What kind of disease is cervical spondylosis?
Cervical spondylosis is a degenerative disease that occurs commonly in any population, and it seriously affects human health and quality of life. The understanding of cervical spondylosis has gone through a long historical process. Cervical spondylosis is defined as the irritation or compression of adjacent tissues by the cervical disc degeneration itself and its secondary changes, which cause various symptoms and/or signs.
The definition of cervical spondylosis shows that the disease is primarily a degenerative disorder, but is closely related to a variety of factors. It stems from cervical disc degeneration, which itself can present many signs and symptoms. Secondary changes include organic changes and dynamic abnormalities. The organic changes include herniated and prolapsed nucleus pulposus, subperiosteal hematoma of the ligament, and bone spur formation. Dynamic changes include cervical instability, such as intervertebral laxity and increased flexion. These pathological changes constitute the essence of cervical spondylosis. Therefore, in addition to the pathological basis of cervical spondylosis, the resulting clinical manifestations need to be included to distinguish it from other similar disorders.
The cervical disc consists of the nucleus pulposus, the annulus fibrosus, and the upper and lower cartilage plates, which form a complete anatomical unit. Degeneration of one of these units can lead to morphological and functional changes, ultimately affecting or disrupting the intrinsic balance of the bony structures of the cervical spine and altering the mechanical balance around them. The nucleus pulposus is a water-rich, well-elastic mucin with a water content of more than 80% at a young age. As age increases, the water content decreases and can be less than 70% in old age. The disc in its normal state accounts for 20% to 24% of the total length of the cervical spine, and its height decreases year by year due to the decrease in water content. The degenerated and herniated nucleus pulposus may also cross the posterior longitudinal ligament fissure and enter the spinal canal, producing direct clinical symptoms.
The fibrous annulus begins to degenerate after about 20 years of age. Microscopic fissures in the annulus fibrosus gradually enlarge and develop into fissures that are visible to the naked eye. The direction and depth of the fissure are consistent with the degree of nucleus pulposus degeneration and the direction and intensity of pressure. The strength of the posterior fibrous ring is relatively weak, coupled with the fact that most modern occupations are often accustomed to a flexed cervical position, resulting in the nucleus pulposus being squeezed to the posterior side, so fracture of the fibrous ring is more common on the posterior side. When the fiber ring is subjected to abnormal pressure, it can stimulate the sinus vertebral nerve and reflect to the posterior branch, causing neck and shoulder pain, collar muscle spasm and other symptoms.
Degeneration of the cartilage plate is mainly manifested as a functional degeneration. This effect is closely related to the water-holding properties and nutrient metabolism of the nucleus pulposus. Bone endplate type cervical disc herniation is a common phenomenon, suggesting that fissures within the nucleus pulposus may extend to the cartilage plate, which may protrude outside the fibrous ring along with the nucleus pulposus.
The degeneration of the three components of the cervical disc interacts with each other and, in general, degenerative changes in the cervical disc after the age of 20 years can lead to increased degeneration resulting in disc bulging and protrusion, decreased resistance to stretching and compression of the annulus fibrosus. The narrowing of the intervertebral space and the relaxation of the surrounding ligaments lead to abnormal intervertebral activity, resulting in bone spurs and protruding discs protruding into the spinal canal at the upper and lower marginal ligament attachments of the vertebral body, causing pressure on the ventral side of the spinal cord. The disc ruptures and prolapses to posteriorly compress the spinal cord, causing symptoms. This is one of the common causes of cervical spondylosis.
How many types of cervical spondylosis are there?
The classification of cervical spondylosis is based on both symptomatology and pathology. The symptomatology classification is more intuitive and is based primarily on clinical features. The symptomatology classification is still the main one.
There are five common types.
1. Cervical cervical spondylosis mainly manifests as pain in the occipital neck, restricted neck movement and stiffness of the cervical muscles. Cervical cervical spondylosis is also called localized cervical spondylosis. In other words, the symptoms and signs are limited to the neck.
2.Neurogenic cervical spondylosis Neurogenic cervical spondylosis is a more common type, mainly manifesting as sensory and motor disorders and reflex changes consistent with the distribution area of spinal nerve roots.
The nerve root symptoms are related to the following factors: the protrusion and prolapse of the nucleus pulposus, the formation of bone redundancy at the posterior edge of the vertebral body, as well as the loosening and displacement of the three adjacent joints to stimulate and compress the spinal nerve root may be important factors in causing symptoms and signs.
3, spinal cord type cervical spondylosis Spinal cord type cervical spondylosis is more common, and the symptoms are serious, once the diagnosis and treatment are delayed, it often develops into irreversible nerve damage. Since the spinal cord is mainly damaged, and the course of the disease is mostly chronic and aggravated by triggers, the clinical manifestation is hypesthesia and upper motor neuron damage symptoms below the damage plane. Below the damage plane, the symptoms are mostly numbness, decreased muscle strength and increased muscle tone.
