NOTE Internal Medicine

Acquired Cervical Secondary to a Meningioma in a Maltese Dog

Dong-In JUNG1), Chul PARK1), Byeong-Teck KANG1), Ju-Won KIM1), Ha-Jung KIM1), Chae-Young LIM1), Soon-Wuk JEONG2) and Hee-Myung PARK1)*

1)Departments of Veterinary Internal Medicine and 2)Veterinary Surgery, College of Veterinary Medicine, Konkuk University, #1 Hwayang-dong Kwangjin-gu, Seoul 143–701, South Korea

(Received 6 March 2006/Accepted 11 July 2006)

ABSTRACT. A 15-year-old female maltese was referred to us because of a 3-month history of ataxia, circling, and acute blindness. A mass was noted in the brainstem on magnetic resonance images. A cerebellar herniation was also detected on T1-weighted sagittal images. The lateral, third and fourth ventricles and of the cervical were enlarged. Based on diagnostic imaging findings, cervical syringomyelia secondary to a brainstem tumor was suspected. The clinical signs were controlled well by lomustine and the dog survived for 8 months after the initial diagnosis. The mass was diagnosed as a meningioma based on histopathological find- ings. This report describes the clinical findings and imaging characteristics of an acquired syringomyelia resulting from a brainstem men- ingioma. KEY WORDS: canine, meningioma, syringomyelia. J. Vet. Med. Sci. 68(11): 1235–1238, 2006

Syringomyelia is condition in which fluid filled cavities weighted images were obtained. Evaluation of the images develop within the spinal cord. It used to be regarded as a revealed a mass on the floor of the brainstem, mainly on the rare condition in veterinary medicine. However, it is now right side, that extended from the midbrain to the medulla considered a common neurological presentation. Although (Fig. 1). The mass appeared isointense on T1-weighted syringomyelia is considered to be associated with congeni- images and hyperintense on T2-weighted images. This tal diseases, improved imaging techniques have revealed lesion was enhanced after intravenous administration of that it can also develop as an acquired disorder. Thus, diag- gadolinium-diethylenetriamine pentaacetic acid (Omnis- nosis of syringomyelia in an adult dog indicates a need to can®; Nycomed, Inc., Princeton, NJ, U.S.A.; 0.1 mmol/kg search for an underlying disease condition. Acquired syrin- gomyelia can be the result of tumors in the caudal fossa, especially meningiomas; cerebellar herniation is fundamen- tal for its formation and progression [2, 4, 5, 17, 19]. A 15-year-old intact female maltese dog with a body weight of 3.6 kg was presented to the Veterinary Medical Teaching Hospital of Konkuk University due to a 3-month history of ataxia, counterclockwise circling, and acute blindness. Three months prior to this evaluation, clinical signs were first noted and then began to worsen progres- sively. On neurological examination, mildly delayed pos- tural reactions of the left side limbs with ataxia were observed. There was mild cervical rigidity; however, cervi- cal was not detected. Cranial nerve deficits included bilaterally decreased menace response and pupillary light reflex. Based on the neurological examination, the clinical signs were likely due to an intracranial lesion. The results of a complete blood count and the serum Fig. 1. MR images of the present case. A: Sagittal T1-weighted chemistry profiles were within the reference ranges. image. A: cerebellar herniation (arrow), dilatations of the cen- Thus, we performed a brain magnetic resonance imaging tral canal (arrowhead) and the third and fourth ventricles (fine ® arrows) were detected. B: Postcontrast sagittal T1-weighed (MRI) scan using a 0.2 T unit (E-scan ; ESAOTE, Genova, image. A brainstem mass was observed in the pons-medullary Italy). T1- and T2-weighted images and postcontrast T1- area (arrow). C: On a transverse T2-weighed image, a well- defined hyperintense lesion was observed (arrow). Dilatations *CORRESPONDENCE TO: PARK, H-M., Department of Veterinary of the were detected (fine arrow). D: Postcon- Internal Medicine, College of Veterinary Medicine, Konkuk Uni- trast transverse T1-weighed image at the same level as panel C. versity, # 1 Hwayang-dong, Kwangjin-gu, Seoul, South Korea A mass was present on the right side (arrow). A mildly nonen- 143–701. hanced central area was observed in the center of the mass. 1236 D-I. JUNG ET AL.

