Cerebrospinal Fluid And Serum Zinc, Copper, Magnesium And Calcium Levels In Children With Idiopathic Seizure
Correspondence Address :
Dr. Rajniti Prasad,Sr Lecturer,Department of Pediatrics,Institute of Medical Sciences,Banaras Hindu University,
Varanasi â€“ 221005. (India).e
Objectives: The present study was conducted to observe the alteration and their relations in cerebrospinal fluid (CSF) and serum Zinc (Zn), Copper (Cu), Magnesium (Mg) and calcium (Ca) levels in patients with different type of idiopathic seizure and to determine the ratios of serum and CSF Ca/Mg and Cu/Zn.
Methods: The children of aged 1 to 14 years, having two or more unprovoked seizures with normal MRI scan and abnormal EEG were included in study group. Control group consisted of 40 healthy children without seizure. Zn, Mg and Cu levels in CSF and serum were analyzed by atomic absorption spectrophotometer.
Results: The study subjects included 34 generalized seizures (GS), 5 cases of simple partial seizure (SPS) and 5 Complex partial seizures (CPS). Serum copper (Cu) was significantly elevated (P-0.01) in children with seizure. Within seizure group, serum Mg was significantly increased in GS and serum copper (Cu) levels were significantly increased in CPS and GS as compared to control (p-0.001). However, calcium and zinc did not show any significant change in all groups. CSF Calcium was significantly increased in CPS patients. The ratio obtained for the levels of these parameters revealed a significant increase in serum Cu/Zn ratio (P-0.002) and CSF Ca/Mg (P-0.04) in patients with idiopathic seizure as compared to control. This ratio was also significant between SPS versus CPS and CPS versus GS.
Conclusion: The findings of present study suggest that high serum Cu and increased ratio of serum Cu/Zn and CSF Ca/ Mg may be responsible for enhanced neuronal excitability in children with idiopathic seizures.
Idiopathic seizure, zinc, copper, magnesium , calcium
The exact pathogenesis of seizure is not fully understood but involves several factors like genetic predisposition, changes in the levels of neurotransmitters and some trace elements. Several reports suggested that the level of some trace elements play a vital role in causation of seizure (1), (2). Among trace elements, Zinc (Zn) acts as a co-factor of glutamic acid decarboxylase, an enzyme which maintains the production of GABA in central nervous system and decreased level of Zn in CSF has also been observed in Febrile seizure (2), (3). Magnesium (Mg) is also involved in neuronal function and inhibits the facilitatory effects of calcium on synaptic transmission and exerts a voltage dependent blockage of N-methyl-D-aspartate (NMDA) receptor channel. Copper (Cu) inhibits Mg++-adenosine triphosphatase(ATPase) and Na+-K+-ATPase enzymes and disturbs the sodium and potassium homeostasis, which results in genesis of epileptiform discharges (4). In some cases the altered levels of trace elements in epileptic patients were attributed to anti-convulsant drugs therapy or due to other unknown reasons.
A careful literature review reveals that a comprehensive record of zinc, copper, magnesium and calcium in serum and CSF and their ratios in children with idiopathic seizures is missing. Hence to observe their significance in children, the current study was conducted to estimate their levels in children suffering from idiopathic seizures. Furthermore, an attempt has been made to find out ratios of them such as Ca/Mg, Cu/Zn and to correlate with types of seizure.
The present study was carried out in Department of Pediatrics, a tertiary care hospital, India from June 2006 to July 2008. A total of 44 children suffering from seizure aged, 1 year to 14 years were enrolled for the study.
Cases: Children of age group 1 year to 14 years, having two or more unprovoked seizures (first presentations in hospitals) with normal CT / MRI Scan and abnormal encephalogram(EEG) were included in study group. Children with GS were treated with sodium and valproic acid, whereas cases with SPS and CPS received carbamazepine and valproic acid respectively.
40 healthy children (22 male and 18 female) without seizures.
Children with malnutrition, acute bacterial meningitis and those taking Cu, Zn, Mg and Ca containing preparations were excluded from the study.
The protocol of study was approved by Institute Postgraduate Medical Board. Parents of each patient were explained about the illness of their child and informed consent was taken from the parent or legal guardian after explaining the procedure, which is an integral part of study.
Collection And Storage Of Samples
Blood samples were collected through vein puncture using aseptic precautions. The serum was separated and transferred into plastic tubes. The patients underwent lumbar puncture and the CSF was collected in acid washed plastic tubes. One millimeter of CSF was used for trace elements estimation. Both CSF and serum samples were stored at -20C until analysis. The glass and polypropylene equipments used for trace elements analysis were soaked in 10% (v/v) nitric acid for 12 hours and then rinsed with double distilled deionized water.
