NECK PAIN RELATING TO HERNIATED DISC, PROLAPSED DISC, SLIPPED DISC
Slipped disc, bulging disc, prolapsed disc… these are all common terms used to define types of injury to the discs which sit between the vertebrae bodies (bones) of the spine.
Commonly described as the “cushions” or “shock absorbers” of the spine, these circular pads of cartilage are composed of tough, fibrous tissue on the outside (annulus fibrosis) and a watery, gelatinous material on the inside (nucleus pulposus). A similar arrangement to a jam doughnut.
The fibres of the outer annulus are deeply woven into the vertebrae above and below. They are arranged in a series of rings which run at oblique angles to one another. This maximises strength into flexion (forward bending) and extension (backwards bending). It also allows maximal resistance to torsional (twisting) forces.
The inner nucleus is hydrophilic (water loving). This means that, when it’s not under compressive force, it draws in water, causing the disc to swell in size. This happens every night while we sleep and is the main reason we are taller first thing in the morning.
An Intervertebral Disc
A key role of intervertebral discs is to dissipate loads during spinal movement. However, these structures can often become injured and can cause both local and referred pain.
WHAT CAUSES A DISC TO BECOME INJURED?
As part of the natural aging process, alterations to the disc structure can occur. Firstly, the nucleus loses its water content, which can result in the annulus bulging outwards beyond the margins of the vertebral body, much the same as a flat tyre would do against the road surface. These age-related changes are very common in patients aged over 20 and are often not associated with symptoms. A “Disc Bulge” per se can be classified when 50-100% of the circumferential disc tissue extends beyond the normal boundaries(1).
Actual injuries can also occur to the internal nuclear and annular structures within the disc. This is referred to as a herniation and these derangements may occur either slowly or quickly, secondary to either degeneration or as a result of accumulative microtrauma. The mechanism of injury is based primarily on compressive forces in repetitive flexion, often with superimposed torque or rotation(2).
With regards to the neck, this condition may be encountered by office workers who spend prolonged periods looking down at documents, laptops or mobile phones. It is therefore important to address workstation setup and practice to reduce the amount of time spent with the neck bent downwards, whether this be through the use of a document stand or separate laptop stand and keyboard. In addition, taking regular breaks.
WHERE DO DISC HERNIATIONS OCCUR IN THE CERVICAL (NECK) SPINE?
The majority of disc bulges within the cervical spine are between the lower two vertebrae within the cervical spine namely C5-6 and C6-7. At these sites, these discal injuries can cause local irritation or compression to the C5, C6, C7 or C8 nerve roots.
SYMPTOMS OF A CERVICAL DISC HERNIATION/BULGE
There can be a large variation in the severity of pain with cervical disc injuries and resultant nerve irritation, ranging from no obvious symptoms to severe persistent neck and shoulder pain to arm pain, pins and needles and muscle weakness in the arm and hand musculature.
This can be explained, because it is only the outer 1 to 3 mm of the disc which is pain sensitive. Furthermore, it is the extent of the chemical (from inflammation) or mechanical (from direct pressure) pressure which determines the severity of the nerve symptoms. Such that, nerve roots are adapted to withstand a degree of mechanical or chemical irritation. However, once this threshold is exceeded, symptoms will be felt by the patient.
The symptoms derived from irritation of the nerve root is defined as radicular pain. This pain is often described by the patient as one-sided, constant, dull “toothache pain” which can occasionally be sharp and lancinating in character. It often follows a distinct pattern within the upper limb which is defined as a “dermatomal” distribution. There may also be changes in sensation, such as numbness or pins and needles.
The symptoms described by patients often relate to aggravating positions which increase the pressure in the discal material, namely sitting, coughing, sneezing, etc. or with manoeuvres which increase the traction on the nerve roots, i.e. carrying shopping.
(1) Tarakad S Ramachandran, MBBS, FRCP(C), FACP (2008) Disk Herniation. Emedicine.
(2) LeFebvre, R et al. Herniated lumbar disc with radiculopathy (1999) Conservative Care Pathways 5-53.
(3) Battie & Videman (2004) Spine 29(23): 2679-90.
(The list of conditions given above and subsequent explanations are intended as a general guide and should not be considered a replacement for a full medical examination. Furthermore, we do not purport to treat all the conditions listed. Should you wish to discuss any of these conditions with our chiropractors, please do not hesitate to phone the clinic on 020 7374 2272 or email firstname.lastname@example.org).