Magnesium Status in Alzheimer's Disease: A Systematic Review

The interest in poor magnesium (Mg) status as risk factor for Alzheimer's disease (AD) is increasing due to its antioxidant and neuroprotective properties. A systematic PubMed literature search of studies investigating Mg status was undertaken comparing AD to healthy controls (HCs) or patients with medical illness (medical controls [MCs]). Standardized mean differences (SMDs) ± 95% confidence intervals (CIs) were calculated for all outcomes. Of 192 potentially eligible studies, 13 were included (559 patients with AD, 381 HCs, and 126 MCs). Compared to HCs, patients with AD had significantly lower Mg in cerebrospinal fluid (2 studies; SMD = -0.35;P= .02) and in hair (2 studies; SMD = -0.75;P= .0001). No differences between AD and controls were evident for serum Mg. In conclusion, AD seems to be associated with a lower Mg status when compared to HCs, while the scarcity of studies limited the findings about MCs.

Evaluation of Magnesium Levels in Serum and Cerebrospinal Fluid of Patients with Febrile Convulsion Hospitalized in Bahrami Hospital in Tehran in 2010-2011

Evaluation of magnesium levels in serum and cerebrospinal fluid of patients with febrile convulsion (FC) hospitalized in Bahrami hospital in Tehran in 2010-2011. In the past, decreased levels of magnesium in serum and CSF of patients with FC were reported. The purpose of this study was to identify the possible role of magnesium in febrile seizures in children. Identifying this condition, we may control seizures and also prevent subsequent convulsion. In this cross-sectional study, inclusion criteria were the existence of convulsion due to fever and exclusion criteria were having a known neurological disease which could induce a seizure, and children younger than one month. In each group (cases include children with febrile convulsion and controls include febrile children without convulsion), Mg was measured in blood, and cerebrospinal fluid of 90 children and then they were compared. The data were analyzed by SPSS (α=0.05). The mean serum and CSF levels of Mg in case and control groups were equal (P<0.87 and P<0.22 respectively). There was no difference between two groups in terms of sex, but mean age was significantly different (P<0.003). There was not an association between serum and CSF levels of magnesium and the presence of FC. Therefore, it's not suggested to measure the level of magnesium in serum or CSF in children with fever routinely.

[Role of magnesium in nerve tissue]

The role of magnesium on nerve tissue was discussed. Two main topics of "magnesium and neural activity" and "magnesium-therapy and brain neurons" were described together with introducing our research on rat cultured neurons of cortex and hippocampus.

Investigating paradoxical hysteresis effects in the mouse neocortical slice model

Clinically, anesthetic drugs show hysteresis in the plasma drug concentrations at induction versus emergence from anesthesia induced unconsciousness. This is assumed to be the result of pharmacokinetic lag between the plasma and brain effect-site and vice versa. However, recent mathematical and experimental studies demonstrate that anesthetic hysteresis might be due in part to lag in the brain physiology, independent of drug transport delay - so-called "neural inertia". The aim of this study was to investigate neural inertia in the reduced neocortical mouse slice model. Seizure-like event (SLE) activity was generated by exposing cortical slices to no-magnesium artificial cerebrospinal fluid (aCSF). Concentration-effect loops were generated by manipulating SLE frequency, using the general anesthetic drug etomidate and by altering the aCSF magnesium concentration. The etomidate (24 μM) concentration-effect relationship showed a clear hysteresis, consistent with the slow diffusion of etomidate into slice tissue. Manipulation of tissue excitability, using either carbachol (50 μM) or elevated potassium (5mM vs 2.5mM) did not significantly alter the size of etomidate hysteresis loops. Hysteresis in the magnesium concentration-effect relationship was evident, but only when the starting condition was magnesium-containing "normal" aCSF. The in vitro cortical slice manifests pathway-dependent "neural inertia" and may be a valuable model for future investigations into the mechanisms of neural inertia in the cerebral cortex.

[Relationship between magnesium concentration in cerebrospinal fluid and delayed cerebral ischemia in patients with aneurysmal subarachnoid hemorrhage]

BACKGROUND

The present study was conducted to determine the relationship between magnesium concentration in cerebrospinal fluid (CSF) and delayed cerebral ischemia (DCI) in patients with subarachnoid hemorrhage (SAH).

METHODS

We studied 39 consecutive patients undergoing surgery after SAH. A spinal drainage catheter was inserted into the lower lumbar vertebrae before surgery. CSF was then sampled and the magnesium concentration measured. General clinical data, Hunt-Hess (H-H) grade and Fisher grade, aneurysm size and site, intracerebral and intraventricular hemorrhage, and blood glucose levels were all recorded on admission. At the same time, the Glasgow coma scale (GCS) score was calculated. Outcomes were assessed using the Glasgow outcome scale at discharge. DCI was defined as a two-point decrease in the GCS score and/or focal deficit, and was confirmed by cerebral angiography. The recorded values were expressed as the median (interquartile range).

RESULTS

Of the 39 patients, 23 (59%) had DCI. The magnesium concentration in the DCI cases was 2.8 (2.7 and 2.9) mg x dl(-1), which was significantly lower than that in the non-DCI cases, i. e., 2.9 (2.8 and 3.0) mg x dl(-1) (P < 0.05). There were no significant differences in the other factors.

CONCLUSIONS

The results indicate that preoperative hypomagnesemia within the CSF might play a role in the development of DCI in patients with SAH; however, further studies will be necessary to confirm this observation.

Concentration of calcium and magnesium and trace elements (zinc, copper, iron and manganese) in cerebrospinal fluid: a try of a pathophysiological classification

The aim of this study is to analyze the variation of the elements (Ca, Mg, Cu, Fe, Zn and Mn) in normal and pathological CSF and develop a classification basing on the increases in cells and proteins and taking into account these variations. A total of 173 cerebrospinal fluids were analyzed. Of these, 37 fulfilled the criteria of normality and, after clinical exploration, were considered to be healthy (control group). The remaining 136 CSFs (pathological group) belonged to people for whom some neurological pathology had been observed in the clinical exploration and whose CSF analysis presented some abnormality. CSF was extracted by puncture in the lumbar cistern. The analysis of metals was performed by atomic absorption spectrophotometry. The statistical values (mean±standard deviation) obtained for each element analyzed in control group were as follows: Ca (mg/dL): 4.95±0.70; Mg (mg/dL): 2.74±0.10; Cu (μg/dL): 15.70±13.50; Fe (μg/dL): 13.10±3.60; Zn (μg/dL): 17.40±9.50 and Mn (μg/dL): 2.50±0.70. In the pathological CSFs, significant increases were found (p<0.050) in relation to the control group for Ca, Cu, Fe, Zn and Mn in groups with an increase of both cells and proteins. A significant decrease of Mg (p<0.050) was found in the groups with cell and protein increases. Given the results obtained in the different subgroups of the proposed classification, we conclude that it is necessary to further categorize the patients' diagnostics in the different subgroups. This would help to validate the classification.

