Glossary

Commonly Used Terms and Medical Jargon

Babinski or Plantar Reflex

“Ba-bin-ski”

The sign was identified by Joseph Babinski, a French neurologist. Babinski’s sign (also known as the plantar reflex) can be a feature of myelopathy involving the cervical spinal cord. It is a test performed by doctors during their neurological examination. By scratching the outer/underside of a patient’s feet, a positive test (i.e. one suggesting central nervous disease, known as “Babinski’s Positive”) causes a reflex to make their toes curl upwards. In a normal test, the toes would curl downwards. This test can be tricky to perform, as most people are ticklish or do not like having their feet touched, so they can recoil in response mimicking a positive Babinski’s test. Interestingly this reflex is also present in babies. It takes a few months before a baby develops the normal, downgoing response.


Cerebrospinal Fluid (CSF) Leak

Cerebrospinal fluid (CSF) is the watery liquid in which the brain and spinal cord sit. It is contained by the dural sheath. CSF is made deep within the brain and flows like a river. It is then drained downstream by the veins which overlie the dura. If an opening in the dura is made and fails to close, fluid can leak out.

Why is this relevant to Degenerative Cervical Myelopathy?

During surgery for DCM, an opening in the dura can be accidentally made. This is often because, due to the disease, the dura has become stuck to the compressing tissues. Therefore during their removal, the dura can tear open, causing a leak. This is a relatively uncommon complication but is more likely during posterior surgery than during anterior surgery.

The signs of a CSF leak include clear, watery fluid leaking from your wound site or headaches/nausea/vomiting on standing (because the pressure inside your head has dropped a little).

If CSF is leaking out, then there is a risk that bacteria can get in and cause an infection such as meningitis. Therefore if this occurs you should return immediately to the hospital.

The management of the leak will depend on the situation, but options include watch and wait, flatbed rest, temporary diversion of CSF flow to allow the hole to heal, or surgery to repair the leaking point.

If there is an opening in the dura, then CSF can leak out.

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Cervical

“ser-vi(e)-cal”

The spine is divided up into 5 different sections; cervical, thoracic, lumbar, sacrum and coccyx. The basic arrangement of structures is largely unchanged between segments but there are important differences between the levels.

What is the relevance to Degenerative Cervical Myelopathy?

Degenerative Cervical Myelopathy, as the name suggests, is a disease process affecting the neck, i.e. the cervical portion of the spine.

The level of the spine is important, as it controls the body from the toes up to that level. For example, the lumbar spine controls leg function but has nothing to do with arm function. However, the cervical spine is important for both arm and leg function.

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The Anatomy of the Spine

This is a normal MRI scan of the cervical spine, viewed from the side. Case courtesy of A.Prof Frank Gaillard, Radiopaedia.org. From the case rID: 35630

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Cervicogenic Headache

Headaches affect almost everybody from time to time, the most common types being ‘tension’ or ‘migraine’ headaches. This is no different for people with degenerative disease of the cervical spine. However, degenerative changes in the neck in rare cases can cause a less common subtype of headache called a ‘cervicogenic’ headache. Whilst this is a controversial diagnosis (in that many professionals are unsure that this is a specific and separate type of headache), it is worth noting that headaches are common amongst people with DCM, and often respond to surgery.


Computed Tomography or CT 

How does it work?

A CT scan is a complicated X-ray. A machine rotates around your body, and sends X-rays through your body. A computer will combine these 2D images to form a 3D picture. The scanner looks like an enlarged ring doughnut (not the narrow tunnel of an MRI scanner). A CT scan is a very quick procedure and lasts about 30 seconds.

Can anyone have a CT Scan?

In principle, yes. Because a CT scan uses X-rays, in some instances (for example pregnancy) it may be avoided or steps taken to reduce exposure.

Is it useful in Degenerative Cervical Myelopathy?

A basic CT scan alone is not very useful in DCM, as the X-rays do not highlight the soft tissue structures such as the spinal cord, most ligaments, or intervertebral discs.