Fig. 2. Transverse T1-weighted MR image at the level of the sec- ond . Notice the acentric central canal dilata- tion that is suggestive of syringomyelia (arrow). body weight, intravenously [IV]). The width of the mass was 13.5 mm, and its length was 13.0 mm (Fig. 1). The brainstem lesion detected via MRI was highly suggestive of a neoplastic process. A cerebellar herniation was detected on T1-weighted sagittal images, and the lateral, third, and fourth ventricles were enlarged (Fig. 1). These ventriculom- egaly suggested hydrocephalus. On the T1-weighted sagit- tal images, a linear hypointense area was detected in the cervical spinal cord segment (Fig. 1). This lesion was sug- gestive of a syrinx formation. These MRI findings suggested a diagnosis of cervical syringomyelia secondary to a brainstem tumor. Fig. 3. Necropsy findings of this case. A: A well-defined mass One week after prednisolone (Prednisolone; Korea was located in the right pons-medullary area (arrow). B: Trans- Pharma Co., Ltd., Korea; 1 mg/kg body weight, per os [PO], verse section of the cervical spinal cord. A dilatation of the cen- q 12 hr) administration, circling and ataxia disappeared. tral canal was detected (arrowhead). However, the patient showed severe vomiting after pred- nisolone administration and melena was observed for two weeks after prednisolone therapy. Therefore, we discontin- segments. Typically, the syrinx contains fluid that is highly ued prednisolone administration and the clinical signs similar in composition to the (CSF) and relapsed. extracellular fluid [1, 20]. On histologic examination, the Lomustine (Medac Gmbh, Hamburg, Germany; 60 mg/ cavity may be a dilatation of the central canal and may be m2, PO, q 6 weeks) was then administered and the clinical lined with ependymal cells (hydromyelia), or it may lie symptoms were controlled well without severe complica- within the parenchymal substance and may be lined with tions. Every five or six weeks after chemotherapy, clinical glial cells (syringomyelia) [20]. It has subsequently been signs including ataxia and hemiparesis relapsed. However, shown that this distinction is often blurred, that hydromyelia these clinical signs improved rapidly after lomustine admin- may burst into spinal canal substance to form a syringohy- istration. dromyelia partially lined by , and that cysts may Eight months after administration of lomustine, the rupture into the central canal. The term syringomyelia is patient was euthanized due to worsening neurologic dys- now generally acceptable for all clinical conditions with spi- function including tetraparesis and cranial nerve deficits. nal cord cavitation containing fluid identical to or closely On necropsy, a well-defined mass was located in the right resembling CSF [1, 4, 20]. In this case, dilatation of the cen- pons-medullary area and dilatation of central canal was tral canal and lining with ependymal cells were observed on observed (Fig. 3). Histopathologically, this tumor was diag- histopathologic examination. Furthermore, the neurons of nosed as a psammomatous-type intracranial meningioma the spinal cord were degenerated because of the acquired and the dilatation of the central canal was diagnosed as a dilatation of the central canal. These results suggested syringomyelia (Fig. 4). hydromyelia, and this change supported syringomyelia sec- Syringomyelia is characterized by a longitudinal cavity ondary to brainstem mass. within the spinal cord that extends over several vertebral A careful clinical evaluation of patients with syringomy- CERVICAL SYRINGOMYELIA SECONDARY TO A BRAINSTEM TUMOR 1237

