Friday, August 10, 2012
Medical Treatment for Myelopathy?
Cervical and thoracic myelopathy have traditionally been thought of as surgically treated diseases. However, in an article in the August 1 issue, a large collaborative group from Japan has raised the possibility of treating thoracic myelopathy medically using Granulocyte Colony Stimulating Factor (G-CSF). While this glycoprotein has traditionally been used to treat neutropenia, animal and human data have suggested that G-CSF can stimulate regeneration of heart, brain, and spinal cord tissue. Based on these findings, this large Japanese group obtained regulatory approval to study the effect of G-CSF on thoracic myelopathy in 10 patients who demonstrated a decline of at least 2 points in their JOA scores over the previous month. Fourteen similar patients were followed as controls. After observing the results of G-CSF or conservative treatment for one month, all patients were then treated with posterior decompression with or without fusion. At one month, the G-CSF patients improved significantly more on their JOA score (1.9 points vs. 0.2 points), ASIA motor score (2.8 points vs. 1.6 points), and ASIA sensory score (6.4 points vs. 1.0 points) compared to the controls. While these improvements were relatively modest, the differences were significant despite the small group sizes.
This study, while not definitive, is certainly provocative as it raises the possibility of improving myelopathy symptoms medically. The authors acknowledge the substantial limitations inherent in their study design—namely lack of randomization and blinding. These methodological shortcomings open the doors to selection bias and the placebo effect, which could certainly explain some of the observed benefit. Nonetheless, these data should serve as a pilot study leading up to a large scale, double blinded, placebo controlled RCT to evaluate the efficacy of G-CSF for myelopathy. The authors do not explain why they chose to study G-CSF in thoracic myelopathy patients rather than cervical patients, and it would be interesting to see its effect in the cervical spine. Additionally, cervical myelopathy is much more prevalent, and it would be easier to recruit cervical rather than thoracic patients for a large RCT. Given the relatively modest improvements observed in this study, it seems unlikely that G-CSF will replace surgical treatment, but it could have a role post-operatively in order to maximize improvement following decompression. Studying it in a post-operative context would also probably assist with patient recruitment and ethical issues given that many myelopathy patients probably do not want to delay surgery for any length of time if that could mean being randomized to a placebo control. Many medical treatments have been proposed for the treatment of spinal cord injuries, and none have emerged as particularly effective when studied in a rigorous fashion. As such, we will have to temper our enthusiasm about G-CSF until a large, level 1 study is performed. However, the current study suggests that G-CSF may someday have a role in improving neurological recovery in myelopathy patients.
Please read Dr. Yamazaki’s article on this topic in the August 1 issue and his accompanying commentary on The Spine Blog. Do you think the G-CSF will end up being an effective medical treatment for myelopathy? Let us now by posting a comment on The Spine Blog.
Adam Pearson, MD, MS
Associate Web Editor