Drug-responsive versus drug-refractory mesial temporal lobe epilepsy: a single-center prospective outcome study

Impact of intracranial subclinical seizures on seizure outcomes after SLAH in patients with mesial temporal lobe epilepsy

OBJECTIVE

To investigate the association between subclinical seizures detected on intracranial electroencephalographic (i-SCSs)recordings and mesial temporal sclerosis (MTS), as well as their impact on surgical outcomes of stereotactic laser amygdalohippocampotomy (SLAH).

METHODS

A retrospective review was conducted on 27 patients with drug-resistant mesial temporal lobe epilepsy (MTLE) who underwent SLAH. The number of seizures detected on scalp EEG and iEEG was assessed. Patients were followed for a minimum of 3 years after SLAH.

RESULTS

Of the 1715 seizures recorded from mesial temporal regions, 1640 were identified as i-SCSs. Patients with MTS were associated with favorable short- and long-term surgical outcomes. Patients with MTS had a higher number of i-SCSs compared to patients without MTS. The numbers of i-SCSs were higher in patients with Engel I-II outcomes, but no significant statistical difference was found. However, it was observed that patients with MTS who achieved Engel I-II classification had higher numbers of i-SCSs than patients without MTS (P < 0.05).

CONCLUSION

Patients with MTS exhibited favorable short-term and long-term surgical outcome after SLAH. A higher number of i-SCSs was significantly associated with MTS in patients with MTLE. The number of i-SCSs tended to be higher in patients with Engel Ⅰ-Ⅱ surgical outcomes.

SIGNIFICANCE

The association between i-SCSs, MTS, and surgical outcomes in MTLE patients undergoing SLAH has significant implications for understanding the underlying mechanisms and identifying potential therapeutic targets to enhance surgical outcomes.

Early identification of seizure freedom with medical treatment in patients with mesial temporal lobe epilepsy and hippocampal sclerosis

BACKGROUND

Mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is usually associated with a poor response to antiseizure medications. We focused on MTLE-HS patients who were seizure free on medication to: (1) determine the clinical factors associated with seizure freedom and (2) develop a machine-learning classifier to better earlier identify those patients.

METHODS

We performed a retrospective, multicentric study comparing 64 medically treated seizure-free MTLE-HS patients with 200 surgically treated drug-resistant MTLE-HS patients. First, we collected medical history and seizure semiology data. Then, we developed a machine-learning classifier based on clinical data.

RESULTS

Medically treated seizure-free MTLE-HS patients were seizure-free for at least 2 years, and for a median time of 7 years at last follow-up. Compared to drug-resistant MTLE-HS patients, they exhibited: an older age at epilepsy onset (22.5 vs 8.0 years, p < 0.001), a lesser rate of: febrile seizures (39.0% vs 57.5%, p = 0.035), focal aware seizures (previously referred to as aura)(56.7% vs 90.0%, p < 0.001), autonomic focal aware seizures in presence of focal aware seizure (17.6% vs 59.4%, p < 0.001), dystonic posturing of the limbs (9.8% vs 47.0%, p < 0.001), gestural (27.4% vs 94.0%, p < 0.001), oro-alimentary (32.3% vs 75.5%, p < 0.001) or verbal automatisms (12.9% vs 36.0%, p = 0.001). The classifier had a positive predictive value of 0.889, a sensitivity of 0.727, a specificity of 0.962, a negative predictive value of 0.893.

CONCLUSIONS

Medically treated seizure-free MTLE-HS patients exhibit a distinct clinical profile. A classifier built with readily available clinical data can identify them accurately with excellent positive predictive value. This may help to individualize the management of MTLE-HS patients according to their expected pharmacosensitivity.

Cluster analysis: Predicting the seizure outcome in temporal lobe epilepsy

OBJECTIVES

We applied the Two-Step cluster analysis on a large cohort of patients with temporal lobe epilepsy (TLE). We hypothesized that there are distinct clusters of patients with TLE based on their clinical characteristics and these clusters may predict their seizure outcome.

