Dorsal root ganglia may be reservoirs of viral infection in multiple sclerosis.

There are presently two competitive theories that attempt to explain the etiology of multiple sclerosis (MS). Briefly summarized, they are: 1. An infection, probably of viral type, may attack the oligodendroglia of the central nervous system; or, 2. An autoimmune process may begin with an infection of the peripheral lymphatic immune system, producing antibodies that cross the blood-brain barrier, leading to myelinoclasia. Since 1935, research has been directed toward myelin of the central nervous system and the myelin sheaths of peripheral nerve; however, dorsal root and cranial sensory ganglia (DRG) have apparently not been studied. The present hypothesis states that an infectious agent (probably viral) finds privileged sanctuary in the dorsal root and cranial sensory ganglia (DRG): thereafter periodically invading the spinal cord, brain, or peripheral nerve. Previously reported erratic spinal fluid viral titers and cultures can be explained by differences in the anatomy of the DRG in which there is a variable and limited contact of spinal fluid with sensory ganglia. Clues to this hypothesis were noted by the author during routine neurological examinations of patients with MS, in which sensory signs and symptoms were frequently encountered. This clinical observation has also been reported by others who found such symptoms in 75% of MS patients, ranking second only to incoordination.