Increased systemic and adipose 11β-HSD1 activity in idiopathic intracranial hypertension

Context

Idiopathic intracranial hypertension (IIH) is a disease of raised intracranial pressure (ICP) of unknown etiology. Reductions in glucocorticoid metabolism are associated with improvements in IIH disease activity. The basal IIH glucocorticoid metabolism is yet to be assessed.

Objective

The objective of this study was to determine the basal glucocorticoid phenotype in IIH and assess the effects of weight loss on the IIH glucocorticoid phenotype.

Design

A retrospective case-control study and a separate exploratory analysis of a prospective randomized intervention study were carried out.

Methods

The case-control study compared female IIH patients to BMI, age, and sex-matched controls. In the randomized intervention study, different IIH patients were randomized to either a community weight management intervention or bariatric surgery, with patients assessed at baseline and 12 months. Glucocorticoid levels were determined utilizing 24-h urinary steroid profiles alongside the measurement of adipose tissue 11β-HSD1 activity.

Results

Compared to control subjects, patients with active IIH had increased systemic 11β-hydroxysteroid dehydrogenase (11β-HSD1) and 5α-reductase activity. The intervention study demonstrated that weight loss following bariatric surgery reduced systemic 11β-HSD1 and 5α-reductase activity. Reductions in these were associated with reduced ICP. Subcutaneous adipose tissue explants demonstrated elevated 11β-HSD1 activity compared to samples from matched controls.

Conclusion

The study demonstrates that in IIH, there is a phenotype of elevated systemic and adipose 11β-HSD1 activity in excess to that mediated by obesity. Bariatric surgery to induce weight loss was associated with reductions in 11β-HSD1 activity and decreased ICP. These data reflect new insights into the IIH phenotype and further point toward metabolic dysregulation as a feature of IIH.

11βHSD1 Inhibition with AZD4017 Improves Lipid Profiles and Lean Muscle Mass in Idiopathic Intracranial Hypertension

BACKGROUND

The enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) determines prereceptor metabolism and activation of glucocorticoids within peripheral tissues. Its dysregulation has been implicated in a wide array of metabolic diseases, leading to the development of selective 11β-HSD1 inhibitors. We examined the impact of the reversible competitive 11β-HSD1 inhibitor, AZD4017, on the metabolic profile in an overweight female cohort with idiopathic intracranial hypertension (IIH).

METHODS

We conducted a UK multicenter phase II randomized, double-blind, placebo-controlled trial of 12-week treatment with AZD4017. Serum markers of glucose homeostasis, lipid metabolism, renal and hepatic function, inflammation and androgen profiles were determined and examined in relation to changes in fat and lean mass by dual-energy X-ray absorptiometry.

RESULTS

Patients receiving AZD4017 showed significant improvements in lipid profiles (decreased cholesterol, increased high-density lipoprotein [HDL] and cholesterol/HDL ratio), markers of hepatic function (decreased alkaline phosphatase and gamma-glutamyl transferase), and increased lean muscle mass (1.8%, P < .001). No changes in body mass index, fat mass, and markers of glucose metabolism or inflammation were observed. Patients receiving AZD4017 demonstrated increased levels of circulating androgens, positively correlated with changes in total lean muscle mass.

CONCLUSIONS

These beneficial metabolic changes represent a reduction in risk factors associated with raised intracranial pressure and represent further beneficial therapeutic outcomes of 11β-HSD1 inhibition by AZD4017 in this overweight IIH cohort. In particular, beneficial changes in lean muscle mass associated with AZD4017 may reflect new applications for this nature of inhibitor in the management of conditions such as sarcopenia.

Neurologic manifestations of iron deficiency in childhood

Iron deficiency is a common disorder in pediatric patients. Although the most common manifestation is that of anemia, iron deficiency is frequently the source of a host of neurologic disorders presenting to general pediatric neurologic practices. These disorders include developmental delay, stroke, breath-holding episodes, pseudotumor cerebri, and cranial nerve palsies. Although frequent, the identification of iron deficiency as part of the differential diagnosis in these disorders is uncommon and frequently goes untreated. The purpose of the current review is to highlight what is understood regarding iron deficiency and it's underlying pathophysiology as it relates to the brain, and the association of iron deficiency with common neurologic pediatric disease.

