With the application of advanced treatment technology, the understanding and diagnosis of the pathogenesis of spinal cord cervical spondylosis has been improved to a large extent, and its surgical treatment has been carried out in succession throughout the country. However, recently we have repeatedly found the phenomenon of clinical misdiagnosis and mistreatment of spinal cord cervical spondylosis, so we again pay attention to its diagnosis and strict surgical indications, and discuss with the majority of clinicians, in order to improve the level of diagnosis and treatment of spinal cord cervical spondylosis in China and reduce errors.
I. Basic concept and diagnostic criteria of spinal cord cervical spondylosis
Spinal cord cervical spondylosis is a kind of degenerative disease of the cervical spine, which is based on the basic pathology of degenerative disc degeneration and the formation of bone redundancy at the posterior edge of the vertebral body of adjacent vertebral segments, which constitutes a compression factor on the spinal cord and/or the blood vessels innervating the spinal cord, resulting in different degrees of spinal cord dysfunction. This disease will increasingly become one of the most common cervical spine disorders that seriously endanger the health of middle-aged and elderly people.
To establish the diagnosis of spinal cord cervical spondylosis, three aspects of homology must be present, namely clinical manifestations, physical signs and imaging features.
(I) Clinical manifestations
The main clinical manifestations are neck pain, arm numbness, walking weakness and change of gait. Pain is a common symptom, which is characterized by aggravation during sleep and disappearance or reduction during daytime; numbness and weakness of upper limbs; and transient impairment of fine hand movements. The above symptoms are related to the degree and location of spinal cord compression, with anterior spinal cord compression showing motor dysfunction and lateral and posterior compression showing sensory dysfunction. The nerve fibers of the sacral, lumbar, thoracic and cervical tracts are arranged from the outside to the inside of the corticospinal tracts, so the order of movement disorders after spinal cord compression is lower limbs first and then upper limbs. The first manifestation is gait staggering in the lower extremities, which gradually develops into increased muscle tone, and then spastic paralysis may appear in the late stage. The order of sensory impairment is also lower extremity first and then upper extremity according to the order of the thalamic tracts in the spinal cord. Numbness of the lower extremities usually appears first, and gradually progresses to the head end. Due to the difference in the degree of the two aspects, the phenomenon of atypical “sensory separation” may occur.
(B) Physical examination
Above the level of spinal cord injury, the typical lower motor neuron signs (upper extremity weakness and reduced or absent reflexes) are manifested; below the level of injury, upper motor neuron signs are manifested, and the effect on the upper extremity is often unilateral, while on the lower extremity is usually bilateral. The Hoffmann reflex and radial aponeurosis reflex are important specific signs of spinal cord compression damage. Hoffmann’s reflex can be affected by changes in head and neck position. When the patient’s head and neck are in posterior extension, a positive Hoffmann reflex can be an important sign for early diagnosis of spinal cervical spondylosis.
(C) Imaging features
Ordinary anteroposterior, oblique, lateral and extension and flexion power radiographs are taken as routine examinations to observe whether there are changes in the intervertebral space, the degree of bulge formation, vertebral slippage and instability, and to measure the sagittal diameter of the spinal canal (less than 11 mm) and the Pavlov ratio (less than 0.75), which are closely related to the occurrence and development of spinal cervical spondylosis and provide a basis for the diagnosis of spinal cervical spondylosis.
The T2-weighted image shows increased signal intensity in the spinal cord, indicating partial irreversible damage to the spinal cord. The spinal cord compression caused by tension reduction of the ligamentum flavum or dynamic fibular ring bulge, vertebral body posterior margin, periarticular foramina, and osteophytes of the small joints can be clearly shown. Dynamic MRI can show the compression of the spinal cord in the dynamic position by early or potential spinal cord compression factors, which is very helpful for the early diagnosis of spinal cervical spondylosis. This can be fully understood in the context of biomechanical changes in cervical spine motion. In posterior extension of the cervical spine, the inferior posterior edge of the superior vertebra moves in the direction of the spinal canal of the inferior vertebra and may protrude into the spinal canal, causing a decrease in the sagittal diameter of the spinal canal by 2-3 mm or sometimes more; at the same time, the spinal cord thickens in the posterior extension position, further reducing the effective space of the spinal canal.