Patients with spinal cord cervical spondylosis mostly have spinal canal stenosis, and the herniated intervertebral disc, bone redundancy, posterior longitudinal ligament and yellow ligament cause secondary stenosis of the spinal canal, and if combined with vertebral joint instability, it increases the stimulation or compression of the spinal cord.
4, vertebral artery type cervical spondylosis The second segment of the vertebral artery passes through the transverse foramen of the cervical spine and travels beside the vertebral body. When the hook vertebral joint is enlarged, it can cause extrusion and irritation to the vertebral artery, causing insufficient blood supply to the brain and producing symptoms such as dizziness and headache. When the cervical spine is degenerated and the vertebral joint is unstable, the relative displacement between the transverse foramina increases, and the vertebral artery traveling between them has more chances to be stimulated, and the vertebral artery itself can be twisted or even spiraled to come into contact with the hyperplastic leptomeningeal joint.
5, mixed cervical spondylosis It is not uncommon for the neurogenic type and spinal cord type to coexist. Those who combine two or more symptoms at the same time are called mixed type.
What are the clinical manifestations of cervical spondylosis?
Since the pathological changes of cervical spondylosis are diverse, each type of cervical spondylosis has different clinical manifestations and presents different imaging features. The clinical manifestations of each type are described below, and a comprehensive analysis is made with the imaging data.
Cervical cervical spondylosis
1. Age The majority of cases are in young adults. Those with cervical spinal stenosis can develop around the age of 45. Some neck trauma makes it possible for almost all patients to have long-term low head work.
2, symptoms The neck feels sore, painful, swollen and other discomfort. This soreness and swelling is mainly in the back of the neck. And female patients often complain of discomfort in the scapula and shoulder as well. Patients often complain that they do not know what position to put their head and neck in to be comfortable. Some patients have limited neck movement, and a few patients may have transient upper limb numbness, but no muscle strength loss or walking impairment.
3. Physical signs The patient’s neck is usually not distorted. The physiological curvature is reduced or disappeared, and the neck is often pressed and pinched by hand. There may be pressure pain in the interspinous process and paraspinous process.
4.X-ray The physiological curvature of the cervical spine is straightened or disappeared, and the cervical vertebrae are mildly degenerated. Lateral extension and flexion power radiographs can reveal loosening of the intervertebral space in about 1/3 of the cases, showing mild trapezoidal changes, or greater flexion and extension mobility.
Nerve root type cervical spondylosis
1. radicular pain Radicular pain is the most common symptom, and the extent of pain corresponds to the spinal nerve distribution area of the involved vertebral segment. Accompanying with radicular pain are other sensory disorders in the distribution area of the nerve, among which numbness, hypersensitivity and sensory loss are common.
2. Neurogenic muscle disorders In the early stage, increased muscle tone may appear, but soon it will be weakened and muscle weakness and myasthenia gravis will appear. In the hand, the atrophy of interosseous muscle and interosseous muscle is the most obvious.
3, tendon reflex abnormality The tendon reflex is active in the early stage, while the reflex gradually weakens in the later stage and disappears in severe cases. However, pathological reflexes do not appear when there is simple radicular compression, and if there are pathological reflexes, it means that the spinal cord itself is damaged.
4.Special test When there is a herniated cervical disc, a positive cervical compression test can be observed. The spinal nerve pull test is positive. The method is to make the patient sit down, the operator holds the patient’s head with one hand, holds the patient’s wrist with the other hand, and pulls the two hands in opposite directions, if the patient feels pain or numbness in the hand, it is positive. This is due to the brachial plexus nerve being pulled and the nerve root being stimulated.
5.X-ray and CT examination The lateral film shows that the physiological anterior convexity of the cervical spine is reduced, straightened or becomes “anti-flexion line”, the vertebral space is narrowed, the diseased vertebral joint has degeneration, and there is bone spur formation at the anterior and posterior edges. Intervertebral instability is seen in extension and flexion lateral views. Corresponding ossification of the collateral ligament is common in the plane of the diseased vertebral segment. Lateral disc herniation or posterior osteophytes in the diseased segment can be detected and used to determine the sagittal diameter of the spinal canal. MRI can also reveal posterior compression of the dural sac by the vertebral body. In cases of combined spinal cord impairment, changes in the spinal cord signal can be seen.
Spinal cord type cervical spondylosis
1. History Patients are 40-60 years old, with a slow onset and a history of trauma in about 20% of cases. There is often a history of falling pillow.
