Efficacy of lacosamide and phenytoin in status epilepticus: A systematic review

Regional determinants for outcome and cost of status epilepticus

OBJECTIVE

Status epilepticus (SE) requires informed management. Since regional differences exist in practice and outcome, we aimed to characterize the epidemiology of SE and identify the factors associated with cost-effective management at the sole level IV epilepsy center of Central New York (CNY).

METHODS

We searched for patients aged 18 years or older admitted at our center's hospitals from February 2018 to November 2019 with the discharge diagnosis of SE. Seventy-seven individuals with definite SE were included. We constructed models to determine the main factors that impact the refractoriness of SE, the clinical outcome, and the estimated cost of hospitalization.

RESULTS

The rate of SE-related disability was 20.8% and the all-cause mortality 36.4%. Our analysis showed that initial anti-seizure medication (ASM) choice did not have a significant influence on the clinical outcome; nor did it affect the refractoriness of SE. Likewise, our anesthetic regimen did not alter the disease course or outcome. In line with prior studies, we demonstrated that age carried a negative predictive value to the SE-related disability and mortality (CI95% [-0.02, 0], p < 0.001). Interestingly, we found that use of midazolam (CI95% [-20.8, -0.08], p = 0.05) and anoxic brain injury as the underlying etiology (CI95% [-33.5, -1.59], p = 0.03) were marginally associated with shorter hospitalizations and reduced cost. The latter might reflect the rapidly-deteriorating course of anoxic brain injury, complicated by its higher likelihood of refractoriness (CI95% [0.14, 0.79], p = 0.006), and consequently, the decision to withdraw care.

CONCLUSION

Taken together, we described the demographics, management, and prognosis of SE locally and further defined the potential determinants for the cost-effective care. We found that similar to other studies, age was the main determinant factor in prognosis. We also noticed that midazolam usage was associated with shorter hospital stay, suggesting that strategic use of midazolam may reduce the direct cost of management of SE. These findings can be adopted to optimize SE management in CNY.

Status Epilepticus: An Update on Pharmacological Management

Status epilepticus (SE) is a neurological emergency that requires timely pharmacological therapy to cease seizure activity. The treatment approach varies based on the time and the treatment stage of SE. Benzodiazepines are considered the first-line therapy during the emergent treatment phase of SE. Antiseizure medicines such as phenytoin, valproic acid, and levetiracetam are recommended during the urgent treatment phase. These drugs appear to have a similar safety and efficacy profile, and individualized therapy should be chosen based on patient characteristics. Midazolam, propofol, pentobarbital, and ketamine are continuous intravenous infusions of anesthetic medications utilized in the refractory SE (RSE) period. The most efficacious pharmacotherapeutic treatments for RSE and superrefractory status epilepticus are not clearly defined.

Pediatric Status Epilepticus: Treat Early and Avoid Delays

Pediatric convulsive status epilepticus (cSE) is a neurologic emergency with potential for morbidity and mortality. Rapid treatment and escalation of therapies to achieve early seizure control is paramount in preventing complications and providing the best patient outcomes. Although guidelines recommend early treatment, cessation of out-of-hospital SE is undermined by treatment delay and inadequate dosing. Logistical challenges include prompt seizure recognition, first-line benzodiazepine (BZD) availability, comfort and expertise in administration of BZD, and timely arrival of emergency personnel. In-hospital, SE onset is additionally impacted by delays to first- and second-line treatment and availability of resources. This review presents an evidence-based, clinically oriented review of pediatric cSE, including its definitions and treatments. It provides evidence and rationale for timely treatment of first-line BZD treatment followed by prompt escalation to second-line antiseizure medication therapies for established SE. Treatment delays and barriers to care are discussed, with practical considerations for opportunities for areas of improvement in the initial treatment of cSE.

Efficacy of a pre-specified timeline-based treatment protocol in children with acute repetitive seizures or seizure clusters

Objectives

Acute repetitive seizures (ARSs) are one of the few commonly encountered neurological emergencies in children. There is a need for an appropriate timeline-based treatment protocol, which will be shown to be safe and efficacious in a clinical study.

Materials and Methods

This was a retrospective chart review to determine the efficacy of a pre-specified treatment protocol for the management of ARSs in children aged 1-18 years. The treatment protocol was specifically applied in children with a diagnosis of epilepsy and not critically ill, who met the criteria for ARSs, with the exemption of new onset of ARSs. The first tier of treatment protocol focused on intravenous lorazepam, optimization of dose of existing anti-seizure medications (ASMs), and control of triggers like acute febrile illness, while second-tier focused on adding one or two additional ASMs, commonly used in cases with seizure clusters or status epilepticus.

