Case Reports / Journal of Clinical Neuroscience 17 649–652 649

Retro-odontoid pseudotumor without atlantoaxial subluxation

Shingo Tanaka, Mitsutoshi Nakada *, Yutaka Hayashi, Masanao Mohri, Yasuhiko Hayashi,Naoyuki Uchiyama, Jun-ichiro HamadaDepartment of Neurosurgery, Division of Neuroscience, Graduate School of Medical Science, Kanazawa University, 13-1 Takaramachi, Kanazawa, Ishikawa 920-8641, Japan

a r t i c l e i n f o

Article history:Received 15 June 2009Accepted 28 July 2009

Keywords:Atlantoaxial subluxationPseudotumorRetro-odontoid mass

a b s t r a c t

A retro-odontoid pseudotumor (ROP) is commonly associated with atlantoaxial subluxation (AAS). Here,we report a patient with ROP but without AAS. The patient was a 72-year-old man who did not have ahistory of rheumatoid arthritis or trauma to the head and neck. The patient was admitted to our hospitalwith gait disturbance, progressive motor weakness in both upper extremities and sensory disturbance inall four extremities. MRI showed a retro-odontoid mass with severe compression of the cervical spinalcord. A CT scan showed spondylotic changes in C5, C6, and C7 and bilateral facet fusion between C3and C4. Dynamic radiography showed no evidence of AAS; there was loss of mobility at C2–C7 and exces-sive mobility at C1. Intraoperative pathological examination revealed that the lesion was a pseudotumor;therefore, posterior C1–C2 fixation was performed. MRI performed 6 months after the operation revealedthat the pseudotumor was markedly reduced. To the best of our knowledge, patients with ROP withoutAAS are uncommon.

� 2009 Elsevier Ltd. All rights reserved.

1. Introduction

A retro-odontoid pseudotumor (ROP) is a non-neoplastic massat the craniovertebral junction; it causes spinal cord compression,which in turn causes neurological symptoms.1,2 In almost all pa-tients with an ROP, it is associated with atlantoaxial subluxation(AAS).1,3–5 ROP is caused by mechanical stress exerted by theAAS on the atlas ligaments.1,3,5,6 From the pathological viewpoint,an ROP is composed of fibrous granulation or fibrocartilaginous tis-sue.2,3,6,7 We present a patient with a rare ROP without AAS; thisROP was caused by atypical biomechanics of the upper cervicalspine.

2. Case report

A 72-year-old man presented with gait disturbance and leftsensory disturbance 3 months prior to referral to our hospital.The patient had no history of rheumatoid arthritis or trauma tothe head and neck. He had attended a local hospital and underwentMRI, which revealed a mass located posterior to the odontoid pro-cess (Fig. 1). Cervical MRI showed an epidural mass located poster-ior to the odontoid process as an isointense area on T1-weightedMRI and as a mixed-intensity area on T2-weighted MRI; the masswas not enhanced with gadolinium. T2-weighted MRI also showedan area of high intensity in the intramedullary region of the uppercervical spinal cord; due to compression of the spinal cord by themass. Additionally, spondylotic changes at C5, C6, and C7 were ob-served. The patient was then referred to our hospital for treatment.

At our hospital, neurological examination revealed severe mye-lopathy with motor weakness of both upper extremities, sensorydisturbance in all the four extremities, clumsy hand movements,increased deep tendon reflex, and a positive Babinski’s reflex. Dy-namic radiography of the cervical spine did not show AAS withan atlas–dens interval less than 4 mm in both flexion and exten-sion. However, radiography revealed limitations in C2–C7 mobilityand excessive C1 mobility. CT scans revealed spondylotic changesat C2 and C3 and bilateral facet fusion between C3 and C4

* Corresponding author. Tel.: +81 76 265 2384; fax: +81 76 234 4262.E-mail address: nakada@ns.m.kanazawa-u.ac.jp (M. Nakada).

(Fig. 2). On the basis of the radiographical findings, the differentialdiagnosis was ROP.

Surgery was performed to decompress the spinal cord and toobtain a biopsy of the mass for pathological diagnosis. The poster-ior cervical canal was decompressed by laminectomy of the atlasand the axis. The mass was approached through the right lateralside of the spinal cord. The mass was slightly yellow and elastic.Because the intraoperative pathological diagnosis was a pseudotu-mor lesion, the mass was not removed. A posterior C1–C2 transar-ticular fixation was performed.

