, , , , , , ,

Diurnal Disc Shape and Height Changes – Basic Science and Natural Variations to Understand Back Pain

Diurnal Disc Shape

The spine undergoes natural shape and fluid changes over the course of 24 hours. Often, back pain symptoms vary as well over the day and night cycle.  But the small changes and the links to pain have not been researched thoroughly. Here, a group of researchers from Duke University looked at the reliability of measuring intervertebral disc shape with recumbent MRI. This large avascular structure is linked to back pain and has significant diurnal variation in the human body. It would seem wise to further understand its diurnal disc shape changes.

Some people feel pain in the mornings and others feel things more so at the end of the day. Yet others feel pain more so when they lie down.

The intervertebral disc hydraulically keeps vertebrae separated. Water is squeezed out throughout the day as the human frame is vertical, and this water gets resorbed when an individual lays down. During the process, the disc changes shape and height. And when pain is involved, these shape and height changes can bear increased ( or decreased ) physical stress on structures that may be inflammatory. These can include annular fissures, disc bulges, disc herniations, disc protrusions, encroaching nerve or rootlets of nerves and the shingling of facet joints, just to name a few.

The purpose of this study was to determine intra and inter-rater reliability using MRI to measure diurnal changes of the intervertebral discs.

They did find excellent reliability, and interestingly they saw the most significant change in the posterior annulus region of L5-1. The diurnal variations were in line with what others had seen in previous work. Boos at al. in 1996 saw a 1-2mm change over the course of an 8h workday while Hutton et al. in 2003 saw a volume change of 1-2 cm3.

This research is essential if we are to fully understand back pain origins. Often pain syndromes related to the lower back present with symptoms that are diurnal. At Dynamic Disc Designs, we have models to help explain these subtle but significant changes to the discs, assisting patients to understand the onset of their pains and the diurnal disc shape and the natural variations.

 

, , , , ,

Exploring the Link Between Lower Back Pain, Disc Degeneration and Intradiscal Pressure

intradiscal pressure, model

A study of in vivo intradiscal pressure in subjects with and without lower back pain (LBP) sought to find out how disc degeneration affects intradiscal pressure, measure the loading capacity of the L4/L5 IVD segment, and determine any relationship between movement in that disc segment and the spinal loading capacity. The researchers found that there was a significant relationship between spinal loading and the angle of the motion segment in healthy discs in vivo. In degenerated discs, the intradiscal pressure was much lower than that measured in healthy discs. Further study with wider parameters is suggested to fully understand the phenomenon and the problems associated with it.

Study Motivation and Design

The only way to directly measure spinal loading in humans is via the measurement of intradiscal pressure—a complex in vivo task. Most current knowledge about loading capacities were derived from pioneering studies in the 1960’s and 1970’s by Nachemson, but little corroborating evidence has been published on the topic since. These early studies utilized an inefficient means of evaluating intradiscal pressure—the polyethylene coated disc pressure needle until 1965, and after that, another needle designed specifically for intradiscal pressure measurements. This new needle was not without its deficits and required special handling and was prone to destroying structural defects on insertion. The current study’s authors utilized a newly designed silicone-based needle to measure the pressure and spinal load in 28 patients suffering from LBP, sciatica, or both at the L4/L5 segment, and in eight healthy volunteers with an average age of 25 years-old.

Magnetic resonance imaging (MRI) was performed on the healthy subjects prior to the beginning of the study to ensure no disc degeneration in the volunteers. The 28 LBP patients (10 women and 18 men with a mean age 45 years) were also imaged prior to pressure measurements being taken to visualize the amount of water content in their discs. These patients were diagnosed with disc herniation (16 patients) or spondylosis (12 patients).

The subjects were measured while in the prone position, without sedation but with a “local” dose of anesthesia. A guiding needle was used to position the pressure sensor needle into the nucleus pulposus of the L4/L5 IVD discs. Fluoroscopy was used to confirm correct placement of the needle had been achieved. The subjects were measured in eight positions: prone, upright standing, lateral decubitus, flexion and extension standing, and upright, flexion, and extension sitting positions. Radiograms of the lateral view were also taken of each of the subjects during their testing.