If a person is unable to have an MRI scan, a CT Myelogram can be performed. This is where dye is injected into the back to highlight these structures.

CTs are however often used to help inform surgical strategy, and potentially evaluate for a subtype of DCM called Ossification of the Posterior Longitudinal Ligament. 


Epidural Haematoma

“Epee-jur-al”

The spinal cord lies within a sac called the ‘dura’ or ‘dural sheath’ or ‘meninges’. Epi (‘outside’) dural (‘the casing around the spinal cord’) haematoma (‘blood clot’) is a description of a blood clot forming around this sheath. This can happen for a variety of reasons; however, because these structures lie within a bony canal, if a blood clot forms here it has nowhere to expand to and will therefore compress the spinal cord causing neurological symptoms.

Why is this relevant to Degenerative Cervical Myelopathy?

An epidural haematoma is a potential complication of surgery for DCM. It affects about 1% of operations.

During an operation, a degree of bleeding is to be expected but the surgeon will endeavour to ensure that this is controlled and stopped. Occasionally a collection of blood can pool within the spinal canal causing spinal cord compression and myelopathy. If this were to occur, it would generally do so within the first 24hrs. A common story for this problem would be to awake after the operation with, or develop within the first few days, a worse function in arms and/or legs. If you are concerned about this, you must talk to your surgeon or seek urgent medical assessment.


Hoffman’s Sign

Hoffman’s sign can be a feature of myelopathy involving the cervical spinal cord. It is a test performed by doctors during their neurological examination. By holding a patient’s hand so that it is weightless, and flicking the nail of their middle finger, a positive test (i.e. one suggesting central nervous disease) causes a reflex to make their thumb and index finger contract spontaneously, as seen in this video.


Intervertebral Disc or Disc

The spine is made up of many different structures. These include bones, ligaments and intervertebral discs. All components work in harmony to provide the combination of strength and flexibility required to function.

The intervertebral discs are essentially water beds, separating each segment (known as a vertebra) of the spine. They are held in place by ligaments. They are important for allowing movement. At each level, there is very little natural movement, but the combination of lots of moving parts means overall the spine is capable of being very flexible but also strong.

What is the relevance to Degenerative Cervical Myelopathy?

As we get older the intervertebral discs age; in very simple terms they dry out, become less flexible and distribute the forces in the back less efficiently.

The speed of the ageing process varies from person to person and at different levels of the spine. If you look at the MRI picture, you can see the discs at the top are whiter and more clearly defined [healthier] than the lower discs, which are darker and compressed.

As the discs age, they become more likely to slip (also known as ‘herniation’ or ‘prolapse’). If the disc moves backwards it can reduce the width of the spinal canal and compress the spinal cord causing DCM. This process can be gradual or sudden.

Whilst these changes are often described as a ‘disease’, e.g. ‘Degenerative Disc Disease’, it is important to note that these changes are very often a normal part of getting older; they will frequently be seen on imaging of healthy adults. This misunderstanding may alter healthcare behaviour. For example, in a recent large randomised controlled trial from North America, where patients with lower back pain undergoing MRI did not receive any context to their MRI report, the use of opioids was significantly higher.

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Side MRI view of the bottom (lumbar) section of the spine. The discs at the top are healthier (well shaped and white) compared to the bottom (dark and compressed).

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Diagram of a side view of the spine, indicating the arrangement of the many structures.

Case courtesy of Dr G Balachandran, Radiopaedia.org. From the case rID: 5222


Lhermitte’s Sign

“Leur-mits”

Lhermitte’s sign, the phenomenon of an electric shock passing down your spine, and/or into your limbs, can be a feature of central nervous system disease. It is typically triggered by bending the neck forward (putting your chin to your chest). It was named after Jean Lhermitte, a French neurologist, who established its significance in 1924.

