Symptomatology of carbamazepine- and oxcarbazepine-induced hyponatremia in people with epilepsy.

OBJECTIVE: To ascertain whether adverse effects experienced by people taking carbamazepine or oxcarbazepine could be attributed to carbamazepine- or oxcarbazepine-induced hyponatremia (COIH). METHODS: We performed an observational study, collecting data between 2017 and 2019 on serum sodium levels and adverse effects retrospectively in people with epilepsy while receiving treatment with either carbamazepine (CBZ) or oxcarbazepine (OXC). We defined hyponatremia as sodium level ≤134 mEq/L and severe hyponatremia as sodium level ≤128 mEq/L. Adverse effects experienced were compared between groups of individuals with and without hyponatremia. RESULTS: A total of 1370 people using CBZ or OXC were identified, of whom 410 had at least one episode of hyponatremia. We checked for symptoms related to the use of CBZ and OXC in 710 people (410 with and 300 without hyponatremia) and found relevant information in 688. Adverse effects occurred in 65% of people with hyponatremia compared to 21% with normal sodium levels (odds ratio [OR] 7.5, P ≤ .001) and in 83% of people with severe hyponatremia compared to 55% in those with mild hyponatremia (P ≤ .001). Significant predictors of adverse effects were the drug (OXC vs CBZ), and the number of concomitant anti-seizure medications. Dizziness (28% vs 6%), tiredness (22% vs 7%), instability (19% vs 3%), and diplopia (16% vs 4%) were reported more often in the hyponatremia group than in patients with normal levels. SIGNIFICANCE: People with COIH had a 7-fold increased risk of developing adverse effects during treatment. Clinicians should consider ascertainment of sodium levels in patients taking CBZ and OXC and act upon findings.

Comparative effectiveness of antiepileptic drugs in juvenile myoclonic epilepsy.

OBJECTIVE: To study the effectiveness and tolerability of antiepileptic drugs (AEDs) commonly used in juvenile myoclonic epilepsy (JME). METHODS: People with JME were identified from a large database of individuals with epilepsy, which includes detailed retrospective information on AED use. We assessed secular changes in AED use and calculated rates of response (12-month seizure freedom) and adverse drug reactions (ADRs) for the five most common AEDs. Retention was modeled with a Cox proportional hazards model. We compared valproate use between males and females. RESULTS: We included 305 people with 688 AED trials of valproate, lamotrigine, levetiracetam, carbamazepine, and topiramate. Valproate and carbamazepine were most often prescribed as the first AED. The response rate to valproate was highest among the five AEDs (42.7%), and significantly higher than response rates for lamotrigine, carbamazepine, and topiramate; the difference to the response rate to levetiracetam (37.1%) was not significant. The rates of ADRs were highest for topiramate (45.5%) and valproate (37.5%). Commonest ADRs included weight change, lethargy, and tremor. In the Cox proportional hazards model, later start year (1.10 [1.08-1.13], P < 0.001) and female sex (1.41 [1.07-1.85], P = 0.02) were associated with shorter trial duration. Valproate was associated with the longest treatment duration; trials with carbamazepine and topiramate were significantly shorter (HR [CI]: 3.29 [2.15-5.02], P < 0.001 and 1.93 [1.31-2.86], P < 0.001). The relative frequency of valproate trials shows a decreasing trend since 2003 while there is an increasing trend for levetiracetam. Fewer females than males received valproate (76.2% vs 92.6%, P = 0.001). SIGNIFICANCE: In people with JME, valproate is an effective AED; levetiracetam emerged as an alternative. Valproate is now contraindicated in women of childbearing potential without special precautions. With appropriate selection and safeguards in place, valproate should remain available as a therapy, including as an alternative for women of childbearing potential whose seizures are resistant to other treatments.

A genome-wide association study of sodium levels and drug metabolism in an epilepsy cohort treated with carbamazepine and oxcarbazepine.

OBJECTIVE: To ascertain the clinical and genetic factors contributing to carbamazepine- and oxcarbazepine-induced hyponatremia (COIH), and to carbamazepine (CBZ) metabolism, in a retrospectively collected, cross-sectional cohort of people with epilepsy. METHODS: We collected data on serum sodium levels and antiepileptic drug levels in people with epilepsy attending a tertiary epilepsy center while on treatment with CBZ or OXC. We defined hyponatremia as Na+ ≤134 mEq/L. We estimated the CBZ metabolic ratio defined as the log transformation of the ratio of metabolite CBZ-diol to unchanged drug precursor substrate as measured in serum. RESULTS: Clinical and genetic data relating to carbamazepine and oxcarbazepine trials were collected in 1141 patients. We did not observe any genome-wide significant associations with sodium level in a linear trend or hyponatremia as a dichotomous trait. Age, sex, number of comedications, phenytoin use, phenobarbital use, and sodium valproate use were significant predictors of CBZ metabolic ratio. No genome-wide significant associations with CBZ metabolic ratio were found. SIGNIFICANCE: Although we did not detect a genetic predictor of hyponatremia or CBZ metabolism in our cohort, our findings suggest that the determinants of CBZ metabolism are multifactorial.