Serum and cerebrospinal fluid magnesium levels, Glasgow Coma Scores, and in-hospital mortality in patients with acute stroke

The aim of this study was to determine the relationship between serum and cerebrospinal fluid (CSF) magnesium(Mg+2) levels, Glasgow Coma Scores (GCS), and 7-day mortality in acute stroke patients. Patients with acute ischemic or hemorrhagic stroke arriving within the first 3 h of symptoms were included in the study. The control group consisted of healthy volunteers. GCS was determined, and blood and CSF samples were taken in order to establish serum and CSF glucose, Mg+2, sodium, potassium, calcium, and chlorine levels.Mortality was recorded at 7 days after admission. CSF Mg+2 in the ischemic infarct group was significantly lower than in the control group (p=0.006). CSF Mg+2 in the ischemic infarct patients with a GCS < or = 8 were significantly lower (p=0.002) than controls and in ischemic infarct patients with a GCS > or = 9. In the ischemic stroke patients, CSF Mg+2 and GCS were significantly correlated (r=55, p=0.031). CSF Mg+2 levels in ischemic stroke patients who died within 7 days were significantly lower than controls, ischemic stroke patients who survived, and hemorrhagic stroke patients who died (p=0.002, p=0.042, and p=0.005,respectively). Low CSF Mg+2 levels in patients with acute ischemic stoke at admission predicted a higher 1-week mortality.

The effect of hypermagnesemic treatment on cerebrospinal fluid magnesium level in patients with aneurysmal subarachnoid hemorrhage

Preliminary evidence has suggested that magnesium sulfate infusion reduces delayed ischemic neurological deficit and improves clinical outcome after aneurysmal subarachnoid hemorrhage. However, little is known about its site of action in vivo. We studied 22 aneurysmal subarachnoid hemorrhage patients with or without magnesium sulfate infusion for 10-14 days. Thirteen patients had external ventricular drains inserted for hydrocephalus and daily cerebrospinal fluid magnesium levels were measured. For patients given magnesium sulfate infusion, the aim was to raise the plasma magnesium level to double the baseline level. We found that the magnesium sulfate infusion bought an 11% to 21% increase in cerebrospinal fluid magnesium. The elevation of cerebrospinal fluid magnesium was sustained for at least nine days. Whether this mild elevation in cerebrospinal fluid magnesium level was adequate for neuroprotection awaits the results of ongoing clinical trials.

Prolonged elevation of magnesium in the cerebrospinal fluid of patients with severe head injury

OBJECTIVES

Several works have investigated the role of serum magnesium (Mg) concentrations in traumatic brain injury. However, there is restricted information about cerebrospinal fluid (CSF) levels of Mg in patients with severe head injury (SHI). We assessed the changes of Mg concentrations in CSF and serum in patients with SHI during the first 10 days after the trauma.

METHODS

Eleven patients with SHI were studied prospectively on days 1-3, 5 and 10 with analysis of CSF and serum levels of Mg and Ca. The control group consisted of nine patients with hydrocephalus.

RESULTS

CSF levels of Mg were significantly higher in patients than controls in the corresponding time points except on days 5 and 10 of trauma. The CSF Mg levels tended to decrease and the highest level was found on day 1 after trauma (2.81 +/- 0.65 mg/dl). In the control group, the CSF level of Mg was 1.95 +/- 0.66 mg/dl. No significant difference can be detected between controls and patients regarding serum Mg and Ca levels. In addition, significantly higher values of Ca in the CSF were observed in all time points after trauma in patients with SHI than in the controls. There was no correlation between the CSF and serum levels of Mg and Ca levels.

DISCUSSION

Our study demonstrates that in patients with SHI, CSF levels of Mg and Ca are elevated during the whole observation period. Further works should be designed in order to show the role and importance of CSF levels of ionized Mg in outcome of patients with SHI.

Serum and Cerebrospinal Fluid Magnesium in Severe Traumatic Brain Injury Outcome

Serum magnesium concentration has a neuroprotective effect in experimental models of traumatic brain injury (TBI). This study was designed to assess the relationship between initial serum magnesium, cerebrospinal fluid (CSF) magnesium, neurological outcome and the efficacy of magnesium replacement therapy (MgSO4). A retrospective analysis was performed on a prospectively collected dataset from 216 patients admitted during 1996-2006 to the University of Pittsburgh Medical Center with severe TBI. Admission serum and CSF magnesium were dichotomized into low and normal magnesium concentration groups for serum and normal and high concentration groups for CSF. A logistic-regression analysis was performed with 6-month Glasgow Outcome Scale (GOS) scores as outcome variable. The outcome of a subset of 31 patients who presented with low serum magnesium and who were rapidly corrected within 24 h of admission was also analyzed. Low initial serum magnesium was measured in 56.67% of all patients. Patients with an initial serum magnesium of <1.3 mEq/L were 2.37 times more likely to have a poor outcome (CI: 1.18-4.78, p = 0.016). The prognostic significance of depressed serum magnesium remained, even in patients whose serum magnesium levels were corrected within 24 h (OR = 11.03, CI: 1.87-68.14, p = 0.008). Patients with an initial high CSF magnesium were 7.63 more likely to have a poor outcome (p = 0.05). Elevated CSF magnesium correlated with depressed serum magnesium only in patients with poor outcome (p = 0.013). Patients with low serum magnesium and high CSF magnesium are most likely to have poor outcome after severe TBI. Rapid correction of serum magnesium levels does not reverse the prognostic value of these markers.

Extracellular calcium and magnesium in preeclampsia and eclampsia

The cause of preeclampsia remains unknown and calcium and magnesium supplement are being suggested as means of prevention. The objective of this study was to assess magnesium and calcium in the plasma and cerebrospinal fluid of Nigerian women with preeclampsia and eclampsia. Setting was University of Benin Teaching Hospital, in Nigeria. It was a cross-sectional study comprising of eleven patients and twenty-three controls. The mean, standard deviation and Standard Error of Mean (SEM) were calculated. Student 't' test method was applied. Plasma calcium was significantly lower in patients than controls (9.2 +/- 1.02 Vs 9.98 +/- 0.87mg/dl, P 0.043) "t" test. The CSF calcium and magnesium levels were lower in patients than controls, (5.66 +/- 1.22 vs 6.67 +/- 1.15 mg/ dl, P 0.043 and 1.75 +/- 0.56 vs 1.91 +/- 0.19 mg/dl, P 0. < 0.0001) respectively. There is extracellular calcium and magnesium reduction in patients with preeclampsia and eclampsia. This reduction may have a cause and effect relationship with these disorders.

Cerebrospinal fluid sodium increases in migraine

BACKGROUND

Pharmaceuticals with calcium- or sodium-channel-blocking activity have proven useful for migraine prophylaxis, and calcium channel, sodium transporter, and sodium channel gene mutations have been found in familial hemiplegic migraine. However, it is not known whether calcium or sodium homeostasis is altered in migraine.

