An Official publication of The Asian Congress of Neurological Surgeons (AsianCNS)

Search Article
Home About us Editorial board Search Ahead of print Current issue Archives Submit article Instructions Advertise Subscribe Contacts Login  Facebook Tweeter
  Users Online: 410 Home Print this page Email this page Small font sizeDefault font sizeIncrease font size  

   Table of Contents      
Year : 2012  |  Volume : 7  |  Issue : 2  |  Page : 84-86

A torcular encephalocele with proAtlas defect and os-terminale

1 Department of Neurosurgery, Bangabandhu Sheikh Mujib Medical University, Shahbagh, Dhaka, Bangladesh
2 Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India

Date of Web Publication18-Jul-2012

Correspondence Address:
Ashok Kumar Mahapatra
Department of Neurosurgery, Cardioneurosciences Centre, All India Institute of Medical Sciences, Ansari Nagar, New Delhi - 110 029
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1793-5482.98652

Rights and Permissions

Encephalocele means if meninges and brain tissue protrude out of the cranium. There are different types of encephalocele. The occipital encephaloceles are the most common type. Craniocervical junction and upper cervical spine abnormalities can rarely be associated with occipital encephalocele. We discuss this case because there is rare association between torcular encephalocele and proatlas anomalies.

Keywords: Cranio-cervical-junction anomaly, os terminale, proatlas anomaly, torcular encephalocele

How to cite this article:
Nath HD, Mahapatra AK, Gunawat P. A torcular encephalocele with proAtlas defect and os-terminale. Asian J Neurosurg 2012;7:84-6

How to cite this URL:
Nath HD, Mahapatra AK, Gunawat P. A torcular encephalocele with proAtlas defect and os-terminale. Asian J Neurosurg [serial online] 2012 [cited 2021 Jan 23];7:84-6. Available from:

  Introduction Top

Occipital encephalocoeles are more common than anterior encephalocoeles. In the Western hemisphere, occipital encephalocoeles constitute 80 to 90% of all encephalocoeles. [1],[2],[3] Abnormalities of craniocervical junction include: Basilar impression, atlanto-occipital dislocation, atlantoaxial dislocation, and occipitalization of the  Atlas More Details or thin or deficient posterior arch of atlas. [4]

Os-odontoideum is a separate bony ossicle of variable size, with smooth cortical borders, separated from a foreshortened odontoid peg, occasionally may fuse with the clivus.

Os-odontoideum mimics type 1 or 2 odontoid fracture. Etiology is debated. Diagnosis and treatment do not depend on which etiologic theory is correct. This is a developmental anomaly, nonunion of dens to body of axis. However, it does not follow known ossification centers, and has been demonstrated in nine patients with previously normal odontoid processes. Acquired ones are postulated to represent an old nonunion fracture or injury to vascular supply of developing odontoid. [5],[6]

In ossiculum terminale, there is failure of fusion of odontoid process. We report a case of torcular encephalocele with OS-terminale and split atlas.

  Case Report Top

An 18-year-female patient, admitted in our unit, with complaints of a swelling at the back of head since birth. The swelling was increasing in size slowly, almost rounded in shape 8 cm in diameter and 21 cm in circumference. Consistency of swelling was soft, non pulsatile. Over laying skin was normal. Headache was present at the back of head for the last two years. Patient was born at a hospital by normal vaginal delivery; her mother died just following her birth, and perinatal period was uneventful. No history of unconsciousness, visual disturbance, seizure, limb weakness, dysphasia, nasal regurgitation, bladder and bowel dysfunctions. Her developmental mile stones were normal. Pupil was bilaterally normal, equal in size and reacting to light. The visual acuity and field of vision and fundi were normal. Other cranial nerves were normal. There was no sensory and motor deficit. Clinical and radiological diagnosis was Torcular encephalocele with pro-atlas defect and os-terminale. Magnetic resonance imaging of brain showed encephalocele and brain tissue herniated into the sac [Figure 1].
Figure 1: Sagittal MRI shows torcular encephalocele containing brain tissue

Click here to view

Surgical procedure

Under general anesthesia with prone position excision and repair of sac was done [Figure 2] and [Figure 3].
Figure 2: Intraoperative photo shows encephalocele sac

Click here to view
Figure 3: Intraoperative photo at the end of surgery showing sutured wound

Click here to view

Comment during discharge

Patient prognosis appeared good in view of minimal gliosed parenchyma present in sac. Patient should continue to wear hard cervical collar. Patient will need posterior fixation for C1 abnormalities. Hence, she must be on regular follow-up in Neurosurgery Out Patient Department.

  Discussion Top

True os-odontoideum is rare. Ossiculum terminale is nonunion of the apex at the secondary ossification center is much more common. Two anatomic types are orthotopic: Ossicle moves with the anterior arch of C1 and dystopic: Ossicle is functionally fused to the basion, and may subluxate anterior to the C1 arch.

