolality and hyperosmolality in animals with intact skull and dura, in comparison with those subjected to extensive bilateral or unilateral craniectomy and dural opening. Four to 5 weeks following extensive unilateral or bilateral craniectomy and dural opening in rats, a 50 mosm/kg decrease in plasma osmolality was produced by systemic administration of distilled water ("water intoxication"), or a 28 mosm/kg increase in plasma osmolality was produced by systemic administration of either 1 M NaCl or 1 M mannitol in 0.34 M NaCl. Tissue water, Na, and K contents were determined after 120 minutes. Tissue water accumulation or water loss was proportional to the decrease or increase in plasma osmolality. However, the tissue water accumulation following "water intoxication" was less (40% of the predicted value) than that predicted for ideal osmotic behaviour. The brain tissue was also found to shrink less than predicted on the basis of ideal osmotic behaviour (40% of the predicted value after mannitol treatment, and 60% after NaCl administration). This non-ideal osmotic response of the brain tissue is consistent with the finding in other studies and indicated a significant degree of volume regulation. Water and electrolyte changes were not different in operated and non-operated animals, demonstrating no effects of extensive skull and dura defects on tissue volume regulation under hypo- and hyperosmolar conditions of a degree that may be encountered under clinical circumstances.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2000

Age-related brain volume reductions in amphetamine and cocaine addicts and normal controls: implications for addiction research.

The study evaluated the relationship between age and frontal and temporal lobe volumes in young cohorts of cocaine-dependent (CD), amphetamine-dependent (Am), and normal control subjects. Ten CD, nine Am, and 16 age- and gender-matched control subjects underwent magnetic resonance imaging (MRI). The volume of the frontal and temporal lobes was measured from an identically positioned slab of seven contiguous 3-mm-thick coronal images. Follow-up measures of the gray and white matter subcomponents of these volumes were also obtained. Both CD and Am groups had a significantly smaller temporal lobe volumes, but only the CD group demonstrated a significantly greater decline in temporal lobe volume with age (intracranial volume, education, and race were controlled for in all statistical analyses). Segmenting the brain regions into gray and white matter revealed that the negative correlation between age and temporal lobe volume of CD patients was mostly due to a significant age-related decline in the gray matter subcomponent. Negative trends between age and gray matter volumes were also observed in the Am and normal groups. In the frontal lobes, age was negatively correlated with gray matter volume in the control, CD, and Am groups. Unlike the consistent decreases in gray matter volumes, white matter showed non-significant increases in volume with age. The data suggest that CD patients may have an accelerated age-related decline in temporal lobe gray matter volume and a smaller temporal lobe volume compared to normal controls. In the frontal lobe, age-related gray matter volume reductions occur in all three groups. These age-related cortical gray matter volume reductions may be a biological marker for the risk of addictive behavior, which also decreases with age.

Adult↗
PubMed2004

Serial MRI in multiple sclerosis: a prospective pilot study of lesion load, whole brain volume and thalamic atrophy.

Using serial magnetic resonance imaging (MRI), we investigated the relationship between diffuse cerebral atrophy, T1 and T2 lesion volumes, mean thalamic volumes and clinical progression in patients with established multiple sclerosis (MS). Eleven patients were included in this prospective serial study. Cerebral volumes, T1 hypointense lesion volumes, and T2 hyperintense lesion volumes at baseline and at up to 3 years follow-up were assessed on MRI brain scans. As a putative measure of cerebral atrophy mean thalamic volumes were also obtained. The outcome measures were the MRI parameters and disability on Kurtzke's expanded disability status scale (EDSS). Of the 11 patients 6 worsened clinically as measured by an increase of 0.5 or more on the EDSS. Cerebral atrophy occurred in 91% of patients and was independent of changes in lesion volumes and was not associated with disease progression as determined by the EDSS.

Adult↗
PubMed2005

Hemispheric brain volume replacement with free latissimus dorsi flap as first step in skull reconstruction.

Large skull defects lead to progressive depression deformities, with resulting neurological deficits. Thus, cranioplasty with various materials is considered the first choice in therapy to restore cerebral function. A 31-year-old female presented with a massive left-sided hemispheric substance defect involving bone and brain tissue. Computed tomography showed a substantial convex defect involving the absence of calvarial bone as well as more than half of the left hemisphere of the brain, with a profound midline shift and a compression of the ventricular system. There was a severe problem due to multiple deep-skin ulcerations at the depression margin, prone to skin perforation with a probability of intracranial infection. In a first step, a free myocutaneous latissimus dorsi flap was transplanted for volume replacement of the hemispheric brain defect, and 4 months later, artificial bone substitute was implanted in order to prevent progressive vault depression deformity. Healing was uneventful, and the patient showed definite neurological improvement postoperatively. Free tissue transfer can be a valuable option in addition to cranioplasty in the treatment of large bony defects of the skull. Besides providing stable coverage for the reconstructed bone or its substitute, it can also serve as a volume replacement.

Adult↗
PubMed2006

Brain volume regulation in response to hypo-osmolality and its correction.