OBJECTIVE

To compare levels of sodium, calcium, potassium, and magnesium in cerebrospinal fluid (CSF) and blood plasma between migraineurs and controls.

METHODS

We recruited 20 migraineurs without aura and 11 controls prospectively, and studied migraineurs in sick (MH(+)) and well (MH(-)) states. We collected lumbar CSF and venous blood plasma, quantified elements with ion-selective electrodes or colorimetry, and determined osmolality by depression of freezing point. We compared levels of Na(+), Ca(2+), K(+), and Mg among and also within subjects who were studied in both MH(+) and MH(-) states.

RESULTS

Mean CSF Na(+) levels were increased by 3 mmol/L in MH(+) compared with MH(-) and by 4 mmol/L compared to controls (P < 0.005). In 4 subjects who were sampled in both MH(+) and MH(-) states, mean CSF Na(+) concentration increased by 2 mmol/L in the MH(+) state compared with the MH(-) state (P < 0.05). Simultaneous plasma Na(+) levels did not differ among the 3 clinical groups, nor did osmolality, total Ca and Ca(2+), K(+), and total Mg levels in CSF.

CONCLUSIONS

Compared to both controls and the MH(-) state, CSF Na(+) concentration increased in MH(+) independently from other clinical or pharmacological fluctuations, CSF concentrations of Ca(2+), Mg, and K(+), and blood plasma Na(+) levels. These results implicate a deviation of Na(+) homeostasis in migraine. The modestly elevated extracellular Na(+) in MH(+) may cause the neural changes that underlie clinical features of migraine.

Changes in magnesium concentration in the serum and cerebrospinal fluid of neuropathic rats

BACKGROUND

Central sensitization of neuropathic pain is associated with an influx of extracellular calcium via the opening of N-methyl-D-aspartate (NMDA) receptor-gated ion channels, which are usually blocked by magnesium plugs. As magnesium-deficient rats develop a mechanical hyperalgesia and intrathecal or intraperitoneal magnesium suppresses neuropathic pain, the magnesium concentrations in serum and cerebrospinal fluid may be altered in neuropathic pain. We therefore compared the magnesium concentrations in serum and cerebrospinal fluid of neuropathic rats with those in injured rats without symptoms of neuropathic pain and normal rats.

METHODS

Mechanical allodynia was induced in male Sprague-Dawley rats by tight ligature of the left lumbar fifth and sixth spinal nerves. The threshold of paw withdrawal was evaluated by the up-down method using withdrawal response to stimulus with a von Frey filament on the third, seventh and 14th days. Rats with a threshold of less than 4 g were selected as the symptomatic group and compared with an asymptomatic group, an unoperated control group and a sham-operated group. On the 16th day, the Mg2+ concentrations in serum and cerebrospinal fluid were measured.

RESULTS

The magnesium concentrations in the serum and cerebrospinal fluid of symptomatic neuropathic rats did not differ from those in the injured rats without symptoms of neuropathic pain, sham-operated rats and normal rats.

CONCLUSION

Our results suggest that physiologic homeostasis is maintained by active transport through the blood-brain barrier despite the activation of NMDA receptor-gated ion channels. However, rats with neuropathic pain may be in a magnesium-deficient condition at the effector site, such that magnesium treatment can decrease neuropathic pain.

Ionized magnesium in the cerebrospinal fluid of patients with head injuries

BACKGROUND

In head injury patients, a decrease in the serum ionized magnesium (iMg) concentration is considered to be related to the severity of the injury, however, this phenomenon is still not completely understood. The cerebrospinal fluid (CSF) iMg concentration has not been well documented under such conditions and, moreover, its normal value has not yet been established. We hereby intended to investigate the role of the iMg concentration and other parameters in both the serum and CSF of head injury patients and identify any relationship with other parameters.

MATERIALS AND METHODS

The subjects consisted of head injury patients without any other serious injuries. Ten healthy volunteers were selected as control subjects. Arterial blood and CSF specimens were simultaneously obtained and measured. We measured the Glasgow Coma Scale scores (GCS), the intracranial pressure (ICP), pH, po2, pco2, sodium, potassium, iCa, iMg, glucose, lactate, urea nitrogen. All data are expressed as the mean+/-SD and the units of iMg and iCa (corrected under pH 7.40) are given in mmol/L.

RESULTS

In the healthy subjects, the iMg concentration in the serum/CSF was 0.48 +/- 0.02 / 0.66 +/- 0.14, and iCa was 1.14 +/- 0.05 / 0.94 +/- 0.07. The GCS of the 15 head injury subjects at examination was 8.7 +/- 4.5. When the subjects were divided into 3 groups according to the GCS level (3 and 4, 5-8, and > or =9) at the time of examination, the serum iMg concentration was thus found to be related to the severity of injury based on the GCS level (p = 0.028), but not the CSF iMg concentration (p = 0.89). No relationship was observed between the iMg concentration in the serum and CSF when all specimens were compared, but an extremely close correlation was seen in the group with GCS 3 and 4 (p < 0.0001, r = 0.995), although no such correlation was seen in the other 2 groups (p = 0.12, r = -0.56 in the group with GCS 5-8, and p = 0.26, r = -0.35 in the group with GCS > or = 9). There was a significant correlation between the serum iMg and iCa (p = 0.0093, r = 0.47), and also between the CSF iMg and iCa concentrations (p < 0.0001, r = 0.67).

CONCLUSION

The serum iMg concentration has been suggested to possibly affect the neurologic state through CSF iMg in patients with the most severe head injury. In patients with moderate or mild head injuries, however, the ionized magnesium concentration is also probably associated with the degree of neurologic deficit based on the ionized calcium level. The CSF and serum ionized magnesium dissociation may thus result from the slow movement of ionized magnesium through the blood brain barrier.

Analysis of the brain bioavailability of peripherally administered magnesium sulfate: A study in humans with acute brain injury undergoing prolonged induced hypermagnesemia*

OBJECTIVE

Based on preclinical investigations, magnesium sulfate (MgSO4) has gained interest as a neuroprotective agent. However, the ability of peripherally administered MgSO4 to penetrate the blood-brain barrier is limited in normal brain. The current study measured the passage of intravenously administered Mg into cerebrospinal fluid in patients with brain injury requiring ventricular drainage.

DESIGN

A prospective evaluation of the cerebrospinal fluid total and ionized magnesium concentration, [Mg], during sustained hypermagnesemia was performed.

SETTING

Neurosciences intensive care unit at a major teaching institution.

PATIENTS

Thirty patients with acute brain injury secondary to subarachnoid hemorrhage, traumatic brain injury, primary intracerebral hemorrhage, subdural hematoma, brain tumor, central nervous system infection, or ischemic stroke were studied.

