Clin. RadioL (•967) 18, 166-172

C H R O N I C N O N - S P E C I F I C S P I N A L E P I D U R A L G R A N U L O M A

F R A N K L I N R O B I N S O N and R O B E R T S H A P I R O

From the Departments of Neurosurgery and Radiology, the Hospital of St. Raphael and Yale University School of Medicine, New Haven, Connecticut, U.S,A.

The enti ty o f chronic non-specific spinal ep idura l g ranu loma is presented. A brief review of the l i terature is appended together with persona l experience with a series o f four cases. The var ious radiological techniques and findings helpful in establishing a correct pre- operat ive diagnosis are discussed.

THE occurrence o f chronic in f l ammatory g ranu loma within the ex t radura l space in a series o f pat ients present ing in t ractable back pa in p r o m p t e d review o f this p rob lem with par t icu lar reference to its radiologica l aspects. A l t h o u g h there are a number o f excellent cont r ibut ions to the subject o f pyogenic infections o f the spinal cana l (Gasul and Jaffe, 1935; Campbel l , 1937; Browder and Meyers , 1941; Gran t , 1945), they deal pr inc ipa l ly wi th acute abscess fo rmat ion in the ex t radura l space. I so la ted descr ipt ions o f chronic spinal ex t radura l inf lamma- to ry masses, excluding those o f luetic or tuberculous et iology, were made as ear ly as 1903 by Schultze and by Mendel (1909). However , the clinical ent i ty was no t f irmly es tabl ished unt i l the classic p a p e r b y D a n d y (1926). In this cont r ibut ion , D a n d y presented 25 cases of ex t radura l abscess collected f rom the l i terature and a d d e d 3 personal cases o f in f l ammatory t u m o r (one tuberculous) . The reports o f Ryerson (1922), Elsberg (1927), Wat t s and Mixter (1931), Turnbul l , H y l a n d and McKenz ie (1933), Cohen (1938), G r a n t (1941 and 1945) and War ren and R o m a n o (1942) have a d d e d to our knowledge o f this pa tho log ica l entity.

There is little in the l i terature concerning the rad iograph ic techniques and findings per t inent to the diagnosis o f chronic ex t radura l g ranu loma o f the spine. The only comprehensive pape r in the recent radiological l i terature deal ing with this subject is that o f Campbel l and Silver (1954). In view of the difficulty in establishing a correct preopera t ive diagnosis, the clinical and roentgeno- graphic findings associated with this ent i ty mer i t considerat ion.

CASE REPORTS Case 1.--M.K., a 63 year-old white lady was hospitalized

on August 8, 1960 with intractable lower back pain of 21 months duration radiating into both lower extremities. Her symptoms began shortly after a fall from a chair in which she struck both buttocks on the floor. Back pain gradually increased and was aggravated by bending, coughing, sneez-

ing and standing. On examination on July 19, 1960, she was in moderate discomfort and limped, favoring the right leg. There was no postural deformity although bending move- ments were restricted. There was no muscular weakness or atrophy of the lower extremities. The knee and ankle jerks were diminished bilaterally. Straight-leg raising tests were negative and Lasegue's sign was absent. The plantar res- ponses were flexor. Sensation was intact. The clinical im- pression was lower lumbar intervertebral disc herniation secondary to trauma. Radiographs of the lumbosacral spine revealed minimal hypertrophic osteoarthritic changes. Lum- bar myelography was performed as an out-patient. The initial pmlcture at the L3-L4 interspace yielded no fluid and 2 hal. of Pantopaque were introduced at the L2-L3 level. Complete spinal block at the L3-L4 interspace with tapering of the myelographic column was demonstrated (Figs. 1, 2). An extradural hematoma resulting from the lumbar puncture and causing the obstruction was considered likely. On hospitalization 2 weeks later, x-rays of the lumbar spine showed residual Pantopaque in the caudal sac of the suba- rachnoid space. Utilizing this Pantopaque, a complete block to cephalad flow was demonstrated at the L4-L5 level. The diagnosis of a posterior extradural space-occupying lesion extending from the 3rd to the 4th lumbar interspace was made. Bilateral laminectomy of L3 and L4 was performed and a firm well encapsulated, gray-yellow mass was removed from the posterior extradural space, measuring 5 cm. in length and 1 to 1-5 cm. in diameter. Frozen section was reported as "inflammatory tissue" and permanent sections revealed a dense fibrous stroma infiltrated by large numbers of lymphocytes, lesser numbers of polymorphonuclear leucocytes and scattered eosinophils and plasma cells. Post- operatively /here was gradual, progressive symptomatic relief of back and lower extremity pain. The patient has been followed at intervals for 5 years, during which there have been complaints of intermittent dull lumbar aching but no recurrence of the root symptoms which characterized her preoperative state.

