.1 Neurol. Neurosurg. Psychiat., 1955, 18, 305.

LOCALIZED ENLARGEMENT OF THE SPINAL CANAL IN THEABSENCE OF TUMOUR: A CONGENITAL ABNORMALITY

BY

ANTONY JEFFERSON*From the Department of Neurological Surgery, Radcliffe Ilfirmary, Oxford

When Elsberg and Dyke (1934), having studieda series of antero-posterior radiographs of normalspines, reported the range of normal variation inthe distance separating the inner borders of thevertebral pedicles, they provided information whichhas required no important modification since thattime. They pointed out that an unusual andlocalized increase in the distance between the pedicleswas to be seen in the presence of intraspinal tumoursthat were both intrathecal and extrathecal. Theywrote (p. 392) that after excluding recent or oldfractures of the spine " the enlargement of thevertebral canal described in this paper was foundexclusively in expanding lesions within the vertebralcanal, and the increase in size always correspondedto the position of the neoplasm ". They observedthat only further experience would show whether" enlargement of the interpedicular space " occurredexcept with an expanding lesion. Elsberg, Dyke,and Brewer (1934) made it clear that an " expandinglesion" was not necessarily a neoplasm, by describ-ing four adolescent patients who had upper thoracicextradural cysts and showed eroded vertebralpedicles. Earl Walker (1944) recorded the findingsin four cases where the neurological signs and astudy of the pedicles indicated intraspinal neoplasm,but in all four patients a congenital anomaly of thecord was present. In only one case was there anyclinical suggestion of spinal cord compression andin two of his cases (p. 581) " there was much moreroom in the subarachnoid space than usual ". Thepresent writer has been unable to trace publishedreports recording dilatation of the vertebral canal,apparently similar to that described by Earl Walker,but unassociated with abnormalities of the spinalcord. This publication reports two such cases and,by contrast, a third case in which a somewhatsimilar vertebral appearance was associated with anextradural cyst, without signs of cord compression.

* Nuffield Foundation Fellow.

Case ReportsCase 1.-A woman, aged 22 (R.l. 180511/53), at the

age of 11 years was said to have outgrown her strengthand developed a slight scoliosis. Remedial exerciseswere performed with satisfactory results. Five yearsbefore admission she began training in a dancing collegeand discovered that after a day of mental and physicalexercise she would find herself very tired. Quite fre-quently she would wake in the morning with a stiff back.Fifteen months before admission, at a time when shewas unusually busy, she began to get an occasional" red hot feeling" on each side of the lower thoracicspine. Because of this complaint she came under medicalobservation and, subsequently, radiographs of her backwere taken. At no time did she have any neurologicalsymptoms, and examination at the time of her admissiondisclosed no neurological abnormalities. The move-ments of the spine were full and painless, straight legraising was unimpaired, and the power, tone, reflexes,and sensation in the legs were entirely normal. Theonly abnormality on clinical examination was that thespine of the eleventh thoracic vertebra was less prominentthan were its neighbours. The radiographs of the spinein the lateral view confirmed that the spine of theeleventh thoracic vertebra (T.11) was rudimentary andalso showed stunting of the spine of the twelfth thoracicvertebra. The lateral view showed that the antero-posterior diameter of the spinal canal was increasedopposite the bodies of T.12 and the first lumbar vertebra(L.1), suggesting an enlargement of the spinal canal asby an expanding lesion. The antero-posterior viewshowed a fusion defect in the lamina of T.11 and anunusually slight shadow for the spine of T.12. Therewas, in addition, widening of the vertebral canal withnarrowing of the pedicles of T.12 and L.1 (Fig. 1).With the exception of T.12 and L.1 the measurementsbetween the pedicles throughout this patient's spineapproached the lower limit of normal as given byElsberg and Dyke (1934). The interpedicular distanceat T.12 and L.1 increased sharply to the upper limits ofnormal. (The measurements of the interpediculardistance were: T.10= 18 mm., T.1 =- 20 mm.,T.12= 25 mm., L.l = 27 mm., L.2= 25 mm., L.3 -

24 mm., L.4= 25 mm.) The figures published byElsberg and Dyke (1934) are reproduced in the Table.