INTERVENTIONS

Patients underwent 24 hrs of induced hypermagnesemia during which total and ionized cerebrospinal fluid [Mg] was measured. Serum [Mg] was adjusted to 2.1-2.5 mmol/L. Cerebrospinal fluid [Mg] was measured at baseline, at 12 and 24 hrs after onset of infusion, and at 12 hrs following infusion termination.

MEASUREMENTS AND MAIN RESULTS

At baseline, total (1.25 +/- 0.14 mmol/L) and ionized (0.80 +/- 0.10 mmol/L) cerebrospinal fluid [Mg] was greater than serum total (0.92 +/- 0.18 mmol/L) and ionized (0.63 +/- 0.07 mmol/L) [Mg] (p < .05). Total (1.43 +/- 0.13 mmol/L) and ionized (0.89 +/- 0.12 mmol/L) cerebrospinal fluid [Mg] was maximally increased by 15% and 11% relative to baseline, respectively, during induced hypermagnesemia (p < .05).

CONCLUSIONS

Hypermagnesemia produced only marginal increases in total and ionized cerebrospinal fluid [Mg]. Regulation of cerebrospinal fluid [Mg] is largely maintained following acute brain injury and limits the brain bioavailability of MgSO4.

Studies on cerebrospinal fluid ionized calcium and magnesium concentrations in convulsive children

BACKGROUND

The concentrations of ionized calcium (iCa) and ionized magnesium (iMg) were measured in the cerebrospinal fluid (CSF) of convulsive and non-convulsive children, to investigate the relationship between seizure manifestation and CSF iCa and iMg concentrations. Standard concentrations of CSF iCa and iMg were also established.

METHODS

CSF samples from 23 patients, ages 0-15 years, with various forms of seizures and 26 age-matched non-convulsive children were collected by lumbar puncture. CSF was obtained anaerobically and the concentrations of CSF iCa and iMg were measured with an electolyte analyzer (Stat Profile Ultra M1, NOVA, USA) immediately after the lumbar puncture.

RESULTS

The concentrations of CSF iCa were significantly higher in non-convulsive children younger than 11 months old compared with children older than 12 months. The concentrations of CSF iMg in non-convulsive children did not differ significantly with aging. The concentrations of CSF iCa in convulsive children did not differ significantly from the concentrations of non-convulsive children. The concentrations of CSF iMg in convulsive children were significantly lower than in non-convulsive children.

CONCLUSION

These results suggest that seizure manifestation is related to age-dependent changes in iCa and decreased iMg in the developing brain.

Preventing noise induced otoacoustic emission loss by increasing magnesium (Mg2+) intake in guinea-pigs

This study aimed to explore the effects of increased Mg2+ intake on the activity of the outer hair cells as manifested in Click and Distortion Evoked Otoacoustic Emissions (CEOAEs; DPOAEs) in 25 animals. Thirteen animals were fed with high Mg2+ intake (39 mmol Mg2+/l in drinking water) and 12 without the Mg2+ additive. The OAE amplitudes and frequency ranges as well as the DPOAE thresholds were affected significantly less by noise exposure in the animals fed Mg2+-enriched water. Following the exposure, the auditory recovery was faster in the high than the low Mg2+ animals (controls). In addition, a relationship was found between the Mg2+ level and the emission loss. The post-exposure measures may result from the effect of Mg2+ on cochlear metabolic processes and vascular microcirculation. The results demonstrate that pre-existing low Mg2+ levels will exacerbate noise induced hearing loss (NIHL), and increased Mg2+ intake provides a significant biological cochlear protective effect.

A model of magnesium metabolism in young sheep: transactions between plasma, cerebrospinal fluid and bone

An extension of the previously proposed model of Mg metabolism (Robson et al. 1997) has been developed to consider the transactions of Mg that are associated with cerebrospinal fluid (CSF) and bone. The representation of the CSF as a single MG compartment with uptake from the plasma described by Michaelis-Menten kinetics gives very good agreement with published experiments. Analysis of the available information on resorption of Mg from adult bone indicated that this process makes a negligible contribution to Mg homeostasis and can be omitted from the model.

[Role of calcium and magnesium ions in cerebrospinal fluid in alcoholic-traumatic coma]

The goal of investigation was to determine the role of calcium and magnesium ions in the cerebrospinal fluid in ethylic-traumatic coma. We measured the level of calcium in the cerebrospinal fluid within simple photometric test and the magnesium level within xylidyl blue photometric test. We found a high mortality in patients with high level of calcium in cerebrospinal fluid and low level of magnesium in cerebrospinal fluid. At patients with ethylic-traumatic coma high levels of calcium in cerebrospinal fluid are caused by the excitatory amino acids cascade and increased of hematoencephalic barrier permeability. Decreased levels of magnesium in cerebrospinal fluid are associated with convulsions and a poor prognosis of the patients. These analyses are very important for establishment of prognosis in patients with ethylic-traumatic coma.

Intravenous magnesium sulfate does not increase ventricular CSF ionized magnesium concentration of patients with intracranial hypertension

Magnesium sulfate has attracted interest as a potential neuroprotectant but passage of magnesium ion into the central nervous system has not been well documented. For this study, we quantified plasma and cerebrospinal fluid (CSF) ionized magnesium concentration after systemic magnesium sulfate infusion in patients with intracranial hypertension. Patients ( N = 9) received an intravenous infusion of 5 g/20 mmol magnesium sulfate (125 mL of a 4% wt/vol solution) over 30 minutes. Before and after dosing, CSF (from an indwelling ventricular catheter) and blood samples were collected at hourly intervals. Ionized magnesium concentration in all samples was determined using an electrolyte analyzer. Baseline plasma and CSF ionized magnesium concentrations were 0.58 +/- 0.05 and 0.82 +/- 0.06 mmol/L, respectively. Intravenous magnesium sulfate infusion significantly increased plasma ionized magnesium concentration (peak, 0.89 +/- 0.11 mmol/L), but CSF magnesium levels did not change during the 4-hour study. Systemic administration of magnesium sulfate failed to increase CSF ionized magnesium concentration in patients with intracranial hypertension despite increasing plasma magnesium levels by >50%.

Magnesium sulfate does not reduce postoperative analgesic requirements

BACKGROUND

Because magnesium blocks the N-methyl-D-aspartate receptor and its associated ion channels, it can prevent central sensitization caused by peripheral nociceptive stimulation. However, transport of magnesium from blood to cerebrospinal fluid (CSF) across the blood-brain barrier is limited in normal humans. The current study was designed to evaluate whether perioperative intravenous magnesium sulfate infusion affects postoperative pain.

METHODS

Sixty patients undergoing abdominal hysterectomy received 50 mg/kg intravenous magnesium sulfate as a bolus dose followed by a continuous infusion of 15 mg x kg(-1) x h(-1) for 6 h (magnesium group) or the same volume of isotonic saline (control group). At the end of surgery, serum and CSF magnesium concentration were measured in both groups. The cumulative postoperative analgesic consumption was measured to assess the analgesic effect using a patient-controlled epidural analgesia device. Pain intensities at rest and during forced expiration were evaluated at 6, 24, 48, and 72 h postoperatively.

