Anthony M.Maina FCS(ECSA)(Ortho) Orthopaedic Surgeon, Head of Orthopaedic Surgery, AIC KIJABE HOSPITAL. (KOA Scientific Conference,Eldoret,2016) SUCCESSFUL OCCIPITO- CERVICAL FUSION FOR BASILAR INVAGINATION- A REPORT OF 2 CASES.

Smith JS et al,Neurosurgery,2010 Menezes AH,Childs Nerv Sys,2008 INTRODUCTION Basilar invagination(BI)-developmental anomaly of the occipital bone and upper cervical spine resulting in an abnormally high vertebral column prolapsed into the skull base. Considered a radiographic finding-look for underlying anomaly. Reported etiologies:-Clivus hypoplasia -Occipital condyle hypoplasia -Atlas hypoplasia -Incomplete C1 ring -Achondroplasia -Atlanto-occipital assimilation 25-35% of p'ts with BI have assoc neural axis abnormalities-Chiari malformation,syringomyelia/-bulbia and hydrocephalus.

Andrei FJ, Arq Neuropsiquiatr, 2014 Diagnosis-when the tip of the odontoid process crosses over the Chamberlain's line(posterior margin of the hard palate to the Opisthion). To establish diagnosis(no consensus)-odontoid tip should be above the Chamberlain's line by 2mm, 5mm or even 6.6 mm. Several large series- described association between BI and Chiari malformation;but most didn't report criteria of diagnosing BI. Lack of strict criteria of diagnosis-variability of BI incidence.

Other Parameters

Smith JS et al,Neurosurgery,2010 Categories In Treatment  Reducible: after traction with neurologic improvement-proceed to posterior Occipitocervical decompression and fusion.  Irreducible: after traction, consider posterior Occipitocervical decompression and fusion and anterior(transoral) decompression(Odontoidectomy).

AIM To describe successful occipito-cervical arthrodesis of 2 cases of Basilar Invagination.

CASE REPORT AND DISCUSSION First case: 15 yr old male patient history of minor trauma and tonsillitis followed by progressive weakness of his upper and lower limbs. Diagnosis: basilar invagination due to atlanto-occipital assimilation was made. Treatment:-skull traction, -Post OC decompression and - Fusion (3.5mm reconstruction plates and screws). Improved from Ranawat Stage IIIB to I. Second case: Hx-6 yr old female presented with a 6 month history of progressive quadriplegia and difficulty in breathing. Diagnosis: basilar invagination due to atlanto-occipital assimilation. Treatment:-skull traction, -Post OC decompression, -Duraplasty and -Fusion (Occipito-cervical plate-rod constructs). Improved from Ranawat Stage IIIB to II. Prolonged intubation and tracheostomy; recurrent pneumonias.

Case 1

Case 2

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