CT scan has its own features in the diagnosis of spinal cord cervical spondylosis compared with MRI, which can clearly show soft tissue structures, but CT is superior to MRI in identifying bony structures, and CT can be used as an adjunct to MRI to distinguish between disc tissue and bone, and CT can clearly show the ossified posterior longitudinal ligament in cross-section.
The above are the general features of spinal cord cervical spondylosis, but the clinical reality is more complex, but it is necessary to extract highly unified and causal (i.e. homologous) clinical manifestations, signs and imaging features from the complex manifestations, and the diagnosis of spinal cord cervical spondylosis cannot be established with only one or two manifestations. Therefore, the diagnosis of spinal cord cervical spondylosis should comply with the principle of “clinical symptoms, signs and imaging should not be missing, and all three should be homologous”.
II. Treatment principles and surgical methods
The pathogenesis and pathological process of spinal cord cervical spondylosis is the direct compression of nerve tissues resulting in ischemia and nerve cell damage. The anterior spinal artery provides 65% to 70% of the blood supply to the spinal cord tissue, and because it is located in the median sagittal position of the spinal cord, it is easily compressed by the bony nucleus and the protruding nucleus pulposus. Most patients with spinal cord cervical spondylosis present with various forms of anterior spinal cord syndrome without posterior spinal cord involvement and loss of vibration sensation, indicating that the main pathological features of early disease are anterior spinal cord compression and ischemia. Therefore, early relief of compression and improvement of spinal cord blood supply has the potential to inhibit the ongoing development of spinal cord lesions.
The mechanical factors in the pathogenesis of spinal cord cervical spondylosis can be divided into static and dynamic factors. Static factors include herniated discs, ossification of the posterior longitudinal ligament, vertebral redundancy and thickened ligamentum flavum, etc. The absolute narrowing of the sagittal diameter of the spinal canal is more important for the development of spinal cord cervical spondylosis; dynamic factors include normal and abnormal motion and load on the cervical spine, which can lead to the instability of a section of the cervical spine, and the local symptoms of the neck are dominant at this time. The two are mutually related, resulting in the formation of vertebral redundancy and other static factors can inhibit the dynamic factors, slowing down the development of the disease; the dynamic factors are not controlled, the static factors continue to grow, and the compression of the spinal cord leads to the occurrence and development of spinal cord cervical spondylosis. Therefore, non-surgical treatment is an effective prevention and treatment method in the early stage of spinal cord cervical spondylosis.
The main purpose of non-surgical treatment is to protect the cervical spine from abnormal dynamic damage, reduce trauma and restore the physiological curvature of the cervical spine. This is achieved by braking, relieving muscle spasm in the neck, reducing nerve root congestion and edema, and reducing disc pressure. Good work and sleep posture is important to maintain or restore the physiological curvature of the cervical spine. Studies have shown that when the cervical spine is excessively flexed forward, the muscles and ligaments at the back of the neck are damaged by tension, and the posterior wall of the dural sac is also affected by tensile stress, thus forming a compressive stress on the spinal cord, and if there is a bone redundancy or disc protrusion in front of the spinal canal, compression of the spinal cord can be formed.
According to the study of the natural course of cervical spondylosis, 70% to 80% of spinal cervical spondylosis has progressive development, therefore, most scholars believe that surgery should be considered once spinal cervical spondylosis is diagnosed. As for the timing of surgery, it is usually believed that it should be within 6 months after clinical onset. For those with clear spinal cord dysfunction, it is not advisable to wait and see, and surgical intervention is an important means to restore spinal cord function.
