tDCS Associated to Blindsight Rehabilitation for the Treatment of Homonymous Hemianopsia
tDCS Associated to Blindsight Rehabilitation for the Treatment of Homonymous Hemianopsia
Homonymous hemianopia is one of the most common symptoms following a neurologic damage and
 has many negative effects on functional abilities and daily activities.

 There are two main kind of restorative rehabilitation of hemianopia: "border training", which
 involves exercising vision at the edge of the damaged visual field, and "blindsight
 training", which is based on exercising the unconscious perceptual functions in the mild of
 the blind hemifield.

 In literature only border training effects were shown to be facilitated by transcranial
 direct current stimulation (tDCS).

 The investigators treat two patients with blindsight rehabilitation associated to tDCS over
 parieto-occipital cortex. The two patients undergo a cycle of blindsight treatment associated
 to tDCS and a cycle of blindsight training alone in inverted order.

 Aim of the study is to investigate if the anodic stimulation of perilesional areas enhance
 the improvement induced by blindsight rehabilitation treatment.
The study design is a crossover AB BA. Treatment A consist in a cycle of blindsight training
 associated to tDCS, Treatment B consist in a a cycle of blindsight training alone.

 During the blindsight training, the patient is asked to maintain central fixation and is
 exposed to visual stimuli in his blind hemifield. The patient task is detection and/or
 discrimination of stimuli.

 During each session the patient is subjected to around 700 different stimuli variously
 associated in space and/or time.

 One out of two blindsight training cycles is associated to tDCS treatment. Anodal tDCS is
 applied using a battery-driven constant current stimulator, and a pair of surface
 saline-soaked sponge electrodes (5 x 5 cm). Current intensity is of 2 mA (Fade-in/-out= 10
 sec), for a total duration of 30 min. The stimulation start at the beginning of the
 rehabilitation session, and continue for 30 min, during treatment.

 Anode is placed over the parieto-occipital cortex. The cathode is placed in the contralateral
 supraorbital position.

 To assess the actual improvement patients performed:

 1. Clinical-instrumental assessment: Threshold visual field Humphrey SITA-standard 30-2
 program is used to measure the visual perception within the central 30 degrees.

 2. Peripheral visual field test Schofield Vienna PP-R test is used to measure the visual
 perception up to 180 degrees. A double task in central vision was performed in order to
 verify test reliability.

 3. Functional visual field assessment: Test for Attention Performance (TAP - v. 2.3) visual
 field 92 stimuli subtest (26) is performed.

 4. Ecological assessment: during initial and final interview an ICF profile of the subject
 is edited. The profile includes mainly the Activity and Participation categories of ICF.

 All these investigations is performed before the treatment and after each cycle
Inclusion Criteria:

 -  The subject is able to give his informed consent

 -  Stroke

 -  Hemianopsia brain damage documented by means of TAC or RMN

 -  Hemianopsia diagnosed by means automated visual field and Neurological Evaluation

 -  Time from lesion at least six months

 -  normal or corrected-to-normal visual acuity

 Exclusion Criteria:

 -  Presence of Ophthalmologic neuropsychologic or psychiatric pathology

 -  Global cognitive deficit,

 -  Presence of other neurological pathology

 -  Presence of cardiac peacemaker

 -  Presence metallic or electronic items in the head or in the body

 -  Story/familiarity of epilepsy, taking medications that can induce epileptic crisis

 -  Severe heart disease

 -  History of high alcohol consumption

 -  Pregnancy