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Basilar Impression in an 8-year-old Male

History

The patient is an 8-year-old male who presents complaining of neck pain and headaches for 9 months. Recently, the patient experienced upper and lower extremity weakness. He has been walking with assistance for 4 months.

Examination

Upon examination, there was limited occipitocervical range of motion. Mild diffuse upper extremity weakness, 5-/5, upper/lower extremity hyper-reflex. Pyramidal signs were positive (Hoffman, Babinski signs).

Images

lateral CT scan, basilar impressionFigure 1. Lateral CT scan shows basilar impression.

sagittal mri, brainstem, migration of odontoid into foramen magnumFigure 2. Sagittal MRI shows impression of the brainstem, migration of the odontoid into the foramen magnum. Cervical syringomyelia occurred due to basilar compression.

axial ct, ondontoidFigure 3. Axial CT

Diagnosis

The patient was diagnosed with a basilar impression and basilar artery occlusion. A basilar impression is a congenital craniovertebral congenital anomaly. There is no medical treatment. It requires total resection, if feasible.

Suggest Treatment

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Selected Treatment

In this case, there were two stages to the surgery:

The patient was placed in halo traction, after an uncomplicated transoral resection of the anterior ring of C-1 and the odontoid process of C-2 (Figure 4). Next the patient was placed prone and an occiput-C4 posterior fusion was performed using occiput rods and autologous bone grafting. The patient was discharged one week later. Six weeks after surgery he returned to home.

intraoperative photograph, odontoid processFigure 4

Outcome

The patient did well following surgery except for the need of a nasogastric tube for one week.

There was no any neurologic deficit and he hasn't displayed pryamidal signs. He is walking without assitance. The patient continues to be closely followed.

Figures 5A, 5B and 5C (below): Post-operative CT (sagittal, axial, coronal) imaging.

post-operative sagittal ct, basilar impressionFigure 5A

axial ct, ondontoidFigure 5B

post-operative coronal ct, basilar impressionFigure 5C

Author's Discussion

Basilar impression, the most common malformation of the craniocervical junction,1 is a well-recognized cause of neck pain, hydrocephalus, cerebellar dysfunction, cough, headache, lower cranial nerve palsies, corticospinal signs, syringomyelia, and syringobulbia, as first reported by Homen2 in 1901.

A short neck and flat skull base are often visible on inspection. Hypernasal speech (ie, velopharyngeal insufficiency) with or without palatal clefts is an occasional clue. The neurological signs3 are notably variable. It is associated with other malformations of the notochord and craniovertebral junction, such as occipitalization of the atlas, Klippel-Feil anomaly, Chiari type I malformation and syringomyelia.

The association of platybasia, occipitalization of the atlas and fusion of cervical vertebrae in those with and without a Chiari malformation, indicates a common developmental origin.4

The transoral-transpharyngeal approach to the upper cervical spine and clivus is well described. It is most commonly used to address cervicomedullary compression due to lesions and anomalies of the odontoid and basilar impression.1 In most cases, removal of the odontoid and its associated transverse and alar ligaments renders the occipitocervical complex unstable.

Transoral decompression of the cervicomedullary junction, followed by occipitocervical fusion using titanium rods and screws, is associated with good neurological outcome and acceptable complication rates for patients with basilar impression and occipitocervical anomalies. The fusion rate is excellent with the Philadelphia collar.

References
1. Kotil K,Bilge T. Management of cervicomedullary compression in patients with congenital and acquired osseous-ligamentous pathologies. J clin Neuroscie.14: June 2007, Pages 540-549.

2. Homen EA. Zur Kenntnis der rhachitischen. Deformationen der Schädelbasis und der basalen Schädelhyperostosen. Dtsch Z Nervenheilkd 1901;20:1.

3. Ray BS. Platybasia with involvement of the central nervous system. Ann Surg 1942;116:231-250.

4. Hayes M, Parker G, Ell J, Sillence D. Basilar impression complicating osteogenesis imperfecta type IV: the clinical and neuroradiological findings in four cases. J Neurol Neurosurg Psychiatry, 1999;66:357-364.

Case Discussion

Odontoid pathologies with basilar impingement typically present in the young as congenital malformations or in the elderly as an advanced rheumatoid panus. The treatment option presented here is a typical treatment of either. Ideally one would spare the anterior arch of C1 and perform a transarticular fixation of C1-C2, thus obviating the need for cranial fixation and its associated morbidity. Hwang1 described this procedure well for Chiari I malformations.

However, the high-riding dens in this case would be difficult to resect sparing the arch. One additional factor that complicates this case is the retro-flexed odontoid. This exacerbates the bony invagination. Both of these factors also make a solely posterior approach inadequate.

Nasogastric feeding for one week post-op is the expected course post-operatively. I would not consider this an exception to his good outcome. Some patients may develop velo-pharyngeal insufficiency as a complication from the procedure as well. This risk can be reduced by confining the posterior mucosal splitting to a purely vertical approach.

The posterior fusion appears to utilize lateral mass screws. It appears to extend to C5 on the right which some may argue is longer than necessary. I would advocate a somewhat shorter construct (to C3) with the addition of posterior Songer cables for additional fixation.

Reference
1. Hwang SW, Heilman CB, Riesenburger RI, Kryzanski J. C1-C2 arthrodesis after transoral odontoidectomy and suboccipital craniectomy for ventral brain stem compression in Chiari I patients. European Spine Journal. 2008 September;17(9):1211-1217. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2527411/ Accessed: April 22, 2010.

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