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Vitamin D status of untreated children and adolescent Egyptian patients with genetic generalized epilepsy: A case–control study
YEBEH-106840; No of Pages 4 Epilepsy & Behavior xxx (xxxx) xxx
Contents lists available at ScienceDirect
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Vitamin D status of untreated children and adolescent Egyptian patients with genetic generalized epilepsy: A case–control study Alaa Elmazny a, Hanan Amer a, Laila Rashed b, Sarah Khalil a, Rehab Magdy a,⁎ a b
Department of Neurology, Kasr Al-Ainy Faculty of Medicine, Cairo University, Cairo, Egypt Department of Medical Biochemistry and Molecular Biology, Kasr Al-Ainy Faculty of Medicine, Cairo University, Cairo, Egypt
a r t i c l e
i n f o
Article history: Received 20 November 2019 Revised 3 December 2019 Accepted 3 December 2019 Available online xxxx Keywords: Genetic generalized epilepsy Treatment-naive Vitamin D
a b s t r a c t Purpose: Antiepileptic drugs (AEDs) are commonly incriminated for vitamin D deficiency in children with epilepsy. The aim of this study was to examine 25(OH) vitamin D status among children and adolescents with genetic generalized epilepsy (GGE) who had never received AEDs and its relation to seizure frequency and epilepsy duration. Methods: This case–control study was conducted on 42 recently diagnosed patients with GGE, aged ≤18 years and 40 age- and gender-matched controls. Serum 25(OH) vitamin D level was performed for all participants. Results: Serum 25(OH) vitamin D level was significantly lower in patients (median = 22 ng/ml, interquartile range (IQR) = 16.6–28.6) compared with controls (median = 58.4 ng/ml, IQR = 53–68), (P-value b 0.001). Patients with ≥ 4 seizures per month had a significantly lower level of serum 25(OH) vitamin D (median = 17.7 ng/ml, IQR = 16–24) than patients with lower seizure frequency (median = 28.3 ng/ml, IQR = 24.2– 40.2), (P-value = 0.004). Also, there was a statistically significant negative correlation between the duration of epilepsy and serum 25(OH) vitamin D level (r = −0.309, P-value = 0.046). The receiver operating characteristic curve analysis showed that serum 25(OH) vitamin D level with a cutoff value of 23.9 distinguished patients with low seizure frequency (five or less per year) from patients with higher seizure frequency with a sensitivity and specificity of 80% and 74%, respectively (area under the curve (AUC) = 0.798). Conclusion: Vitamin D deficiency is found in treatment-naive children with epilepsy and adolescents with GGE, and it is associated with higher seizure frequency, longer disease duration, and younger age at onset. © 2019 Elsevier Inc. All rights reserved.
1. Introduction Genetic generalized epilepsies (GGEs), also known as idiopathic generalized epilepsies, account for nearly one-third of all epilepsies [1]. Genetic generalized epilepsies may start in infancy, childhood, or adolescence. They are genetically determined and affect otherwise healthy individuals of both sexes and all races [2]. Vitamin D deficiency is a global health concern affecting all age groups. Vitamin D plays an important role in maintaining bone health, immune function, and neurotransmission in the central nervous system in healthy children [3]. Several neurological disorders have been linked with vitamin D deficiency as multiple sclerosis [4], cerebrovascular disorders, Alzheimer's, and Parkinson's disease [5]. Vitamin D is increasingly recognized as a modulator of neuronal excitability and seizure susceptibility. Vitamin D receptors, as well as the 1-alpha-hydroxylase enzyme (responsible for the formation of the active form of vitamin D), have been found in all brain tissues, neuronal and glial cell types [6]. ⁎ Corresponding author. E-mail address: [email protected] (R. Magdy).
The association between antiepileptic drugs (AEDs), vitamin D deficiency, and bone health in individuals with epilepsy had been recognized in previous studies [7]. Knowing whether epilepsy itself is linked to vitamin D status or not, requires studies targeting principally the untreated patients with epilepsy. Up to our knowledge, only one study measured serum vitamin D levels in untreated children with epilepsy, yet, it did not investigate its relation to seizure control and duration of untreated epilepsy [8]. The aim of this study was to determine vitamin D status in treatment-naïve Egyptian children and adolescent patients with GGE and to explore its relation to seizure frequency and epilepsy duration.
