J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.31.1.61 on 1 February 1968. Downloaded from J. Neurol. Neurosurg. Psychiat., 1968, 31, 61-66 Protrusion of the posterior longitudinal ligament simulating herniated lumbar intervertebral disc ROBERT A. BEATTY, OSCAR SUGAR, AND THEODORE A. FOX From the Departments ofNeurological Surgery and Orthopedic Surgery, University ofIllinois College ofMedicine, and Illinois Masonic Hospital, Chicago, Illinois, U.S.A. The most common cause of lumbar or sacral nerve- ne'rVe root compression, however, in whom no root compression probably is herniation of the herniation is found at operation; instead the nerve nucleus pulposus. There are some patients with root is compressed by a fold in the posterior longi- typical clinical-and even radiological-evidence of tudinal ligament, and, when this is excised, there is TABLE I CLINICAL SUMMARY OF 13 PATIENTS Age Sex Occupation Signs and symptoms Operation Length of Late results follow-up Protected by copyright. 37 F Housewife Pain in right hip radiating to lateral L5-S1 laminotomy right. 6 yr Asymptomatic. Active aspect right ankle. Absent right ankle Fusion housewife jerk. Hypaesthesia lateral aspect right foot 53 M Carpenter Pain left calf and foot. Atrophic left Left L4-5 laminotomy and 5 yr Still has burning dysaes- calf foraminotomy thesias in leg; no impairment of bending 19 M Student Weakness and numbness right calf. Right L5-S1 laminotomy 4 yr Mild back pain with Weak right plantar flexion. Hypaes- activity thesia lateral aspect right foot 48 F Housewife Low back pain into left leg. Decreased Left laminotomy, L4-5, - Lost to follow up left ankle jerk. Hypaesthesia lateral L5-Sl. Foraminotomy L4-5 left foot 34 F Factory Low back pain. Left paraspinal spasm. Bilateral laminotomy L4-5, 4 yr No back pain worker Hypaesthesia dorsum left foot L5-S1 33 M Steel worker Low back pain. Straight leg raising 30' Right laminotomy L4-5, 3 yr Less strenuous job. Pain on right L5-Sl. Transdural approach in leg and low back to L4-5. Fusion improved 35 M Newspaper- Low back pain into left leg. Left Left laminotomy L4-5, 3 yr Back at work; no leg pain; man straight leg raising limited L5-Sl. Fusion occasional mild backache http://jnnp.bmj.com/ 30 M Dock Low back pain into left leg. Weak Left laminotomy L4-5, 3 yr Working as dockhand. worker dorsiflexion left foot L5-S1 Fusion Mild leg and lumbar pain. No weakness 37 F Housewife Low back pain into right leg. Absent Bilateral L4-5 laminotom:iy. 2yr Occasional mild leg and right ankle jerk. Bilateral weak foot Fusion low back pain. No dorsiflexors weakness 40 F Housewife Low back pain into right leg. Hypaes- Bilateral L5-Sl laminotonmy. I yr Asymptomatic; no straight- thesia lateral right foot Fusion leg raising impairment 41 M Businessman Low back pain into right leg. Decreased Bilateral laminotomy L4-'*5, 11 months No impairment of bend- on October 1, 2021 by guest. right ankle jerk. Limited right straight- L5-Sl. Fusion ing; straight-leg raising leg raising normal 15 M Student Low back pain into right foot. Weak Right laminotomy L4-5, 8 months No list, bends well, no right foot dorsiflexors L5-S1 pain, no muscle spasm; straight-leg raising normal 44 M Dairy Low back pain into left leg. Absent Left laminotomy L5-Sl 8 months No back or leg pain worker left ankle jerk. Hypaesthesia lateral left thigh 61 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.31.1.61 on 1 February 1968. Downloaded from 62 Robert A. Beatty, Oscar Sugar, and Theodore A. Fox FIG. 1. Drawing of operative exposure showing protruded Protected by copyright. posterior longitudinal ligament over which the nerve root is stretched. Inset shows redundant ligament when disc space is narrowed. FIG. 3. Myelogram of same patient showing filling defect at the L 4-5 interspace. little or no intervertebral disc material to be found in the interspace. We are reporting a series of 13 such patients. CLINICAL MATERIAL .. | {e ,:e.: - PREOPERATIVE EVALUATION Thirteen patients were drawn 'C,':' ,.' i E2 W.5! :- -L---vi, a --R from both neurosurgical and orthopaedic practices ...... .... _ A | _ (Table I). The duration of symptoms before operation ;.' - a | _ varied from two months to 13 years, with the majorityhttp://jnnp.bmj.com/ _ ::_N 111 a _ at three years. Ten patients related the onset of their symptoms to a specific episode of trauma, usually, E :::'.o i_ * | _ bending or lifting. Low back pain radiating into one leg w 3'< y_ < | _ '_1 i@N | _ was present in 10, and into both legs in two. In three, *:..:SP:N,j73_ n | _ ... ,._ | | _ the initial complaint was calf or hip pain. There were : :. }: o=a2 a | _ :.,ffl ;,-111 | _ objective signs of nerve-root compression (hypaesthesia, _§ 'as:' . : ....:. .. ......,2Eo..X22Z ::j _SiSB | S1_ ::eYR,<i6gpc; .. :^ E1|1111| _ 11 patients, while _ gc ...................:, K .... stretch reflex, weakness) in _ Rg | _ depressed ..........:_:'.: Cg *| .