[Progress on the cause and mechanism of a separation of clinical symptoms and signs and imaging features in lumbar disk herniation].

A few of patients with lumbar disk herniation having a separation of clinical symptoms and signs and imaging features, can be found in clinic, but the traditional theory of direct mechanical compression of nerve roots by herniated nucleus pulposus can't be used to explain this abnormal protrusion of lumbar intervertebral disc. The clinical symptoms and signs of the atypical lumbar disk herniation are affected by multiple factors. The indirect mechanical compression and distraction effect of spinal nerve roots may play an important role in the occurrence of the separation, and the appearance of abnormal clinical symptoms and signs is closely related to the migration of herniated nucleus pulposus tissue, transmission of injury information in the nervous system, and the complex interactions among the nucleus pulposus, dural sac and nerve roots. Moreover,the changes of microcirculation and inflammation secondary to the herniated nucleus pulposus tissue, the hyperosteogeny in the corresponding segment of the lumbar vertebrae and the posture changes all results in a diversity of symptoms and signs in patients with lumbar intervertebral disc herniation. Besides, there exist congenital variation of lumbosacral nerve roots and vertebral bodies in some patients, and the misdiagnosis or missed diagnosis of imaging finding may occur in some cases. However, the appearance of a separation of clinical symptoms and signs and imaging examination in patients may be caused by a variety of reasons in clinic. The exact mechanism involved in the interaction among nucleus pulposus tissue, dural sac and nerve root, secondary changes of pathophysiology and biomechanics around the nucleus pulposus, the determination of lesioned responsible segments, and how to overcome the limitations of imaging all need the further researches.