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04-04-2013 | Stroke | Article

Electrical brain stimulation alone may not improve chronic aphasia


Free abstract

medwireNews: Findings from an Italian study suggest that transcranial direct current stimulation (tDCS) may only improve chronic aphasia symptoms when combined with specific synaptic activation achieved through behavioral treatment.

Seven of eight chronic aphasia patients showed no difference in language recovery after tDCS without behavior-based speech therapy (off-line) versus sham brain stimulation.

"These data could be taken as an indirect evidence for the critical importance of simultaneity in time between tDCS and a behavioral learning task as evidenced by recent neurophysiologic findings obtained from animal studies," the authors say.

As reported in the journal Behavioral Brain Research, all patients had aphasia secondary to stroke and were aged 42-70 years at the start of the study.

The patients received 10 sessions of anodal tDCS, lasting 20 minutes, over a 2-week period and another 10 sessions of 20-minute sham stimulation (as a control) over another 2-week period.

Each tDCS session involved the delivery of a 2 mA anodal constant current over Broca's area. Sham stimulation was carried out in the same way, but the stimulator was turned off after 30 seconds.

The patients all undertook a computer-based picture naming task at the start of study to determine baseline noun and verb naming ability. This test was then repeated at the start and end of the tDCS and sham stimulation treatment programs.

Only one patient showed significant improvement in noun and verb naming ability after tDCS compared with baseline ability.

Chiara Volpato (IRCCS Fondazione Ospedale San Camillo, Venice) and co-authors say that "this single patient showed a rapidly changing language performance compared to the other patients. Thus, it is possible that he was more susceptible to electrical stimulation."

They add that the patient also started with a "more severe naming deficit than the other patients, making it more likely to observe a significant change in performance."

Volpato and team say that the small size of the current study "restricts generalization of the results", but they conclude that the findings "should be taken into account by clinicians who intend to use tDCS in language rehabilitation."

By Lauretta Ihonor, medwireNews reporter

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