Case 2.--P.V., a 55 year-old white gorcer was hospitalized on December 29, i963, with a 3 month history of increasingly severe lower back pain; 2 years previously he had pushed a crate and had a transient attack of lower back pain. Thereafter, he experienced back pain when lifting or bending. Later, pain radiated into the buttocks and perineum and was inten- sified by coughing, sneezing, and straining at stool. There were no symptoms suggestive of sphincter disturbance. Examination revealed flattening of the lumbar lordotic curve and tenderness on percussion of the lumbosacral region. Flexion of the spine was restricted beyond 30 degrees with

166

CHRONIC NON-SPECIFIC SPINAL EPIDURAL GRANULOMA 167

FIG. 1A

FIG. 2 (Case 1). Spot film (head tilted down) taken two weeks later. The Pantopaque left in the subarach-

• noid space has migrated caudally and now demon- strates a complete block to cephalad flow at the

L4-L5 level.

pain referred to both buttocks. Extension of the spine was also grossly limited. There was good power in both lower extremities. Straight leg raising tests were positive at 60 degrees. Bilateral jugular compression precipitated lumbo. sacral pain. The knee and ankle jerks were grossly dimin- ished. The plantar responses were flexor. There was no demonstrable sensory impairment in either lower extremity and the gait was normal.

Conventional radiography (and tomography) of the lumbosacral spine revealed mild scoliosis and moderate hypertrophic osteoarthritis. The patient failed to improve on a course of bed rest, traction, and physiotherapy. Panto- paqne myelography performed on the 10th hospital day demonstrated a large extradural defect at the L4-L5 level, thought to be due to intervertebral disc herniation (Figs. 3, 4). Bilateral laminectomy of L4-L5 was performed and a pink- gray, firm granular mass was encountered overlying the posterior and lateral aspects of the dura. The extradural mass was exceedingly vascular and bled readily on manipu- lation. The gross appearance of the lesion was st.lggestive of metastatic tumor or granuloma and was removed piece- meal. Frozen section was report¢d as "granulation tissue with no evidence of malignancy . There was no intervertc- bral disc herniation or bony involvement. The dura was considerably thickened and on intradural inspection the cauda equina was noted to be involved in a process of dense scar- ring. The postoperative course was uneventful and progres- sive remission of both back and lower extremity pain fol- lowed. The pathological report was "granulation tissue with areas of focal necrosis". The patient was discharged from the hospital on the 21st postoperative day, fully ambulant and without complaints. He has remained asymptomatic for 20 months.

Case 3,--E.L., a 66 year-old white male entered the hospital on October 7, 1962 with severe low back pain of 2 months duration radiating to both lower extremities. The pain appeared following a fall at home in which he struck his back upon the floor. He was admitted to another hospital

168 CLINICAL RADIOLOGY

Fm. 3 FIG. 4A FIC. 4B FIG. 3. Case 2. Lateral radiograph of lumbar spine demonstrating mild osteoarthritic changes. FiG. 4. Case 2. A and B. AP and lateral decubitus myolographic films showing a prominent defect beginning at the L4-L5 interspace and extending over the body of L5. In addition to the extradural granuloma, there was extensive arachnoiditis. No,disc herniation was found at surgery.