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LOCALIZED ENLARGEMENT OF SPINAL CANAL WITHOUT TUMOUR

TABLE

INTERPEDICULAR DISTANCE'ELSBERG AND DY

Usual Size of Inter-Vertebra pedicular Space (mm.)

C.45

67

T.1

10i112

L.12345

27-3228-3227-3227-3123-2719-2318-2217-2017-2016-2016-2017-2017-2218-2119-2321-2623-2824-2925-3025-3128-33

By " usual size Elsberg and Dyke80 to 950O of the cases ".The "extremes" were the lowest a

in the measurements of 200 normal spin(Their paper showed that the measure

affected when the tube-film distance41 in.)

These findings made a lumtThe initial pressure was 130 mrslightly sluggish rise on jugular co

fall. The fluid contained 40 rr

red blood cells, and four lymphcThe conclusion was drawn fi

the spinal canal was enlarged a

evidence of malformation of tintraspinal dermoid or lipoma n

ever, the fact that there were i

malities and no manometric bliindicated that compression of theLargely at the insistence of thethe abnormal region was explospines of T.11 and T.12 were fothough the supraspinous ligarattachments were well developcremoved and the normal amounencountered in the vertebral can

had a bluish tinge, as though a tbut after the dura was incised itvertebral canal was greatly disterand its roots appeared normal, a

There was no obstruction abovea catheter passed freely both upv

Post-operatively the patient dafter the operation was symptorr

Case 2.-A woman, aged 18years before admission began Iand pain at the lateral aspect olwithout preceding trauma andpain had many of the characterby a prolapsed intervertebral dipossibility in mind that she fil

care. She was admitted to hospital after conservativeS AS PUBLISHED BY treatment had failed to relieve her. At the time of'KE (1934) admission the only abnormalities on examination were

very slight weakness at the left ankle which may haveExtreme Sizes (mm.) been partly occasioned by pain. and a little blunting ofLowest Highest sensation to pin-prick on the outer aspect of the left

25 34 lower leg. The back movements, though initially good,25 33 were later limited, as was straight leg raising on the left.25 33 Further radiographs were taken and these disclosed21 30 a dilatation of the spinal canal, as indicated by scalloping18 22 of the posterior aspect of the vertebral bodies, especially15 20 the first lumbar vertebra, and by an increase in the15 21 interpedicular distance with narrowing of the pedicles14 21 (Fig. 2). The distances between the pedicles from T.715 22 to T.11 were at the extreme upper limit of normal given14 23 by Elsberg and Dyke (1934), and, although the pedicles16 20 of T.12, L.l, and L.2 had a more abnormal form, they20 33 were not separated by such an unusually great distance.22 33 (The measurements were: T.7 = 22 mm., T.8 = 22 mm.,23 35 T.9-23 mm., T.l=024 mm., T.11=25 mm.,24 39 T.12 = 27 mm., L.1 = 29 mm., L.2 = 29 mm.,

meant " the range in from L.3 - 28 mm., L.4- 28 mm., L.5 - 30 mm.) Therewere in addition some minor congenital abnormalitiesLnd highest figures obtained of the vertebrae. Because of the expanded vertebral

ments observed were scarcely canal a spinal cord tumour was suspected and a lumbarvaried between 30 in. and puncture showed an initial pressure of 135 mm. of water

with normal responses to jugular compression. Thebar puncture desirable. protein level was 40 mg./100 ml. and there were no cells.i. of water, there was a A myelogram showed no abnormality at the lumbo-ompression, but a normal dorsal junction and equivocal changes only at the L.4-5ig. protein/l00 ml., no disc interspace. Because the symptoms remained severe

