The present invention relates to implantable neuromodulation systems and methods, and in particular to modular neuromodulation systems suitable for implantation in a minimally invasive manner, methods of manufacturing the modular neuromodulation systems, and methods of treating rheumatoid arthritis using the modular neuromodulation systems. Particularly, aspects of the present invention are directed to a medical device that includes an implantable neurostimulator including a housing having a width of less than 10 mm and a height of less than 10 mm, one or more feedthroughs that pass through the housing, and an electronics module within the housing and connected to the one or more feedthroughs. The medical device further includes a lead assembly including a lead body including a conductor material, a lead connector that connects the conductor material to the one or more feedthroughs, and one or more electrodes connected to the conductor material.