All symptoms improved immediately after surgery. At the 6-month follow-up examination, MRI revealed a significant reduc-tion of the mass and in spinal cord compression (Fig. 3).

3. Discussion

A pseudotumor is a non-neoplastic mass in the retro-odontoidregion that occurs in elderly people. The mechanical stress due toAAS is considered to cause ROP. Alternatively, ROP is sometimesassociated with rheumatoid arthritis, which causes AAS.8 A typicalMRI finding of ROP is a hypo- or isointense area on T1-weightedMRI and an area of low or mixed intensity on T2-weighted MRI.ROP is not enhanced after gadolinium administration.1–3,6,7 Therecommended surgical management of ROP is a combination oflaminectomy and posterior C1–C2 fixation with transarticularscrews, without removal of the ROP.3,4,9,10 The ROP gradually re-duces within 1 year after surgery, as observed in our patient.3–5,11

Differentiation of the retro-odontoid mass is often difficult. Inparticular, tumorous masses such as meningioma, chordoma, oste-ochondroma, and metastatic tumors should be included in the dif-ferential diagnosis.1,2,12 Although our patient showed the typicalfindings of an ROP, tumor was considered as a differential diagno-sis because of the absence of AAS. Intraoperative pathological diag-nosis is helpful to determine the exact diagnosis, as for our patient.

The cause of ROP in our patient may be related to the cervicalmotion at the atlantoaxial segment. The atlantoaxial joint hadexcessive mobility since mobility below the C2 cervical spinewas limited by spondylosis and facet fusions. The excessive mobil-ity increased the mechanical stress between C1 and C2 at the timeof neck flexion and extension. Repeated tear and repair of theligaments, including the posterior longitudinal ligament and

Fig. 1. (A, left) Axial T1-weighted MRI showing the lesion as an isointense retro-odontoid mass (dotted line); (B, center) it appears as an area of mixed intensity on sagittal T2-weighted MRI; and (C, right) does not enhance after gadolinium administration. The T2-weighted MRI reveals an area of high intensity in the intramedullary regions of C1 andC2 (due to compression by the retro-odontoid mass) and spondylosis of C5, C6, and C7.

Fig. 2. Dynamic flexion cervical radiographs (A, left) and extension (B, center) showing no evidence of atlantoaxial subluxation (arrows) and loss of mobility below the C2level and excessive C1 mobility. (C, right) A coronal CT scan showing bilateral facet fusion between C3 and C4.

650 Case Reports / Journal of Clinical Neuroscience 17 649–652

transverse ligament, occurred, resulting in the development of aROP.2,7,13

Since the MRI findings of retro-odontoid cervical disc herniationare sometimes similar to those of ROP, there have been many casereports of the difficulty in differentiating between a C2–C3 cervicaldisc prolapse and ROP.12,14–16 On the basis of previous case reportsand our patient, we have classified ROP into 3 types according tothe etiology and MRI findings (Table 1).

Type 1 and type 2 ROPs are classified according to differencesin etiology. Type 1 is the classical and common ROP caused byAAS and is mainly associated with rheumatoid arthritis. Type 2shows similar MRI findings as type 1, but is not associated withAAS. According to previous case reports, spondylosis, ankylosis ofthe cervical segment, and ossification of the anterior longitudinalligament can induce the formation of an ROP.7,17 Some spinaldiseases cause loss of mobility at middle and lower cervical seg-ments, which in turn leads to excessive motion of the C1–C2segment during flexion and extension and transfer of the

mechanical stress to the C1–C2 segment. Mechanical stress tothe atlantoaxial segment is a cause of both type 1 and type 2ROP; therefore, the same surgical management is applicable toboth these types.