Third, the differences and misunderstandings in diagnosis and treatment
(1) It is unscientific to search for imaging degenerative signs from fragmented clinical manifestations or to diagnose from imaging degenerative signs combined with fragmented clinical manifestations. Here, we emphasize that “high uniformity” means that the symptoms and signs of neurological damage obtained on physical examination should match with the imaging manifestations, and the three have homology.
(2) Degenerative changes of the cervical spine are a necessary but not sufficient factor for the diagnosis of spinal cord cervical spondylosis. Degeneration has existed since the beginning of life, and when the individual matures, degeneration becomes the main aspect of the conflict, and the cervical spine gradually develops narrowing of the intervertebral space, instability of some motion segments, and compensatory bone formation in the vertebral body. Only when the degeneration reaches a certain degree and the intervertebral disc protrudes (or prolapses) and the bone superfluous overgrowth compresses the spinal cord, does it become the pathological basis of spinal cord cervical spondylosis.
(c) The significance of disc protrusion is determined according to the degree of disc protrusion and the compensatory capacity of the spinal canal. In clinical practice, it is often found that imaging shows obvious disc herniation without corresponding symptoms and signs, or only minor local symptoms in the neck, because the spinal canal is wider and the compensatory capacity is stronger, and despite the large disc herniation, there is no spinal cord injury, so the diagnosis of spinal cord cervical spondylosis is not based on enough. However, there is a potential for morbidity, so follow-up should be strengthened, and once the corresponding symptoms and signs appear, the diagnosis can be made and dealt with in a timely manner.
(d) Whether headache, dizziness, nausea and even vomiting are symptoms of spinal cervical spondylosis is still very doubtful. This symptom is the main complaint in the first consultation, and it can be considered as a possible concomitant symptom of spinal cervical spondylosis, but not the main symptom. Only when the typical symptoms and signs of spinal cord cervical spondylosis, such as numbness of fingers, unstable walking and hyperactive deep reflexes, are extracted from the complicated symptoms of these patients, together with the imaging basis, can the diagnosis of spinal cord cervical spondylosis be established.
(E) Cervical instability has received more and more attention in recent years, and some experts have done a lot of research on it and written it into textbooks as an independent disease. Cervical instability has two kinds of regression: one is through non-surgical treatment, the cervical spine regained stability and healed, mostly seen in traumatic instability; one is unstable, further development, resulting in degeneration of the segment, disc prolapse, vertebral body posterior edge osteophytes, compression of the spinal cord, etc., resulting in the corresponding symptoms, the development of spinal cervical spondylosis, mostly seen in degenerative instability. Therefore, cervical instability and cervical spondylosis cannot be equated, and effective management of instability is of great significance to the prevention of spinal cervical spondylosis.
(f) We believe that the diagnosis of spinal cord cervical spondylosis should be differentiated from neurological disorders with similar symptoms. The unified symptoms, signs and imaging manifestations of spinal cord cervical spondylosis should be summarized from the complex complaints of patients, otherwise the diagnosis should not be made. If the development of spinal cord cervical spondylosis leads to aggravation, surgical treatment of spinal cord cervical spondylosis should be carried out under the coordination of neurology, otherwise, medical treatment and orthopedic follow-up should be carried out.
(7) Correctly understand the value of imaging data in the diagnosis. With the development of high technology and the widespread use of CT, MRI, CTM and other diagnostic techniques, the value of imaging data has been emphasized one-sidedly, and the phenomenon of “a film to determine surgery” has become more and more common, ignoring the comprehensive physical examination; we still emphasize that detailed and comprehensive physical examination is the primary, basic, non-negligible and most valuable information for the diagnosis of spinal cervical spondylosis.
(H) Early diagnosis of spinal cord cervical spondylosis is the fundamental guarantee of better treatment. The symptoms and signs of diagnosed spinal cord cervical spondylosis can be broadly divided into two categories, namely the early and late manifestations of spinal cord cervical spondylosis. The early manifestations are mainly: slowed or uncoordinated rapid change movements, difficulty in tandem gait, absence of fine movements, mild hyperreflexia, mild or discontinuous clonus, decreased proprioceptive function, and positive Hoff-mann sign in posterior cervical extension. In the late stage, the symptoms are: spasticity, difficulty in regular gait, obvious motor deficits, obvious hyperreflexia, continuous clonus, obvious impairment of balance, and positive Babins-ki sign. Early clinical and imaging manifestations should be correctly grasped to make timely diagnosis.
