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Spinal Arachnoiditis Mimicking a Spinal Cord Tumor : A Case Report and Review of the Literature M . Vloeberghs, M .D., P. Herregodts, M .D., T . Stadnik, M.D ., A . Goossens, M .D ., and J . D'Haens Department of Neurosurgery, Radiology, and Pathology, Free University of Brussels, Brussels, Belgium

Vloeberghs M, Herregodts P, Stadnik T, Goossens A, D'Haens J . Spinal arachnoiditis mimicking a spinal cord tumor : a case report and review of the literature . Surg Neurol 1992 ;37 :211-5 .

We report on an unusual case of idiopathic arachnoiditis mimicking a spinal cord tumor in a 50-year-old man with progressive paraparesis. The medical imaging work-up showed an enlarged terminal cone with adjacent cysts . Although there was no enhancement of the terminal cone or the surrounding structures, the diagnosis of spinal cord tumor was maintained and surgery was carried out . Exploration of the cauda equina and the tissue surrounding the terminal cone did not reveal a tumor . The patient improved dramatically after surgery but the symptoms recurred 1 year later . We review arachnoiditis, its pathology, and its treatment with special attention drawn to the primary form of spinal arachnoiditis . KEY WORDS :

Arachnoiditis ; Spinal cord tumor

Most cases of spinal arachnoiditis are secondary to an underlying spinal disease, tumor or infection, lumbar puncture, previous surgery, or trauma . In a minority of cases the origin of the disease remains unknown . Because the spinal cord is afflicted, the medullary signs are prominent, making differential diagnosis from spinal cord tumor difficult . Even though medical imaging techniques have greatly improved, the definite diagnosis of spinal cord tumor may be difficult in some cases .

Case Report A 57-year-old man complaining of loss of strength and hypoesthesia in both legs was referred to our center . The symptoms had been evolving progressively over a 2-year period . Upon admission the results of the general physical and general neurological examinations were

Address reprint requests to : Dr . M. Vloeberghs, Department of Neurosurgery, A .Z .-V .U .B ., Laarbeeklaan 101, 1090 Brussels, Belgium . Received July 2, 1991 ; accepted September 13, 1991 .

© 1992 by Elsevier Science Publishing Co ., Inc .

normal . The patient had a paretic gait, Romberg's test showed instability that was not lateralized, and there was sagging of the left leg . The strength in the lower limbs was diminished to 3/5 bilaterally . Somatognosia was more disturbed in the left foot than in the right . There was symmetrical hyperreflexia of the knee and ankle jerk . Plantar reflexes were extensor on both sides ; clonus was absent . The medical imaging work-up consisted of standard x-ray film, myelogram, computed tomography (CT) scan after contrast injection, and plain and contrast-enhanced magnetic resonance imaging (MRI) (Figures 1-6) . Feeble passage of contrast medium is seen at the D12 level on both the head-down myelogram and the CT scan after lumbar contrast injection (Figures 1-3) . There was no enhancement of the terminal cone, the spinal cord, or the surrounding structures on the intravenous gadoliniumenhanced MRI (Figure 6) . The imaging work-up could not exclude a spinal cord tumor, and no other spinal lesion explaining the symptoms was seen (Figure 7), so in view of the progressive nature of the symptoms the diagnosis of low-grade ependymoma was maintained and the patient was treated surgically . The operation consisted of a laminectomy from D9 to L3 . The dural sac was opened and dense fibrous tissue was found within that encased the cauda equina, the terminal cone, and partly the spinal cord . The tissue around the terminal cone and part of the spinal cord was split at the midline . The spinal cord was not split because it appeared normal-more atrophic than swollen . Multiple biopsies of the fibrous tissue surrounding the spinal cord were taken (Figure 8) . The cysts were not dissected . Any attempt to dissect these would have damaged the terminal cone . The tissue was fairly avascular, and there were no signs of infection, neoplasm, or recent or old hemorrhage . The postoperative course was uneventful and the patient's neurological status improved immediately after surgery . After a period of 1 year, with a slight disturbance of somatognosia as the only remaining neurologi0090-3019/92/ $5 .00



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Figures 1 and 2 . Profile of the head-down myelogram. The lumbar root canalfills abnormally, several roots are clumped, and there is little contrast medium passing the D12 level.

Figure 3 . CT scan after lumbar contrast injection . The root canal appears filled with dense tissue . There is very little contrast at the D12 level.

cal sign, the symptoms recurred . Two years after surgery the patient has returned to a status comparable to his preoperative neurological condition . The MRI at this point remains unchanged : The arachnoiditis has not worsened and there is no enhancement of any structure on the MRI after intravenous contrast injection .

Discussion Arachnoiditis is a secondary condition in 94% of the cases [1,3,4,6-9,14} . Lumbar disk herniation and prior spinal surgery are the most common causes of arachnoiditis, along with infection, trauma, traumatic lumbar puncture, and myelography with nonhydrosoluble contrast media [1,4,7,8,11,14} . In 6% of the cases no etiology is determined [11, 14} . The clinical signs and symptoms are mostly limited to monoradicular or polyradicular pain syndromes that may be accompanied by power loss and sensitivity disorders [3,4,7,11,14] . The occurrence of pyramidal signs suggesting spinal cord involvement are rare and so is the evolution to paraparesis or paraplegia [3,4,7,11,14} . The symptoms of com-



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trathecal cortisone radiotherapy and surgery have uncertain results, and conservative treatment is nearly always advised [1,3,4,7,11] . Two other similar cases of primary arachnoiditis involving the spinal cord have been described [2] . These patients were operated on with satisfactory results, although long-term follow-up is lacking . One patient was followed for 9 months, the other for 18 months [2] . Although MRI has greatly improved the accuracy of diagnosis, there remain cases in which the presence of a tumor cannot be proven or disproven . In our case the diagnosis of spinal cord tumor was maintained because of the rapid progression of the clinical signs and because the imaging was compatible with a low-grade spinal cord tumor, that is, a swollen terminal cone with adjacent cysts suggesting a low-grade ependymoma . We emphasize that care must be taken in evaluating neuroradiological images and point out that spinal arachnoiditis may closely resemble a spinal cord tumor .