| :_ - two showed limitation of straight leg raising on the . e MY .. .. :} . only * sS t.t':.e, ... , ..... : ... ;.,£ C . l - on October 1, 2021 by guest. _y .. v.:: :' : .e . : . .. :'.:i".:.:'.qg ::.:.- 8§| l_ _ ! . 3,j :.ox, X X | _ affected side, in addition to persisting complaints of _F" w | _ -11-Sy -e 101* _ sciatica. _Fe' .' r!i> / .... ... .. :s * 11111111111i#ieSi;:g8R |- _ Narrowing of the appropriate intervertebral disc space :;^. '' _ corresponding to the radicular signs was demonstrated _,.::_P,,. .... :: : sSE :.:s ;S7S1gN9eq111| 11|1 sl _ _ on plain radiographs of the lumbosacral area in seven of FIG. 2. Lateral view of lumbar spine showing what 12 patients (one set of films was inadvertently destroyed). appears to be a normalt' wXL ............45 interspace.' :Note X .. ..the lover- l - Myelography was performed in six patients, five ofwhom riding_C.:.Sacers narrowingg|s::.:g . .the ... .nerve-root : : :,. ^'."z;.78:Re 2 _foramen..2i.|*_*_ s.:: ........ :| a_ a_ Q _ || * _ _ _ had abnormalities. In three of-these, there were unilateral J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.31.1.61 on 1 February 1968. Downloaded from Protrusion of the posterior longitudinal ligament simulating herniated lumbar intervertebral disc 63 Protected by copyright. FIG. 5. Cadaver lumbar canal after removal of laminae andpedicles on one side. FIG. 4. Posterior-anterior view of same myelogram. was also explored (and vice versa), to assure the absence of a typical herniated nucleus with false localization. In seven patients, spinal fusion was carried out by the ortho- filling defects in the column of contrast medium, while, paedist with an H-shaped iliac graft interposed between in two, bilateral defects were found. Electromyography the spinous processes of the fourth lumbar and first (EMG) carried out in 11 patients showed evidence of sacral vertebrae. The material removed from the disc lower lumbar or first sacral radiculopathy in nine. space was usually degenerated cartilage, compatible When the nerve root indicated by EMG corresponded to with degenerated intervertebral disc. the clinical picture, Pantopaque myelography was not We have followed cases as long as six years post- always done, for it is our opinion that one does not operatively. In 1966, five patients in the series were re- operate because of a positive or negative myelogram. examined, and a questionnaire was sent to the others. One was lost to follow-up. All patients reported that OPERATION This was carried out with the patient prone, they were improved and were either asymptomatic or http://jnnp.bmj.com/ sometimes with the legs dropped into a kneeling position, were experiencing only mild backaches. None of the and under general endotracheal anaesthesia. After re- patients examined demonstrated limitation of straight- moval of the ligamentum flavum and as much laminar leg raising or paraspinal muscle spasm. Hypaesthesia edge as was needed for exposure, the dural sac was and depressed stretch reflexes tended to persist, however. retracted and the nerve root visualized, mobilized, and retracted (Fig. 1). The bulging posterior longitudinal CASE REPORT ligament was incised and the disc space entered. The amount of cartilaginous material (disc and cartilage The syndrome is illustrated in the following typical case plate) was always scant and never protruding. The nu- report. T.T., a 30-year-old dock worker, developed low on October 1, 2021 by guest. cleus pulposus was practically non-existent. In some back pain with radiation into the left leg following an patients, the interspace was so narrowed that only a automobile accident two years previously. Persistence of small curette (No. 0 or 1) could be inserted. Thorough pain and weakness of the left foot led to hospitalization. curettage was always carried out. The part of the bulg- The most striking finding was weakness of the dorsi- ing ligament, over which the nerve root was stretched, flexors of the left foot. Plain radiographs of the was exised. If the level explored was between the fourth spine (Fig. 2) showed straightening of the normal lum- and fifth lumbar vertebral bodies, the next lower level bar lordotic curve, retained height of the intervertebral J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.31.1.61 on 1 February 1968. Downloaded from 64 Robert A. Beatty, Oscar Sugar, and Theodore A. Fox Protected by copyright. FIG. 6. Same specimen as Fig. S after removal of one nucleus pulposus and application of longitudinal com- pression. Note marked bulge of posterior longitudinal ligament (arrow), slight bulge of ligamentum flavum, and narrowing ofnerve-root foramen. http://jnnp.bmj.com/ FIG. 7. Radiographs of lateral view of cadaver lumbar spine after removal of nucleus pulposus (from in front, at arrow).