Argentine President Cristina Fernandez is expected to have surgery tomorrow for a subdural haematoma, or bleeding on the brain.
Ms Fernandez has been told by doctors to take a month off because of the condition, forcing her to abandon campaigning for important congressional elections taking place later this month.
Her condition may have been brought on after she hit her head in a fall in August, although she was cleared by her physicians at the time
Doctors at the Buenos Aires medical centre where she is being treated said Ms Fernandez was admitted to hospital for pre-surgical checks after reporting a tingling sensation in her left arm.
Vice President Amado Boudou, who cut short a journey to France to return to Argentina and take over the president's duties, said he and other governmental officials would continue with the president's agenda while she recovered.
Ms Fernandez, president since 2007, had her thyroid glands removed last year after she was diagnosed with cancer, although later tests indicated no cancer was present.
The surgery will keep the 60-year-old out of action ahead of 27 October mid-term congressional elections that will determine how much legislative clout she enjoys during her final two years in office.