Section of the posterior roots of the cord (Abbe, Forster) is a useful procedure if the conditions are suitable, i. e. if the pain is sharply delimited. Three factors limit the suitability of this operation: first, it is necessary to determine precisely the delimitation of the painful area and choose the corresponding nerve root. This proves difficult particularly in the inferior half of the spinal cord. The difficulty occurs because as the cord proceeds inferiorally, the roots descend more and more obliquely, and in the lumbar spine the roots are arranged next to each other in a tight bundle, which makes correct selection and precise definition of the innervated area far from easy. Secondly, great attention must be paid to the vessels which accompany the roots, since section of these along with the root can interfere with the blood supply of the corresponding segments of the cord and cause functional disturbances. I have experienced such an interruption of cord function after section of a single sensory root, where the accompanying vessel was quite insignificant and did not even bleed after section. This danger is the greater if several roots are cut simultaneously, and in patients with vascular changes. Thirdly, after such surgery there is an area of complete insensitivity far greater than after chordotomy. This is not of great issue on the trunk, but is so in the extremities. A completely deafferented extremity is deprived of all reaction to the surroundings and orientation proves of great difficulty to the patient, even though muscular function is preserved.
Fears have been and still are expressed that with the removal of a large number of intervertebral discs, in order to secure an approach to a larger number of roots for section, the stability of the spinal column may be affected. Our experience has shown (on the basis of more than four hundred laminectomies) that this danger can be removed by observing certain rules.
Section of the central root of the trigeminal nerve also belongs among these radicotomies by virtue of its physiological-anatomical character.. This will be discussed under intracranial approaches in the therapy of this neuralgia.