Estimation of Cu, Zn, Ca and Mg
The Cu, Zn, Ca and Mg levels in CSF and serum were assayed by atomic absorption spectrophotometer in the Department of Botany, Faculty of Science, Banaras Hindu University, Varanasi. Both CSF and serum samples were diluted with double deionized distilled water and dilution factor was 1:3 and 1:6 for zinc and copper respectively and 1:10 for Ca, Mg estimation. The standard solution contained 100 g/ml of each element and used for calculation in analysis of Cu, Zn, Ca and Mg levels in CSF and serum. Sample reading was taken thrice and arithmetic mean was calculated.
The data was analyzed using SPSS software version 10. Studentâ€˜tâ€™ test and Man Whitney U-test was used to compare the significant difference of means between control and patients. Data, which did not follow normal Gaussian distribution ,were compared by Wilcoxan Rank sum or Kruskal- Wallis test. Post-hock test has been used to find out pair wise significant difference, if one way ANOVA is significant. The ratio and correlation coefficients were also calculated. Categorical data were compared by calculating the chi-square value or by Fischer exact test.
Serum copper levels in children with seizure and their subgroups were significantly increased as observed by other workers (5), (6), (7), (8), (9) but Smith et al.(10) and Kurekci et al.(11) have reported no significant change. The increased copper levels in serum may be due to effect of anti-epileptic drugs, increased hepatic synthesis or decreased breakdown or both of copper binding protein, altered intestinal absorption and altered excretion patterns, changes in the distribution among body tissues or some combination of above factors (8), (9). CSF Cu were found comparable in both cases and control as observed by Goody et al.(12) This variation in serum and CSF value might be due to some unknown factors which need to be further evaluated.
Zinc is essential for normal development of the brain. Although serum and CSF Zn level in patients with seizure was found to be decreased but statistically insignificant as observed by other workers (9), (10), (12). Low Zn concentrations have been reported in serum and CSF of patients with epilepsy (13). The mechanism by which depletion of zinc facilitates seizure activity is hypothesized as its inhibitory effect on GABA, an inhibitory neuro-transmitter. Zinc also plays an important role in both the synthesis and function of GABA (14). Goody et al;(12) and Kapaki et al;(15) had reported increased CSF concentration in patients with neurological disorders.
The present study demonstrated low serum and CSF Mg levels in cases but insignificant. Our results are simillar with study of other workers (16), (17), (18), (19). However Alwarez-Dominiguez et al. (20) showed higher serum magnesium level in epilepsy. Rude (21) hypothesized that magnesium deficiency is responsible for hyper- excitability of neuron. It is apparent from the study that in normal subjects the serum magnesium levels is lower than levels in CSF, suggesting that some mechanism other than mere diffusion is responsible for maintaining this relatively higher concentration in CSF.
It is well documented that low levels of calcium are responsible for initiation of seizures. However, in present study serum calcium in seizure remained comparable to the control as reported by Rutter et al (22) but other workers (18), (19) showed higher levels of calcium in epileptic children. Calcium facilitates the release of acetylcholine by nerve impulses, which may be responsible for neuromuscular irritability. Hypomagnesemia and hypercalcemia combine to produce a membrane state, which becomes responsive to an otherwise sub-threshold stimulus.
Generalized seizure group had significantly higher levels of serum Mg as compared to partial seizure group in present study. Shah et al (16) had found nearly comparable levels unlike our result. The present study also showed significant decrease in CSF Ca in children with SPS and CPS. We can hypothesize that type of seizure had influence on concentration of Mg and Cu in serum.
It was observed that serum Cu/Zn and CSF Ca/Mg ratios were significantly elevated in study group. The elevated Cu/Zn ratio may be closely associated with initiation and continuance of seizures. Leaver et al.(23) also observed decline both in calcium and magnesium concentrations and high serum Ca/Mg ratio as with our result. Our observation on the possible use of Cu/Zn ratio is a new concept and may help to judge enhancement of neuronal excitability.
The strongest correlations observed in our study were between CSF Ca and CSF Mg (r=0.39) as observed by Woodbury et al.(24) and Bogden JD et al. (25) The correlation between plasma and CSF Mg (r=0.35) although significant, is not strong enough to allow a useful estimate of Mg concentration in CSF from its concentration in plasma.
The estimation of serum and CSF levels of Ca, Mg, Cu and Zn and their ratios are essential for the rational understanding of pathogenesis and management of childhood idiopathic seizure and their sub-groups. The changes in trace metals might be associated to type of seizure rather than anti-convulsant therapy. However, it is suggested to conduct a study with greater sample size to evaluate the role of trace elements and their ratios in childhood seizures.
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