J. Neurosurg. / Volume 31 / September, 1969

Sensory Rhizotomy Following Operation for Ruptured Intervertebral Disc* A Review of 62 Cases

DEAN H. ECHOLS, M.D. Department of Neurosurgery, Ochsner Clinic, and the Tulane University School of Medicine, New Orleans, Louisiana

ENSORY rhizotomy for the relief of pain due to scarred or damaged nerve roots. chronic pain, first carried out in 1888 In 1966 White 5 published a report entitled S by both Bennett and Abbe, had nearly "Posterior Rhizotomy: A Possible Substitute been abandoned by 1925 because of its high for Cordotomy in Otherwise Intractable rate of failure to relieve pain and because of Neuralgias of the Trunk and Extremities of the introduction of cordotomy2 Interest in Nonmalignant Origin." He pointed out that the procedure disappeared early for such cordotomy is often an unsatisfactory method diseases as arterial hypertension, vascular of obtaining permanent relief from pain in syndromes, spasticity, postherpetic neuralgia, individuals with normal life expectancy. In gastric crisis, and painful amputation stump. his experience, the rate of success for cor- However, dorsal rhizotomy continued to be dotomy for pain in the lower half of the used to some extent for such entities as an- body was only 60% after 1 year and 50% gina pectoris and carcinoma of the brachial after 5 years. In discussing rhizotomy, he plexus. One of the last substantial communi- said that unlike cordotomy it was unlikely to cations on root section was by Ray in 1942. a be followed by paresthesia. In addition, he Some surgeons continued to employ the l~ointed out that, because of the overlap of procedure from time to time when it seemed sensory distribution, multiple rhizotomy for worth trying in a particularly difficult situa- pain in the upper or lower extremity does tion. In 1959, Bohm and Franksson 1 advo- not produce a useless limb provided one or cated section of the coccygeal and lower sa- more important sensory roots of the brachial cral roots for coccygodynia and sacral pain. or lumbosacral plexus have been left intact. In 1964 Crue and Todd'-' wrote on sacral Moreover, the overlap from adjacent der- root section for pain due to pelvic malig- matomes is more extensive for the sense of nancy so advanced that sphincter function touch and posture than for pain. When such was no longer important. In 1966, Scoville * important sensory roots as C-6 or C-7 or L- reported on 12 rhizotomies for chronic pain 5 or S-1 have been cut, it is difficult to dem- at various levels. onstrate a definite sensory loss. When C-6 Probably the chief reason for the rein- and C-7 or L-5 and S-1 have been cut, the statement of sensory rhizotomy as a conven- sensory loss is surprisingly small, and the pa- tional procedure for selected pain problems tients do not seem to be more than tempo- was the realization, thanks to Jason Mixter, rarily handicapped. that most chronic sciatica is due to compres- sion of a single nerve root by a ruptured in- Material and Method tervertebral disc. Failures in disc surgery provide a pool of patients needing spinal fu- A review of consecutive sensory rhizoto- sion, rhizotomy, or cordotomy for persistent mies on 159 patients performed by the writer in an arbitrary 20-year period ending on December 31, 1967, discloses that 62 of Received for publication October 23, 1968. * Presented at the Annual Meeting of the Ameri- the operations were done on patients who can Academy of Neurological Surgery, October had chronic upper or lower extremity pain 7, 1968, Colorado Springs, Colorado. following one or more operations for rup- 335 336 Dean H. Echols tured intervertebral disc. Many of these pa- that all pain will be relieved by section of a tients had had good results from disc surgery single root. only to end up with a recurrence of radiating Most of these 62 rhizotomies were done pain which was not relieved by one or more intradurally. However, several were done by additional disc operations with or without opening the sheath of the nerve, just proxi- spine fusion. Most of the rhizotomies were mal to the ganglion. In 12 patients, the en- of L-5 or S-1 or both. There were no post- tire root was severed. In one instance, an at- operative deaths. This operation failed to tempt was made to cut the L-5 and S-1 sen- solve the pain problem in about 40% of the sory roots at spinal cord level because severe patients (Table 1). arachnoiditis had frustrated my first attempt As far as I can ascertain, most neurosur- at rhizotomy at the conventional level. This geons still avoid spinal rhizotomy. Perhaps patient had had disc operations and a good they are wise because, except in the case of cordotomy elsewhere without relief from trigeminal neuralgia, rhizotomy frequently unilateral sciatica. At my second operation fails to relieve pain and it may produce a in May, 1964, a suture was put around the higher incidence of malpractice claims than filum terminale just distal to the conus, the do other neurosurgical procedures. One rea- sensory bundles counted, and the appropri- son for the latter is the ever present possibil- ate ones sectioned. However, the postopera- ity of cutting the wrong root or roots. Th!s tive evaluation indicated that only part of can happen because landmarks are often ob- L-5, all of S-l, and part of S-2 had been scured by massive extradural scar tissue, sacrificed as evidenced by slight but not in- bone grafts and severe arachnoiditis, or the convenient numbness of the penis. He re- absence of spinous processes and laminae. turned to work 2 months later but had a Moreover, most candidates for rhizotomy mild recurrence of sciatica 4 years later and have had multiple unsuccessful operations consequently has been classified in the fail- and tend to be hostile toward the medical ure group. I offered to cut a few more L-5 profession. In performing the operation, fibers at cord level, but he requested and re- great care needs to be taken to obtain orien- ceived a percutaneous cordotomy, which tation by means of x-rays made during the proved to be of some value. This single ex- operation, and by electrical stimulation of perience with sectioning of lumbar and sa- roots when feasible. In general, if there is cral roots at cord level suggests that it would doubt as to whether L-5 or S-1 should be be an excellent operation if a reliable cut in a patient who has had repeated curet- method could be developed for counting or tage of the fourth and fifth discs, it may be otherwise identifying the proper roots. If better to cut both rather than risk another perfected, the difficult task of removing scar operation. However, preoperative diagnostic tissue or bone graft could be avoided. injection of a root with procaine or stimula- I have sacrificed both motor and sensory tion of roots at the time of operation under root on 12 occasions (Table 1). The C-6 local anesthesia may convince the surgeon motor and sensory rhizotomy was done on a

TABLE 1 Sensory rhizotomy on 62 patients following one or more disc operations

,5, C5, Level of rhizotomy C6 L3 L3, L5 Sl 1 ;1, Total C6 L4 ~2 ~2

Number of patients 1 -3-i- 1 16 18 2 i 62 Author's own disc patients 0 0 0 1 9 9 1 0 28 Patient had 2 or more prior operations 0 2 0 0 7 9 1 1 31 Prior spinal fusion 0 3 0 0 1 2 0 1 13 Bilateral rhizotomy 0 0 0 0 2 3 0 0 10 Motor root also cut 0 1 1 0 5 5 0 0 0 12 Rhizotomy failed to stop pain 0 1 0 0 5 10 7 2 0 25 Rhizotomy stopped pain 1 2 1 1 11 8 12 0 1 37