METHODS

This was a longitudinal study of a prospectively developed database. All patients with a diagnosis of TLE were studied at the outpatient epilepsy clinic, Shiraz, Iran, from 2008 until 2021. The Two-Step cluster analysis (Schwarz's Bayesian Criterion: BIC) was applied to the whole dataset considering the demographic data, clinical characteristics, imaging, and electroencephalography data. The seizure outcome was compared between the clusters of patients.

RESULTS

Three hundred and seventy-four patients had the inclusion criteria and were studied. The Two-Step cluster analysis showed that there were two distinct clusters of patients with TLE. The most important clinical predictors were the presence (or absence) of focal impaired awareness seizures or focal to bilateral tonic-clonic seizures, aura with seizures, and the brain imaging findings. The seizure outcomes were significantly different between these two clusters (p = 0.008).

CONCLUSION

The Two-Step cluster analysis could identify two distinct clusters of patients with TLE; these data are helpful in providing prognosis and counseling for patients and their care-givers. These data may also be used to develop a practical outcome prediction tool for patients with TLE.

Altered topological properties of brain functional networks in drug-resistant epilepsy patients with vagus nerve stimulators

PURPOSE

To explore abnormalities of topological properties in drug-resistant epilepsy (DRE) patients after vagus nerve stimulation (VNS) by analyzing brain functional networks using graph theory.

METHODS

Fifteen patients and eight healthy controls (HC) were scanned separately with resting-state functional magnetic resonance imaging (rs-fMRI). Graph theoretical analyses were chosen to compare the global (small-world parameters [γ, λ, σ, Cp, and Lp], and network efficiency [Eg and Eloc]), and nodal (BC, DC, and NE) properties in preoperative patients (EPpre), postoperative patients (EPpost) and HC.

RESULTS

HC, EPpre and EPpost all satisfied the criteria for small-world properties (σ > 1) within the sparsity range of 0.05-0.5. Compared with EPpre, EPpost performed higher in λ and Eloc but lower in γ, σ, and Cp. Compared with HC, EPpre exhibited decreased BC, DC or NE in the right inferior frontal gyrus, right superior temporal gyrus, bilateral cingulate gyri, right supplementary motor area, right superior occipital gyrus, right Heschl gyrus, and left calcarine fissure; increased BC in the left postcentral/precentral gyrus, right paracentral lobule, left rolandic operculum, and left supramarginal gyrus, and increased NE in the right caudate nucleus. Compared with EPpre, EPpost showed increased BC, DC or NE in the bilateral inferior frontal gyrus, right middle frontal gyrus, bilateral cingulate gyri, right superior temporal gyrus, and right Heschl gyrus and decreased BC in the left fusiform gyrus.

CONCLUSION

VNS downregulated small-world properties in DRE, and caused changes in some key nodes to reorganize the transmission ability of the large-scale network.

Seizure and social outcomes in patients with non-surgically treated temporal lobe epilepsy

OBJECTIVES

To investigate the seizure outcome with medical treatment in patients with temporal lobe epilepsy (TLE) and its associated factors. We also investigated the social outcome of the patients.

METHODS

This was a retrospective study of a prospectively built electronic database of patients with epilepsy. All patients with a diagnosis of TLE were studied at the outpatient epilepsy clinic at Shiraz University of Medical Sciences, Shiraz, Iran, from 2008 until 2019. In a phone call to the patients, at least 24 months after their diagnosis at our center, we investigated their current seizure control and social status.

RESULTS

Two hundred and twenty-two patients were studied; 101 patients (45.5%) were seizure free. A lower number of the prescribed drugs was the only factor with a significant association with the seizure-free outcome (Odds Ratio: 1.460; p = 0.001). At the time of the phone call, 76 patients (37.6%) reported having a college education, 103 patients (51%) were employed, 146 patients (72.3%) were married, and 81 patients (40%) reported driving a motor vehicle. The employment status, college education, and driving a motor vehicle were significantly associated with a seizure-free outcome status. The social achievements of the patients, who were partially responsive to medical therapy, were significantly worse than those who were seizure free.