2. Subjects & methods 2.1. Study design and participants This case–control study was conducted between May 2018 and August 2018. Forty treatment-naïve patients with GGE according to the new International League Against Epilepsy (ILAE) classification of epilepsy syndromes [2] with ages 18 years or less were recruited from
https://doi.org/10.1016/j.yebeh.2019.106840 1525-5050/© 2019 Elsevier Inc. All rights reserved.
Please cite this article as: A. Elmazny, H. Amer, L. Rashed, et al., Vitamin D status of untreated children and adolescent Egyptian patients with genetic generalized epi..., Epilepsy & Behavior, https://doi.org/10.1016/j.yebeh.2019.106840
2
A. Elmazny et al. / Epilepsy & Behavior xxx (xxxx) xxx
the Kasr Al Aini Hospital, Faculty of Medicine, Epilepsy Clinic, Cairo University. During the aforementioned period, children accompanying their mothers to the obstetrics and gynecology clinics in the same hospital were assessed for eligibility, and 42 age- and gender-matched subjects with no history of febrile seizures or family history for epilepsy served as healthy controls. Patients with hypocalcemia, history of skeletal, metabolic, endocrinal or malabsorption diseases, and those receiving vitamin D supplements at the time of enrollment and up to six months before, were excluded. All patients were subjected to full medical and neurological history and examination with special emphasis on the age at onset, duration of epilepsy, seizure frequency, and family history of both epilepsy and febrile seizures. The study protocol was approved by the Neurology Department, Faculty of Medicine, Cairo University review board and follows the principles outlined in the Declaration of Helsinki. Written informed consent was obtained from parents or legal guardians of participants prior to enrollment. 2.2. Sample collection and biochemical assay Serum 25-OH vitamin D levels were measured by collecting 2 ml of venous blood. The sample was centrifuged, and the serum was separated immediately and stored at − 20 °C until the time of analysis. Serum levels were separated and analyzed by using a commercially available enzyme-linked immunosorbent assay (ELISA) kit supplied by ORGENTEC Diagnostika, GmbH, Germany according to the manufacturer's protocol. According to the Endocrine Society [9], vitamin D deficiency state was defined as a serum level of 25-OH vitamin D below 20 ng/ml and vitamin D insufficiency state as a serum level between 20 and 30 ng/ml, whereas levels above 30 ng/ml were considered normal. 2.3. Electroencephalography (EEG) Interictal electroencephalography (EEG) was done for all patients using the 10–20 international system of electrode placement for 20 min. It was done under standard conditions and with provocation techniques (photic stimulation and hyperventilation). Interpretation of the EEG was done as regards the background activity and the presence of generalized epileptic discharges. 2.4. Statistical analysis The Statistical Package for Social Science (SPSS version 24) was used for data analysis. The median and interquartile range (IQR) were used for the summary of skewed quantitative data, and frequencies were used for qualitative data. Comparison of proportions was performed using the chi-square and Fisher's exact tests where appropriate. Spearman correlation was used to compare abnormally distributed quantitative data. The level of significance was set at a P-value level b0.05. The receiver operator characteristic (ROC) curve was used to select the best cutoff for serum vitamin D level that best predicts the lower seizure frequency. 3. Results 3.1. Demographics and clinical characteristics of the study population The study population included 82 subjects, 42 treatment-naïve patients with GGE and 40 apparently healthy age- and gender-matched controls. The age of patients ranged from 8 to 18 years in both the patients and control groups with a median of 15 (IQR = 13–15) and 15 (IQR = 13–17), (P-value = 0.6), respectively. There were 23 females (54.8%) among patients, versus 24 (60%) among controls, (P-value =
0.8). The clinical characteristics of the patients' group are outlined in Table 1. 3.2. Serum 25(OH) vitamin D levels in the study population Serum 25(OH) vitamin D level was significantly lower in patients compared with controls (P-value b 0.001) (Table 2). Seventeen patients (40.47%) had deficient, 16 (38.1%) had insufficient levels, and 9 (21.43%) had normal 25(OH) vitamin D levels. Only one out of the forty controls had insufficient 25(OH) vitamin D levels, all the remaining subjects had normal levels. 3.3. Serum 25(OH) vitamin D levels in relation to patients' clinical characteristics Patients with seizure frequency of ≥4 times per month had a significantly lower level of serum 25(OH) vitamin D than those with lower seizure frequency (Table 2). No statistically significant difference was found between the two genders or different epileptic syndromes (Table 2). Patients with insufficient serum 25(OH) vitamin D levels had a significantly lower age at onset of epilepsy (median = 9, IQR = 8–12) than patients with deficient (median = 10, IQR = 8–12.5) or normal levels (median = 14, IQR = 11–16) (P-value = 0.046). There was a statistically significant negative correlation between duration of epilepsy in years and serum 25(OH) vitamin D level (r = −0.309, P-value = 0.046). However, there is no statistically significant correlation found with serum 25(OH) vitamin D level and each of age, age at onset, or seizure frequency. 3.4. Serum 25(OH) vitamin D predicting low seizure frequency with GGE The ROC curve analysis determined that serum 25(OH) vitamin D showed the best sensitivity/specificity trade-off for discriminating patients with low seizure frequency (≤5 times per year) from those with higher seizure frequency (≥4 times per month and 1–3 times per month), set at cutoff point of 23.9 ng\ml (area under the curve (AUC) = 0.798) (Fig. 1). 4. Discussion Limited or no studies addressing vitamin D levels in untreated epileptic syndromes in patients with different age groups, seizure control, epilepsy duration, and age at onset currently exist. As far as we know, this is the first Egyptian study to assess vitamin D status among untreated children as well as adolescents with GGE and its relation to the previously mentioned clinical aspects.