The landscape of epilepsy-related GATOR1 variants.

PURPOSE: To define the phenotypic and mutational spectrum of epilepsies related to DEPDC5, NPRL2 and NPRL3 genes encoding the GATOR1 complex, a negative regulator of the mTORC1 pathway METHODS: We analyzed clinical and genetic data of 73 novel probands (familial and sporadic) with epilepsy-related variants in GATOR1-encoding genes and proposed new guidelines for clinical interpretation of GATOR1 variants. RESULTS: The GATOR1 seizure phenotype consisted mostly in focal seizures (e.g., hypermotor or frontal lobe seizures in 50%), with a mean age at onset of 4.4 years, often sleep-related and drug-resistant (54%), and associated with focal cortical dysplasia (20%). Infantile spasms were reported in 10% of the probands. Sudden unexpected death in epilepsy (SUDEP) occurred in 10% of the families. Novel classification framework of all 140 epilepsy-related GATOR1 variants (including the variants of this study) revealed that 68% are loss-of-function pathogenic, 14% are likely pathogenic, 15% are variants of uncertain significance and 3% are likely benign. CONCLUSION: Our data emphasize the increasingly important role of GATOR1 genes in the pathogenesis of focal epilepsies (>180 probands to date). The GATOR1 phenotypic spectrum ranges from sporadic early-onset epilepsies with cognitive impairment comorbidities to familial focal epilepsies, and SUDEP.

Correction: The landscape of epilepsy-related GATOR1 variants.

The original version of this article contained an error in the spelling of the author Erik H. Niks, which was incorrectly given as Erik Niks. This has now been corrected in both the PDF and HTML versions of the article.

Correction to: The landscape of epilepsy-related GATOR1 variants.

The original version of this Article contained an error in the author list where the corresponding author Stéphanie Baulac was repeated twice. This has now been corrected in the HTML, the PDF was correct at the time of publication.

Comparative effectiveness of antiepileptic drugs in patients with mesial temporal lobe epilepsy with hippocampal sclerosis.

OBJECTIVE: Mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is a common epilepsy syndrome that is often poorly controlled by antiepileptic drug (AED) treatment. Comparative AED effectiveness studies in this condition are lacking. We report retention, efficacy, and tolerability in a cohort of patients with MTLE-HS. METHODS: Clinical data were collected from a European database of patients with epilepsy. We estimated retention, 12-month seizure freedom, and adverse drug reaction (ADR) rates for the 10 most commonly used AEDs in patients with MTLE-HS. RESULTS: Seven hundred sixty-seven patients with a total of 3,249 AED trials were included. The highest 12-month retention rates were observed with carbamazepine (85.9%), valproate (85%), and clobazam (79%). Twelve-month seizure freedom rates varied from 1.2% for gabapentin and vigabatrin to 11% for carbamazepine. Response rates were highest for AEDs that were prescribed as initial treatment and lowest for AEDs that were used in a third or higher instance. ADRs were reported in 47.6% of patients, with the highest rates observed with oxcarbazepine (35.7%), topiramate (30.9%), and pregabalin (27.4%), and the lowest rates with clobazam (6.5%), gabapentin (8.9%), and lamotrigine (16.6%). The most commonly reported ADRs were lethargy and drowsiness, dizziness, vertigo and ataxia, and blurred vision and diplopia. SIGNIFICANCE: Our results did not demonstrate any clear advantage of newer versus older AEDs. Our results provide useful insights into AED retention, efficacy, and ADR rates in patients with MTLE-HS.

Carbamazepine- and oxcarbazepine-induced hyponatremia in people with epilepsy.