one week after this accident because of severe back pain. Although improvement occurred after bed rest, pain returned when activity was resumed. There were no symptoms sug- gestive of sphincter disturbance and no parasthesia of the lower extremities.. Examination revealed marked spasm of the iliolumbar musculature and moderate weakness of the extensors of the ankles and toes bilaterally. Straight leg raising tests were positive bilaterally at 45 degrees and were accompanied by Lasegue's sign. The knee jerks were diminished and the ankle jerks were absent. The plantar responses were flexor. There was hypaesthesia and hyp- algesia across the dorsomedial and dorsolateral aspects of both feet, and position sense was diminished in the toes bilaterally. The clinical impression was lower lumbar inter- vertebral disc herniation with accompanying nerve root impingement. There was a leucocytosis of 12,200. X-rays of the lumbar spine showed some narrowing of the L2-L3 vertebral interspace with localized erosion of the anterior superior margin of L3 and slight diffuse osteoporosis of the dorsolumbar spine with anterior spurring (Fig. 5). A skeletal survey showed no metastases. Lumbar myelography revealed marked narrowing of the Pantopaque column at the L2-L3 level, extending to the intervertebral space below. These findings were thought to be secondary to a herniated inter- vertebral disc although an extradural tumor could not be excluded (Fig. 6). The cerebrospinal fluid was clear and colorless and the CSF protein was 25 mg. per cent. Left hemilaminectomy was performed at L2-L3, the lamina of L3 being considerably thickened, resembling pagetoid bone.

Samples of the lamina, subjected to decalcification and microscopic study, were subsequently reported as normal. Pink-gray, gelatinous tissue was encountered immediately anterior and superior to the third lumbar nerve root, and was found to extend medially in the extradural space anterior to the dural sac. Frozen sections on several representative fragments showed no evidence of malignancy. The extradural mass, approximately 5 mm. in thickness, extended inferiorly to the L2-L3 vertebral interspace where it was contiguous with a fragment of herniated intervertebral disc. A midline tear in the posterior longitudinal ligament was seen and the herniated intervertebral disc material was excised. Culture of the extradural tissue yielded staphylococcus albus, which was considered to be a contaminant. Nevertheless the patient was given a prophylactic course of penicillin and streptomy- cin. His convalescence was characterized by gradual sub- sidence of back pain and relief of sciatica. The pathological sections of the extradural tissue showed chronic inflamma- tion. The patient was discharged on the twenty-second post- operative day at which time he was fully anabulant and had but minimal residual lumbar discomfort. He was seen at intervals over a period of 2½ years, during which he remained free of symptoms.

Case 4.--G.M., a 61 year-old white married male experi- enced sudden, sharp pain in the right scapular region on Marcia 15, 1959 without apparent cause. Thoracic pain became un- relenting and spread to the left scapular region and anterior chest, being aggravated by movement and relieved by sitting or recumbency. -He was admitted to another hospital 12

CHRONIC N O N - S P E C I F I C SPINAL EPIDURAL GRANULOMA 169

Fro. 5 (Case 2) Lateral view of lumbar spine demonstrating some osteoporosis and an- terior spurring. Note the narrowing at the L2-L3 in- terspace witb erosion of the

anterior lip of L3.

days later where laboratory studies and a full x-ray examina- tion were negative. During the preceding year, he had deve- loped cough, decreased 1½ ins. in height, and lost 24 ]bs. The patient was hospitalized again on May 4, 1959 when slight ptosis and miosis of the left eye were noted. Extreme tender- ness was elicited over the region of the 3rd thoracic spinous process. Downward pressure upon the top of the head pro- duced pain referred to the region of the left 6th thoracic dermatome. There were no signs of spinal cord disturbance. The presence of a tumor involving the upper and and dorsal spine was suspected. Blood count, urinanalysis, serology, acid and alkaline phosphatase determinations were normal. Extensive x-ray studies showed a mass in the posterior medi- asfinum with some erosion of the bodies of the 4th and 5th thoracic vertebrae. Bronchoscopic examination, bone marrow, and scalene node biopsy were negative. Deep x-ray therapy to the upper thoracic region produced some reduction of pain and the patient was discharged from the hospital on May 15, 1959, slightly improved. He was re-admitted on June 7, 1959, because of intractable interscapular pain which had persisted during the course of radiation therapy. X-rays of the thoracic spine showed further destruction of the 4th and 5th thoracic vertebrae with angulation, wedging and obliteration of the intervertebral disc space (Fig. 7) . There