The phenomenon occurs because the back of the spinal cord comes into contact with the spinal canal. This sign is most commonly associated with multiple sclerosis where an inflamed and swollen spinal cord contacts the spinal canal. The sign has been described in several other diseases of the spinal cord, including DCM.

Why does it matter in Degenerative Cervical Myelopathy?

In addition to indicating spinal cord disease, Lhermitte’s sign can be a feature of DCM. ​

It can be one of the earliest signs of cord compression.

We could think about the following scenario: when the spinal canal starts to narrow, the cord may not be compressed all the time. The cord might only get squashed when your neck is in certain positions. This ‘dynamic’ process can still cause damage, but to a lesser extent than continuous compression.

Watch a demonstration of Lhermitte’s Sign.


Magnetic Resonance Imaging or MRI

How does it work?

An MRI scanner uses a powerful electromagnet, and the properties of hydrogen ions, called ‘protons’ (for example from water molecules), throughout your body to generate an image. The magnetic field forces these ions into a specific pattern. These are then manipulated by a different force: a radiofrequency pulse. As the response of these ions is determined by the tissue they arise from, this can be used to generate an image.

Can anyone have an MRI Scan?

No. Due to the role of magnets, any person with implanted magnetic metal or a risk of having metal inside their body cannot have an MRI scan as this may become dislodged and cause damage to internal structures. If you are unsure whether this applies to you, download our MRI safety questionnaire or talk to your MRI team. In these instances, the alternative is a CT Myelogram.

What is the process?

An MRI scan is a slow process, because the sensors need to record over a period of time. To scan the cervical spine can take 20 to 30 minutes; this will be made up of many short sequences (a few minutes at a time).

The scanner is essentially a very tight and narrow tunnel. Some people find it claustrophobic. To reduce unwanted movement of your head, you will also be positioned in a special headset. This also contains the sensor which records the information. 

The switching on and off of the magnets, and the rotation of the sensors, create a lot of noise. Noise-reducing headphones or ear buds are therefore used, but the sounds can still be heard. 

Like the CT scanner, 2D images are reconstructed to form 3D images. 

Due to the length of time it takes to acquire an image, any movement can affect the reconstruction. It is therefore really important to remain perfectly still. This can even include simple movements such as swallowing. The radiographer who conducts the MRI scan will help you to recognise when this is particularly important.

Is it useful in Degenerative Cervical Myelopathy?

Yes. This is currently the best and safest way of providing a picture of all the structures of the spinal column. 

What are dynamic or flexion / extension MRI scans?

These are MRI scans performed with the neck bent forward (flexion) and the neck bent backward (extension). These are not routinely performed or available at all hospitals. However, they have great value because scans taken in a lying down (supine), slightly manipulated position (e.g. in a head coil) may camouflage spinal cord compression which occurs when in a normal position or during cervical spine movement. 

What is an upright MRI?

An upright MRI is a special MRI machine built to allow imaging to occur with people in a seated (upright) position. These are, again, not widely available, but are often better tolerated by people who suffer with claustrophobia or similar. The downside of the technology is that the quality of the imaging is poorer, due to the sensors being further away from the cervical spine.


Myelomalacia

“My-ello-ma-lay-sha” = ‘White Spot’

Myelo (‘spinal cord’) malacia (‘softening’) is a descriptive term for abnormal changes seen within the spinal cord on MRI images that indicate spinal cord damage. These often include ‘signal intensity changes’ or ‘white spot’ sign. As a descriptive term, there are a variety of disease processes that can cause this and it would generally be considered a potentially significant finding.

However it is not specific to a particular disease, nor specific for an active disease (i.e. it could be a longstanding and static finding). It can be seen in healthy people without DCM. It must therefore be interpreted in the context of an individual’s symptoms.

What is the relevance to Degenerative Cervical Myelopathy?

DCM can cause myelomalacia. However it is not a specific diagnostic feature; i.e. it can be seen in healthy people without DCM, and does not have a role in how the disease will progress or respond to surgery. Myelomalacia most often will persist following surgery. 