2.Symptoms The patient starts with bilateral or unilateral sinking and numbness in the lower limbs, followed by difficulty in walking, tightness of the muscles in the lower limbs, slow lifting and inability to walk fast, and in severe cases, obvious gait staggering and even inability to run fast. Poor coordination of both lower limbs and inability to cross obstacles. Both feet have a cotton-like feeling. Self-reported stiffness of the neck and numbness of the extremities when extending the neck back. Sometimes the symptoms of the upper limbs may appear before the symptoms of the lower limbs, but usually slightly later than the lower limbs. Numbness and pain in the upper extremities appear on one side or both sides successively. In the early stage, the hands feel weak when wringing towels in the morning, and often fall to the ground when holding small objects, and cannot button clothes. Some patients have sphincter dysfunction and urinary retention. In addition to the symptoms of the extremities, there is often decreased sensation of the skin below the chest and tightness of the chest and abdomen, i.e. the feeling of girdling.
The most obvious sign is elevated muscle tone in the extremities. In severe cases, muscle spasm can be induced by a slight movement of the extremities, and the lower extremities are often more pronounced than the upper extremities. The symptoms of the lower limbs are mostly bilateral, but the severity may vary. Muscle tone is also elevated in the upper extremities. However, sometimes the prominent symptoms in the upper extremity are muscle weakness and myasthenia with radicular hyperalgesia, while the lower extremity muscle atrophy is not obvious, mainly manifested as myospasm, hyperreflexia, ankle clonus and patellar clonus. The tendon reflexes of all four limbs can be hyperactive, especially in the lower limbs. Hoffmann’s sign is positive in the upper extremity (thumb flexion caused by snapping the finger from above or flicking the middle finger from below is positive), and unilateral positivity of Hoffmann’s sign is more meaningful because it is an important sign when the cervical spinal cord is compressed, and in severe cases, it is often positive bilaterally. In addition to hyperactive tendon reflexes in the lower extremities, ankle clonus is present at a higher rate. The abdominal wall reflex and testicular reflex may be weakened or even disappear.
4.Imaging examination
(1) X-ray lateral film shows that the physiological anterior curvature of the cervical spine disappears or straightens, and most of the vertebrae have degeneration, which is manifested by the formation of bone redundancy at the anterior and posterior edges and narrowing of the vertebral space. Extension and flexion lateral films may show instability of the affected segment, and the collateral ligament in the corresponding plane may sometimes have ossification. Measurement of the sagittal diameter of the spinal canal can be less than 13 mm, and due to individual differences and magnification effects, measurement of the ratio of the spinal canal to the sagittal diameter of the vertebral body can be more revealing, with those less than 0.75 being judged as developmental spinal stenosis. Tomography is relevant in cases of suspected ossification of the posterior longitudinal ligament.
(2) CT examination is more intuitive and rapid in determining the posterior edge of the vertebral body, the size of the sagittal diameter of the spinal canal and disc herniation. It is also possible to find out whether the posterior edge of the vertebral body is located medially or is offset. (3) MRI is more discriminative, and its outstanding advantage is that it can directly observe whether the dural sac is compressed from the sagittal section. Spinal cord cervical spondylosis often shows an arc-shaped compression in front of the spinal cord on MRI images, and multiplanar degeneration can cause the anterior edge of the spinal cord to wave. In cases with degeneration of the spinal cord, enhanced spinal cord signal is seen at the site of degeneration, i.e., the site of heaviest compression. In severe cases, cavity formation may be present.
Vertebral artery type cervical spondylosis
1. Vertigo The most characteristic of this disease is the vertigo attack caused by the rotation of the head. Under normal circumstances, the head rotates mainly between the atlantoaxial vertebrae, where the vertebral artery is compressed. If one side of the vertebral artery is squeezed and the blood flow is reduced, when the head is turned to the healthy side, it can cause vertigo due to insufficient blood supply to the brain.
2.Headache is caused by insufficient blood supply to the vertebral-basilar artery, resulting in the expansion of blood vessels in the collateral circulation. The headache is mainly in the occipital and parieto-occipital areas, but can also be radiated to the deep temporal areas on both sides, with throbbing and swelling pains, often accompanied by nausea and vomiting, sweating and other symptoms of plant nervous disorders.
3.Sudden collapse is a special symptom of the disease. There is no warning before the onset of the disease, and it mostly occurs when walking or standing, and can be triggered when the head and neck are overly rotated or extended and flexed. Before the fall, the patient notices sudden weakness in the lower limbs and falls to the ground, but is conscious, has no impairment in vision, hearing or speech, and can immediately get up and continue to move. This situation is mostly caused by vasospasm of the vertebral artery after stimulation and reduced blood flow.
4.Sensory disorders abnormal facial sensation, numbness around the mouth or tongue, occasional phantom hearing or smell.
5.Imaging features Vertebral artery angiography may reveal twisting and narrowing of the vertebral artery.