CONCLUSION

Many patients with TLE may suffer from drug-resistant seizures. Ongoing seizures in these patients may affect their social lives substantially. Seizure reduction (not freedom) is not good enough to help the patients with TLE enjoy a healthy life with satisfactory social achievements.

Brain structural changes in patients with cardio-facio-cutaneous syndrome: effects of BRAF gene mutation and epilepsy on brain development. A case-control study by quantitative magnetic resonance imaging

PURPOSE

To evaluate the brain volumetric changes caused by BRAF gene mutation in non-epileptic CFC patients and the influence of the age of epilepsy onset on brain development in 2 cohorts of epileptic CFC patients.

METHODS

We enrolled CFC patients carrying BRAF gene mutations without epilepsy (4 patients) and with epilepsy (16 patients). CFC epileptic patients were divided into two cohorts based on the age of seizure onset: early-age onset (7 children) and late-age onset (9 adolescents). All three cohorts of patients underwent 3D FSPGR T1-weighted imaging to assess supratentorial and infratentorial brain volumes. Moreover, for each compartment, gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) volumes were measured. All measurements were compared with those of age-matched controls without neuroimaging abnormalities.

RESULTS

All CFC patients showed supratentorial and infratentorial WM reduction and supratentorial ventricular enlargement (p < 0.01). However, patients with early age of epilepsy onset, compared with the other two cohorts of CFC patients, showed both GM and a more pronounced WM volume reduction (p < 0.01).

CONCLUSION

In non-epileptic CFC children, we demonstrated WM volumetric reduction suggesting a direct effect of BRAF gene mutation on brain development. Nevertheless, in CFC epileptic patients, the age of epilepsy onset may contribute to brain atrophy. Brain atrophy in CFC patients, in part due to the natural history of the disease, may be worsened by epilepsy when it begins in the early ages because of interference with brain growth at that critical age of development.

Predictors of successful valproate withdrawal in women with epilepsy

OBJECTIVE

Valproate (VPA) use was restricted due to its teratogenic risks in women with epilepsy (WWE). We aimed to assess the outcome and predictors of treatment decisions of withdrawal/switch or continuation of VPA in WWE.

METHODS

We included 214 consecutive WWE with a follow-up time of 9.57 ± 7.04 years, who have used (n = 142) or are still using VPA (n = 72) during their reproductive ages. The demographic, clinical, and electroencephalography (EEG) properties of WWE who could withdraw (successful withdrawal; n = 142) and could not withdraw VPA (unsuccessful withdrawal; n = 36) were compared statistically.

RESULTS

The main reasons for still using VPA were high risk of seizure recurrence (63.9%), cognitive impairment (27.8%), and no pregnancy prospect (8.3%). In the successful withdrawal group, 67 (47.1%) patients maintained remission after VPA withdrawal and 26 of them (38.8%) had relapse during the follow-up. The rate of side effects related to the new drugs (levetiracetam and lamotrigine) was 52/142 (36.6%). The unsuccessful withdrawal rate was 13.9% in focal epilepsy whereas it was 86.1% in generalized epilepsy (p = 0.002). Co-occurrence of three types of seizures and anti-seizure medication (ASM)-resistance was related to unsuccessful withdrawal in genetic generalized epilepsy (GGE) (p = 0.02 for both).

CONCLUSIONS

Although women with focal epilepsies are more ASM-resistant and more likely to have continuing seizures, they do not usually deteriorate after VPA discontinuation, therefore posing them to teratogenic risk is often unnecessary. In GGE, certain predictors such as previous ASM-resistance and the presence of three seizure types must be taken into account, before a withdrawal attempt of VPA treatment.