The use of selective posterior (dorsal) rhizotomies for the treatment of spasticity arose from its success in treating unremitting limb pain. In September 1888, a New York neurologist, Dr. Charles Dana, first suggested cutting nerves to treat pain in a letter to Dr. Robert Abbe, who quickly adopted the technique. As his experience with the technique grew, he had occasion to operate on patients with painful spasticity. He found that not only did the pain abate, but the spasticity also resolved.
In 1913 the great German neurologist Otfrid Foerster published a review of his group's experience with this procedure. Among 159 patients discussed, he singled out 88 cases of congenital spastic paraplegia (spastic legs due to a birth injury). It was his opinion that this subgroup responded particularly favorably to posterior rhizotomy because their motor nerves (nerves going from the spinal cord to muscles and involved in movement) were spared. However, the density of his lesioning led to unacceptable side effects, mainly sensory abnormalities and skin sores. This, coupled with a lack of post-operative rehabilitory support, resulted in the procedure's falling into disfavor.
Then, in 1973, at the International Congress of Neurological Surgery in Tokyo, a French surgeon named Claude Gros presented his experience using a modification of Foerster's operation: to treat 50 individuals (18 infantile spastic diplegics [spastic CP], 14 post-traumatic spastic paraplegics and 18 spastics with a degenerative myelopathy [progressive loss of function in the spinal cord]). He used a modification of Foerster's operation where he left one-fifth of the rootlets (subdivisions of a nerve root) of a given root uncut. The results were described as effective in reducing or suppressing hypertonicity (increased muscle tone). In later presentations his group discussed refinements in the decision-making process as to which rootlets were selected for cutting. Their important contribution was to demonstrate that subtotal sectioning of nerve roots was sufficient to treat the spasticity.
An Italian surgeon named V. A. Fasano took a different approach. He noted, as had others, that in spastic patients the reflex circuits within a nerve rootlet not only had effects on the intensity of contraction in muscles normally supplied by the rootlet, but that they also triggered activity in muscles not normally supplied by the circuit. So, in the case of the tendon jerk reflex (muscle movements elicited by tapping their tendons, such as at the knee, which results in a leg jerk) in spastic individuals, tapping the knee not only results in the leg straightening but it also caused tightening of muscles throughout the body. His technique involved electrically stimulating the sensory rootlets, while simultaneously noting the patterns of muscle responses.
One abnormal reaction noted was diffusion of muscle activity in response to stimulating of the nerves (typically activity in both legs and sometimes the arms), mimicking what occurs with the tendon jerk reflex in spastic children. He reported his patients as doing well clinically at two- to seven-year follow-up, with no report of the spasticity.
Peacock moved the site of the operation lower in the spinal canal out of concern for bladder function. This allowed a secure identification of the roots being operated on. He subsequently used his modification on 60 children with good results. It was his reporting of these results during the mid-1980s that regenerated interest in North America for using rhizotomies to treat spasticity.