Presentation of os-odontoideum included occipitocervical/neck pain, myelopathy and intracranial signs and symptoms. [7]

Most patients are neurologically intact and present with atlantoaxial instability which may be discovered incidentally. Many symptomatic and asymptomatic patients have been reported with no new problems over many years of follow-up. [8] Conversely, cases of precipitous spinal cord injury after seemingly minor trauma have been reported. [9]

Generally, patients with an occipital encephalocele are operated in the prone position with controlled ventilation and close temperature monitoring. Aspiration of the cerebrospinal fluid prior to incision in patients with large encephalocele helps in dissection of the sac. For a circular encephalocele with a small occipital bone defect, a transverse incision is ideal. The sac is separated from the flap. Patients in whom the encephalocele extends above and below the posterior fossa need a vertical incision. Sometimes, the brainstem and occipital lobe are present in the sac. Care must be taken to identify the contents of the sac. Rarely, the sagittal sinus torcular and the transverse sinus are in the vicinity of the sac. It is preferable to preserve the neural tissue. The dura is repaired meticulously to get a water tight closure. The dural defect can be repaired by using the pericranium as a graft. In neonates and infants, no attempt should be made to cover the bone defect by a bone graft. [10],[11]

A large number of factors influence the outcome in patients with occipital encephaloceles. These are the site, the size, the amount of brain herniated into the sac, the presence of brainstem or occipital lobe with or without the dural sinuses in the sac and the presence of hydrocephalus. [12],[13],[14],[15]

Previous authors described a 4-day-old boy was admitted with a large posterior fontanelle encephalocele. The baby had a small head with a circumference of 30 cm only and encephalocele with a circumference of 37 cm. Excision and repair of encephalocele was done without neurological postoperative complications or neurological deficit. [16] In our case, simultaneously presented with torcular encephalocele with os-teminale and there was only neck pain and no neurological deficit.

There was no hydrocephalus. X-ray of the cervical region showed os-terminale [Figure 4], split atlas, both anterior and posterior arch defect [Figure 5]a and b.

The patient was operated in a prone position, and immobilized neck by hard cervical collar during surgery. At operation, there was gliosed brain inside the sac, which was excised. Bone defect was 3 cm in diameter. Dura was closed using 5-0 vicryl and wound was closed in multiple layers. Patient had an uneventful recovery was discharged on 8 th postoperative day. She was followed-up after 15 days, when she had no problem.
Figure 4: Lateral X'Ray CVJ showing OS Terminale

Click here to view
Figure 5: (a) Sagittal and (b) axial view CT CV junction show OS terminale and encephalocele with bone defect

Click here to view

We advised use a cervical collar and regular monthly follow-up at neurosurgery outpatient department, for os-terminale, which may need a surgery, if required.

  Conclusion Top

There is a rare association between torcular encephalocele and pro-atlas defect with Os-terminale. So this will bring attention to the world neuro scientist. Neural tube defect sometime presented with different type of congenital anomaly.

  References Top

1.Martínez-Lage JF, García Santos JM, Poza M, Puche A, Casas C, Rodriguez Costa T. Neurosurgical management of Walker-warburg syndrome. Childs Nervs Syst 1995;11:145-53.  Back to cited text no. 1
2.Morika M, Marubayashi T, Masamitsu T. Basal encephloceles with morning glory syndrome and progressive hormonal and visual disturbances. Case report and review of literature. Brain Dev 1995;17:196-201.  Back to cited text no. 2
3.Sargent LA, Seyfer AT, Gunby EN. Nasal encephalocele. Definite one stage reconstruction. J Neurosurg 1988;68:571-5.  Back to cited text no. 3
4.Jain VK, Mittal P, Banerji D, Behari S, Acharya R, Chhabra DK. Posterior occipitoaxial fusion for atlantoaxial dislocation associated with occipitalized axis. J Neurosurg 1996;84:559-64.  Back to cited text no. 4
5.Fielding JW, Hensinger RN, Hawkins RJ. Os opdontoideum. J Bone Joint Surg 1980;62A:376-83.  Back to cited text no. 5
6.Ricciardi JE, Kaufer H, Louis DS. Acquired os odontoideum following acute ligament injury. J Bone Joint Surg 1976;58A:410-2.  Back to cited text no. 6
7.Clements WD, Mezue W, Mathew B. Os odontoideum: Congenital or acquired? That's not the question. Injury 1995;26:640-2.  Back to cited text no. 7
8.Spierings EL, Braakman R. The management of os odontoideum. Analysis of 37 cases. J Bone Joint Surg Br 1982;64:422-8.  Back to cited text no. 8
9.Menezes AH, Ryken TC. Craniovertebral abnormalities in down's syndrome. Pediatr Neurosurg 1992;18:24-33.  Back to cited text no. 9
10.Mahapatra AK. Frontoethmoidal encephalocele. A study of 42 patients. In: Samii M (Editor): Skull base anatomy, radiology and management. Basel: S Karger 1994; p. 220-3.  Back to cited text no. 10
11.Mazolla RT. Congenital malformation in the frontonasal areas. Their pathogenesis and classification. Clin Plast Surg 1976;13:513-9.  Back to cited text no. 11
12.Caviness VS, Evrad P. Occipital encephaloceles. A pathological and anatomical analysis. Acta Neurpath 1995;32:245-55.  Back to cited text no. 12
13.Copty M, Vervet S, Langelier R, Contreras C. Intranasal meningoencephalocele with recurrent meningitis. Surg Neurol 1979;12:49-52.  Back to cited text no. 13
14.Friede RL. Uncommon syndrome of cerebellar vermis aplasia, II Tectocerebellar dysraphia with occipital encephalocele. Dev Med Child Neurol 1978;20:764-72.  Back to cited text no. 14
15.Hayashi T, Utsahmiya H, Hashimoto T. Transethmoidal encephaloceles. Surg Neurol 1985;24:251-5.  Back to cited text no. 15
16.Mahapatra AK, Gupta PK, Dev EJ. Giant torcular encephalocele: A case report. Pediatr Neurosurg 2002;36:40-3.  Back to cited text no. 16


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]


Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)  

  In this article
  Case Report
   Article Figures

 Article Access Statistics
    PDF Downloaded279    
    Comments [Add]    

Recommend this journal