[A clinicopathological study of demyelination pseudotumors of the brain]

OBJECTIVE

To study the clinicopathological characteristics diagnosis, differential diagnosis and etiology of demyelination pseudotumors of the brain.

METHODS

The clinical features, CT, MRI scan findings, corticosteroid therapeutic effects and follow-up data of 3 cases of demyelination pseudotumors of the brain were analysed, and pathological changes were observed by histologic (HE, Luxol fast blue and Bodian) and immunohistochemical (S-P method) techniques.

RESULTS

The acute onset of demyelination pseudotumors appeared to be more predominant in our data. Clinical manifestations included headache, vomiting, a depressed conscious level, dysphasia, and paresis. CT, MRI scans showed solitary or multiple lesions in cerebral hemisphere. All the patients presented excellent response to steroid treatment. Follow-up for a period of 6 to 31 months, revealed the absence of progression or recurrence. The pathological changes were mainly located in both cerebral hemispheres, in which there were relative axonal preservation in foci loss of myelin, reactive gliosis, profuse perivascular lymphocytic infiltration and mixtures of foamy macrophages.

CONCLUSION

Demyelination pseudotumor is a distinct clinicopathologic encephalitic entity. The findings of this study suggest that the cause of tumefactive demyelination may be related to an allergic reaction triggered by viral infection.

Safety issues in children and adolescents during growth hormone therapy--a review

The action of growth hormone (GH) via its receptor involves many organ systems and metabolic pathways. These diverse actions are reviewed in this paper in the context that they may represent unwanted side-effects of GH therapy for growth promotion. The monitoring of GH therapy in large multicentre international databases has demonstrated a low frequency of adverse events. Tumour recurrence or new malignancy are not increased. Headaches, especially in the first few months of therapy, require close evaluation as benign intracranial hypertension is found infrequently, especially in children with GH deficiency and chronic renal failure (CRF). Children at risk for slipped capital femoral epiphysis and scoliosis require close monitoring during therapy. Decreased insulin sensitivity that is dose-dependent is observed during GH therapy. Glucose homeostasis, however, is not affected, but a recent report of increased incidence of Type 2 diabetes mellitus in children undergoing GH therapy requires prospective surveillance.

Multimodal monitoring in patients with head injury: evaluation of the effects of treatment on cerebral oxygenation

BACKGROUND

Recently, invasive intensive care unit monitoring of cerebral oxygenation has become feasible. The purpose of this study was to investigate the effects of standard therapeutic interventions used in the treatment of intracranial hypertension on cerebral oxygenation and other physiologic parameters in comatose patients.

METHODS

In the neurosurgical intensive care unit, Ptio2, and jugular bulb oxygen saturation (Sjvo2), arterial blood pressure, intracranial pressure (ICP), and cerebral perfusion pressure (CPP) were prospectively studied (0.1 Hz acquisition rate) with a multimodal monitoring system in 21 patients with severe traumatic brain injury during various treatment modalities: dopamine and mannitol infusion, head positioning, and induced arterial hypocapnia.

RESULTS

For baseline CPP values below 40 mm Hg, dopamine infusion was more effective in decreasing ICP and improving Ptio2 and Sjvo2 than for initial CPP values above 60 mm Hg. Treatment with mannitol, although improving CPP and lowering ICP, did not affect Ptio2 and Sjvo2. CPP in this group, however, was always above 60 mm Hg. Forced hyperventilation to an end-tidal Pco2 of 21 mm Hg normalized ICP and CPP, but significantly reduced cerebral oxygenation.

CONCLUSION

A CPP > 60 mm Hg emerges as the crucial factor guaranteeing sufficient brain oxygenation. Any intervention used to further elevate CPP does not improve cerebral oxygenation, to the contrary, forced hyperventilation even bears the risk of inducing brain ischemia.