was slight gibbus deformity and tenderness over the region of T4-T5. The abdominal reflexes were absent. The knee and ankle jerks were sluggish and the left plantar response was extensor. No sensory disturbance was noted. Bilateral jugular compression failed to produce thoracic pain. The clinical impression was that of an osteolytic lesion of un- known etiology involving the 4th and 5th thoracic vertebrae. An inflammatory process was considered more likely than neoplasm in view of involvement of the intervertebral disc. Blood count, urinalysis, serology and agglutination studies were again negative. Lumbar myelography demonstrated complete obstruction at the level of T5 due to an extradural mass lesion (Fig. 8). Bilateral lamineetomy of T4 and T5 was performed and a firm gray-white, mass approximately I cm. in thickness, within the extradural space was encountered posteriorly. Frozen section showed inflammatory tissue with no evidence of malignancy. The extradural grauuloma could be completely stripped from the posterior aspect of the dural sac, as well as laterally fro m each side where it had insinuated itself about the adjacent nerve roots. Culture of the extra- dural tissue was sterile. The postoperative course was un- eventful except for persistent cough productive of muco- purulent sputum from which pneurnococcns was cultured. Sputum cultures were negative for tubercle bacilli. The patient was treated with ebloromycetin with satisfactory control of the puhnonary condition. The pathological report of the extradural tissue was 'non-specific granuloma- tous process with marked chronic inflammatory reaction, necrosis and fibrosis in which plasma cells and fat-laden histiocytes predominated'. The patient was transferred to another institution on June 23, 1959 for a course of chemo- therapy for possible tuberculosis of the spine although this diagnosis was not definitely established. Subsequent tomo- grams of the spine failed to reveal any progression of the destructive bone lesion. In February 1960, roentgenographic evidence of new bone formation was noted. Sputum exami- nations were repeatedly negative for tumour cells and cultures were negative for acid-fast bacilli. The patient gained 20 Ibs. during the succeeding 9 months and resumed full activities wearing a supporting brace. He has remained well to the present.

D I S C U S S I O N

T h e s y n d r o m e o f ch ron i c non-speci f ic sp inal ex t r adu ra t g r a n u l o m a is essent ia l ly tha t o f b a c k a n d nerve r o o t p a i n f o l l o w e d by s y m p t o m s o f sp inal c o r d o r c a a d a e q u i n a compress ion . T h e cl inical man i f e s t a t i ons o f an acute e x t r a d u r a l in fec t ion differ s t r ik ingly f r o m those o f a ch ron i c i n f l a m m a t o r y mass. T h e f o r m e r cond i t i on is f r equen t ly assoc ia ted w i t h a h i s to ry o f a n t e c e d e n t in fec t ion (i.e. fu rune le , tonsi l l i t is o r os teomyel i f i s ) 2 to 3 weeks p r io r to the a b r u p t onse t o f severe, re lent less b a c k p a i n w i t h o r w i t h o u t r o o t s y m p t o m s . S o o n this m a y be f o l l o w e d by the a p p e a r a n c e a n d r a p i d p rog re s s ion o f m o t o r , sensory , and sph inc te r d i s tu rbance , o f ten c u l m i n a t i n g in signs o f a t r ans - verse spinal lesion. T h e cl inical p ic tu re is essent ia l ly one o f acu te f u l m i n a t i n g sepsis. By cont ras t , a h i s to ry o f in fec t ion is c o m m o n l y l ack ing in t he pa t i en t h a r b o r i n g a c h r o n i c e x t r a d u r a l g r a n u l o m a . T h e pa in is usua l ly ins id ious in onse t a n d m a y be

170 C L I N I C A L R A D I O L O G Y

FIG. 6A FIG. 6B

F~G. 6. Case 3. A and B. AP and lateral decubitus films during myelography, In addition to the bulging of the discs at multiple levels, there is a prominent defect beginning at the level of L2-L3 which extends over the upper half of the body of L3. At surgery, in addition to an

extradural granuloma, there was also a large herniated intervertebral disc fragment.

FIG. 7 FIG. 8

FIG. 7. Case 4. Lateral tomogram of the upper thoracic spine (June 7, 1959) showing wedging and some erosion of the anterior inferior margin of T4. There is also involvement of the T4-T5 intervertebral disc space with bony debris anteriorly. FiG. 8. Case 4. Myelogram (taken with head down) demonstrating an

extradural obstruction at T4-T5.

