Friday, November 18, 2011

Low Vitamin D Hinders Spine Health

Vitamin D Two recently reported studies explore the importance of adequate vitamin D for patients undergoing spine surgeries and in those with inflammatory spinal cord disease. Although further research is required to confirm the benefits, vitamin D supplementation in these patients could be an essential component of improved spine health and effective pain management.

Vitamin D Deficiencies Hamper Recovery from Spine Surgery

Speaking at the 26th Annual Meeting of the North American Spine Society, orthopaedic surgeons from Washington University School of Medicine in St. Louis reported that more than half of 313 patients undergoing spinal fusion surgery had inadequate levels of vitamin D; a quarter of them were severely deficient [Stoker et al. 2011].

One of the study authors, Jacob M. Buchowski, MD, said he became aware of the vitamin D problem when a patient in her 40s experienced a slow recovery after spinal fusion surgery. While he was trying to determine why the vertebrae did not fuse properly the woman mentioned that she had recently been diagnosed with vitamin D deficiency. “It was like a ‘light bulb’ went off,” he stated. Consequently, Buchowski and colleagues started routinely screening patients prior to spinal fusion surgery for vitamin D deficiency.

Low vitamin D levels are known to be common in elderly patients; surprisingly, however, patients in this study most likely to have inadequate levels were younger; on average, 55 years old. One quarter of the patients, predominantly those who were older, had taken vitamin D supplements in the past.

The researchers found that the main risk factors for inadequate vitamin D were smoking, obesity, disability prior to surgery, and never having taken vitamin D or multivitamin supplements. Although an earlier study had shown inadequate vitamin D levels in 43% of patients undergoing orthopedic procedures, this is the first to look solely at patients having spine surgery.

Vitamin D is important for calcium absorption and patients with a deficiency are at risk for osteomalacia that hinders new bone formation. As a follow-up to this study, Buchowski and colleagues are planning an investigation of whether there is a link between low vitamin D and poor outcomes following spinal fusion. In the meantime, he recommends that patients should be getting sufficient vitamin D prior to orthopedic surgery.

Low Vitamin D May Influence Inflammatory Spinal Cord Disease

A second study — this one from researchers at Johns Hopkins University, Baltimore — suggests that vitamin D levels are significantly lower in patients with recurrent inflammatory spinal cord disease, including transverse myelitis and neuromyelitis optica [Mealy et al. 2011]. In transverse myelitis (TM) there is involvement of the myelin sheath that protects nerve fibers; symptoms include back pain and weakness in the legs. Neuromyelitis optica (NMO) is a disease of the central nervous system that affects the optic nerves and spinal cord.

Writing in an early online edition of the Archives of Neurology, Maureen A. Mealy, RN, BSN, and colleagues report a retrospective analysis of vitamin D levels among 77 patients, comparing monophasic versus recurrent inflammatory diseases of the spinal cord (TM/NMO), and adjusting for season, age, sex, and race. They found that vitamin D levels were significantly deficient — 25(OH)D < 20 ng/mL — in patients who developed recurrent spinal cord disease compared with those having nonrecurring monophasic disease.

“This is consistent with other recurrent autoimmune conditions and points to a common link between low vitamin D levels and immunologic dysregulation,” the researchers write. They suggest that further studies are needed to assess the relationship between vitamin D and painful, recurrent spinal cord disease.

Practice Perspectives

Both studies were observational in nature and definitive cause-effect relationships of vitamin D and the conditions in question cannot be surmised. Furthermore, the researchers did not report specific beneficial effects of vitamin D supplementation in the affected patients. Therefore, it must be considered that these studies are a relatively low level of evidence and the results are suggestive of potential vitamin D benefits but need further confirmation.

Despite those reservations, the importance of vitamin D for bone health is well known. It makes sense that sufficient levels of vitamin D — measured via the 25(OH)D metabolite — could facilitate better recovery from orthopedic surgeries, and this could be of particular importance when new bone growth is essential for a successful outcome.

The first study suggests that it could be of value to screen patients for 25(OH)D levels well in advance of anticipated spine surgery, and to correct any deficiencies. Buchowski states, “We think those with insufficient levels of vitamin D may benefit from taking 50,000 international units of the vitamin once a week for eight weeks before surgery as this may help the recovery after spinal fusion surgery.”

The second study is a reminder that, in recent years, low levels of vitamin D have been linked to a variety of autoimmune conditions, including multiple sclerosis (MS, a disease of the central nervous system marked by numbness, weakness, loss of muscle coordination, and other neurological symptoms). The new evidence from Mealy et al. further suggests a role of vitamin D in recurrent non-MS spinal cord diseases, including transverse myelitis and neuromyelitis optica.

Transverse myelitis often manifests as back pain and weakness in the legs, and other painful conditions of the spine may similarly involve immune-system-modulated inflammation of nerves and/or the surrounding tissues. The role of vitamin D supplementation in preventing, modifying, or ameliorating these conditions requires further study; meanwhile, it is worth considering that screening for vitamin D deficiencies in these patients and adequate supplementation, if indicated, might be of some value as an adjunctive component of effective pain management.

As we have written previously [see papers here], vitamin D supplementation generally has a favorable benefit to cost ratio with minimal risks. In all likelihood, it would do no harm and probably could do much good; including, as suggested above, in patients undergoing spine surgeries and those with inflammatory-related spinal nerve pain.

> Mealy MA, Newsome S, Greenberg BM, et al. Low Serum Vitamin D Levels and Recurrent Inflammatory Spinal Cord Disease. Arch Neurol. 2011(Nov 14); online ahead of print [
abstract here].
> Stoker GE, Buchowski JM, Bridwell KH, et al. Vitamin D status of adults undergoing surgical spinal fusion. Presented November 3, 2011 at the 26th Annual Meeting of the North American Spine Society in Chicago, Ill.