tumor was detected on an initial MRI scan and that syrinx was not detected on an MRI scan after radiation therapy. It is logical to assume that the brainstem mass caused the cer- ebellar herniation, resulting in syrinx formation, and that its resolution was associated with shrinkage of the tumor and return of the cerebellum to a normal position. Unfortu- nately, resolution of syringomyelia after chemotherapy was not evaluated in our case. However, the current case had no history of trauma to the cervical portion of the vertebral col- umn or of any other neurological signs until presented to our hospital. Therefore, we can conclude that the brainstem mass may have been associated with cervical syringomyelia in this case. The prognosis for treatment of canine meningioma is guarded. Canine meningioma patients that received only symptomatic therapy with corticosteroids and/or anticon- vulsants have a mean survival time raging from 59 to 81 days [25]. In a recent report [24] of canine intracranial men- ingioma, the median post-operative survival time was 7 months. Radiation therapy for canine meningioma as the sole therapy resulted in a median survival time between 5 and 9 months, and dogs that underwent tumor resection fol- lowed by radiation therapy had a median survival time of 16.5 months (range: 3 to 58 months) [24]. Surgical removal was not performed in this case due to the size and location of the mass. Radiation therapy was not performed because the client declined this treatment. Thus, we initiated chemotherapy. There are limited reports of che- motherapeutic attempts to treat meningiomas in dogs. Hydroxyurea has been shown to be an effective chemother- apeutic agent against meningioma in both human and veter- Fig. 4. Histopathological findings of this case. A: Psammoma- inary medicine [8, 21, 22]. Recently, long-term survival tous meningioma. Meningothelial cells with a whorled pattern after chemotherapy with lomustine for an intracranial men- (× 400, hematoxylin and eosin stain). B: Cervical spinal cord. ingioma in a dog was reported [10]. In that report [10], the The hydromyelic central canal is lined with ependymal cells (× patient with the intracranial meningioma survived for 13 400, hematoxylin and eosin stain). months with only a combination chemotherapy of lomustine and prednisolone. Thus, we selected a lomustine chemo- elia will, in almost all instances, reveal an associated disor- therapeutic agent in this case, and the response was good. der characterized by either obstruction of CSF flow, In conclusion, this case report describes the clinical find- tethering of the spinal cord, or . The reported ings, imaging characteristics, and pathologic features of a causes of syringomyelia can be classified as diseases of the brainstem meningioma with acquired cervical syringomye- craniocervical junction or spinal cord. Acquired syringo- lia and long-term survival after lomustine therapy. Further- myelia secondary to intervertebral disk herniation or spinal more, this report demonstrates that syringomyelia is a trauma has been described in dogs [3]. An association possible complication of brainstem masses. between syringomyelia and brain tumors, although rare, has been identified in humans [13, 14]. An association of REFERENCES hydrocephalus with syringomyelia has been reported in dogs [7, 11, 23], and hydrocephalus was also present in this 1. Batzdorf, U. 2001. pp. 3–9. Syringomyelia: Current Concepts case. in Pathologenesis and Management. 1st ed., Springer-Verlag Recently, one case of intracranial tumor and associated Tokyo, Inc. syringomyelia has been reported in the veterinary medical 2. Cauzinille, L. and Kornegay, J. N. 1992. J. Am. Vet. Med. Assoc. 201: 1225–1228. literature [20]. In that report, vestibular signs were the main 3. Child, G., Higgins, R.J. and Cuddon, P.A. 1986. J. Am. Vet. reason for consultation and clinical signs were improved Med. Assoc. 189: 909–912. after radiation therapy. Our case was presented because of 4. Clare, R. 2005. pp. 340–342. Proceedings of the 23th Annual circling, ataxia, and cranial nerve deficits. Furthermore, the A.C.V.I.M. clinical signs improved after chemotherapy. A recent report 5. Clare, R., Emer, M., Jeremy, V. D., Kate, C., Sue, N. F., Ruth, [20] described that cervical syringomyelia with brainstem D., Rodolfo, C. and Simon, J. W. 2000. J. Am. Anim. Hosp. 1238 D-I. JUNG ET AL.

Assoc. 36: 34–41. 16. Oldfield, E.H., DeVroom, H.L. and Heiss, J.D. 2001. pp. 75– 6. Clare, R. and Susan, P. K. 2004. J. Vet. Intern. Med. 18: 673– 89. Syringomyelia: Current Concepts in Pathologenesis and 678. Management. 1st ed., Springer-Verlag Tokyo, Inc. 7. Itoh, T., Nishimura, R., Matsunaga, S., Kadosawa, T., Mochi- 17. Patnaik, A. K., Kay, W. J. and Hurvitz, A. I. 1986. Vet. Pathol. zuki, M. and Sasaki, N.1996. J. Am. Vet. Med. Assoc. 209: 23: 369–373. 934–936. 18. Robert, M. K., Linda, S. J., Jeremy V. D. and Jean E. 1997. 8. Jason, B. 2004. pp. 340–342. Proceedings of the 22th Annual Vet. Radiol. Ultrasound 38: 30–38. A.C.V. I.M. 19. Robin, E. L., David, L. and Anne, E. C. 1999. Vet. Radiol. 9. Johnson, L., Rolsma, M. and Parker, A. 1992. Prog. Vet. Neu- Ultrasound 40: 332–341. rol. 3: 82–86. 20. Ronaldo, C. D., Joane, M. P., Roberto, P. and Carolina, D. 10. Jung, D. I. 2006. J. Vet. Med. Sci. 68: 383–386. 2004. J. Am. Vet. Med. Assoc. 225: 1061–1064. 11. Kirberger, R. M., Jacobson, L. S., Davies, J. V. and Engela, J. 21. Schrell, U. M. H. 1997. J. Neurosurg. 86: 840–844. 1997. Vet. Radiol. Ultrasound 38: 30–38. 22. Schrell, U. M. H. 1997. J. Neurosurg. 86: 845–852. 12. Klekamp, J. 2002. Acta. Neurochir. (Wien). 144: 649–664. 23. Taga, A., Taura, Y., Nakaichi, M., Wada, N. and Hasegawa, T. 13. Klekamp, J., Samii, M., Tatagiba, M. and Sepehrnia, A. 1995. 2000. J. Small Anim. Pract. 41: 362–365. Acta. Neurochir. (Wien). 137: 38–43. 24. Todd, W. A. and Matt, L. M. 2002. J. Am. Vet. Med. Assoc. 14. Koziarski, A. and Zielinski, G. 2001. Neurol. Neurochir. Pol. 221: 1597–1600. 35: 139–152. 25. Turrel, J. M., Fike, J. R. and LeCouteur, R. A. 1984. J. Am. 15. Levin, D.N. 2004. J. Neurol. Sci. 220: 3–21. Vet. Med. Assoc. 184: 82–86.