Increased brain water self-diffusion in patients with idiopathic intracranial hypertension

PURPOSE

To investigate changes in brain water diffusion in patients with idiopathic intracranial hypertension.

METHODS

A motion-compensated MR pulse sequence was used to create diffusion maps of the apparent diffusion coefficient (ADC) in 12 patients fulfilling conventional diagnostic criteria for idiopathic intracranial hypertension and in 12 healthy volunteers.

RESULTS

A significantly larger ADC was found within subcortical white matter in the patient group (mean, 1.16 x 10(-9) m2/s) than in the control group (mean, 0.75 x 10(-9) m2/s), whereas no significant differences were found within cortical gray matter, the basal nuclei, the internal capsule, or the corpus callosum. Four of 7 patients with increased ADC in subcortical white matter also had increased ADC within gray matter.

CONCLUSION

Measurement of diffusion coefficients in vivo demonstrated increased local water mobility within subcortical white matter in 7 patients with idiopathic intracranial hypertension that otherwise appeared normal on conventional MR imaging. Further studies are necessary to assess the clinical significance of these observations.

Combined continuous monitoring of systemic and cerebral oxygenation in acute brain injury: preliminary observations

OBJECTIVE

To continuously evaluate the relationship between global systemic and cerebral oxygenation during temporary profound hypocapnia, which was attempted for prompt management of posttraumatic intracranial hypertension.

DESIGN

Prospective, intervention study.

SETTING

Neuroscience intensive care unit of a university hospital.

PATIENTS

Young adults (n = 21) with acute brain trauma, undergoing routine monitoring of jugular bulb and pulmonary artery oxyhemoglobin saturations, along with other monitoring.

MEASUREMENTS AND MAIN RESULTS

In 102 multivariate observations carried out on days 2 and 3 post-trauma, two new physiologic variables were assessed. These variables, systemic-cerebral oxygenation index and the systemic-cerebral ventilatory index, were evaluated in terms of baseline and post-hyperventilation changes. Overall, when intracranial pressure was largely increased, this increase was associated with decreased cerebral oxygen extraction ("luxury perfusion"), and high values of systemic-cerebral oxygenation index. In response to transient profound hypocapnia, the cerebral oxygen extraction normalized (increased), as did the systemic-cerebral oxygenation index (decreased), under most circumstances. The systemic-cerebral ventilatory index showed adequate systemic-cerebral response to hypocapnia in 92 (90.2%) observations. In the remaining ten (9.8%) observations, this response was considered inadequate, but it did not result in abnormal systemic or cerebral oxygenation parameters.

CONCLUSIONS

In young adults with severe acute brain trauma who require prompt management of intracranial hypertension, transient profound hypocapnia is effective in lowering the intracranial pressure, as well as in offsetting the cerebral luxury perfusion, while improving or maintaining adequate systemic oxygenation. The systemic-cerebral oxygenation index and the systemic-cerebral ventilatory index are potentially useful, physiologically monitorable variables for the combined assessment of global systemic and cerebral oxygenation in a variety of areas involving physiologic and/or therapeutic approaches.

Cerebrospinal fluid protein and opening pressure in idiopathic intracranial hypertension (pseudotumor cerebri)

We studied the relationship between the CSF protein concentration and the degree of elevation of the CSF opening pressure in 177 patients with idiopathic intracranial hypertension (pseudotumor cerebri). There was no linear correlation between the CSF protein and opening pressure. In addition, low CSF protein (less than 20 mg/dl) was present in only 26% of the patients. Our findings fail to confirm previous reports of an inverse relationship between the CSF opening pressure and CSF protein as well as low CSF protein in these patients.

