Atlantoaxial dislocation associated with stenosis of canal at atlas.
A Goel, D Muzumdar, K Dindorkar, K Desai
Department of Neurosurgery, King Edward Memorial Hospital, Parel, Mumbai, India., India
Department of Neurosurgery, King Edward Memorial Hospital, Parel, Mumbai, India.
Three rare cases of stenosis of spinal canal at the level of atlas associated with atlantoaxial dislocation are presented. An atlantoaxial lateral mass fixation with plate and screws after posterior midline bony decompression was successfully performed in these cases.
|How to cite this article:|
Goel A, Muzumdar D, Dindorkar K, Desai K. Atlantoaxial dislocation associated with stenosis of canal at atlas. J Postgrad Med 1997;43:75-7
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Goel A, Muzumdar D, Dindorkar K, Desai K. Atlantoaxial dislocation associated with stenosis of canal at atlas. J Postgrad Med [serial online] 1997 [cited 2022 Dec 6 ];43:75-7
Available from: https://www.jpgmonline.com/text.asp?1997/43/3/75/399
Isolated stenosis of the spinal canal at the level of atlas is rare. Only two such cases could be traced from the literature,. We encountered a rare situation where atlantoaxial dislocation was associated with stenosis of spinal canal at atlas. Such an anomaly has not been reported earlier. The surgical problems encountered in such cases where a posterior decompression was required in addition to a fixation procedure are enumerated in this report. A lateral mass plate and screws as described by us in an earlier report was found to be suitable in this situation [Figure:1]. Midline decompression did not affect the fixation procedure.
Three patients of stenosis at atlas associated with atlantoaxial dislocation were treated surgically. All the patients were males and their age at seven, thirty-four and seventy-four years respectively. The duration of preoperative symptoms ranged from four months to three years. These patients presented with varying degree of symptoms and signs of cervico-medullary compression.
The patients underwent magnetic resonance imaging (MRI), tomograms and X-rays of the region. These patients had atlantoaxial dislocation. In two patients the dislocation reduced completely on extension [Figure:2a], [Figure:2b] while in one, only minimal mobility could be detected on tomography. There was no other associated bony and neural anomalies.
The patients were operated in prone position under traction. After adequate preparation and exposure of the region, lateral mass atlantoaxial [Figure:1] plate and screw fixation was carried out [Figure:2c]. The screws were placed in the facet joints of atlas and axis as described in an earlier report. Bone graft taken from the iliac crest was stuffed in the articular cavity of the facet joints and longer pieces were placed in the midline extending from the foramen magnum to lamina of the axis.
After an average follow-up of 10 months (range 3 months to 3 years) neurological symptoms and signs in all patients. In one patient (age 7 years) the screw application on the articular facet of the atlas on one side could not be done firmly. Immediate postoperative X-rays showed that the screw in the atlas had come out. The plates were in good position. The child was placed in Minerva plaster cast which was removed after three months. After fifteen months follow-up, a firm fixation of the region was seen with plates in position and one screw lying in the subcutaneous tissues. Due to the use of stainless steel plates, postoperative MRI or CT scan could not be performed. Bony fusion was observed on tomography. All patients improved significantly in their neurological symptoms.
Lateral fixation methods for atlantoaxial dislocation have been described,,. These methods have the advantage in that the midline surgical procedures as necessary can be carried out without affecting the fixation. In the rare situation described in this report a posterior decompression in the form of excision of the posterior arch of the atlas in addition to a fixation procedure is necessary. Lateral mass fixation with plates and screws was found to be a suitable alternative in such cases. The technique provided immediate rigid internal fixation permitting early mobilisation with minimal external support. Onlay and inter-facetal bone graft subseqently produced bony fusion. Direct application of screws to the atlas and axis, thus utilizing the firm purchase in their thick and large cortico-cancellous lateral mass, provided a biomechanically strong fixation of the region. Other methods described in the literature such as fixation of the occipital bone with axis and other lower cervical vertebrae with the help of metal loupes and rectangle could also be done in these cases after excision of the posterior arch of the atlas,. However segmental fixation achieved by the application of plates and screws could be advantageous used in such a condition. Titanium plates and screws (commercially available) can be used to provide MRI compatibility. However, due to non-availabilty of the Titanium plates, stainless steel “radius-ulna” internal fixation plates and screws were used. The metal implant provided temporary stabilisation and immobilitywhich was considered to be crucial for the ultimate bony fusion. The articular cartilage of the atlanto-axial joint were denuded and bone chips from iliac crest were placed in the joint cavity. The adjoining articular surfaces provided area for bony fusion.
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