Type 3 ROP is a retro-odontoid cervical disc herniation. ThisROP is caused by a herniated disc between C2 and C3 that pene-trates the posterior longitudinal ligament and migrates upwardto the retro-odontoid space.12,14 The disc hernia is probably relatedto mid cervical and lower cervical spondylosis.12 Because of thepresence of the herniated tissue, type 3 ROP would appear as alow intensity or an isointense area on T1-weighted MRI and alow intensity area on T2-weighted MRI. A typical finding of type3 ROP is that a disc hernia at C2–C3 is continuous with the retro-odontoid mass. Surgical removal of the retro-odontoid mass is rec-ommended for type 3 ROP.12,14

Here, we have reported a patient with a rare ROP without AAS.To prevent the progression of ROP, we performed surgery to relievethe mechanical stress at the atlantoaxial junction. The stabilization

Table 1Types of retro-odontoid pseudotumor

Type 1 Type 2 Type 3

Incidence Common1,4–7,9–11,17 Rare2,8,13 Rare3,12,15,16

Etiology � Atlantoaxial subluxation � Spondylosis� Ankylosis� Ossification of the anterior longitudinal ligament

� Disc herniation

MRI findings T1: hypo- or isointenseT2: mixture of low and high signal intensity

Same as type 1 T1: hypo- or isointenseT2: low signal intensityC2/3 soft disc continues to retro-odontoid mass

Treatment C1/2 fixation and laminectomy Same as type 1 Removal of herniated disc

Fig. 3. Six months after surgery showing (A, left) coronal T1-weighted MRI; (B, center) sagittal T2-weighted MRI, and (C, right) sagittal T1-weighted MRI, showing asignificant reduction of the retro-odontoid mass and a residual area of high intensity in the intramedullary regions of C1 and C2.

Case Reports / Journal of Clinical Neuroscience 17 649–652 651

of C1–C2 resulted in the spontaneous regression of ROP. Therefore,we consider that C1–C2 fixation is a suitable therapeutic option forthis type of ROP.

References

1. Sze G, Brant-Zawadzki MN, Wilson CR, et al. Pseudotumor of thecraniovertebral junction associated with chronic subluxation: MR imagingstudies. Radiology 1986;161:391–4.

2. Crockard HA, Sett P, Geddes JF, et al. Damaged ligaments at the craniocervicaljunction presenting as an extradural tumor: a differential diagnosis in theelderly. J Neurol Neurosurg Psychiatry 1991;54:817–21.

3. Goel A, Phalke U, Cacciola F, et al. Atlantoaxial instability and retroodontoidmass: two case report. Neurol Med Chir (Tokyo) 2004;44:603–6.

4. Takami T, Goto T, Tsuyuguchi N, et al. Posterior C1–2 fixation with cancellousscrew and rod system for retro-odontoid pseudotumor associated with chronicatlantoaxial subluxation. Neurol Med Chir (Tokyo) 2007;47:189–94.

5. Isono M, Ishii K, Kamida T, et al. Retro-odontoid soft tissue mass associatedwith atlantoaxial subluxation in an elderly patient: a case report. Surg Neurol2001;55:223–7.

6. Yamaguchi I, Shibuya S, Arima N, et al. Remarkable reduction or disappearanceof retroodontoid pseudotumors after occipitocervical fusion: report of threecases. J Neurosurg Spine 2006;5:156–60.

7. Chikuda H, Seichi A, Takeshita K, et al. Radiographic analysis of the cervicalspine in patients with retro-odontoid pseudotumors. Spine (Phila Pa 1976)2009;34:E110–4.

652 Case Reports / Journal of Clinical Neuroscience 17 652–653

8. Goel A, Dange N. Immediate postoperative regression of retroodontoid pannusafter lateral mass reconstruction in a patient with rheumatoid disease of thecraniovertebral junction: case report. J Neurosurg Spine 2008;9:273–6.

9. Jun BY. Complete reduction of retro-odontoid soft tissue mass inosodontoideum following the posterior C1–C2 transarticular screw fixation.Spine 1999;24:1961–4.

10. Suetsuna F, Narita H, Ono A, et al. Regression of retroodontoid pseudotumorsfollowing C-1 laminoplasty: report of three cases. J Neurosurg Spine2006;5:455–60.

11. Ito K, Sakai K, Yako T, et al. Atlantoaxial dislocation associated with a mass inthe extradural craniovertebral junction unrelated to rheumatoid arthritis: casereport. Neurol Med Chir (Tokyo) 2007;47:182–5.