Table 1 Clinical characteristics of the patients. n = 42 GGE syndrome according to the new ILAE classification system, no (%) Childhood absence epilepsy 10 (23.8%) Juvenile myoclonic epilepsy 13 (31%) Generalized tonic–clonic seizures alone 19 (45.2%) Age at onset, median (IQR) 11 (8–13) Duration of epilepsy in years, median (IQR) 2 (1–5) History of febrile seizures, no (%) 5 (11.5%) Family history of epilepsy, no (%) 18 (42.9%) Seizure frequency, n (%) ≥4 times per month 27 (64.3%) 1–3 times per month 7 (16.7%) ≤5 times per year 8 (19%) Interictal EEG abnormalities, n (%) 12 (28.6%) GGE: genetic generalized epilepsy, ILAE: International League Against Epilepsy, IQR: interquartile range, EEG: electroencephalography.
Please cite this article as: A. Elmazny, H. Amer, L. Rashed, et al., Vitamin D status of untreated children and adolescent Egyptian patients with genetic generalized epi..., Epilepsy & Behavior, https://doi.org/10.1016/j.yebeh.2019.106840
A. Elmazny et al. / Epilepsy & Behavior xxx (xxxx) xxx Table 2 Serum 25 (OH) vitamin D in different study groups.
Patients (n = 42) Controls (n = 40) Male patients (n = 19) Female patients (n = 23) Childhood absence epilepsy (n = 10) Juvenile myoclonic epilepsy (n = 13) Generalized tonic–clonic seizures alone (n = 19) ≥4 times per month (n = 27) 1–3 times per month (n = 7) ≤ 5 times per year (n = 8) History of febrile seizures (n = 5) No history of febrile seizures (n = 37) Family history of epilepsy (n = 5) No family history of epilepsy (n = 37) Normal EEG (n = 30) Abnormal EEG (n = 12)
25 (OH) vitamin D (ng/ml) Median (IQR)
P-value
22 (16.6–28.6) 58.4 (53–68) 20.9 (16.2–29.6) 22.3 (16.9–28.3) 17 (15–23) 25.3 (16.4–36.3) 24.2 (19.4–28.3)
b0.001 0.561
0.137
17.7 (16–24) 20.4 (16.7–29) 28.3 (24.2–40.2) 15.6 (14–28.8) 22.3 (17–30) 21.6 (17.2–26.6) 23 (16.4–31.1) 21.7, (16.7–27.4) 26.9, (16.5–40)
0.004 0.244 0.684 0.373
IQR: interquartile range, EEG: electroencephalography, P-value b 0.05 is significant. Bold data indicate significant findings.