These are relatively new perspectives and historically many professionals used myelomalacia (e.g. a signal change within the cord or ‘white spot’) to confirm or exclude DCM, or to indicate a poorer prognosis if present. 

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New MRI techniques, such as Diffusion Tensor Imaging (DTI), are enabling changes within the spinal cord to be mapped more accurately. It is likely, therefore, that changes within the spinal cord detected through new imaging techniques will become valuable to care.

What does Dr Mark Kotter think?

Additional information

A systematic review of MRI characteristics that affect treatment decision making and predict clinical outcomes in patients with cervical spondylotic myelopathy.

A clinical prediction rule for functional outcomes in patients undergoing surgery for Degenerative Cervical Myelopathy: Analysis of an international prospective multicenter data set of 757 subjects.


Myelopathy

“mye-lop-a-thee”

Myel (‘spinal cord’) opathy (‘problem’) is a disease of the spinal cord. This can be distinguished from radiculopathy or neuropathy based on the symptoms and findings during a doctor’s examination. 

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What is the relevance to Degenerative Cervical Myelopathy?

Myelopathy is a descriptive term and many different disease processes can cause it.

In DCM, compression of the spinal cord causes myelopathy. This can be caused by any surrounding structure, e.g. a prolapsed intervertebral disc, or ligament or bony spur.

Learn more about the concept of Myelopathy.


Osteophyte

“os-tee-o-fight”

Osteo (‘bone’) phyte (‘growth’) is an abnormal protrusion or outgrowth of bone. These are commonly referred to as ‘bone spurs’. They can occur from any bone. They are a feature of osteoarthritis, ‘wear and tear’ damage to bones. It is commonly thought that they represent an attempt by the body to limit movement in a joint, in an attempt to halt further joint damage. 

What is the relevance to Degenerative Cervical Myelopathy?

Osteophytes can occur in the cervical spine. Their growth can lead to contact with the spinal nerve roots (causing radiculopathy) or the spinal cord (causing myelopathy). This can lead to pain and loss of neurological function. 

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A pathological specimen. Osteophytes are shown by the arrows.

Learn more about Osteophytes.


Radiculopathy

“Radic-u-lop-a-thee”

Radicul (‘spinal nerve root’) opathy (‘problem’) refers to a disease of the spinal nerve root as it leaves the spinal cord. The symptoms and findings during a doctor’s examination can distinguish this from myelopathy. 

It is a descriptive term and can therefore be caused by a variety of disease processes.

What is the relevance to Degenerative Cervical Myelopathy?

Radiculopathy can occur with myelopathy in DCM, as the same changes which lead to compression of the spinal cord can affect the small opening through which the spinal nerve root leaves.

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Difference between myelopathy and radiculopathy

Myelopathy and Radiculopathy are medical terms that relate to disease of specific parts of the nervous system. They have different patterns, symptoms and signs of disease.

Learn more about the difference of Myelopathy vs Radiculopathy.


Spinal Cord or Cord

The spinal cord, along with the brain, makes up the central nervous system. For the most part, the spinal cord processes information from the body before it is sent on to the brain for decision making; however, some basic decisions are made by the spinal cord; we call these basic decisions ‘reflexes’. 

What is the relevance to Degenerative Cervical Myelopathy?

The spinal cord is housed within the spinal canal. Narrowing of the spinal canal causes compression of the spinal cord and DCM.

The spinal cord is internally highly organised. If you look at a thin slice of the spinal cord, it is possible to map the part of the body it controls.

This is of interest in DCM as the area controlling arm function is slightly closer to the edge of the cord and in a position where a degenerating surround structure, such as a disc or osteophyte, is more likely to press.

This may explain why common early symptoms of DCM are hand/arm symptoms. However, later on, it can progress to affect the legs.

View the Anatomy and Physiology textbook on OpenStax.


Downloadable Fact Sheet

Download the Myelopathy Fact Sheet – answers to key questions from people affected by DCM.