Lumbar Disc Assessment of Bedrest using MRI
Lumbar disc assessment of glycoaminoglycan content by MRI was investigated using gadolinium to look at the changes that took place after 21 days of bedrest. This research published in PLOS One investigated the effects of recumbancy on the lumbar discs to get a better understanding of whether the discs imbibe water or increase proteoglycan content with unloading. Spaceflight has effects of disc swelling and associated back pain.
Using bedrest as an analog to spaceflight, five volunteers, healthy, non-smoking males were subjected to 24hr bed rest with a 6 degree head down tilt for 21 days. Magnetic Resonance Imaging (MRI) scans were taken according to the delayed gadolinium-enhanced magnetic resonance imaging (dGEMRIC) protocol before and after bedrest.
Results showed significant changes in T1 which indicated that insufficient sleep can be a risk factor for low back pain. These researchers concluded that sufficient recumbency (unloading, decompression) is necessary for the intervertebral discs to recover from mechanical load and strain of daily activities. Interestingly, they not only showed how water increases to the discs with bedrest but also glycosaminoglycan content.
Clinically, patients often complain of symptoms related to sleep or lack thereof. They also complain of back pain related to the diurnal timing of load and respective disc height loss. That is, some complain of symptoms early in the morning after a period of recumbency (indicative if a degenerative disc) and others complain of symptoms later in their day, likely due to the progressive and hydraulic disc height loss of vertebral approximation irritating intradiscal tissue and/or facets with the associated articular capsule/synovial folds.
A careful dissection of the timing of patients symptoms will help point the investigator to the anatomy in question. Our models can assist in the patient education of the diurnal timing of symptoms and the importance of bedrest and unloading of interverterbal discs.
Explaining the timing of pain onset helps in the management of back pain. When patients understand that symptoms are related to hydraulic height loss, lying down or taking a nap mid-day may be a viable therapeutic strategy to increase disc height.