In this study, a significantly lower level of serum 25(OH) vitamin D in patients was noticed when compared with the healthy controls. This showed total agreement with [8], who also targeted untreated children with epilepsy but with focal and generalized type. There is a link between vitamin D and epileptogenesis, which must be taken into consideration. Vitamin D is considered a neurosteroid signaling
3
via nuclear and membrane-associated receptors [6]. The anticonvulsant role of vitamin D is probably achieved by both genomic and nongenomic mechanisms; it can regulate gene expression through nuclear Vitamin D3 receptor that consequently lowers the expression of some proconvulsant cytokines including interleukin-1 beta and tumor necrosis factor-α and increases the expression of anticonvulsant growth factors such as glial cell-derived neurotrophic factor and neurotrophin-3 [10], in addition to the calcium-binding protein parvalbumin that is known for its antiepileptic effect [11]. Faster, nongenomic mechanisms involve tuning of calcium and chloride currents across neuronal membranes, thus decreasing neuronal excitability and seizure susceptibility [12]. Although vitamin D did not differ significantly between different epileptic syndromes of GGE, the seizure frequency did, as patients with a seizure frequency ≥4 times per month had a significantly lower level of serum 25(OH) vitamin D than those with lower seizure frequency. This result suggests that regardless of the epilepsy syndrome, the mere presence of vitamin D deficiency might carry poor prognostic potentials in patients with GGE. Complementary to this result, the ROC curve analysis in the current study showed that serum 25(OH) vitamin D distinguished patients with low seizure frequency (≤5 times per year) from those with higher seizure frequency with a cutoff value of 23.9 ng \ml (AUC = 0.798). Thus, detection and correction of vitamin D deficiency are recommended in children and adolescent patients with GGE, hand in hand with AEDs being a relatively cheap and easy method that might improve seizure control. This finding is in concordance with previous pilot studies that found a significant reduction in seizure frequency after vitamin D replacement in patients with epilepsy [13,14].
Asymptotic 95% Confidence Interval Area
Cutoff value
P-value
Sensitivity
Specificity
Lower Bound
Upper Bound
0.798
23.9
0.002
80.0%
74.1%
0.645
0.950
Fig. 1. ROC curve analysis for potential ability of 25(OH) vitamin D level to predict low seizure frequency in patients with GGE.
Please cite this article as: A. Elmazny, H. Amer, L. Rashed, et al., Vitamin D status of untreated children and adolescent Egyptian patients with genetic generalized epi..., Epilepsy & Behavior, https://doi.org/10.1016/j.yebeh.2019.106840
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A. Elmazny et al. / Epilepsy & Behavior xxx (xxxx) xxx
In the present study, we found that patients with insufficient serum 25(OH) vitamin D levels had a significantly lower age at epilepsy onset than those with deficient and normal levels, although age at epilepsy onset is variable across individuals, even those with the same epilepsy syndrome [15]. Serum levels of vitamin D may contribute to the early age at seizures' onset. As far as we know, no studies discussed the relationship between age at onset of epilepsy and vitamin D status. For epilepsy duration, this study showed a statistically significant negative correlation with serum 25(OH) vitamin D levels in our patients who never received AEDs. Many studies previously discussed the negative correlation between the duration of AED administration and vitamin D levels in patients with epilepsy [16–18], but none addressed the duration of epilepsy in correlation to vitamin D levels. This raises the question of whether the previous findings were actually related to AED intake or to epilepsy itself and warrants further research. Although Shariatpanahi et al. [19] found that vitamin D level was deficient in 7.5% and insufficient in 72.5% of pediatric patients with the first episode of febrile seizure, we did not find this relation. The strength of our study is that we only recruited newly diagnosed patients with GGE who had not yet started any antiepileptic medication to try to avoid the possible effect of these drugs on serum vitamin D levels. Moreover, samples were obtained at the same time of the year and in the same season to try to overcome the seasonal variation of serum 25(OH) vitamin D levels. The main weakness of the study is the lack of knowledge about our patients' diet and sun exposure. However, all patients were enrolled from the same university hospital that provides various services and treatment free of charge thus, reducing differences based on socioeconomic status and social customs. In conclusion, this study emphasizes the need to detect vitamin D deficiency in recently diagnosed children with epilepsy and adolescents with GGE. Hence, vitamin D correction may help to improve seizure control. Financial support This research received no specific grant from any funding agency, commercial or not-for-profit sectors. Declaration of competing interest All authors have no conflicts of interest to disclose. Acknowledgment The authors acknowledge patients and controls for their participation and cooperation in this study. References
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[1] Jallon P, Latour P. Epidemiology of idiopathic generalized epilepsies. Epilepsia 2005; 46(Suppl. 9):10–4. https://doi.org/10.1111/j.1528-1167.2005.00309.x [PubMed PMID: 16302871; eng].
