Elsevier

Brain Stimulation

Volume 9, Issue 5, September–October 2016, Pages 790-792
Brain Stimulation

Letter to the Editor
The Effects of Cathodal Transcranial Direct Current Stimulation in a Patient with Drug-Resistant Temporal Lobe Epilepsy (Case Study)

https://doi.org/10.1016/j.brs.2016.05.011Get rights and content

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Case description

A 48-year-old female was admitted as a surgical candidate for 5 days to the Video-EEG Monitoring Unit at the Royal Melbourne Hospital. She was diagnosed with a Grade 2 right fronto-temporal pleomorphic astrocytoma 10 years earlier. She reported having 5–10 seizures per day at the time of admission. The seizures were focal sensory seizures with left hemi-sensory changes (tingling sensation in face > leg, lasting 15–30 sec), occasionally associated with eye and hand twitching and sometimes with a

Intervention

Two sessions of c-tDCS (9–20–9 protocol) were applied in the last two days of the patient's admission. The protocol involved a total of 18 minutes c-tDCS, with 20 minutes rest after the first 9 minutes. A DC-stimulator (Chattanooga Intelect® Advanced Combo) was used to deliver a 1 mA continuous galvanic current to the brain via two surface electrodes with surrounding saline-soaked sponges (0.9% NaCl). The active surface electrode (cathode, 3 × 4 cm) was placed over the right temporal lobe, and

Assessment

The patient was asked to keep a record of her seizures in a daily seizure diary for 4 weeks. Paired-pulse transcranial magnetic stimulation (TMS) (Magstim Bistim2) was used to assess GABAergic intracortical inhibitory circuits (ICI) before and after each intervention. In this method, TMS that is subthreshold for a motor response activates ICI circuits and reduces the size of the motor evoked potential (MEP) elicited by a supra-threshold test TMS pulse delivered up to 5 ms later [6]. The

Results

The c-tDCS intervention was well tolerated, with no adverse effects. ICI increased from 57% at baseline to 67% after the second treatment session (Fig. 1).

Seizures reduced from 6–10 per day to 0–3 seizures per day. Seizure diaries showed that seizure rates remained as low as 0–3 per day for 4 months and then started to increase again.

Discussion

The anti-epileptic effects of c-tDCS can be explained due to the fact that c-tDCS decreases cortical excitability by hyperpolarising the membrane potentials and subsequently altering synaptic efficacy [7]. Our results in this case study are consistent with those of Yook et al. [8], who applied c-tDCS application (20 min, 2 mA, 5 days/week for 2 weeks) over the area of the abnormal EEG wave in an 11-year-old female with focal cortical dysplasia. Over the two-month monitoring period the frequency

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