Hyponatremia exerts most of its clinical effects on the brain. An acute onset (usually in <24 hours) of hyponatremia causes severe, and sometimes fatal, cerebral edema. Given time, the brain adapts to hyponatremia, permitting survival despite extraordinarily low serum sodium concentrations. Adaptation to severe hyponatremia is critically dependent on the loss of organic osmolytes from brain cells. These intracellular, osmotically active solutes contribute substantially to the osmolality of cell water and do not adversely affect cell functions when their concentration changes. The adaptation that permits survival in patients with severe, chronic (>48 hours' duration) hyponatremia also makes the brain vulnerable to injury (osmotic demyelination) if the electrolyte disturbance is corrected too rapidly. The reuptake of organic osmolytes after correction of hyponatremia is slower than the loss of organic osmolytes during the adaptation to hyponatremia. Areas of the brain that remain most depleted of organic osmolytes are the most severely injured by rapid correction. The brain's reuptake of myoinositol, one of the most abundant osmolytes, occurs much more rapidly in a uremic environment, and patients with uremia are less susceptible to osmotic demyelination. In an experimental model of chronic hyponatremia, exogenous administration of myoinositol speeds the brain's reuptake of the osmolyte and reduces osmotic demyelination and mortality caused by rapid correction.

Acute Disease↗
PubMed2005

Brain volumes in healthy adults aged 40 years and over: a voxel-based morphometry study.

BACKGROUND AND AIMS: Gender and age effect on brain morphology have been extensively investigated. However, the great variety in methods applied to morphology partly explain the conflicting results of linear patterns of tissue changes and lateral asymmetry in men and women. The aim of the present study was to assess the effect of age, gender and laterality on the volumes of gray matter (GM) and white matter (WM) in a large group of healthy adults by means of voxel-based morphometry. This technique, based on observer-independent algorithms, automatically segments the 3 types of tissue and computes the amount of tissue in each single voxel. METHODS: Subjects were 229 healthy subjects of 40 years of age or older, who underwent magnetic resonance (MR) for reasons other than cognitive impairment. MR images were reoriented following the AC-PC line and, after removing the voxels below the cerebellum, were processed by Statistical Parametric Mapping (SPM99). GM and WM volumes were normalized for intracranial volume. RESULTS: Women had more fractional GM and WM volumes than men. Age was negatively correlated with both fractional GM and WM, and a gender x age interaction effect was found for WM, men having greater WM loss with advancing age. Pairwise differences between left and right GM were negative (greater GM in right hemisphere) in men, and positive (greater GM in left hemisphere) in women (-0.56+/-4.2 vs 0.99+/-4.8; p=0.019). CONCLUSIONS: These results support side-specific accelerated WM loss in men, and may help our better understanding of changes in regional brain structures associated with pathological aging.

Adult↗
PubMed2004

Variations in estrogen receptor alpha gene and risk of dementia, and brain volumes on MRI.

The role of estrogens in Alzheimer's disease (AD) is controversial. We investigated the association between well-recognized, and potentially functional, polymorphisms in the estrogen receptor (ER) alpha gene and the risk of AD in a prospective study of 6056 Caucasian older men and women aged 55 years and over. In a subset of 468 participants, we assessed volumes of the hippocampus and amygdala, which have a high density of ER alpha, with brain magnetic resonance imaging (MRI) (1.5 T MR unit). During a total of 35 405 person-years of follow-up (mean per persons 5.8 years), 312 new cases of dementia were detected, of whom 230 were diagnosed with AD. Neither the PvuII nor the XbaI polymorphism or haplotypes thereof were associated with the risk of all-cause dementia or AD. In contrast, we found that nondemented women who carried the PvuII p allele or haplotype 'px' had smaller amygdalar volumes on MRI in an allele-dose-dependent fashion. Total amygdalar volume was 4.50 (SE 0.10) in PP genotype, 4.45 (SE 0.06) in Pp genotype, and 4.18 ml (SE 0.08) in pp genotype (P trend=0.008). Further studies are required to investigate whether this smaller amygdalar volume has functional significance.

Aged↗
PubMed1998

Gamma knife radiosurgery for large volume brain tumors: an analysis of acute and chronic toxicity.

Gamma Knife radiosurgery is often used to treat intracranial tumors <4 cm (approximately 13.5 cm3) in mean diameter. Larger lesions are rarely treated because of the expectation that increasing target volume will increase toxicity. We retrospectively analyzed 35 patients with primary or metastatic brain tumors of more than 13.5 cm3 treated with the Gamma Knife. Only 3 (8.5%) patients developed acute clinical toxicity. Nine (25%) patients developed post-Gamma Knife radionecrosis based on imaging studies, with only 3 of these patients (9% of the study population) having clinical progression of symptoms. Necrosis was not found to be related to prescribed dose, treatment volume or number of treated isocenters. We found no undue toxicity from the treatment of large brain tumors with the Gamma Knife.

Acute Disease↗
PubMed1981

Relationship between brain volume and size of dural venous sinuses in human fetuses and adults.

A quantitative study of 50 human fetuses, ranging in size from 64 to 259 mm crown-rump length (CRL), and 12 adult cadavers was carried out. After removal of each brain from the cranial cavity and measurement of its volume (BV), the cross-sectional area (CSA) of the transverse (TS) and sigmoid (SS) dural venous sinuses were measured; the measurements were taken at the same anatomical point in all fetuses and adults. For each fetus and adult, indices CSA . TS/BV and CSA . SS/BV were calculated. The results of the statistical analysis showed that the mean CSA TS/BV . and CSA . SS/BV indices in fetuses were significantly greater than those of the adults, i.e., relative to the size of the brain, the dural venous sinuses in fetuses were greater than in adults. Furthermore, a significant negative correlation was found between the CSA . SS/BV index and the CRL of the fetuses; this means that as the brain and sinuses grow during fetal development, the growth rate of the sinuses decreases. By implication, the rate of growth of the arterial blood supply decreases proportionately. A similar, progressive decrease in the growth rate of the brain takes place during fetal life.

Adult↗