Please cite this article as: A. Elmazny, H. Amer, L. Rashed, et al., Vitamin D status of untreated children and adolescent Egyptian patients with genetic generalized epi..., Epilepsy & Behavior, https://doi.org/10.1016/j.yebeh.2019.106840
Contents lists available at ScienceDirect
Epilepsy & Behavior journal homepage: www.elsevier.com/locate/yebeh
Vitamin D status of untreated children and adolescent Egyptian patients with genetic generalized epilepsy: A case–control study Alaa Elmazny a, Hanan Amer a, Laila Rashed b, Sarah Khalil a, Rehab Magdy a,⁎ a b
Department of Neurology, Kasr Al-Ainy Faculty of Medicine, Cairo University, Cairo, Egypt Department of Medical Biochemistry and Molecular Biology, Kasr Al-Ainy Faculty of Medicine, Cairo University, Cairo, Egypt
a r t i c l e
i n f o
Article history: Received 20 November 2019 Revised 3 December 2019 Accepted 3 December 2019 Available online xxxx Keywords: Genetic generalized epilepsy Treatment-naive Vitamin D
a b s t r a c t Purpose: Antiepileptic drugs (AEDs) are commonly incriminated for vitamin D deficiency in children with epilepsy. The aim of this study was to examine 25(OH) vitamin D status among children and adolescents with genetic generalized epilepsy (GGE) who had never received AEDs and its relation to seizure frequency and epilepsy duration. Methods: This case–control study was conducted on 42 recently diagnosed patients with GGE, aged ≤18 years and 40 age- and gender-matched controls. Serum 25(OH) vitamin D level was performed for all participants. Results: Serum 25(OH) vitamin D level was significantly lower in patients (median = 22 ng/ml, interquartile range (IQR) = 16.6–28.6) compared with controls (median = 58.4 ng/ml, IQR = 53–68), (P-value b 0.001). Patients with ≥ 4 seizures per month had a significantly lower level of serum 25(OH) vitamin D (median = 17.7 ng/ml, IQR = 16–24) than patients with lower seizure frequency (median = 28.3 ng/ml, IQR = 24.2– 40.2), (P-value = 0.004). Also, there was a statistically significant negative correlation between the duration of epilepsy and serum 25(OH) vitamin D level (r = −0.309, P-value = 0.046). The receiver operating characteristic curve analysis showed that serum 25(OH) vitamin D level with a cutoff value of 23.9 distinguished patients with low seizure frequency (five or less per year) from patients with higher seizure frequency with a sensitivity and specificity of 80% and 74%, respectively (area under the curve (AUC) = 0.798). Conclusion: Vitamin D deficiency is found in treatment-naive children with epilepsy and adolescents with GGE, and it is associated with higher seizure frequency, longer disease duration, and younger age at onset. © 2019 Elsevier Inc. All rights reserved.
1. Introduction Genetic generalized epilepsies (GGEs), also known as idiopathic generalized epilepsies, account for nearly one-third of all epilepsies [1]. Genetic generalized epilepsies may start in infancy, childhood, or adolescence. They are genetically determined and affect otherwise healthy individuals of both sexes and all races [2]. Vitamin D deficiency is a global health concern affecting all age groups. Vitamin D plays an important role in maintaining bone health, immune function, and neurotransmission in the central nervous system in healthy children [3]. Several neurological disorders have been linked with vitamin D deficiency as multiple sclerosis [4], cerebrovascular disorders, Alzheimer's, and Parkinson's disease [5]. Vitamin D is increasingly recognized as a modulator of neuronal excitability and seizure susceptibility. Vitamin D receptors, as well as the 1-alpha-hydroxylase enzyme (responsible for the formation of the active form of vitamin D), have been found in all brain tissues, neuronal and glial cell types [6]. ⁎ Corresponding author. E-mail address: [email protected] (R. Magdy).
The association between antiepileptic drugs (AEDs), vitamin D deficiency, and bone health in individuals with epilepsy had been recognized in previous studies [7]. Knowing whether epilepsy itself is linked to vitamin D status or not, requires studies targeting principally the untreated patients with epilepsy. Up to our knowledge, only one study measured serum vitamin D levels in untreated children with epilepsy, yet, it did not investigate its relation to seizure control and duration of untreated epilepsy [8]. The aim of this study was to determine vitamin D status in treatment-naïve Egyptian children and adolescent patients with GGE and to explore its relation to seizure frequency and epilepsy duration.
