**6.4 Deep brain stimulation**

This approach has attained approval as adjunctive therapy for refractory seizure in EU and USA [68]. Bilateral stimulation of the anterior nuclei of the thalamus (ANT) for epilepsy is indicated as an adjunctive therapy for reducing the frequency of seizure in adult patients with partial onset seizure with or without secondary generalized seizure [68]. The long-term data showed a median seizure reduction at 1 year of 41% increasing to 69% after 5 years [68]. The mechanism of action remains unknown. These modalities of adjunctive procedures are eventually available in most developed countries [69].

#### **6.5 (t-VNS)**

Transcutaneous vagus nerve stimulation has been proposed as an alternative method for the treatment of various psychiatric disorders. The application of this device in refractory seizures is still not conclusive concerning the efficacy, and future trials are needed [70].

#### **6.6 Ablative procedure**

There are multiple varieties of ablative procedures for refractory seizures, including:

#### *6.6.1 SEEG-guide radiofrequency thermos coagulation*

SEEG-guide RF-TC has been developed and expanded [71]. A single or multiple lesionotomy by coagulation should be performed between continuous electrode contacts, with progressive increasing in power till the impedance suddenly changes indicating that thermos coagulation has occurred. The best response was observed in patients with periventricular heterotopia, results showed pooled seizure free rate of 23% and response rate of 58% [71].

#### *6.6.2 Laser interstitial thermal therapy (LITT)*

LITT is also a stereotactic laser ablation (SLA). The laser applicator sheath is placed and lesionotomy performed with precise imaging technique using MRI. The ablation is carried out under continuous monitoring of MRI thermal image near real time. In MTLE, improvement of 58% was achieved according to Engle scale I outcome after 1 year [72].

### *6.6.3 Radiosurgery*

Radiosurgery has been used for (MTLS), gelastic epilepsy associated with hypothalamic hamartomas and epilepsy with vascular malformation, and it has demonstrated a decrease in seizure frequency in MTLS, hamartomas of the hypothalamus, and AVM. Delayed therapeutic effect must be considered in treatment decision [73], and recently, it has been shown that radiosurgery of corpus callosum may in some cases result in seizure reduction [74].