[Pharmacokinetic basis of mannitol administration in the treatment of raised ICP]

To study the most effective way of mannitol administration for the treatment of raised intracranial pressure (ICP), pharmacokinetics of mannitol were analysed, and the relationship among mannitol concentration, serum osmolality and changes of intracranial pressure (ICP) were examined in cats. 10%, 20% and 30% of mannitol were made and intravenously administrated with the same volume and speed (0.667 ml/kg/min) for 15 minutes to each mannitol concentration group of cats. Sequential changes of ICP were monitored and serial mannitol concentration, serum osmolality and electrolytes were then performed. Changes of mannitol concentration showed a biexponential curve and best fitted to the two-compartment model analysis. There was a strong positive correlation (r = 0.9286) between mannitol concentration and extrinsic serum osmolality. The disposition of mannitol in cats was similar to that which had been reported in dogs and humans. The distribution half-time was faster in 30% mannitol, but the elimination half-time was similar in all groups. The integrated values of mannitol concentration difference between the central (Cc) and the peripheral compartment (Pc) were greatly correlated with the changes of ICP reduction during mannitol administration (for 15min). The time to vanish the mannitol concentration difference between Cc and Pc showed strong reverse correlation with the time to reach the lowest ICP level. The result indicates that the more rapidly mannitol was administrated, the more rapidly the concentration difference between the two compartments was created, and, the higher the effective osmolality was developed, then, the more profound and prolonged ICP reduction can be obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral venous oxygen content as a measure of brain energy metabolism with increased intracranial pressure and hyperventilation

In order to test the hypothesis that the cerebral arteriovenous oxygen difference (AVDO2) and venous oxygen content (VO2) could be used to monitor brain energy metabolism in the setting of increased intracranial pressure (ICP). 12 cats were studied with 31P-magnetic resonance spectroscopy. six cats were subjected to intracranial hypertension by cisternal infusion of saline. Energy failure occurred at an average AVDO2 of 8.4 +/- 3.2 vol% (+/- standard deviation) (range 4.7 to 14.7 vol%). The VO2 at the point of metabolic failure averaged 1.45 +/- 0.6 vol% and extended over a narrower range (1.0 to 2.9 vol%). In an additional six cats, ICP was raised to the threshold of metabolic failure and hyperventilation was then instituted (pCO2 10 to 18 torr). Five of the six cats experienced a drop in VO2 with hyperventilation. In two of these animals, hyperventilation resulted in a VO2 of 1.1 vol% or less and in metabolic failure as evidenced by a fall in phosphocreatine. It is concluded that a VO2 of less than 2 vol% is correlated with brain ischemia and that the safety of hyperventilation in the setting of increased ICP can be monitored by the use of VO2.

Brain water accumulation in pseudotumour cerebri demonstrated by MR-imaging of brain water self-diffusion

We studied brain water self diffusion in pseudotumour cerebri by MR-imaging using single spin echo pulse sequences with pulsed magnetic field gradients of different magnitude. The methods is based on the fact that the movement of water molecules is restricted in brain tissue and that accumulation of water in the brain tissue will enhance the self diffusion of water. In order to evaluate the brain water content in pseudotumour cerebri we compared the water self diffusion coefficient in various regions of the brain in pseudotumour patients with that of healthy controls. Ten patients with pseudotumour cerebri were studied. All had increased ICP and increased resistance to CSF outflow. All patients had normal conventional MR spin echo images without focal lesions and a normal sized ventricular system. All patients had abnormal diffusion images showing increased water diffusion. Some patients had in particular increased diffusion in the periventricular regions, others in the whole brain. The diffusion coefficients in all brain regions of interest were significantly higher in patients than in controls. The findings suggest that patients with pseudotumour cerebri have a convective transependymal flow of water causing an interstitial brain oedema and in addition an intracellular brain water accumulation.