2. Subjects & methods 2.1. Study design and participants This case–control study was conducted between May 2018 and August 2018. Forty treatment-naïve patients with GGE according to the new International League Against Epilepsy (ILAE) classification of epilepsy syndromes [2] with ages 18 years or less were recruited from
https://doi.org/10.1016/j.yebeh.2019.106840 1525-5050/© 2019 Elsevier Inc. All rights reserved.
Please cite this article as: A. Elmazny, H. Amer, L. Rashed, et al., Vitamin D status of untreated children and adolescent Egyptian patients with genetic generalized epi..., Epilepsy & Behavior, https://doi.org/10.1016/j.yebeh.2019.106840
2
A. Elmazny et al. / Epilepsy & Behavior xxx (xxxx) xxx
the Kasr Al Aini Hospital, Faculty of Medicine, Epilepsy Clinic, Cairo University. During the aforementioned period, children accompanying their mothers to the obstetrics and gynecology clinics in the same hospital were assessed for eligibility, and 42 age- and gender-matched subjects with no history of febrile seizures or family history for epilepsy served as healthy controls. Patients with hypocalcemia, history of skeletal, metabolic, endocrinal or malabsorption diseases, and those receiving vitamin D supplements at the time of enrollment and up to six months before, were excluded. All patients were subjected to full medical and neurological history and examination with special emphasis on the age at onset, duration of epilepsy, seizure frequency, and family history of both epilepsy and febrile seizures. The study protocol was approved by the Neurology Department, Faculty of Medicine, Cairo University review board and follows the principles outlined in the Declaration of Helsinki. Written informed consent was obtained from parents or legal guardians of participants prior to enrollment. 2.2. Sample collection and biochemical assay Serum 25-OH vitamin D levels were measured by collecting 2 ml of venous blood. The sample was centrifuged, and the serum was separated immediately and stored at − 20 °C until the time of analysis. Serum levels were separated and analyzed by using a commercially available enzyme-linked immunosorbent assay (ELISA) kit supplied by ORGENTEC Diagnostika, GmbH, Germany according to the manufacturer's protocol. According to the Endocrine Society [9], vitamin D deficiency state was defined as a serum level of 25-OH vitamin D below 20 ng/ml and vitamin D insufficiency state as a serum level between 20 and 30 ng/ml, whereas levels above 30 ng/ml were considered normal. 2.3. Electroencephalography (EEG) Interictal electroencephalography (EEG) was done for all patients using the 10–20 international system of electrode placement for 20 min. It was done under standard conditions and with provocation techniques (photic stimulation and hyperventilation). Interpretation of the EEG was done as regards the background activity and the presence of generalized epileptic discharges. 2.4. Statistical analysis The Statistical Package for Social Science (SPSS version 24) was used for data analysis. The median and interquartile range (IQR) were used for the summary of skewed quantitative data, and frequencies were used for qualitative data. Comparison of proportions was performed using the chi-square and Fisher's exact tests where appropriate. Spearman correlation was used to compare abnormally distributed quantitative data. The level of significance was set at a P-value level b0.05. The receiver operator characteristic (ROC) curve was used to select the best cutoff for serum vitamin D level that best predicts the lower seizure frequency. 3. Results 3.1. Demographics and clinical characteristics of the study population The study population included 82 subjects, 42 treatment-naïve patients with GGE and 40 apparently healthy age- and gender-matched controls. The age of patients ranged from 8 to 18 years in both the patients and control groups with a median of 15 (IQR = 13–15) and 15 (IQR = 13–17), (P-value = 0.6), respectively. There were 23 females (54.8%) among patients, versus 24 (60%) among controls, (P-value =