12. Nishizawa S, Yamaguchi M, Kitahama Y. Retro-odontoid mass in high elderlypatients: genesis, therapeutic strategies and post-operative care. Spinal Surg2005;19:11–8.

doi:10.1016/j.jocn.2009.07.116

Cavernoma in the pineal region

Antonio Figueiredo a, Shradha Maheshwari a, Atul Goea Lilavati Hospital and Research Centre, Bandra West, Mumbai, Indiab Department of Neurosurgery, Seth G.S. Medical College and King Edward Memorial Hospi

a r t i c l e i n f o

Article history:Received 2 August 2009Accepted 4 August 2009

Keywords:CavernomaMidbrainPineal region

a b s t r a c t

A 19-year-old girl presentedlarge and partly calcified lesioradically resected. Followingthe pineal region are rare. Th

1. Introduction

Although brain cavernomas have been found in up to 0.5% of thepopulation in a large autopsy and MRI series,1,2 these lesions arenot common in clinical practice and the true prevalence of caver-nomas is largely unknown. Location of cavernomas in the pinealregion is particularly uncommon.3 We report a patient with acavernoma in the pineal region, review the literature and discussits management.

2. Case report

A 19-year-old girl had moderate headaches for 8 months. Theheadaches worsened acutely over 15 days and she developed dip-lopia. She had bilateral papilloedema. There was no clear gazerestriction or extraocular muscle weakness. There was no otherneurological deficit.

Investigations revealed a large, partly calcified, enhancing le-sion in the region of the pineal gland accompanied by moderatehydrocephalus. She underwent surgery by a supracerebellar infra-tentorial approach (Fig. 1). During the operation a large lesion wasidentified with multiple blood vessels over its surface and withinit. There were areas suggesting old hemorrhage, and of xantho-chromia within and around the lesion. The entire lesion was dis-sected progressively from the adjoining neural structures and

* Corresponding author. Tel.: +91 22 24129884; fax: +91 22 24143435.E-mail address: atulgoel62@hotmail.com (A. Goel).

13. Jun BY, Yoon KJ, Crockard A. Retro-odontoid pseudotumor in diffuse idiopathicskeletal hyperostosis. Spine (Phila Pa 1976) 2002;27:E266–70.

14. Matsuno A, Nakashima M, Murakami M, et al. Microsurgical excision of a retro-odontoid disc hernia via far-lateral approach: successful treatment of a rarecause of myelopathy. Neurosurgery 2004;54:1015–8.

15. Nishizawa S, Ryu H, Yokoyama T, et al. Myelopathy caused by retro-odontoiddisc hernia. Neurosurgery 1996;39:1256–9.

16. Rosenberg WS, Rosenberg AE, Poletti CE. Cervical disc herniation presenting asa mass lesion posterior to the odontoid process: report of two cases. J Neurosurg1991;75:954–9.

17. Yamazaki M, Okawa A, Mannoji C, et al. C1 dome-like laminectomy andposterior C1–C2 polyaxial screw-rod fixation for a patient with cervicalmyelopathy due to a retro-odontoid pseudotumor. J Clin Neurosci 2009;16:99–103.

l b,*

tal, Acharya Donde Marg, Parel, Mumbai 400012, India

with symptoms of severe headache and diplopia. Investigations revealed an in the pineal region. At surgery a large cavernoma was identified and was

surgery, the patient recovered from all her symptoms. Giant cavernomas ine literature on the subject is reviewed.

� 2009 Elsevier Ltd. All rights reserved.

resected. There was a relatively well-defined plane of dissection.Histopathology of the lesion showed multiple large vascular chan-nels in various stages of hemorrhage along with thrombosis andcalcification in some vessels, confirming the operative impressionof a cavernoma (Supplementary Fig. 1). The patient recovered rap-idly from her symptoms, and at 2-year follow-up, she was asymp-tomatic. Repeat investigation at this time confirmed resection ofthe lesion (Supplementary Fig. 2).

3. Discussion

Cavernomas in the region of the pineal gland are rare. Ourliterature search revealed 16 reported cases of cavernomas in thislocation,4 the youngest patient being 4 weeks old.5 Our patient wasyoung and the lesion was large with areas of calcification. Theseclinical and tumor morphological characteristics could easilybe mistaken for those of other pineal region tumors such aspineocytoma, pineoblastoma and germinoma, all of which may ex-hibit calcifications. The large lesion, presence of large blood vesselsand the location close to the midbrain and other critical structuresmade surgery a formidable task. Surgical resection was made eas-ier by a relatively well-defined plane of dissection in this patient.The histology confirmed the lesion to be cavernous hemangiomain the majority of reported patients,4 but mixed hemangioma hasalso been reported.5,6 Total resection of the lesion was achievedin nine reported patients.4,7 Partial resection of the tumor was re-ported to have led to repeated episodes of subarachnoid hemor-