Spread of Poliomyelitis Virus Along Nerve Fibers of the Sympathetic System.

Abstract

Flexner and Lewis were the first to show that poliomyelitis could be produced in monkeys by the intranasal instillation of the virus. Faber states that the virus is absorbed by way of the olfactory bulb along the base of the brain, thence proceeding to the medullary area and to the cord. After intracerebral injection, the spread of the virus would presumably be along the same route after it reaches the base of the brain. The axones are the main transmitting structures (Hurst3) and the spinal fluid plays no part in the spread (Jungeblut and Spring4). Monkeys may contract poliomyelitis after intraperitoneal and subcutaneous injections of massive doses of virus, but, to my knowledge, never after the injection of the small doses that produce the disease when the virus has been intracerebrally and intrasciatically injected or intranasally instilled. The intrasciatic, intracerebral, intraperitoneal and subcutaneous routes are highly artificial portals of entry. When the virus is intranasally instilled, it enters the system through a natural portal of entry, and the spread along nerve fiber connections can easily be traced to the brain. Many workers believe that the nasal area is the usual and natural portal of entry in the human. The following experiments were performed to show that the virus may spread by way of the sympathetic fibers in monkeys experimentally infected with poliomyelitis. Our purpose was to isolate the cord carrying the virus from its axones, and thus to leave the sympathetic system as the only means of communication between the upper cord and the injected peripheral nerve. Transabdominal operations were technically impossible and the operations to expose the sympathetic chain posteriorly were usually followed by death of the animal. The only feasible method was to cut out the cord at some strategic point so that all the communications between the somatic nerves and upper cord would be destroyed and then to inject a peripheral nerve, which in these experiments was the sciatic.