RESULTS

At the end of surgery, patients in the magnesium group had significantly greater postoperative serum magnesium concentrations compared with both preoperative and control group values (P < 0.001). Despite significantly higher serum magnesium concentrations in the magnesium group, there was no significant difference in magnesium concentration measured in postoperative CSF. Cumulative postoperative analgesic doses were similar in both groups. However, there was observed an inverse relation between cumulative postoperative analgesic consumption and the CSF magnesium concentration in both groups. Visual analog pain scores at rest and during forced expiration were similar and less than 4 in both groups.

CONCLUSIONS

Perioperative intravenous administration of magnesium sulfate did not increase CSF magnesium concentration and had no effects on postoperative pain. However, an inverse relation between cumulative postoperative analgesic consumption and the CSF magnesium concentration was observed. These results suggest that perioperative intravenous magnesium infusion may not be useful for preventing postoperative pain.

Postmortem biochemical markers of experimentally induced hypomagnesaemic tetany in cattle

Severe hypomagnesaemia and tetany were induced in 10 lactating cows by feeding them semi-synthetic low magnesium diets and the animals were used to study the stability of postmortem markers of hypomagnesaemic tetany. There were significant relationships between the concentrations of magnesium in either cerebrospinal fluid (CSF) or plasma and either aqueous or vitreous humour. The onset of hypomagnesamic tetany was also associated with low magnesium concentrations in plasma, CSF and aqueous and vitreous humour. Magnesium concentrations less than 0.25 mmol/litre in fresh aqueous humour may be indicative of severe hypomagnesaemia and possible tetany in lactating cows, but the concentration of magnesium in aqueous humour was unstable postmortem. The concentration of magnesium in vitreous humour was relatively stable and a concentration of less than 0.55 mmol/litre could be used as a diagnostic marker of tetany in cattle for up to at least 48 hours postmortem, at ambient temperatures typical of Northern Ireland.

Postmortem biochemical markers of experimentally induced hypomagnesaemic tetany in sheep

Hypomagnesaemic tetany was induced in non-lactating and lactating ewes by feeding them semi-synthetic low magnesium diets containing additional potassium chloride and citric acid. Aqueous and vitreous humour were sampled from one eye at the time of death (fresh) and from the second eye after the head had been stored at ambient temperature for 24 hours (24-hour). There were significant relationships between the concentrations of magnesium in cerebrospinal fluid and plasma and its concentrations in fresh aqueous humour and fresh vitreous humour. Magnesium concentrations of < 0.33 mmol/litre in fresh aqueous humour and < 0.50 mmol/litre in 24-hour aqueous humour were associated with severe hypomagnesaemia and tetany. However, the concentration of magnesium in aqueous humour is relatively unstable and, unless the time of death was known accurately, its interpretation would be difficult. Magnesium concentrations of < 0.60 mmol/litre in fresh vitreous humour and < 0.65 mmol/litre in 24-hour vitreous humour were associated with severe hypomagnesaemia and tetany in adult sheep. The concentration of magnesium in vitreous humour was relatively stable for up to 48 hours postmortem.

Regional brain monoamine concentrations and their alterations in bovine hypomagnesaemic tetany experimentally induced by a magnesium-deficient diet

Monoamines are important brain neurotransmitters. An investigation was carried out to determine if hypomagnesaemic tetany was associated with alterations in regional brain monoamine concentrations in bovines. The results, established in cows with normal magnesium status, demonstrated that regional differences existed in the distribution and concentration of brain monoamines in the adult bovine, which were similar to those in other species. In magnesium-deficient cows, severe hypomagnesaemia and lowered cerebrospinal fluid (CSF) magnesium concentrations were associated with significant alterations in monoamine concentrations in some brain regions. Alterations in 3,4-dihydroxyphenylalanine (DOPA) and dihydroxyphenylacetic acid (DOPAC) concentrations in the corpus striatum, and dopamine (DA) in the cerebral cortex and cerebellum were recorded. These regions play an important role in both voluntary and involuntary motor function, and therefore these alterations may play a role in the aetiology of hypomagnesaemic tetany. However, there was no significant change in DA concentrations in the corpus striatum (the main dopaminergic region in the brain) associated with hypomagnesaemia. In addition, a significantly lower norepinephrine (NE) concentration in the corpus striatum of hypomagnesaemic animals was also recorded. Norephinephrine is generally excitatory and therefore lowered NE concentrations would be expected to result in depression rather than stimulation of motor function.

High serum and cerebrospinal fluid Ca/Mg ratio in recently hospitalized acutely depressed patients

Calcium (Ca) and magnesium (Mg) are involved in many processes related to depression. Evaluations of serum and plasma Ca and Mg levels in depressive disorders do not show consistent results. The few studies that examined their cerebrospinal fluid (CSF) levels tended to find no differences between depressed patients and controls. Because both hypercalcemia and hypomagnesemia are associated with depression, and as Mg may function as a Ca antagonist, it is suggested that the relationship between these cations could be different in depressed patients and controls. We examined CSF and serum Ca and Mg in acutely depressed patients diagnosed as having major depressive disorder or being in a depressive episode of bipolar disorder. Controls were subjects undergoing lumbar puncture as part of an evaluation for headache or suspected meningitis and found to demonstrate no physical or mental disorder. Serum and CSF Ca/Mg ratios were found to be elevated in the depressed patients compared with the controls. A retrospective analysis of previous trials assessing serum/plasma or CSF Ca and Mg does not seem to refute the findings of this study. We further discuss our findings in their relation to the acuteness of the depressive disorders.

Fenfluramine blocks low-Mg2+-induced epileptiform activity in rat entorhinal cortex

PURPOSE

The entorhinal cortex (EC) represents the main input structure to the hippocampus and seems to be critically involved in temporal lobe epilepsy. Considering that the EC receives a strong serotonergic projection from the raphe nuclei and expresses a high density of serotonin (5-HT) receptors, the effect of the 5-HT-releasing drug fenfluramine (FFA) on epileptiform activity generated in the EC was investigated in an in vitro model of epilepsy.

METHODS

The experiments were performed on 43 horizontal slices containing the EC, the subiculum, and the hippocampal formation obtained from 230-250 g adult Wistar rats. Using extracellular recording techniques, we investigated the effect of bath-applied FFA (200 micromol/L to 1 mmol/L) on epileptiform activity induced by omitting MgSO4 from the artificial cerebrospinal fluid.

