Non-radiographic crestal fracture dislocation cervical medullary injury is a special type of crestal medullary injury. Previous reports have referred to this type of injury as non-fracture-dislocated crestal medullary injury or non-radiographic abnormal crestal medullary injury, which is a confusing name and imprecise meaning. This type of injury is not uncommon in clinical practice, and there is an increasing trend year by year. From May 1997 to April 2000, 30 patients with this type of injury were admitted to our department, and we will discuss the classification of this group of cases. I. Clinical data of patients A total of 30 patients in this group were non-radiographic crest fracture dislocation cervical medullary injury, including 25 male patients, 5 female patients, the minimum age of 24 years, the maximum age of 67 years, only 5 cases under 40 years. Medical history: shortest 2 hours, longest 7 months. The causes of injury included: fall injury, fall injury, and traffic injury. The mechanism of injury was mostly extension type, and flexion type was predominant. The majority of the cases were incomplete crestal palsy, including 21 cases of central crestal palsy, 3 cases of anterior crestal palsy, and 6 cases of complete crestal palsy. Imaging data X-ray and CT examination: all cases had no signs of fracture and dislocation by X-ray examination, and there were 24 cases of cervical degenerative lesions. 8 cases were examined by CT, 6 cases of spinal stenosis, 4 cases of ossification of the posterior longitudinal ligament and 3 cases of ossification of the ligamentum flavum, 2 of which had both ossification of the posterior longitudinal ligament and ossification of the ligamentum flavum. MRI findings: cervical disc degeneration in 24 cases, disc herniation and prolapse in 21 cases, labral hyperplasia at the vertebral body margin in 23 cases, and spinal stenosis (including discogenic, posterior longitudinal ligament ossification, and ossification of the ligamentum flavum) in 23 cases. Crestal medullary morphology and signal changes: no obvious changes in crestal medullary morphology in 8 cases, local curvature, flattening or depression of the crestal medulla or bead-like changes in 22 cases; crestal medullary signal changes in 28 cases, suggesting crestal medullary hemorrhage and edema in 24 cases, and late crestal medullary degeneration, softening and cavity formation in 6 cases. Among the 30 patients, 12 cases were treated conservatively (occipito-mandibular traction, application of dehydrating agents, hormones, nerve growth factor, etc.) and 18 cases were treated surgically, including 5 cases of anterior decompression fusion and 13 cases of posterior expanded hemivertebral laminectomy or total laminectomy. IV. Discussion About the diagnosis of cervical medullary injury without radiographic crest fracture dislocation. Acute cervical medullary injury is mostly seen after cervical fracture and dislocation, but fractureless dislocation-type cervical medullary injury is not uncommon in clinical practice. In the past, because of the limitations of the detection means, the cause is often presumed to be a transient cervical dislocation, subluxation or the so-called “whip-like injury”, so most of the traction, braking and other methods of conservative treatment, missed diagnosis, misdiagnosis and mistreatment, wrong treatment often occur. With the wide application of CT and MRI in clinical practice in recent years, the diagnosis level has been improved and the understanding of the pathology and injury mechanism has been further deepened. MRI examination is the most reliable examination for diagnosing cervical medullary injury without radiographic crestal fracture dislocation, which can not only show the structure around the vertebral body, the degree of spinal canal stenosis, morphological changes of crestal medullary compression, but also a series of changes such as crestal edema, contusion bleeding, transection and late degeneration, cavity formation and atrophy can be observed in the early stage. Any patient who encounters cervical trauma, including minor injuries such as sensory motor or sphincter dysfunction of the extremities after a fall, as well as patients with a previous history of cervical spine disease who have worsened symptoms or developed paralysis after the injury, must be carefully examined neurologically and routinely photographed with frontal and lateral cervical spine films. If no obvious signs of cervical fracture or dislocation are found, the disease should be highly suspected, and MRI examination is essential at this time. CT examination has a certain diagnostic rate for the disease, but it is easy to miss the diagnosis and is not as direct and objective as MRI, so we think MRI examination should be preferred. V. Etiology and pathogenesis The mechanism of injury is mostly hyperextension type injury, due to the age of the cervical spine often has: disc degeneration, narrowing of the intervertebral space, hypertrophy of the ligamentum flavum, ossification of the posterior longitudinal ligament, osteophytes at the posterior edge of the vertebral body, bone superfluous formation, etc. These primary pathologies are often the pathological basis of cervical marrow injury without fracture dislocation. The mechanism of cervical marrow injury can be summarized into two main categories: hyperextension injury is the main mechanism of injury, the primary lesion of the cervical spine reduces the effective reserve space of the vertebral canal, and the cervical spine is hyperextended during trauma, making the sagittal diameter of the vertebral canal even narrower, resulting in bone superfluous or ossified posterior longitudinal ligament and hypertrophic yellow ligament folds at the posterior edge of the vertebral body, squeezing the crestal marrow from the anterior to posterior direction, causing crestal marrow injury. Another mechanism of injury is acute post-traumatic cervical disc herniation compressing the crestal medulla caused by flexion violence, which is mostly seen in younger patients. When the force is applied to the top of the head or the back of the head, such as a fall from a height, the cervical spine is stressed in a flexion position, the stress is concentrated in the segment with the intervertebral disc as the fulcrum, the superior cervical spine is in anterior dislocation, the posterior fibrous annulus is suddenly under greater tension, and the pressure in the intervertebral disc ruptures, resulting in posterior protrusion of the nucleus pulposus and compression of the crestal medulla. The MRI of this injury is characterized by a significant posterior protrusion of the nucleus pulposus in the corresponding intervertebral space plane to compress the crestal medulla and signal changes of crestal medulla injury. The traditional view is that most of these injuries are central crural injuries, which are usually treated conservatively and have a good prognosis, but the intrinsic hand muscles recover poorly and hand dysfunction is obvious, therefore, most experts advocate early surgery in recent years. We believe that patients without obvious cremaster compression or without spinal stenosis can be treated conservatively on a trial basis, while cremaster injuries with spinal stenosis should be treated with early decompression. Surgical decompression can not only reduce the secondary damage caused by bleeding and edema, but also has a positive significance in preventing re-injury. The pathological changes suggested by MRI can be used not only as an indication for the selection of surgical indications, but also as a basis for the selection of surgical approach. Anterior decompression is indicated for single-segment or two-segment disc herniation compressing the crestal medulla without spinal stenosis, and for limited ossification of the posterior longitudinal ligament compressing the crestal medulla. Posterior decompression is indicated for crestal medullary injuries with spinal stenosis, and expanded hemilaminectomy decompression can be achieved without affecting the stability of the cervical spine. The prognosis of this disease depends on the severity of the crestal medullary injury, but the early or late surgical intervention can affect the outcome of treatment.