Dissociation between activation of the hypothalamo-hypophyseal antidiuretic system and the type of diuresis during acute intracranial hypertension. Experimental observation

Acute cerebral compression by a supra- and infratentorial balloon produced a triphasic pattern of diuresis. The 1st phase was characterized by polyuria associated with five fold increase of plasma (p) antidiuretic hormone (ADH) concentration, decreased urine osmolality in spite of natriuresis and blood pressure elevation. The 2nd phase was characterized by oliguria, a decrease of pADH and reduced urine Na+ concentration, whereas urine osmolality transiently increased. At this stage there was respiratory arrest and fall of blood pressure. The final stage was diabetes insipidus (DI), when EEG activity had disappeared. An increase of serum osmolality mainly occurred during the last DI phase. Serum Na+ concentration fluctuated slightly during the whole period of diuresis. These results present evidence, that the diuresis pattern reflects the hypothalamo-hypophyseal antidiuretic system (HHAS) reaction to acute intracranial pressure (ICP) increase with the vegetative symptoms of cerebral shock.

In vivo measurement of water self diffusion in the human brain by magnetic resonance imaging

A new pulse sequence for in vivo diffusion measurements by magnetic resonance imaging (MRI) is introduced. The pulse sequence was tested on phantoms to evaluate the accuracy, reproducibility and inplane variations. The sensitivity of the sequence was tested by measuring the self diffusion coefficient of water with different temperatures. This phantom study showed that the water self diffusion could be measured accurately and that the inplane deviation was less than +/- 10 per cent. Seven healthy volunteers were studied with a 10 mm thick slice through the lateral ventricles, clear differences between grey and white matter as well as regional differences within the white matter were seen. In two patients with infarction, alternations in water self diffusion were seen in the region of the infarct. Likewise, pronounced changes in brain water self diffusion were observed in a patient with benign intracranial hypertension. The results indicate that brain water self diffusion can be measured in vivo with reasonable accuracy. The clinical examples suggest that diffusion measurements may be clinically useful adding further information about in vivo MR tissue characterization.

Pentobarbital pharmacokinetics in patients with severe head injury

Intravenous administration of high-dose pentobarbital has been proposed as a treatment for elevated intracranial pressure refractory to other measures in brain-injured patients. The purpose of this clinical study was to examine the pharmacokinetics of high-dose continuous intravenous infusion of pentobarbital in this critical care setting. Six patients received a 25-34 mg/kg intravenous loading dose followed by a 1-3 mg/kg/h continuous infusion for 61-190 hours. Dosing rates were adjusted based on the patient's clinical status. The mean clearance was 0.72 ml/min/kg, with a volume of distribution (Vd) of 1.03 L/kg and a terminal half-life of 19.1 h. Considerable variation in individual patient parameters was observed. In addition, a change in clearance was suggested in patients requiring a longer infusion duration.

Endocrinology of pseudotumor cerebri

This article will review the endocrine function of obese young women with pseudotumor cerebri and primary empty sella syndrome. The literature can be difficult to interpret. Much of it predates the era of CT scanning. Often, cases of primary and secondary empty sella syndrome are comingled. The author reviews specific endocrinologic disorders that have sometimes been associated with increased intracranial pressure excluding pituitary adenomas.

Regional cerebral oxygen utilization, blood flow, and blood volume in benign intracranial hypertension studied by positron emission tomography

Using PET, we measured regional cerebral oxygen utilization, oxygen extraction, blood flow, and blood volume in five patients with benign intracranial hypertension. No significant differences in regional cerebral function were found between the patients and 15 age-matched normal controls. Cerebral decompression with a lumboperitoneal shunt produced little change in regional cerebral function in one patient studied serially. The raised CSF pressure of benign intracranial hypertension is therefore not associated with any significant deterioration in cerebral oxygen metabolism or hemodynamics.

Cerebrospinal fluid and plasma vasopressin during short-time induced intracranial hypertension

The response of plasma and ventricular cerebrospinal fluid vasopressin concentration to short-time induced intracranial hypertension was studied in 8 patients with hydrocephalus, defined as ventricular enlargement on computerized tomography. In connection with measurement of conductance to cerebrospinal fluid outflow, the concentration of vasopressin in plasma and cerebrospinal fluid was measured during perfusion at a low (less than 10 mmHg) and at a high (greater than 20 mmHg) intraventricular pressure level. Mean plasma vasopressin concentration was increased from 2.4 +/- 0.4 pg/ml (SEM) during perfusion at the low pressure level to 4.2 +/- 0.8 pg/ml (p less than 0.01) at the high pressure level. The cerebrospinal fluid concentrations of vasopressin at the low and high intraventricular pressure were 1.2 +/- 0.1 pg/ml and 1.7 +/- 0.2 pg/ml (p less than 0.05), respectively. However, only half of the patients responded to the increase in intraventricular pressure with an increase in cerebrospinal fluid vasopressin concentration exceeding 50%. The results of the present study suggest that an increase in the intracranial pressure might be a stimulus for vasopressin release in both the blood and the cerebrospinal fluid.