)cytes per c.mm. an exploration of the disc spaces at L.4-5 and L.5-S.1rom these findings that on the left hand side was carried out. No abnormalitiesLnd that in view of the were detected. The opportunity provided by this:he vertebral spines an operation was taken to explore the upper lumbar spine,night be present. How- and the spine and lamina of the second lumbar vertebrano neurological abnor- were removed. The bone of the lamina was undulyock on spinal puncture thick and hard. Microscopical examination of it, how-@ cord had not occurred. ever, disclosed no significant abnormality. The spinalpatient and her family, canal was seen to be enlarged, and after opening thered. At operation the dura it was possible to be absolutely satisfied that the)und to be rudimentary, cord and the spinal nerve roots were normal. Post-nents and the muscle operatively the patient was unexpectedly relieved of hered. The laminae were leg pain and when seen three months later was symptomit of extrathecal fat was free and had a full range of movements in her back.ial. The unopened dura Discussion)ig cyst might be within,t could be seen that the Enlargement of the spinal canal with congenitalided and the spinal cord abnormalities of the cord is not particularly uncom-vs did the leptomeninges. mon. Herren and Edwards (1940), for example,or below this level, for drew attention to dilatation of the spinal canal

vards and downwards. associated with duplication of the spinal cord, andlid well and 18 months the literature on diastemato-myelia contains several*ifree. accounts of dilatation of the spinal canal. Earl(R.I. 198481 54), four Walker (1944) recorded abnormal enlargement of

to have low back pain the spinal canal, apparently similar in type to thatof gradual onset. The noted here, but all his patients had abnormalitiesristics of sciatica caused of the spinal cord with resulting neurologicalisc and it was with this disabilities. The two cases reported here differedrst came under medical from Walker's in another minor respect, for his

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ANTONY JEFFERSON

patients all had abnormally short vertebral spinesand the laminae were wider and thinner than normal.Although in Case 1 the spine of T. 11 was short, itwas not associated with a notably deformed laminaand in Case 2 the lamina appeared thicker thanusual. Walker suggested that the enlargement ofthe spinal canal in his cases had occurred in thedevelopment of the individual. He was able to saythis because the associated abnormality of the cordprovided unequivocal evidence of abnormal develop-ment in that region, and the excessive size of thespinal canal clearly resulted from maldevelopmentand not from pressure erosion. Among the publishedcases of intrathoracic meningocele enlargement ofthe spinal cord and erosion of some of the vertebralpedicles are, in many of the reports, either describedor may be inferred to have occurred; scallopingof the posterior aspects of the vertebral bodies wasa feature of some cases. These changes were wellillustrated by Kessel (1951) who also referred tothe previous literature. In addition Kessel quotedand illustrated a personal communication fromBull (1950) which is of considerable interest. Thereport concerned a 37-year-old woman with neuro-fibromatosis who had gross enlargement of thevertebral canal and, at necropsy (death was due tocerebral tumour), the posterior aspects of thevertebral bodies T.12-L.3 were seen to be hollowedout. The " distended theca" bulged through thelarge intervertebral foramina. Bull's patient mayhave shown a more advanced example of theabnormality described by the present writer. (Seealso the case reported by Mendelsohn and Kayin 1949.)A congenital abnormality of a single vertebral

pedicle sometimes occurs. In the example recordedby Steinbach, Boldrey, and Sooy (1952) one cervicalpedicle appeared to be eroded, but there were noabnormal neurological findings and a surgicalexploration revealed no tumour. These authorssuggested that future cases might be correctlydiagnosed because of the compensatory structuralchanges in the bone.

Case 1 reported here came under observationbecause of mild back pain and Case 2 had nosymptoms referable to the upper lumbar spine. Inneither case were there any significant neurologicalabnormalities, the slight changes in Case 2 beingpresumably referable to another pathological pro-cess. The experience of these two cases shows thatwhen the relevant symptoms are mild, and whenthere are no neurological abnormalities and thelumbar puncture findings are normal, then dilatationof the spinal canal, especially when associated withcongenital abnormalities of the affected vertebrae,

may be regarded as a benign condition and of noserious significance. However, when pain is aprominent symptom, enlargement of the upperlumbar spinal canal associated with normal neuro-logical findings and a normal cerebrospinal fluidmay have an alternative origin. The following casewhich I saw at operation illustrates this. (Thepatient had been referred to Professor Sir GeoffreyJefferson by Mr. D. Li. Griffiths and I am indebtedto them for permission to record these findings.)

