Multiple sclerosis, Baclofen pump therapy. Surgeon using a syringe to add Baclofen to an intrathecal pump to be implanted inside a patient. Baclofen functions by activating GABA (gamma-aminobutyric acid) receptors. It is used to alleviate symptoms of spastic movement disorders including cerebral palsy and multiple sclerosis. An intrathecal pump delivers drugs to the space between the spinal cord and its protective sheath. Multiple sclerosis is a progressive disorder in which the body's immune system attacks the myelin sheaths that cover nerve fibres. It can cause tingling, speech disorders, lack of coordination, paralysis and death.