The aim of this study is to evaluate whether the Transcutaneous Electrical Nerve Stimulation (TENS) is effective on improvement of cognitive disorders in Multiple sclerosis patients.

Multiple sclerosis (MS) is one of the most common autoimmune diseases in the world. One of the complications of MS, is cognitive disorder.

In some studies on rats, stimulation of somatosensory neurons has improved the hippocampus activity by increasing the amount of acetylcholine. Hippocampus has a major role in cognition and behavior.

TENS is a non-invasive method in which the electrical pulses are sent to the body trough skin by electrodes. This device can stimulate the somatosensory neurons by electrical impulses. In several studies, the effect of TENS has been proved on short term memory and verbal fluency in patients with mild stages of Alzheimer disease. Also it has been effective on some aspects of cognition on old people suffering from forgetfulness.

Inclusion Criteria:

• patients with confirmed multiple sclerosis by McDonald criteria;
• score 25 or less in mini mental state examination (MMSE)

Exclusion Criteria:

• MMSE score greater than 25;
• the history of psychiatric problems;
• addiction to alcohol; head trauma; cerebrovascular disease; hydrocephalus; neoplasm; epilepsy; renal or respiratory diseases; impaired consciousness