Cerebral blood flow and metabolism in comatose patients with acute head injury. Relationship to intracranial hypertension

Cerebral blood flow (CBF) measurements were made in 75 adult patients with closed head injuries (mean Glasgow Coma Scale score 6.2) using the xenon-133 intravenous injection method with eight detectors over each hemisphere. All patients were studied acutely within 96 hours of trauma, and repeatedly observed until death or recovery (total of 361 examinations). Arteriojugular venous oxygen differences (AVDO2) were obtained in 55 of the patients, which permitted assessment of the balance between metabolism and blood flow, and provided estimates of cerebral metabolic rate for oxygen (CMRO2). Based on mean regional CBF, the patients were classified into two groups: those who exhibited hyperemia on one or more examinations, and those who had a consistently reduced flow during their acute illness. "Hyperemia" was defined as a normal or supernormal CBF in the presence of coma, a definition that was independently confirmed by narrow AVDO2's indicative of "luxury perfusion". During coma, all patients showed a significant depression in CMRO2. Forty-one patients (55%) developed an acute hyperemia with an average duration of 3 days, while 34 patients (45%) consistently had subnormal flows. Although more prevalent in younger patients, hyperemia was found at all age levels (15 to 85 years). There was a highly significant association between hyperemia and the occurrence of intracranial hypertension, defined as an intracranial pressure above 20 mm Hg. Patients with reduced flow showed little or no evidence of global cerebral ischemia, but instead revealed the expected coupling of CBF and metabolism. The CBF responses to hyperventilation were generally preserved, with the hyperemic patients being slightly more reactive. In 10 patients with reduced flow, hyperventilation resulted in wide AVDO2's suggestive of ischemia.

Recent research into the nature of cerebrospinal fluid formation and absorption

Recent information regarding the nature of bulk cerebrospinal fluid formation and absorption is reviewed, integrated with previous knowledge, and applied to the clinical setting.

Pseudotumor cerebri in an obese woman with Turner syndrome

Extraovarian estrogen production was studied in an obese young woman with pathologically confirmed mosaic Turner syndrome and pseudotumor cerebri. Diet plus enough dexamethasone to suppress adrenal steroidogenesis promptly lowered cerebrospinal fluid testosterone. Estrone was detected in cerebrospinal fluid before and after but not during dexamethasone treatment. Extraovarian estrogen probably produces the menstrual irregularities of obese young women with pseudotumor cerebri and may be involved in the pathogenesis of that syndrome.

Cerebral hemodynamics and metabolism in pseudotumor cerebri

A comprehensive analysis of cerebral hemodynamics and metabolism was carried out in 14 patients with pseudotumor cerebri. Tracer techniques were employed to measure cerebral blood flow (CBF) and vascular reactivity to acute changes in arterial carbon dioxide tension and blood pressure, cerebral blood volume (CBV), and the cerebral metabolic rate for oxygen and glucose. There was a small reduction (p less than 0.01) in CBF (44 +/- 7 ml/100 gm/min; normal, 54 +/- 9) with normal vascular reactivity; an increase (p less than 0.005) in CBV (4.8 +/- 0.8 ml/100 gm; normal, 3.6 +/- 0.5), and normal cerebral metabolism. We conclude that an abnormality of the cerebral microvasculature is responsible for an elevation in CBV, but the intracranial hypertension can be explained only by tissue swelling due to an increase in water content. The relationship between the vascular abnormality and the tissue swelling remains to be defined.