0.8). The clinical characteristics of the patients' group are outlined in Table 1. 3.2. Serum 25(OH) vitamin D levels in the study population Serum 25(OH) vitamin D level was significantly lower in patients compared with controls (P-value b 0.001) (Table 2). Seventeen patients (40.47%) had deficient, 16 (38.1%) had insufficient levels, and 9 (21.43%) had normal 25(OH) vitamin D levels. Only one out of the forty controls had insufficient 25(OH) vitamin D levels, all the remaining subjects had normal levels. 3.3. Serum 25(OH) vitamin D levels in relation to patients' clinical characteristics Patients with seizure frequency of ≥4 times per month had a significantly lower level of serum 25(OH) vitamin D than those with lower seizure frequency (Table 2). No statistically significant difference was found between the two genders or different epileptic syndromes (Table 2). Patients with insufficient serum 25(OH) vitamin D levels had a significantly lower age at onset of epilepsy (median = 9, IQR = 8–12) than patients with deficient (median = 10, IQR = 8–12.5) or normal levels (median = 14, IQR = 11–16) (P-value = 0.046). There was a statistically significant negative correlation between duration of epilepsy in years and serum 25(OH) vitamin D level (r = −0.309, P-value = 0.046). However, there is no statistically significant correlation found with serum 25(OH) vitamin D level and each of age, age at onset, or seizure frequency. 3.4. Serum 25(OH) vitamin D predicting low seizure frequency with GGE The ROC curve analysis determined that serum 25(OH) vitamin D showed the best sensitivity/specificity trade-off for discriminating patients with low seizure frequency (≤5 times per year) from those with higher seizure frequency (≥4 times per month and 1–3 times per month), set at cutoff point of 23.9 ng\ml (area under the curve (AUC) = 0.798) (Fig. 1). 4. Discussion Limited or no studies addressing vitamin D levels in untreated epileptic syndromes in patients with different age groups, seizure control, epilepsy duration, and age at onset currently exist. As far as we know, this is the first Egyptian study to assess vitamin D status among untreated children as well as adolescents with GGE and its relation to the previously mentioned clinical aspects.
Table 1 Clinical characteristics of the patients. n = 42 GGE syndrome according to the new ILAE classification system, no (%) Childhood absence epilepsy 10 (23.8%) Juvenile myoclonic epilepsy 13 (31%) Generalized tonic–clonic seizures alone 19 (45.2%) Age at onset, median (IQR) 11 (8–13) Duration of epilepsy in years, median (IQR) 2 (1–5) History of febrile seizures, no (%) 5 (11.5%) Family history of epilepsy, no (%) 18 (42.9%) Seizure frequency, n (%) ≥4 times per month 27 (64.3%) 1–3 times per month 7 (16.7%) ≤5 times per year 8 (19%) Interictal EEG abnormalities, n (%) 12 (28.6%) GGE: genetic generalized epilepsy, ILAE: International League Against Epilepsy, IQR: interquartile range, EEG: electroencephalography.
Please cite this article as: A. Elmazny, H. Amer, L. Rashed, et al., Vitamin D status of untreated children and adolescent Egyptian patients with genetic generalized epi..., Epilepsy & Behavior, https://doi.org/10.1016/j.yebeh.2019.106840
A. Elmazny et al. / Epilepsy & Behavior xxx (xxxx) xxx Table 2 Serum 25 (OH) vitamin D in different study groups.
Patients (n = 42) Controls (n = 40) Male patients (n = 19) Female patients (n = 23) Childhood absence epilepsy (n = 10) Juvenile myoclonic epilepsy (n = 13) Generalized tonic–clonic seizures alone (n = 19) ≥4 times per month (n = 27) 1–3 times per month (n = 7) ≤ 5 times per year (n = 8) History of febrile seizures (n = 5) No history of febrile seizures (n = 37) Family history of epilepsy (n = 5) No family history of epilepsy (n = 37) Normal EEG (n = 30) Abnormal EEG (n = 12)
25 (OH) vitamin D (ng/ml) Median (IQR)
P-value
22 (16.6–28.6) 58.4 (53–68) 20.9 (16.2–29.6) 22.3 (16.9–28.3) 17 (15–23) 25.3 (16.4–36.3) 24.2 (19.4–28.3)
b0.001 0.561
0.137
17.7 (16–24) 20.4 (16.7–29) 28.3 (24.2–40.2) 15.6 (14–28.8) 22.3 (17–30) 21.6 (17.2–26.6) 23 (16.4–31.1) 21.7, (16.7–27.4) 26.9, (16.5–40)
0.004 0.244 0.684 0.373
IQR: interquartile range, EEG: electroencephalography, P-value b 0.05 is significant. Bold data indicate significant findings.
