Is this the evidence we’re looking for to prove that poor neck posture causes trapped nerves?
A recent publication by a Japanese team in January 2016 has demonstrated on MRI that when people suffer with trapped nerves in the neck, a condition often called “cervical radiculopathy”, the muscles at the back of the neck which provide extension, are weakened.
The group measured the muscle mass of a specific neck extension muscle called multifidus on MRI. They found 16 people who had pain due to a single C6 nerve compression and 24 people of similar age and gender who had no pinched nerves in the neck and no pain.
The MRI appearance of multifidus between the two groups was striking, in that the people with a single pinched C6 nerve had significantly less multifidus muscle bulk compared with the healthy controls.
The group explained that a trapped nerve, or nerves, means that the electricity supply to the nearby neck muscles is compromised and this in turn causes fatty changes in the muscle which weakens them. This in turn causes postural problems with the neck.
A second, older, publication in 2008 gave a convincing MRI association between worn discs, or disc degeneration, and loss of normal neck posture. They demonstrated that when the normal curvature in the neck is lost, called loss of cervical lordosis in medical jargon, there is more wear in the discs. The worst and most extensive wear is seen when the lordosis is actually reversed into a forward flexion or kyphosis of the neck.
Finally, a radiology publication in 2002 demonstrated that disc bulges were made to either partially or completely resolve on MRI when the patients’ necks were placed in an inflatable neck collar which provided continuous mobile traction.
If we put this information published over the last 14 years together, it appears that when he bend our necks forward as a postural habit, such as when we read a book, lean forward while using computer monitors, text on mobile phones or even sleep with our chins on our chests, we are encouraging our necks to lose the normal lordotic or C shaped curve, which distributes the 5Kg weight of our heads evenly through our necks. The result is that our discs bear more weight than they were designed to carry, because our heads are constantly further forward than they are meant to be held. We can support this opinion using the 2002 publication, whereby the bulging discs improve when the weight of the head is taken off them by a traction collar. We are not designed to wear traction collars, of course, but we are not designed to constantly look down either.
Assuming that our habitual neck flexion causes excessive loading of our discs, then it can be argued that the loss of normal neck posture is responsible for the disc wear reported in the 2008 publication. We are now just one small step away from arguing pretty convincingly that the disc wear causes the C6 pinched nerves reported in the 2016 article. The weakened neck extension muscles are seen, not because they have a reduced nerve stimulation from the trapped C6 nerve, but because they have not been used in the first place. The weakened neck extension muscles are the cause of the trapped nerve, not the other way around.
The multifidus muscle has its nerve supply from multiple nerves, not just the C6 nerve, so it sounds a little implausible to blame weak multifidus muscles on a single pinched nerve.
So, in summary, it appears that people who have weak extension muscles in their necks due to chronic, habitual poor neck posture, are at risk of developing pain in the neck and arm, called cervical radiculopathy. The treatment of this condition includes surgery, which has a roughly one in a thousand risk of causing paralysis as a complication. Maybe, if we pulled our shoulders back and focussed on being as upright as possible (draw yourself up to your full height!), then this problem would be a lot less common than its current reported estimated annual prevalence of 3.5 per 1000 people