Results

We included the first 100 consecutive patients (7.6 ± 3.2 years, 63% boys). Our treatment protocol was successful in 89 patients (58 and 31 required first-tier and second-tier treatment). The absence of pre-existing drug-resistant epilepsy and the presence of acute febrile illness as a triggering factor (P = 0.02 and 0.03) were associated with the success of the first tier of the treatment protocol. Excessive sedation (n = 29), incoordination (n = 14), transient gait instability (n = 11), and excessive irritability (n = 5) were the most common adverse effects observed during the initial 1 week.

Conclusion

This pre-specified treatment protocol is safe and efficacious in controlling ARSs in cases with established epilepsy who are not critically sick. External validation from other parts of the world/centers and a more diverse epilepsy population are required before generalizing the protocol into clinical practice.

Management of convulsive status epilepticus: recent updates

Convulsive status epilepticus (SE) is a medical emergency associated with high morbidity and mortality. Recently, clinical trials and meta-analyses investigating medical treatment of SE have been published. Benzodiazepine is well known as the first-line treatment for SE. Recent evidence suggests the equivalence of intravenous fosphenytoin, valproate, and levetiracetam for treatment of established SE. There is lack of evidence regarding treatment for refractory SE. Intravenous midazolam is commonly used, and recent evidence supports the use of ketamine. Additional studies are needed to improve the management of convulsive SE.

Optimal Management of Status Epilepticus in Children in the Emergency Setting: A Review of Recent Advances

Convulsive status epilepticus (CSE) is the most common neurological emergency in children and the second most common neurological emergency in adults. Mortality is low, but morbidity, including neuro-disability, learning difficulties, and a de-novo epilepsy, may be as high as 22%. The longer the duration of CSE, the more difficult it is to terminate, and the greater the risk of morbidity. Convulsive status epilepticus is usually managed using specific national or local algorithms. The first-line treatment is administered when a tonic-clonic or focal motor clonic seizure has lasted five minutes (impending or premonitory CSE). Second-line treatment is administered when the CSE has persisted after two doses of a first-line treatment (established CSE). Randomised clinical trial (RCT) evidence supports the use of benzodiazepines as a first-line treatment of which the most common are buccal or intra-nasal midazolam, rectal diazepam and intravenous lorazepam. Alternative drugs, for which there are considerably less RCT data, are intra-muscular midazolam and intravenous clonazepam. Up until 2019, phenobarbital and phenytoin (or fosphenytoin) were the preferred second-line treatments but with no good supporting RCT evidence. Robust RCT data are now available which has provided important information on second-line treatments, specifically phenytoin (or fosphenytoin), levetiracetam and sodium valproate. Lacosamide is an alternative second-line treatment but with no supporting RCT evidence. Current evidence indicates that first, buccal or intranasal midazolam or intravenous lorazepam are the most effective and the most patient and carer-friendly first-line anti-seizure medications to treat impending or premonitory CSE and second, that there is no difference in efficacy between levetiracetam, phenytoin (or fosphenytoin) or sodium valproate for the treatment of established CSE. Pragmatically, levetiracetam or sodium valproate are preferred to phenytoin (or fosphenytoin) because of their ease of administration and lack of serious adverse side-effects, including potentially fatal cardiac arrhythmias. Sodium valproate must be used with caution in children aged three and under because of the rare risk of hepatotoxicity and particularly if there is an underlying mitochondrial disorder.

Evidence for Inhibitory Perturbations on the Amplitude, Gating, and Hysteresis of A-Type Potassium Current, Produced by Lacosamide, a Functionalized Amino Acid with Anticonvulsant Properties