C H R O N I C N O N - S P E C I F I C S P I N A L E P I D U R A L G R A N U L O M A 171

attributed to an episode of trauma (Cases 1, 2 and 3). The pain may vary from dull and aching in quality to severe, lancinating and intolerable. Localized tenderness over the spine may or may not be present. The onset of pain may precede the neurological findings by a variable but signific- antly prolonged interval and be disproportionately severe (Case 4) compared with the paucity of motor or sensory changes. The sensory disturbances may consist of hypalgesia and hypaesthesia of a dermatomal pattern or sensory level. Depending upon the level of spinal involvement (i.e. spinal cord or cauda equina), signs of corticospinal tract or nerve root involvement may present. It may not be possible, on clinical grounds alone, to differentiate chronic extradural granuloma from neoplasm o r intervertebral disc herniation. Examination of the spinal fluid may be of little differential diagnostic value since any o f the aforementioned lesions may produce a spinal block with accompanying CSF protein elevation.

The granuloma can originate either as a direct extension from a contiguous vertebral infection or as a haematogenous metastasis from a remote focus. Although early reports in the literature mention the possibility of a primary extradural space infection, this seems unlikely. The failure to detect a primary source of infection elsewhere in the body does not exclude the presence of an underlying occult focal vertebral osteomyelitis (Browder and Meyers, 1937). The extensive venous anastomoses within the extradural space demon- strated by Batson (1940) may explain the route of infection in some instances. Ordinarily, no specific organism can be cultured either from the blood stream or from the extradural space and tissues. Occasionally, staphylococcus, brucella, pneumo- coccus or other organisms have been recovered. Case 3 represents art interesting association of herniated lumbar intervertebral disc and spinal extradural granuloma which may be no more than coincidence.

Dandy's dissections in cadavers provide an anatomical explanation for preferential localization of extradural infections in the posterior thoracic and lumbar regions. As Dandy has pointed out, the spinal extradural space, containing loose areolar tissue and veins, is present as an actual compart- ment only posterior to the plane of emergence of the spinal nerves from the spinal canal. Anteriorly, the extradural compartment throughout the spinal axis is only a potential space, the dura lying in close apposition to the posterior longitudinal ligament and the vertebral body. In the cervical region, the spinal extradural space begins

posteriorly at the level of C7 and gradually increases in depth to 0.5-0.75 cm. in the mid thoracic region (T4-TS). Below this level, it tapers somewhat to the level of Tll-L2 and ultimately attains its greatest depth at L3-$2.

It may be difficult to differentiate granuloma from benign or malignant neoplasm at operation and frozen section may be extremely helpful. Micro- scopically, the lesion is one of a non-specific chronic

inflammatory process in which a dense fibrous stroma is infiltrated by lymphocytes, plasma cells and poly-morphonuclear leucocytes. Focal micro- abscesses may be enclosed within the hyperplastic granulation tissue. In general, the older the process, the less the polymorphonuclear infiltrate and the greater the deposition of collagen.

Since the diagnosis of chronic extradural granuloma may be difficult or impossible to establish on clinical grounds, the radiologic findings assume particular importance. The preliminary study should consist of conventional radiography of the spine supplemented by tomo- graphy. These films may be either entirely negative or demonstrate one or more of the following changes:

1. Narrowing of the intervertebral disc space. 2. Changes in the vertebral body or bodies

contiguous to the intervertebral disc space. Early, this may consist of loss of sharpness of outline of the bone immediately adjacent to the articular plate. As the lesion progresses, there may be actual bone destruction and eventual wedging and collapse of the involved vertebra. Occasionally, similar changes may involve the bony neural arch or the vertebral end of the rib.

3. Localized paravertebral soft tissue mass. The plain roentgenograms should be followed by

myelography. It is wise to do a cisternal puncture or to avoid making the tumbar puncture at a level of demonstrable bone involvement. Myelography usually reveals a prominent extradural defect with varying degrees of obstruction to the flow of contrast medium. The lateral film with a horizontal beam is helpful in demonstrating the anterior or posterior localization of the lesion. Early in the course of the disease, there may be impingement on only one side of the opaque column of contrast medium extending over one or more vertebral segments. This may progress to a more prominent defect with partial obstruction. Large granulomas may compress the thecal sac and produce complete obstruction with tapering of the head of the column of contrast medium. Hassin (1928) has shown that the extradural inflammatory process may extend

172 CLINICAL RADIOLOGY

into the subarachnoid space. This is well i l lustrated by the findings in Case 2 in which there was an intense araehnoiditis in addi t ion to the epidural granuloma. Both of these abnormali t ies contr ibuted to the part ial block demonstrated at myelography. I t is evident that the myelographic findings p er se are no t sufficiently specific to be diagnostic, and in the absence of vertebral art icular erosion the changes may be indist inguishable f rom those found in massive disc prot rus ion and epidural mal ignant disease. In addit ion, condit ions such as hyper t rophy of the l igamenta flava commonly seen in association with degenerative disc disease, thickening of the bony laminae, and arachnoidit is may produce similar myelographic deformity al though they may not produce complete myelo- graphic block.