In this study, a significantly lower level of serum 25(OH) vitamin D in patients was noticed when compared with the healthy controls. This showed total agreement with [8], who also targeted untreated children with epilepsy but with focal and generalized type. There is a link between vitamin D and epileptogenesis, which must be taken into consideration. Vitamin D is considered a neurosteroid signaling
3
via nuclear and membrane-associated receptors [6]. The anticonvulsant role of vitamin D is probably achieved by both genomic and nongenomic mechanisms; it can regulate gene expression through nuclear Vitamin D3 receptor that consequently lowers the expression of some proconvulsant cytokines including interleukin-1 beta and tumor necrosis factor-α and increases the expression of anticonvulsant growth factors such as glial cell-derived neurotrophic factor and neurotrophin-3 [10], in addition to the calcium-binding protein parvalbumin that is known for its antiepileptic effect [11]. Faster, nongenomic mechanisms involve tuning of calcium and chloride currents across neuronal membranes, thus decreasing neuronal excitability and seizure susceptibility [12]. Although vitamin D did not differ significantly between different epileptic syndromes of GGE, the seizure frequency did, as patients with a seizure frequency ≥4 times per month had a significantly lower level of serum 25(OH) vitamin D than those with lower seizure frequency. This result suggests that regardless of the epilepsy syndrome, the mere presence of vitamin D deficiency might carry poor prognostic potentials in patients with GGE. Complementary to this result, the ROC curve analysis in the current study showed that serum 25(OH) vitamin D distinguished patients with low seizure frequency (≤5 times per year) from those with higher seizure frequency with a cutoff value of 23.9 ng \ml (AUC = 0.798). Thus, detection and correction of vitamin D deficiency are recommended in children and adolescent patients with GGE, hand in hand with AEDs being a relatively cheap and easy method that might improve seizure control. This finding is in concordance with previous pilot studies that found a significant reduction in seizure frequency after vitamin D replacement in patients with epilepsy [13,14].
Asymptotic 95% Confidence Interval Area
Cutoff value
P-value
Sensitivity
Specificity
Lower Bound
Upper Bound
0.798
23.9
0.002
80.0%
74.1%
0.645
0.950
Fig. 1. ROC curve analysis for potential ability of 25(OH) vitamin D level to predict low seizure frequency in patients with GGE.
Please cite this article as: A. Elmazny, H. Amer, L. Rashed, et al., Vitamin D status of untreated children and adolescent Egyptian patients with genetic generalized epi..., Epilepsy & Behavior, https://doi.org/10.1016/j.yebeh.2019.106840
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A. Elmazny et al. / Epilepsy & Behavior xxx (xxxx) xxx
In the present study, we found that patients with insufficient serum 25(OH) vitamin D levels had a significantly lower age at epilepsy onset than those with deficient and normal levels, although age at epilepsy onset is variable across individuals, even those with the same epilepsy syndrome [15]. Serum levels of vitamin D may contribute to the early age at seizures' onset. As far as we know, no studies discussed the relationship between age at onset of epilepsy and vitamin D status. For epilepsy duration, this study showed a statistically significant negative correlation with serum 25(OH) vitamin D levels in our patients who never received AEDs. Many studies previously discussed the negative correlation between the duration of AED administration and vitamin D levels in patients with epilepsy [16–18], but none addressed the duration of epilepsy in correlation to vitamin D levels. This raises the question of whether the previous findings were actually related to AED intake or to epilepsy itself and warrants further research. Although Shariatpanahi et al. [19] found that vitamin D level was deficient in 7.5% and insufficient in 72.5% of pediatric patients with the first episode of febrile seizure, we did not find this relation. The strength of our study is that we only recruited newly diagnosed patients with GGE who had not yet started any antiepileptic medication to try to avoid the possible effect of these drugs on serum vitamin D levels. Moreover, samples were obtained at the same time of the year and in the same season to try to overcome the seasonal variation of serum 25(OH) vitamin D levels. The main weakness of the study is the lack of knowledge about our patients' diet and sun exposure. However, all patients were enrolled from the same university hospital that provides various services and treatment free of charge thus, reducing differences based on socioeconomic status and social customs. In conclusion, this study emphasizes the need to detect vitamin D deficiency in recently diagnosed children with epilepsy and adolescents with GGE. Hence, vitamin D correction may help to improve seizure control. Financial support This research received no specific grant from any funding agency, commercial or not-for-profit sectors. Declaration of competing interest All authors have no conflicts of interest to disclose. Acknowledgment The authors acknowledge patients and controls for their participation and cooperation in this study. References
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Please cite this article as: A. Elmazny, H. Amer, L. Rashed, et al., Vitamin D status of untreated children and adolescent Egyptian patients with genetic generalized epi..., Epilepsy & Behavior, https://doi.org/10.1016/j.yebeh.2019.106840