Cervical Disc Protrusions (Cervical herniated disc)
What are the structures of the cervical spine?
What is a cervical disc protrusion?
When a disc becomes unhealthy the nucleus can become shrunken and loses its normal water content. Thus, the annulus, or covering, tends to bulge, and in some cases, can rupture leading to protrusion of the unhealthy nucleus into the spinal canal.
In most cases a disc protrusion is the end result of ongoing wear and tear which can be a consequence of various activities including employment but also day to day life. Sometimes there may be a specific event that precipitates the disc protrusion but in many other cases it will occur without warning.
What are the symptoms of a cervical disc protrusion?
The clinical consequence of a disc protrusion will depend on the level, the site and side of the disc protrusion and the structures that may be impacted by the disc.
The most common symptom is that of a ‘pinched nerve’ which is also called a cervical radiculopathy. This may be accompanied by neck pain but in many cases, there is no neck pain at all.
If the disc protrusion is more to one side of the spine it usually compresses a nerve root and the result may be a cervical radiculopathy. If the disc is more central then it may compress the spinal cord causing even more serious neurological problems such as cervical myelopathy.
Radiculopathy is a clinical condition usually due to compression of a nerve root. The nerve root is the start of a nerve as it exits from the spinal cord and spinal canal. It usually will join with other nerve roots outside of the spinal canal to form various peripheral nerves. Nerve roots normally supply sensation to an area of the body as well as supply various muscles to make them move.
Radiculopathy may be very painful. The area in which the patient experiences pain will often indicate the nerve involved. In addition, there is often numbness and paraesthesia. Paraesthesia is commonly referred to as pins and needles. Again, these may indicate the nerve root that is affected. Finally, there may be weakness of a muscle or of a movement.
Nerve root compression causing radiculopathy is most commonly due to a disc protrusion or bony spurs (osteophytes). There are many other reasons for radiculopathy such as a synovial cyst for example.
Not all nerve root compression, which is often evident on CT or MRI scans, is symptomatic. We commonly see patients with nerve root compression on imaging but who have no symptoms. This does not require surgery as we are interested only in making the patients better and not their x-rays.
The most common types of cervical radiculopathies are C5, C6 and C7 radiculopathies.
A C5 radiculopathy will cause pain and sometimes numbness or pins and needle over the region of the shoulder and part way down the upper arm. There can be weakness in lifting the arm from the shoulder, which is also called shoulder abduction.
With a C6 radiculopathy symptoms more commonly run across the should but extend down to the forearm and sometimes involve the thumb and index finger of the hand. Flexion of the arm at the elbow may be weak.
A C7 radiculopathy often involves the region of the shoulder blade, extends down the posterior aspect of the upper arm and into the forearm. Pain commonly centres around the elbow. Symptoms will extend down to the back of the hand and into the middle fingers and fingers either side. Extension of the arm may be weak and it may be difficult to do a push up for instance.
There is a lot of variability in these symptoms and the distribution of the nerve supply. However, the pain is normally very severe and normally requires medical management and, in some cases, will require surgery.
Acute spinal cord compression
Acute spinal cord compression is fortunately less common. At extremes it may cause significant weakness including quadriplegia and loss of sensation throughout the body below the neck. A large acute disc can certainly compress the cord and sometimes patients will present with significant weakness but not paralysis. These cases are obviously emergencies and require urgent neurosurgical treatment.
Cervical Myelopathy is a condition that occurs when the spinal cord is compressed, usually over time, and is due to a more central disc protrusion usually in combination with other degenerative changes in the cervical spine.
This spinal cord compression results in neurological changes such as clumsiness of the hands, weakness of the upper limbs and spasticity of the lower limbs. Patients often report difficulty using cutlery and doing up buttons. Eventually their walking becomes unsteady and they may fall or stager.
There are differing degrees of severity and this will influence the expectations and potential outcomes from surgery.
Decompression of the spinal cord is normally required in these cases.
What are the options for treatment of a cervical disc protrusion?
Compression of the spinal cord usually requires surgical treatment, sometimes as an emergency. This may be done from the front (anteriorly) or from the back of the neck (posteriorly), or even a combination of both. Operations from the front may include an anterior cervical discectomy and fusion (ACDF) while operations from the back of the neck usually include a cervical laminectomy.
For a pinched nerve or radiculopathy, despite the condition being very painful, most will improve without surgical treatment. Those patients who do not improve spontaneously may be considered for various treatments. There are three basic groups of treatments.
- Conservative management
- Cortisone injections
Conservative management includes physiotherapy, chiropractic, massage and acupuncture, etc. Most of these treatments are aimed at symptom control. Great caution should be taken when considering even conservative forms of management with a cervical radiculopathy so as not to worsen the condition. An increase in the size of disc protrusion through manipulations may result in spinal cord compression and serious adverse neurological consequences. Gentle exercise, stretches and mobilisation are sometimes used are better suited to when symptoms begin to settle. Traction may reduce the bulge or protrusion temporarily. Discs do however shrink and in some cases, disappear over time. This is most likely due to a natural healing process.
In the initial stages, when pain is severe, bed rest and analgesia are advised. Analgesics should be prescribed by the general practitioner. It may include painkillers such as codeine and paracetamol along with anti-inflammatories. When the initial pain begins to improve, physical therapy with a focus on gentle exercise and stretching is appropriate. Exercises and activities are normally gradually upgraded as the pain resolves. Most patients (80-90%) will be successfully managed in this manner.
Cortisone injections are performed by a radiologist under CT guidance and involve the injection of a steroid and local anaesthetic around the nerve. The response is variable with some patients having no relief but others having long lasting relief. It may take up to 7 days to have its effect. The effects of the injection often wear off after a few months and some patients can have a second injection if required. It is a good option for those with small disc in whom the condition is expected to resolve and where pain is the predominant symptom. It does not treat weakness or numbness.
What are the indications for surgery?
Surgery is indicated if patients fail conservative treatment after a period of 6-8 weeks, have a large disc that is unlikely to improve without treatment or if they exhibit weakness. Weakness needs to be dealt with promptly as the longer it persists then the less the chance of recovery.
There are three main indications for surgery:
1. Failure to respond to conservative management: This is the most common category. As a general rule, patients who have persistent and significant pain after 6 weeks have a lower chance of improvement and in these cases, surgery is a reasonable option. In the absence of weakness, surgery is not an imperative but if pain continues for extended periods (>6 months) then the success rate of surgery may be reduced due to neuropathic pain.
2. Weakness: As a general rule, the longer that weakness persists, the lower the chance of recovery. Weakness can be debilitating especially for very active people. In some patients if there is evidence of continued improvement and the weakness is mild continued conservative treatment may be appropriate although most will proceed to surgery.
3. Large disc with severe symptoms and is unlikely to resolve without surgery: Even large discs can respond to conservative management. However, if a patient is in significant pain and the disc is large, it may take some time for it to resolve. Surgery may be the most rapid and effective treatment in this circumstance.
In some cases, pain and disability from the disc protrusion may be so severe that early surgery is appropriate.
What type of surgery is used to treat a cervical radiculopathy?
The type of surgery used depends on the nature and location of the disc. For patients where the disc protrusion is centrally located, that is, in front of the spinal cord, then surgery will be performed from the front, that is anteriorly. This is most commonly in form of an anterior cervical discectomy and fusion (ACDF).
When a disc protrusion is more laterally located then a either an ACDF or a procedure performed from the back of the neck called a cervical laminoforaminotomy and microdiscectomy may be used to decompress the nerve root and remove the disc.
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