What causes cortical expansion depression

tDCS in acute stroke patients

In a mouse model it was shown that a cathodic polarization of the cortical surface was present with intensities of 30 µA and higher, blocking the propagation depression completely. There is no study that shows this in stroke patients. tDCS is a powerful tool for modulating the excitability of motor areas. Cathodal tDCS induces a 30-50% decrease in evoked motor potential amplitudes. In another study, cathodic stimulation induced a prolonged decrease in tactile discrimination compared to sham a, while sham stimulation did not. In our study, the cathodic stimulation is carried out via the lateral motor area (C3 or C4, 10-20 system) using an intensity of 2 mA to determine whether there is an inhibition, a hyperpolarization of the middle, an ischemic penumbra stroke Cerebral artery can be obtained.

tDCS is characterized by an excellent security profile. tDCS studies on patients were performed with intensities between 1 and 2 mA. Security for these intensities was shown. Minor tDCS side effects have been reported in healthy people and patients with varying degrees of neurological disorders. These tDCS studies were conducted for a wide range of neurological and psychiatric conditions including pain, depression, Parkinson's disease, and stroke rehabilitation. Mild tingling, moderate tiredness, itching under the stimulation electrodes, and headache have been described. Tinnitus has also been reported.

In human studies, the duration of tDCS stimulation is generally between 3 and 40 minutes in iterative sessions. In our study, tDCS is less than 4h30 after the onset of symptoms. Studies with mouse stroke models showed that cathodic tDCS onset 45 minutes after middle cerebral artery occlusion and for 6 hours had a neuroprotective effect that reduced infarct volume by 30% (20% in the 4 hour duration group compared to sham). Based on these data, in our study tDCS is delivered 20 minutes per hour for 6 hours. Usual neurovascular treatments (IV thrombolysis, thrombectomy, if indicated) remain unchanged.

Some simulation studies have shown that roughly half the current is injected while tDCS is passed through the scalp. When using stimulation currents of 2 mA, the magnitude of the current density in relevant regions of the brain is in the order of 0.1 A / m2, corresponding to an electric field of 0.22 V / m. Induced skin burns are rare. Burns of the skin are preceded by a painful feeling. Sponges soaked in saline solution must be placed under the electrodes and remain moist to avoid these burns. In our study, patients are asked about the tolerance of tDCS stimulation per hour. The impedance values ​​of the tDCS electrodes are checked every hour.

A cephalic electrode assembly was chosen. A setup with M1 placement of the target electrode (C3 or C4, 10-20 system) and an extra-cephalic placement of the rear electrode (shoulder) leads to the more frequently used cephalic structure with the compared to a two to three times higher electric field in the brain stem Target electrode over M1 and the return electrode over the contralateral frontopolar area (FP2 or FP1, 10-20 system). Reported changes in cerebral autoregulation may have been mediated through stimulation of the autonomic brain stem centers. The use of a cephalic back electrode assembly is therefore recommended. According to these recommendations, in our study the two electrodes are in a cephalic position: C3 or C4 and FP2 or FP1 (10-20 system).

The main aim of our study is to assess whether cathodic tDCS above M1 (C3 or C4) is acute, enabling stroke patients to preserve the penumbra and reduce the infarct volume (MRI day 1 versus admission MRI).

Secondary goals are:

1. To determine if tDCS improves clinical outcome 7 days after stroke with the National Institute for Health Scale (NIHSS)

2. To determine whether tDCS improves the clinical outcome 3 months after the stroke with the Rankin framework

3. To evaluate the side effects of tDCS