Case 3.-A woman, aged 63, four months beforeoperation had influenza and felt extremely and unusuallyill. She shortly developed a very unpleasant upperlumbar backache which " gripped " her and from whichpain, at times, spread either into the hips or down thebacks of both legs to the knees. The pain continuedand became unbearable, in spite of very large doses ofaspirin, and admission to hospital was arranged. Onexamination spasm of the erector spinae muscles wassevere and, although she could stand out of bed, forwardflexion was impossible. Neurological examination wasentirely normal. A lumbar puncture was normal witha protein level of 35 mg./100 ml. and one white cellper c.mm.The radiographs showed considerable erosion of the

pedicles of T.12, L.1, and L.2 with enlargement of theintervertebral foramina. There was no scalloping ofthe posterior aspects of the bodies of the affectedvertebrae, but the antero-posterior measurement of thespinal canal was greatly increased because the laminaewere thinned and were lying exceptionally far poste-riorly (Fig. 3). At operation the affected laminae wereless deeply situated than is normal and the spinousprocesses were unusually short. The bone of the laminaeof L.1 and of L.2 was in parts little thicker than anegg-shell. On removing the bone a cyst cavity whichextended from T.12 to L.3 (inclusive) was disclosed.Fluid from the cyst contained protein, 30 mg./100 ml.,sug4r, 55 mg./100 ml., and chlorides, 700 mg./100 ml.The cyst cavity was roughly cigar shaped and lay dorsalto the spinal canal; its floor was intimately fused withan altered and semi-transparent dura mater and no extra-dural fat was seen. The dorsal wall of the cavity wasexcised, and microscopical section showed it to consistof collagen with an incomplete layer of endothelial cells.No communication with the subarachnoid space couldbe demonstrated. The dura surrounding the spinalcord was not opened.

This lesion presumably should be classified as anextradural cyst, though it differed in several importantrespects from those described by Elsberg and others(1934).

SummaryTwo cases are described of dilatation of the spinal

canal at the thoraco-lumbar junction with an x-raypicture simulating an expanding lesion. In bothof them full investigations, including operation,disclosed a normal cord lying in an enlarged sub-

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FIG. 3.-Case 3: Radiographs of the thoraco-lumbar junction.

a. Antero-posterior view showing widening of the canal and b. Lateral view, in which the canal is seen greatly widened witherosion of the pedicles. Arrows indicate the well defined pedicles thinned and intervertebral canals consequentlylower margin of extreme expansion of the lamina of L.2 enlarged. The arrow indicates the lower margin of extreme(cf. lateral view). expansion of lamina of L.2.

arachnoid space. The significance of these findingsis briefly discussed and the findings are contrastedwith those in an unusual case of extradural cyst.

I am grateful to Mr. Joe Pennybacker for advice inthe preparation of this paper and for permission torecord Cases 1 and 2. Case 2 was referred by Mr.J. C. Agerholm.

F

REFERENCESBull, J. (1950). Quoted by Kessel, loc. cit.Elsberg, C. A., and Dyke, C. G. (1934). Bull. neurol. Inst. N. Y.,

3, 359., and Brewer, E. D. (1934). Ibid., 3, 395.

Herren, R. Y., and Edwards, J. E. (1940). Arch. Path., Chicago,30, 1203.

Kessel, A. W. L. (1951). J. Bone Jt Surg., 33B, 87.Mendelsohn, H. J., and Kay, E. B. (1949). J. thorac. Surg., 18, 124.Steinbach, H. L., Boldrey, E. B., and Sooy, F. A. (1952). Radiology,

59, 838.Walker, A. E. (1944). Amer. J. Roentgenol., 52, 571.

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