J Neurol Surg B 2014; 75 - A184
DOI: 10.1055/s-0034-1370590

Intraoperative MRI Changes in Cervico-Thoracic Syrinx after Odontoidectomy for Basilar Impression

Pablo F. Recinos 1, Anubhay G. Amin 1, Yuki Otano 1, Ziya L. Gokaslan 1, Jean-Paul Wolinsky 1
  • 1Cleveland, USA

Introduction: Surgical decompression is a treatment option used for syringomyelia caused by compression at the cranio-cervical junction. However, there is limited evidence detailing the exact time course for radiographic resolution of a syrinx after decompression.

Methods: A 28-year-old female presented with progressive myelopathy. She was found to have basilar impression secondary to atlanto-occipital assimilation as well as an extensive cervicothoracic syrinx. A two-staged approach was planned: a posterior occipito-cervical fusion followed by an anterior transcervical odontoidectomy using intraoperative magnetic resonance imaging (MRI). During the anterior procedure an intraoperative pre- and post-decompression MRI was obtained with the patient fixed in the same position to allow for a comparison of equivalent MRI slices. A 3-month postop MRI was also obtained for comparison. The width of the syrinx was measured in the sagittal plane at the C4-T1 levels.

Results: A sequential decrease in the width of the syrinx was seen at the C4 (5.9mm, 3.4mm, 0mm), C5 (6.3mm, 4.7mm, 3.7mm), and C6 (5.5mm, 4.4mm, 3.6mm) when comparing pre-decompression, post-decompression, and 3-month follow-up. A transient increase post decompression followed by overall decrease at the 3-month interval was seen at C7 (6.0mm, 7.0mm, 3.8mm) and T1 (6.5mm, 7.0mm, 4.6mm). Intraoperative MRI revealed that the syrinx diminished immediately after odontoidectomy. Three month postoperative MRI revealed that the syrinx continued to diminish in size. The immediate radiographic reduction of the syrinx after decompression in this case provides further support for treating syringomyelia with surgical decompression and reveals that treatment may result in immediate effects.

Conclusion: Surgical decompression resulted in immediate radiographic changes in the associated cervico-thoracic syrinx. These findings suggest that syringomyelia resolution may begin immediately post decompression.

Table: Anterior-posterior diameter of syrinx
Intra-Op before decompression (mm) Intra-Op after decompression (mm) 3 mo post-Op (mm)
C4 5.9 3.4 0
C5 6.3 4.7 3.7
C6 5.5 4.4 2.6
C7 6.0 7.0 3.8
T1 6.5 7.0 4.6

Fig. 1 Intraoperative Sagital T2WI MRI before (left) and after (right) decompression, demonstrating intraoperative changes in syrinx size.