RESULTS

We demonstrate that FFA reversibly blocks epileptiform activity in the EC. Surprisingly, in the presence of the 5-HT uptake blocker paroxetine, the FFA-induced effect was diminished. Coapplication of the 5-HT1A receptor antagonist WAY100635 prevented the FFA-induced anticonvulsive effect, suggesting that (a) the FFA-induced suppression of epileptiform activity is mediated by the release of 5-HT from synaptic terminals within the EC rather than by an unspecific effect of FFA and (b) released 5-HT most likely blocks the activity by activation of 5-HT1A receptors.

CONCLUSION

FFA, which is primarily used because of its anorectic activity, might get an additional therapeutic value in the treatment of temporal lobe epilepsy with parahippocampal involvement.

[Total magnesium in serum and cerebrospinal fluid in patients with amyotrophic lateral sclerosis]

The significance of trace elements in the aetiopathogenesis of ALS is still unknown. Magnesium plays an essential role in fundamental cellular reactions. The aim of this study was to estimate total magnesium concentration in serum and cerebrospinal fluid of ALS patients. 15 persons with ALS and 12 controls took part in the examination. Magnesium was determined by spectrophotometric atomic-absorption method. Total magnesium concentration in serum of ALS patients was statistically insignificant lower than in the control group, but in cerebrospinal fluid was it statistically insignificantly higher than in the control group. Outcomes of our own investigations do not show any essential role of magnesium in the aetiopathogenesis of ALS.

Increased cerebrospinal fluid glutamine levels in depressed patients

BACKGROUND

There is increasing evidence for an association between alterations of brain glutamatergic neurotransmission and the pathophysiology of affective disorders.

METHODS

We studied the association between cerebrospinal fluid (CSF) metabolites, including glutamine, in unipolar and bipolar depressed patients versus control subjects using a proton magnetic resonance spectroscopy technique. Cerebrospinal fluid samples were obtained from 18 hospitalized patients with acute unmedicated severe depression without medical problems and compared with those of 22 control subjects.

RESULTS

Compared with the control group, the depressed patient group had significantly higher CSF glutamine concentrations, which correlated positively with CSF magnesium levels.

CONCLUSIONS

These findings suggest an abnormality of the brain glial-neuronal glutamine/glutamate cycle associated with N-methyl-D-aspartate receptor systems in patients with depression.

Region-specific modulation of limbic seizure susceptibility by ovarian steroids

Gonadal steroid hormones can markedly affect seizure susceptibility. Ovariohysterectomized female rats given ovarian steroid hormone supplements were used to evaluate the effects of ovarian steroids on epileptiform activity in hippocampal slices in vitro and on flurothyl-induced seizures in vivo. Seizure susceptibility was compared in the entorhinal cortex (EC) and CA1 regions of the hippocampus perfused with Mg(2+)-free medium, which leads to epileptiform discharges caused by a relief of voltage-dependent NMDA receptor block. After in vivo treatment with 500 microg of progesterone for 2 h prior to slice preparation, the latency to onset of low Mg(2+)-induced epileptiform activity of slices was significantly prolonged compared to slices from controls. In contrast, progesterone replacement accelerated the development of epileptiform activity in the CA1 region. Neither estrogen alone (2 x 2 microg of estradiol benzoate, 48 and 24 h prior to the experiment), nor a combined treatment with estrogen plus progesterone, significantly affected seizure susceptibility in either CA1 or the EC. There were no consistent effects of estrogen or progesterone, alone or in combination, on flurothyl-induced seizures in vivo. The data suggest that in vitro, progesterone alters seizure susceptibility in a site- and seizure model-specific fashion. The differential effects of progesterone may be due to differential expression of progesterone receptor isoforms or metabolites in specific brain areas suggesting that selective modulation of NMDA receptor-dependent epileptiform activity may play a role in hormonal effects on epileptogenesis.

Macro- and trace element concentrations in blood plasma and cerebrospinal fluid of dairy cows exposed to electric and magnetic fields

Eight multiparous, nonlactating pregnant Holstein cows (at 198 +/- 35 days of gestation and weighing 608 + 24 kg) and seven nonlactating nonpregnant ovariectomized heifers (weighing 370 + 29 kg) were confined to wooden metabolism crates in an electric and magnetic field chamber. Subarachnoidal catheters were inserted before the activation of the electric and magnetic fields. For 30 days, cows and heifers were continuously exposed in separate trials to electric and magnetic fields (60 Hz, 10 kV/m, and 30 microT). Blood plasma and cerebrospinal fluid samples were collected for 3 consecutive days before the exposure period, the last 3 days of the exposure period, and for 3 days starting 5 days after the exposure period. Concentrations of Ca, Mg, Cu, Zn, Fe, Mn, Na, P, and K in blood plasma and cerebrospinal fluid were determined. Exposure to electric and magnetic fields resulted in decreased concentrations of Mg in blood plasma and in increased concentrations of Ca and P and decreased concentrations of Fe and Mn in cerebrospinal fluid.

Total magnesium concentrations of perilymph, cerebrospinal fluid and blood in guinea pigs fed different magnesium-containing diets

The total magnesium (Mg) concentrations of the perilymph (PL), cerebrospinal fluid (CSF), plasma and red blood cells (RBCs) of anesthetized guinea pigs separated into three groups and fed different Mg-containing diets were determined by atomic absorption spectrometry. Due consideration was given to the significant sources of error connected with the sampling procedure, particularly contamination of PL with CSF. The Mg levels of the individuals fluids differed significantly (P < 0.05/0.01) within each group. In the normal Mg group, the mean values of the PL, CSF and plasma were 0.66, 0.81 and 0.97 mmol/l, respectively, and 7.83 mmol/kg dry weight for RBCs. The analytical data were found to depend on the Mg content of the animals' diet, but to a different degree in the individual specimens (plasma > PL > CSF). A correlation was found to exist between all specimens tested (P < 0.05/0.01), except for CSF and RBCs, with the closest relation being that between plasma and PL. These findings suggest that the perilymphatic Mg equilibrates with the Mg level of plasma rather than with that of CSF. This is the first report showing Mg data of PL, CSF, plasma and RBCs obtained from the same subject, and the dependency on the Mg content of the animals' diet.

[Magnesium and zinc levels in blood serum and cerebrospinal fluid in children with febrile convulsions]

Magnesium and zinc levels in blood serum and cerebrospinal fluid were estimated in 18 children aged 8 months-5 years with febrile convulsions. Control group consisted of 15 apparently healthy children in the same age. On the ground of ethical reasons no control values for cerebrospinal fluid were evaluated. The mean serum concentration of magnesium and zinc was significantly lower in the sick children (p < 0.001 and p < 0.05 resp.). The magnesium levels in cerebrospinal fluid were evidently lower than those quoted in the literature and the mean concentration of zinc was higher in comparison with literature data. The presumable pathogenetic role of disturbed magnesium and zinc metabolism in febrile convulsions is discussed.