(ix) We classify patients with spinal cord cervical spondylosis according to their clinical characteristics: sudden-onset type, progressive aggravation type, stable type and self-limiting type. Sudden type: the patient’s condition will suddenly aggravate, leading to complete or incomplete paralysis of the limbs in severe cases; progressive aggravation type: symptoms and signs from mild to severe, with corresponding changes in imaging performance; stable type: symptoms recurrent but no obvious signs of aggravation; self-limiting type: symptoms improve after medical treatment. The above classification is very important for the identification and treatment of spinal cord cervical spondylosis, the rational selection of treatment methods and the optimization of the overall treatment effect of spinal cord cervical spondylosis. The sudden onset of spinal cord cervical spondylosis is more dangerous, without significant onset signals, and once it occurs, the effect of surgery is negatively correlated with time, so surgery should be performed as early as possible. Spine surgeons should pay high attention to this type of patient and emphasize “surgery as soon as the disease develops”. Progressive exacerbation is the most common type of spinal cord cervical spondylosis, with a history of early symptoms progressing to late symptoms and signs, and imaging manifesting as single-segment or multi-segment disc herniation, most of which require early surgery. The stable type has recurrent symptoms without a tendency to worsen, and the disc degeneration is mostly single-segment, with only slight compression of the spinal cord by the herniated material, and chronic onset, which is mostly treated non-operatively. The self-limited type is treated non-operatively and the symptoms are reduced or disappear, and the imaging data shows obvious disc herniation without clinical symptoms and signs, so follow-up should be strengthened. The word “early” in early surgery for spinal cord cervical spondylosis should be defined as the early clinical manifestation of spinal cord cervical spondylosis and the imaging manifestation before the signal of the compressed part of the spinal cord is changed.
(J) The choice of the surgical approach for spinal cord cervical spondylosis is still controversial. There is no theory to deny that the compression of the spinal cord is the primary factor leading to spinal cord cervical spondylosis, so any approach can be used as long as the compression can be removed, the spinal cord compression can be completely lifted, the trauma is small, the surgery is simple, easy to operate, and the risk is low. However, the larger the surgery, the better, the more complex the better, and some people are keen to perform both anterior and posterior approaches simultaneously, inappropriately expanding the scope of decompression, and it is worth discussing whether these practices are necessary. There are three criteria to measure whether the surgery is good or bad: (1) whether the spinal cord compression is completely lifted, whether the volume and shape of the spinal canal is restored, and whether the normal height of the intervertebral space is restored and maintained; (2) whether the trauma is minimal and the complications are minimal; (3) whether the postoperative function can be restored to the best, with a more lasting effect.
(k) With the development of new technologies and materials, there are more and more devices for internal fixation of cervical spine surgery, and some clinicians also pursue the word “new” and the “first case” report. We believe that it is not desirable to follow the old ways and encourage innovation and development, but we should further realize that the important thing to improve the efficacy of spinal cord cervical spondylosis is not the choice of internal fixation, internal fixation as long as it can achieve the purpose of reconstruction and stability, the key is reasonable decompression, try to avoid the loss of physiological function, one-sided pursuit of the application of advanced internal fixation, ignoring the traditional effective bone grafting methods, which often makes the long-term outcome poor. The long term effect is often poor. There is only one criterion for internal fixation: simple operation, minimal trauma, thorough and reasonable decompression, lowest cost, fewer complications, and stable and reliable internal fixation effect.
The surgical treatment of spinal cord cervical spondylosis has been widely carried out throughout the country, and many mistakes have been made. We propose the above views for discussion with the aim of improving the level of diagnosis and treatment of spinal cord cervical spondylosis in China and improving the quality of medical treatment.