Lacosamide (Vimpat^®, LCS) is widely known as a functionalized amino acid with promising anti-convulsant properties; however, adverse events during its use have gradually appeared. Despite its inhibitory effect on voltage-gated Na⁺ current (I_Na), the modifications on varying types of ionic currents caused by this drug remain largely unexplored. In pituitary tumor (GH₃) cells, we found that the presence of LCS concentration-dependently decreased the amplitude of A-type K⁺ current (I_K(A)) elicited in response to membrane depolarization. The I_K(A) amplitude in these cells was sensitive to attenuation by the application of 4-aminopyridine, 4-aminopyridine-3-methanol, or capsaicin but not by that of tetraethylammonium chloride. The effective IC₅₀ value required for its reduction in peak or sustained I_K(A) was calculated to be 102 or 42 µM, respectively, while the value of the dissociation constant (K_D) estimated from the slow component in I_K(A) inactivation at varying LCS concentrations was 52 µM. By use of two-step voltage protocol, the presence of this drug resulted in a rightward shift in the steady-state inactivation curve of I_K(A) as well as in a slowing in the recovery time course of the current block; however, no change in the gating charge of the inactivation curve was detected in its presence. Moreover, the LCS addition led to an attenuation in the degree of voltage-dependent hysteresis for I_K(A) elicitation by long-duration triangular ramp voltage commands. Likewise, the I_K(A) identified in mouse mHippoE-14 neurons was also sensitive to block by LCS, coincident with an elevation in the current inactivation rate. Collectively, apart from its canonical action on I_Na inhibition, LCS was effective at altering the amplitude, gating, and hysteresis of I_K(A) in excitable cells. The modulatory actions on I_K(A), caused by LCS, could interfere with the functional activities of electrically excitable cells (e.g., pituitary tumor cells or hippocampal neurons).

Efficacy and Tolerability of Lacosamide in Lennox–Gastaut Syndrome: A Systematic Review and Meta-analysis

Purpose  Lennox–Gastaut syndrome (LGS) is one of the most difficult to treat childhood-onset epileptic encephalopathies. There is growing evidence that lacosamide is safe and efficacious in patients and adults with refractory epilepsy. However, the evidence regarding the efficacy of lacosamide in LGS is controversial so far. We aimed to evaluate the efficacy and tolerability of lacosamide in patients with LGS.

Methods  We conducted a systematic review on MEDLINE, EMBASE, COCHRANE CENTRAL, Google Scholar, and Web of Science, collating all available literature till July 31, 2020. The qualitative review included case reports, case series, and both controlled/uncontrolled trials as well as retrospective studies, but for determining pooled estimates, we only included studies with a sample size of 5 or more. The primary outcome was the efficacy of lacosamide in patients with LGS. Clinical variables related to efficacy and adverse events attributed to lacosamide were extracted from each publication. The pooled estimate of variables related to these parameters was performed using a random-effect model.

Results  Of the 68 items identified by the search, 14 were reviewed as full-text. Eleven articles including two prospective and six retrospective studies fulfilled eligibility criteria and described outcomes in 81 patients (42 adults, 39 children, 60% male, range—1.4–61 years). On average, 35.2%, 27.9%, 7.3%, and 29.4% patients had > 50% reduction, < 50% reduction, no change, and worsening of seizure frequency, respectively. Although 36% of patients had adverse events like somnolence, behavioral abnormalities including irritability, aggressiveness, nausea, tremor, memory problems, dizziness, gastrointestinal discomfort, vomiting, and weight loss, no serious adverse events were noted.

Conclusion  The evidence available in the current literature is not sufficient to support or refute the use of lacosamide in patients with LGS. Although it is one of the possible therapeutic options worth exploring in patients with LGS, caution is still necessary, as there are reports of worsening of seizure frequency in some patients.

Efficacy and safety of rufinamide as adjunctive therapy in patients with Lennox Gastaut syndrome: A systematic review and Meta-analysis

INTRODUCTION

Rufinamide is an antiseizure medication that acts through sodium channels and is found to be efficacious in patients with Lennox Gastaut syndrome (LGS). However, no systematic review has been conducted in LGS patients to provide an estimate of the efficacy and safety of rufinamide.

METHODS

Different electronic databases were searched for articles describing the use of rufinamide in patients with LGS. For determining primary efficacy outcomes as compared to placebo, we included only studies comparing the efficacy of rufinamide with placebo in LGS patients. We performed an additional analysis to include other uncontrolled studies with a minimum sample size of 20 to provide a more comprehensive estimate of efficacy.

RESULTS

A total of ten studies included 557 patients. Out of them, five studies were placebo-controlled, enrolling a total of 265 patients in the rufinamide group and 203 patients in the placebo group. The average percentage reduction in total seizure frequency per 28 days during the double-blind phase was 29.3% in the rufinamide group compared with 8.3% in the placebo group (difference between the two groups was 20.9%, 95%CI-14.4%-27.3%, p <0.00001). Even for individual seizure types like tonic-clonic seizures, atypical absence seizures, atonic seizures, focal seizures, and myoclonic seizures, rufinamide was more efficacious than placebo(p<0.00001). The number of patients with at least one treatment-emergent adverse effects was significantly higher in rufinamide treated patients (60.2%vs50.7%, p=0.02, RR-1.24(1.03,1.51).

CONCLUSION

Rufinamide is efficacious as adjunctive therapy in patients with LGS in terms of reduction in total seizure frequency and has mild adverse reaction.