OBJECTIVE: To ascertain possible determinants of carbamazepine (CBZ)- and oxcarbazepine (OXC)-induced hyponatremia in a large cohort of people with epilepsy. METHODS: We collected data on serum sodium levels in people with epilepsy who were attending a tertiary epilepsy center while on treatment with CBZ or OXC. We defined hyponatremia as Na+ ≤134 mEq/L and severe hyponatremia as Na+ ≤128 mEq/L. RESULTS: We identified 1,782 people who had used CBZ (n = 1,424) or OXC (n = 358), of whom 50 were treated with both drugs. Data on sodium level measurements were available in 1,132 on CBZ and in 289 on OXC. Hyponatremia occurred in 26% of those taking CBZ and 46% of those taking OXC. This was severe in 7% in the CBZ group and 22% in the OXC group. Hyponatremia was symptomatic in 48% and led to admissions in 3%. Age over 40 years, high serum levels of CBZ and OXC, and concomitant use of other antiepileptic drugs were the main risk factors for hyponatremia in both treatment groups. Female patients on OXC were at a higher risk than male patients of hyponatremia. The risk of hyponatremia on CBZ was significantly associated with the risk of hyponatremia on OXC within a subgroup that used both drugs consecutively. SIGNIFICANCE: Hyponatremia is a common problem in people taking CBZ or OXC. Regular ascertainment of sodium levels in those taking either drug is recommended and results should be acted on.

Complex SCN8A DNA-abnormalities in an individual with therapy resistant absence epilepsy.

BACKGROUND: De novo SCN8A missense mutations have been identified as a rare dominant cause of epileptic encephalopathy. We described a person with epileptic encephalopathy associated with a mosaic deletion of the SCN8A gene. METHODS: Array comparative genome hybridization was used to identify chromosomal abnormalities. Next Generation Sequencing was used to screen for variants in known and candidate epilepsy genes. A single nucleotide polymorphism array was used to test whether the SCN8A variants were in cis or in trans. RESULTS: We identified a de novo mosaic deletion of exons 2-14 of SCN8A, and a rare maternally inherited missense variant on the other allele in a woman presenting with absence seizures, challenging behavior, intellectual disability and QRS-fragmentation on the ECG. We also found a variant in SCN5A. CONCLUSIONS: The combination of a rare missense variant with a de novo mosaic deletion of a large part of the SCN8A gene suggests that other possible mechanisms for SCN8A mutations may cause epilepsy; loss of function, genetic modifiers and cellular interference may play a role. This case expands the phenotype associated with SCN8A mutations, with absence epilepsy and regression in language and memory skills.

SMART syndrome: a late reversible complication after radiation therapy for brain tumours.

With intensified treatment leading to longer survival, complications of therapy for brain tumours are more frequently observed. Regarding radiation therapy, progressive and irreversible white matter disease with cognitive decline is most feared. We report on four patients with reversible clinical and radiological features occurring years after radiation for brain tumours, suggestive for the so called SMART syndrome (stroke-like migraine attacks after radiation therapy). All four patients (males, age 36-60 years) had been treated with focal brain radiation for a primary brain tumour or with whole-brain radiation therapy for brain metastases. Ranging from 2 to 10 years following radiation therapy patients presented with headache and focal neurological deficits, suggestive for tumour recurrence. Two patients also presented with focal seizures. MRI demonstrated typical cortical swelling and contrast enhancement, primarily in the parieto-occipital region. On follow-up both clinical and MRI features improved spontaneously. Three patients eventually proved to have tumour recurrence. The clinical and radiological picture of these patients is compatible with the SMART syndrome, a rare complication of radiation therapy which is probably under recognized in brain tumour patients. The pathophysiology of the SMART syndrome is poorly understood but bears similarities with the posterior reversible encephalopathy syndrome (PRES). These four cases underline that the SMART syndrome should be considered in patients formerly treated with radiation therapy for brain tumours, who present with new neurologic deficits. Before the diagnosis of SMART syndrome can be established other causes, such as local tumour recurrence, leptomeningeal disease or ischemic disease should be ruled out.

Dominant hemochromatosis due to N144H mutation of SLC11A3: clinical and biological characteristics.

Hereditary hemochromatosis is classically inherited as a recessive trait but is genetically heterogeneous. Mutations in the HFE and the TFR2 genes account for about 80% of patients and a third locus on chromosome 1q is responsible for juvenile hemochromatosis. We describe here the clinical and biological characteristics of autosomal dominant form of iron overload due to the N144H mutation of the SLC11A3 gene. Clinical signs of iron overload in patients include joint pains, cardiomyopathies, liver fibrosis and hormonal disorders including diabetes mellitus. The main and most common clinical symptoms in this family were joint complaints and early signs of arthrosis. Serum ferritin levels in iron overloaded subjects varied from 31 to 2179 ng/ml and the transferrin saturation from 13 to 88.6%. The iron overload is moderate compared to patients with type 1 hemochromatosis but the deferoxamine test was normal in all patients. The disease in this family segregated as a dominant trait. None of the patients was homozygous or compound heterozygous for any known mutation in the HFE or TFR2 genes. The disease in this family represents a non-classical form of iron overload caused by the N144H mutation in the SLC11A3 gene. The reports of other distinct mutations in SLC11A3 suggest that this gene may be of interest for further etiologic research.