Therapy consists of laminectomy and surgical removal of the granuloma preferably without opening the dura. Fol lowing complete removal of the lesion, the prognosis should be good.

REFERENCES BATSON, O. V. (1940). Ann. Surg., 112, 138. BROWDER, J. & MEYERS, R. (1937). Amer. J. Surg., 37, 4. BROWDER, J. & MEYERS, R. (1941). Surgery, 10, 296. CAMPBELL, J. A. & SILVER, R. A. (1954). Amer. J. Roentgenol.,

72, 229. CAMPBELL, M. M. (1937). Bull neuroL Inst. N.Y. (1938)., 6,

574. COHEN, I. (1938). Ann. Surg., 108, 992. DANDY, W. E. (1926). Arch. Surg., 13, 477. ELSBERG, C. A. (1927). In Nelson's Loose-Leaf Living

Surgery, Vol. 2, p. 460. New York: Thomas Nelson & Sons.

GASUL, B. M. & JAFEE, R. H. (1935). Arch. Pediat., 52, 361. GRANT, F. C. (1941). Trans. Amer. neurol. Ass., 67, 99. GRANT, F. C. (1945). J. Amer. reed. Ass., 128, 509. HASSlN, G. B. (1928). Arch. Neurol. Psychiat. (Chic.), 20, 110. MENDEL, K. A. (1909). Berl. klin. Wschr., 46, 2239. RYERSON, E. W. (1922). Arch. Neurol. Psychiat., 7, 270. SCHVLTZE, F. (1903). Mitt. a.d. Grenzgeb. d. Med. u. Chit.,

12, 153. TURNBULL, F. A., HYLAND, H. H., & MCKENzIE, K. G.

(1933). J. Canad. reed. Ass., 28, 415. WARREN, J. V. & ROMANO, J. (1942). Arch. NeuroL Psychiat.

(Chic.), 48, 789. WATaS, J. W. & MIX'tE~, W. J. (1931). New Engl. J. Med.,

204, 1335.

B O O K R E V I E W

Aspects of Venous Function in the Lower Limbs. By JOHN LUDBROOK, 137 pages. (Charles C. Thomas, Springfidd, Illinois, U.S.A. 1966.)

This short text-book is intended to provide the practising vascular surgeon with a physiological basis for the diagnosis and treatment of venous pathology in the lower limbs. Professor John Ludbrook is a notable authority on his subject and has contributed much original work to this field; he has also based his opinions on the most important papers contributed by other workers.

In the first chapter the author defines precisely the terms he uses throughout the text--a useful beginning as in- accuracy in terminology can be a major source of confusion.

In subsequent chapters he discusses the gross and functional anatomy of the venous system and deals in some detail with the complex subjects of venous pressure, resistance and blood-flow. The important topic of the effect of exercise on the venous system is discussed separately in Chapter 5; the author's method of measuring intra-muscular pressures during muscular contraction by the use of fine catheters seems to produce more accurate measurements than can be obtained by the use of needles. The concept of the calf

muscle pump as a booster to local venous return rather than as a "peripheral heart" is stressed in Chapter 6. The author also mentions the possible importance of the thigh muscle pump which has so far been little investigated.

A large section of the book (Chapter 7) is devoted to disorders of venous functions which the author divides into two main categories, venous dilatation and venous obstruction, or as he prefers to call the latter obstruction to venous blood-flow. The discussion on venous obstruction is of particular interest to the diagnostic radiologist and Professor Ludbrook rightly emphasises (page 112) that the radiological demonstration of narrowing of a eon~non iliac vein can not in itself be assumed to explain swelling of the lower limb on a basis of venous obstruction; additional evidence is required, namely raised venous pressure in the limb, either at rest or on exercise. For this reason these reviewers always measure the femoral venous pressure at the time of iliac phlebography.

Although this is a surgical text-book, it is strongly recommended to all radiologists interested in phlebography of the lower limbs.

M. LEA THOMAS F, B. COCr~ETT