[Concentration of magnesium in serum and cerebrospinal fluid in patients with stroke]

Magnesium concentration in blood serum and cerebrospinal fluid (CSF) was determined in 131 patients aged from 21 to 91 years, with RIND, complete stroke, cerebral haemorrhage and control group. Magnesium was estimated by the use of colorimetry and the method of Mann and Yoe. The results are presented in figures. Statistical evaluations revealed significant decrease of magnesium concentrations in blood serum and CSF in ischaemic stroke compared with control group. In complete stroke significantly lower concentrations of magnesium in blood serum and CSF were found compared with RIND. In ischaemic stroke higher MgSER/MgCSF index was found compared with control group. Magnesium concentration in blood serum was not statistically different within 2 weeks of the disease. No relationships were found between blood serum or CSF Mg concentrations and gender or age.

Cerebrospinal fluid magnesium level as a prognostic factor in ischaemic stroke

Magnesium has been reported to have a dilatatory effect on cerebral arteries. Reduction of extracellular Mg+2 has been shown to be directly correlated with the intensity of cerebral spasm. A neuroprotective effect of magnesium in stroke has also been hypothesized. The aim of our study was to examine the Mg+2 levels in serum and cerebrospinal fluid (CSF) in the early stage of stroke and to evaluate the correlation between Mg+2 levels and the development of neurological deficits. Between 1986 and 1994, 96 patients who had a stroke of 24- to 48-h duration were enrolled in the study. Serum and CSF levels of magnesium were checked on admission, 2448 h after the onset of stroke. Using a neurological score, the neurological deficit was assessed on the 1st day, 1 and 4 weeks later. Computed tomography (CT) was performed after 1 week, and the volume and location of infarction were calculated and measured. Statistical analysis was performed for cortical and subcortical patients separately, using Spearman correlation and multiple linear and logistic regression analyses. Significant correlation was found between CSF Mg+2 and the size of the infarct (P < 0.0001). There was no correlation between serum Mg+2 and CSF Mg+2 levels. Regression analysis demonstrated an increase in the values of the Mathew Neurological Score with higher CSF Mg+2 levels. This association remained true after other factors such as age, associated heart disease, diabetes and infarction size had been taken into account by the regression model. The results confirm that there is a relationship between a low Mg+2 concentration in CSF during the first 48 h after onset of ischaemic stroke and the intensity of the neurological deficit. The therapeutic consequence of this finding may have some importance.

Role of excitatory aminoacids in neonatal hypoglycemia

BACKGROUND

In many neurological disorders, injury to neurons may be due in part to overstimulation of the receptors for the excitatory amino acids glutamate and aspartate. The same excitotoxic mechanism and high aspartate levels in experimental studies led to this study of the concentrations of glutamate and aspartate and zinc, copper, and magnesium levels in the cerebrospinal fluid (CSF) of hypoglycemic newborns.

METHODS

Aspartate and glutamate were determined by high-performance liquid chromatography, and magnesium, zinc and copper by atomic absorption spectrophotometer.

RESULTS

The CSF levels of aspartate (3.98 +/- 1.77 mumol/L) and glutamate (1.7 +/- 1.05 mumol/L) in 20 hypoglycemic newborns were significantly higher when compared with the values of aspartate (2.19 +/- 0.6 mumol/L) and glutamate (0.77 +/- 0.34 mumol/L) of 10 control newborns. In the hypoglycemic patients, the concentration of zinc (0.57 +/- 0.13 microgram/mL), but not copper (0.39 +/- 0.40 microgram/mL) was significantly lower when compared with the control values. There was no difference in the magnesium levels between the two groups.

CONCLUSIONS

The higher levels of excitatory amino acids found in the CSF of hypoglycemic infants than in controls were consistent with previous animal studies, which may indicate the role of excitatory amino acids in the late biochemical effects of hypoglycemia in newborn brain metabolism.

[Magnesium in cerebrospinal fluid in acute cerebral ischemia: its relation to glutamate neurotoxicity]

INTRODUCTION

In animal models it has been shown that there is an increase in tissue magnesium concentration during cerebral ischemia. We studied the changes in magnesium levels in the cerebrospinal fluid (CSF) during the acute phase of cerebral ischemia.

MATERIAL AND METHODS

We included 95 patients with first ischemic cerebral infarcts admitted to hospital within the first 24 hours and also 37 controls. CT scan was done on admission and between four and seven days later (when the volume of the infarct was determined). The neurological defect was evaluated on the Canadian scale on admission, after 48 hours, on the seventh day and after three months. The CSF magnesium concentration was determined using a colorimetric method and the glutamate by HPLC.

RESULTS

The CSF magnesium concentrations were significantly higher in the patients than in the controls (2.6 +/- 0.6 mmol/l vs 2.2 +/- 0.6 mmol/l p = 0.0001). The magnesium concentration was higher in the larger infarcts (Pearson's coefficient = 0.2901, p = 0.0043), and in those presenting greater neurological defects after 48 hours (Spearman's coefficient = -0.4649, p < 0.0001). The magnesium concentration was not related to the presence of early signs on the initial CT scan and the Canadian scale rating on admission. The concentration of magnesium was significantly correlated with that of glutamate (Pearson coefficient = 0.7735, p < 0.0001).

CONCLUSIONS

The levels of magnesium in the CSF were satisfactorily related to the volumes of the infarct and the intensity of the neurological defect. However, this association was late, occurring more than 48 hours after onset of the condition.

Cerebrospinal fluid passage of intravenous magnesium sulfate in neurosurgical patients

Increasing evidence suggests a neuroprotective potential of magnesium sulfate (MgSO4). Only limited information about the passage of MgSO4 to the cerebrospinal fluid (CSF) is available in neurosurgical patients. However, with regard to the clinical relevance of magnesium's neuroprotective properties, quantitative data about its CSF passage are needed. The present study aims to assess the amount and the time course of magnesium's CSF passage in neurosurgical patients. To this end, 20 patients undergoing general anesthesia for neurosurgery and needing CSF drainage were included. Patients received an i.v. bolus of 60 mg/kg MgSO4. The increase in plasma and CSF magnesium concentration were measured 30, 90, and 240 min after the end of the MgSO4 infusion. These values were compared with the baseline levels taken before the start of the MgSO4 infusion. Thus, each patient served as his or her own control. Values are expressed as means +/- SD. The plasma magnesium levels were measured as follows: baseline, 0.74 +/- 0.12 mM; at 30 min, 1.24 +/- 0.1 mM (p < 0.01); at 90 min, 0.95 +/- 0.15 mM (p < 0.01), and at 240 min, 0.82 +/- 0.14 mM (p < 0.05). The CSF magnesium levels were measured as follows: baseline, 0.95 +/- 0.11 mM; at 30 min, 1.00 +/- 0.15 mM (NS); at 90 min, 1.10 +/- 0.17 mM (p < 0.01); and at 240 min, 1.13 +/- 0.19 mM (p < 0.001). We concluded that a bolus of 60 mg/kg of MgSO4 leads at least after 90 min to a significant increase in the CSF magnesium concentration. Moreover, the increase in plasma and CSF magnesium concentration is not parallel. Thus, plasma magnesium concentration cannot be used to predict the changes in CSF concentrations.