Observations

Pressure measurements in this study indicate that respiration creates a fluctuation in intradiscal pressure even when subjects are in the prone position and utilizing no other muscle activities. An IVD that is healthy is also elastic, with an intradiscal pressure that fluctuates in correspondence to muscle activities and respiration. It is possible that the normal pressure changes involved with respiration could be associated with the maintenance of the nutritional content inside the nucleus pulposus. There was a slight difference between horizontal and vertical pressures in healthy and degenerated discs and in the silicon gel, which may indicate that the nucleus pulposus has a similar pressure tropism to silicon gel. Normal discs had high water content, which explains the small difference between the horizontal and vertical pressure measurements. There was, however, a significant difference between the pressures of the total value (horizontal and vertical and whole posture) of healthy and degenerated discs. These values may not have been significant enough to measure in previous studies utilizing the less efficient needle-types. The information obtained in this study through the use of the sensitive silicone pressure needle will help in developing a better understanding of degenerative disc disease.

 

KEYWORDS: Link Between Lower Back Pain, Disc Degeneration and Intradiscal Pressure, relationship between spinal loading and the angle of the motion segment in healthy discs, respiration creates a fluctuation in intradiscal pressure, degenerative disc disease

, , , ,

sciatica – coughing, sneezing and straining

Sciatica, disc, model

Sciatica is often worsened by coughing, sneezing and straining. It is a sign that patients complain about in the case of back pain. In some, the act of coughing or sneezing can actually cause a disc herniation.

In a recent study in The European Spine Journal, researchers wanted to find out if the act of coughing, sneezing or straining is important in the assessment of nerve root compression or disc herniation on MRI.

In “A diagnostic study in patients with sciatica establishing the importance of localization of worsening of pain during coughing, sneezing and straining to assess nerve root compression on MRI” 1 they found that the worsening of leg pain with these actions which includes increasing intradiscal pressure 2 has good diagnostic value for nerve root compression and disc herniation with MRI.

The research revealed the importance of asking whether the patient has these symptoms in the history taking.

At Dynamic Disc Designs, our models showcase how compression will extrude the nucleus….helping patient’s understand their pain.

Quote by the famous Karel Lewit:

“The first task for the physician is to show the patient the cause of their pain”.

  1.  Eur Spine J. 2016 May;25(5):1389-92. doi: 10.1007/s00586-016-4393-8. Epub 2016 Feb 2.
  2.  Spine (Phila Pa 1976). 1999 Apr 15;24(8):755-62. New in vivo measurements of pressures in the intervertebral disc in daily life. Wilke HJ1, Neef P, Caimi M, Hoogland T, Claes LE.
, , ,

Disc Protrusion Seen Sitting – Upright MRI Reveals

Disc Protrusion, Pain, sitting, back pain, upright MRI

Disc protrusion is defined by an extension of nuclear material extending beyond the confines of the annulus (if the base of the material is larger than the material protruding). In the flexed position, the nucleus pulposus is driven backwards (posteriorly) into the spinal canal. If there are nerves in the area, related pains can extend down into the leg (or legs) causing sciatica.

MRI is our powertool for looking at disc injuries. It was developed in the early 1980s and primarily used to look for pathological conditions like cancer. And because it was and still is important to keep the patient still, lying down (recumbent) MRI was the standard.

However, when looking for load related pain, lying a patient down is not always the best strategy as often a patient’s symptoms disappear when they are on their backs. So it would seem reasonable to image patients in a vertical or upright position to look closely at the tissues as they are loaded….this only makes sense.

Here is an example of how the diagnosis was seen when the spine was placed in the seated position. This patient only had symptoms while sitting. And you can see why below.

Disc Protrusion with Upright MRI

Standing, Case, Modeling, MRI, Upright

Pain, sitting, back pain, upright MRI

In this case, the patient demonstrates further protrusion with sitting…and the upright MRI clearly shows this difference from standing to sitting. This is why it is important to consider upright MRI when the patient presents with a load dependent complaint. Upright MRI can help with the diagnosis.

All MRI images on this page are property of Medserena Upright MRI Centre.