Figure 5 . T2-weighted image in the same region as in Figure 4 . Notice the swollen appearance of the terminal cone . On this image two cysts are seen : The first proximal and the second distal to the terminal cone. The cysts are not within the spinal cord, (1, 5 Te la ; TR = 2 . 2 ; Te = 90 .)

Figure 4 . TI -weighted image of the lumbodorsal region . The terminal cone appears enlarged; a cystic adherence is seen at the top of the terminal cone . (1,5Tesla;TR=0 .93 .TE= 15 .)

mon arachnoiditis usually evolve over several years, although rapidly evolving cases have been described [4,7] . Three radiologically different types of arachnoiditis have been described [12] . In the first two types there is either central (type I) or peripheral (type II) clumping of the roots . Our case is a radiological type III arachnoiditis, which entails filling of the subarachnoid space by dense fibrous tissue that may compress the spinal cord . In these cases the spinal cord may appear enlarged on myelogram and MRI [12] . It is in these cases that differential diagnosis from spinal cord tumor is difficult [12,16,17] . Neither a CT scan nor an MRI with intravenous contrast media enhances the arachnoiditis tissue because it is fairly avascular . Some low-grade ependymomas may not be clearly enhanced either [5,10,12,13,16,17] . In our case there was no prior spinal disease nor did the biopsies show any signs of underlying pathology . Several treatments of arachnoiditis have been suggested . In-



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Figure 6 . MRI after intravenous injection of gadolinium . There is no enhancement of the terminal cone nor of the surrounding structures . A definite diagnosis of arachnoiditis cannot be made . (1, 5 Tesla; TR = 0, 96 : TE = 15 .)

Figure 7 . Full spine MRI . There is no other spinal cord pathology . The thickened terminal cone is clearly seen . (T2-weighted; 1, 5 Tesla : TR = 2, 3 : TE = 90 .)

Figure 8 . The arachnoid membrane is thick, fibrotic, and acellular and contains calcifications and ossifications. There are no signs of inflammation, hemorrhage . or neoplasm (hematoxylin and eosin x 120) .



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References 1 . Benner B, Ehni G . Spinal arachnoiditis . The postoperative variety in particular. Spine 1978 ;3 :40-44 . 2 . Bose B, Myers D, Osterholm J . Arachnoiditis presenting as a cervical cord neoplasm : two case reports . Neurosurgery 1983 ;12 :120-2 . 3 . Brodsky A . Cauda equina arachnoiditis . A correlative clinical and roengenologic study . Spine 1978 ;3 :51-60 . 4 . Burton C . Lumbosacral arachnoiditis . Spine 1978 ;3 :24-30 . 5 . Bydder G, Brown J, Niendorf H, Young I . Enhancement of cervical intraspinal tumors in MR imaging with intravenous gadolinium-DTPA . J Comput Assist Tomogr 1985 ;9 :847-50 . 6 . Haugton V, Eldevik P, Ho K, Larson S, Unger G . Arachnoiditis from experimental myelography with aqueous contrast media. Spine 1978 ;3 :65-9 . 7 . Hoffman G . Spinal arachnoiditis . What is the clinical spectrum? Spine 1983 ;8 :538-40 . 8 . Hoffman G, Ellsworth C, Wells E, Franck L, Mackie R . What is the clinical spectrum? II . Spine 1983 ;8 :541-51 . 9 . Johnston J, Matheny J . Microscopic lysis of lumbar adhesive arachnoiditis . Spine 1978 ;8 :36-9 .

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10 . Parizel P, Baleriaux D, Rodesch G, Segebarth C, Lalmand B, Christophe C, Lemort M, Haesendonck P, Niendorf P, FlamentDurant J, Brotchi J . Gd-DPTA enhanced MR imaging of spinal tumors . Am J Roentgenol 1989 ;10 :249-58 . 11 . Quiles M, Marchisello P, Tsairis P . Lumbar adhesive arachnoiditis . Spine 1978 ;3 :45-50 . 12 . Ross J, Masaryk T, Modic M, Delamater R, Bohlman H, Wilbur G, Kaufman B . MR imaging of lumbar arachnoiditis . Am j Roentgenol 1987 ;149 :1025-32 . 13 . Scotti G, Scialfa G, Colombo N, Landoni L . Magnetic resonance diagnosis of intramedullary tumors of the spinal cord . Neuroradiology 1987 ;29 :130-5 . 14 . Shaw M, Russel J, Grossart W . The changing pattern of spinal arachnoiditis . J Neurosurg Psychiatr 1978 ;41 :97-107 . 15 . Skalpe I . Adhesive arachnoiditis following lumbar myelography . Spine 1978 ;3 :61-4 . 16 . Teplick G, Haskin M . Intravenous contrast enhanced CT of the postoperative lumbar spine . Am j Roentgenol 1984 ;143 :845-55 . 17 . Valk J . Gd-DTPA in MR of spinal lesions . Am J Roentgenol 1988 ;150 :1163-8 .

Spinal arachnoiditis mimicking a spinal cord tumor: a case report and review of the literature.

We report on an unusual case of idiopathic arachnoiditis mimicking a spinal cord tumor in a 50-year-old man with progressive paraparesis. The medical ...
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