Essential trace element alterations in amyotrophic lateral sclerosis

Although trace elements have been implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS) for a long time, new evidence has connected familial ALS with the metalloenzyme copper-zinc superoxide dismutase, thus reinforcing the study of their metabolism. This work presents the results of serum and cerebrospinal fluid levels of copper, zinc, manganese and magnesium, by atomic absorption spectrophotometry. Statistically significant decreased cerebrospinal fluid and serum copper levels were found in patients compared to the control group (20.25 +/- 7.09 vs. 30.86 +/- 16.02 SD micrograms/l and 913.21 +/- 165.55 vs. 1020.17 +/- 197.76 SD micrograms/l) while serum manganese levels were found to be increased in patients (3.59 +/- 0.89 SD micrograms/l) compared to controls (3.03 +/- 1.23 SD micrograms/l). Zinc and magnesium levels were unchanged. Our findings indicate an essential trace element imbalance in the disease.

Trace elements, age, and sex in amyotrophic lateral sclerosis disease

The statistical tests analysis of variance, analysis of covariance, correlation coefficient, Kolmogorov-Smirnov test, t-test, and Tukey test were applied to copper, magnesium, manganese, and zinc content in serum (S) and in cerebrospinal fluid (CSF) of controls and of a sporadic form of Amyotrophic Lateral Sclerosis (ALS) disease. This is carried out in order to evaluate statistically the possible relationships among the trace elements when ALS patients and controls are considered as independent groups, within sex groups and within age decades of both patients and control classes. A statistically significant difference between older controls (age > 40) and ALS patients (age > 40) for copper in CSF, copper in S, manganese in S, and zinc in CSF was found. Statistically significant correlation coefficients within the different classes formed for this study were observed. Within this pool, a correlation of patient group can differ statistically from the corresponding one of controls and vice versa. Thus, this correlation could be characteristic of the group from which is extracted, e.g., the correlation between copper in S and zinc in S, which is characteristic of ALS patients when considered as an independent group as well as members of the male patient class.

Serum and cerebrospinal levels of calcium and magnesium in acute versus remitted schizophrenic patients

Serum and cerebrospinal fluid levels of calcium and magnesium were measured in acute schizophrenics versus schizophrenic patients in remission. The acute schizophrenics demonstrated statistically significant lower levels of cerebrospinal fluid magnesium. The mechanism that underlies this difference is not clear.

Baseline serum and cerebrospinal fluid magnesium levels in normal pregnancy and preeclampsia

OBJECTIVE

To determine whether baseline cerebrospinal fluid magnesium levels in preeclampsia differ from those in normal pregnancy, and to ascertain whether pre-treatment cerebrospinal fluid magnesium levels correlate with serum levels, which would suggest a baseline alteration in the blood-brain barrier in preeclampsia.

METHODS

When spinal analgesia or anesthesia was administered for delivery, serum and cerebrospinal fluid magnesium levels were determined in 20 normal gravidas and 20 preeclamptic women not treated with magnesium sulfate. Data were analyzed by two-sided Student t test and regression analysis.

RESULTS

Mean (+/- standard deviation) cerebrospinal fluid magnesium level for preeclamptic patients was 2.23 +/- 0.09 mEq/L, which was not significantly different from controls. Regression analysis revealed no significant correlation between cerebrospinal fluid and serum magnesium levels for either normal or preeclamptic gravidas.

CONCLUSION

During the third trimester, there is no difference in baseline, pre-treatment cerebrospinal fluid magnesium levels in preeclamptic patients compared to normal subjects, and no correlation between cerebrospinal fluid and serum magnesium over the range of baseline values.

Cerebrospinal fluid variables in clinically normal foals from birth to 42 days of age

To determine the effects of age on each analyte, CSF variables were evaluated in healthy foals from birth through 42 days of age. Cerebrospinal fluid was collected from 14 clinically normal, naturally delivered cross-bred foals and was analyzed for glucose, sodium, potassium, magnesium, and total protein concentrations, total and differential WBC counts, RBC count, and lactate dehydrogenase, aspartate transaminase, and creatine kinase activities. Samples were collected in 3 foals < 48 hours old, and at 11 to 14 days of age in 4 foals, 21 to 22 days of age in 3 foals, and 31 to 42 days of age in 4 foals. Each foal was tested only once, to avoid any effects of CSF sample collection on subsequent analysis. Regression analysis confirmed age-related effects on CSF glucose, protein, and magnesium concentrations, but did not indicate an effect of age on CSF sodium and potassium concentrations or cell counts. Results indicate that CSF glucose concentration decreases with age; foals < 2 days old had the highest CSF glucose values, 98.8 +/- 12.0 mg/dl (mean +/- 1 SD). In foals 10 to 14 days old, CSF glucose concentration was 67.3 +/- 12.0 mg/dl, was 65.3 +/- 4.5 mg/dl in foals 21 to 22 days old, was 70.0 +/- 5.4 mg/dl in foals 31 to 42 days old, and was 51.1 +/- 2.5 mg/dl in adults.(ABSTRACT TRUNCATED AT 250 WORDS)

CSF magnesium in affective disorder: lack of correlation with clinical course of treatment

There has been recent renewed interest in the role of magnesium in affective disorder, particularly in the bipolar subtype. However, determinations of serum magnesium concentrations have not yielded consistent findings and little is known about cerebrospinal fluid (CSF) magnesium in these patients. We analyzed CSF magnesium levels from 173 medication-free patients with affective disorder (76 bipolar I, 54 bipolar II, and 43 unipolar) and 59 healthy volunteers. In addition, we examined CSF magnesium from 32 patients before and during carbamazepine treatment and 13 patients before and during lithium treatment. CSF magnesium levels varied significantly according to gender (with lower concentrations in women) but not with respect to age, diagnosis, mood state, or treatment with carbamazepine or lithium. An abnormality of magnesium in affective disorders, if it exists, is not readily detectable in CSF.

HPLC determination of inorganic cation levels in CSF and plasma of conscious rabbits

An HPLC method is described using conductimetric detection for the quantitative determination of sodium, potassium, magnesium, and calcium in cerebrospinal fluid (CSF) and plasma of conscious rabbits. This method enabled the four cations to be estimated with rapidity, sensitivity, accuracy, and precision. The mean millimolar concentrations +/- SD found in CSF and (plasma) of 15 untreated animals were as follows: sodium, 146.96 +/- 17.84 (135.06 +/- 20.11); potassium, 3.32 +/- 0.56 (4.57 +/- 1.03); magnesium, 0.90 +/- 0.20 (0.72 +/- 0.13); and calcium, 1.47 +/- 0.19 (3.32 +/- 0.59).