High lumbar disc herniation refers to the herniation of three interstitial spaces (L1 2, L2 3, L3 4) in the upper lumbar vertebrae, which is characterized by its incidence and clinical manifestations due to the difference in spinal canal morphology, nerve root emission level and biomechanics from the lower two intervertebral spaces.
The incidence of high lumbar intervertebral disc herniation is 16%~6.9%, 17%~5.4%。The reason for the wide variation in incidence is closely related to imaging examinations, and with the widespread use of MRI, it has been found that the number of patients with high protrusion and degeneration has increased significantly. Many high protrusions are accompanied by significant low protrusions.
The pathogenesis is related to the structure of the lumbar spine (lumbar sacralization), physiological flexion, and the mode of force on the motor segments. In the case of a high protrusion, the mechanism of symptoms is different from that of a low protrusion. In the lower L5 and Sacral 1 nerve roots, they originate from or above the plane of the superior disc and cross the upper disc in the spinal canal, so when the disc is herniated, the lower nerve root is often compressed or irritated. However, the nerve roots of L1 3 originate at the level of the pedicle and run obliquely outward and descend obliquely out of the foramen. Therefore, when the high lumbar intervertebral disc is herniated, the herniated disc does not contact with the nerve root, and does not directly stimulate or compress the nerve root, and only some of the higher parts of the lumbar 4 nerve root may be involved, and most of them compress the cauda equina nerve through the dura. Second, the high spinal canal is round or prismatic in cross-section, there are no typical lateral recesses, and even if there is a herniated disc, it is not easy to squeeze the nerve root in the stenosis. Therefore, high lumbar disc herniation does not have typical sciatica, but low back pain as the main symptom. If the protrusion is large and the entire dural sac is pinched, cauda equina syndrome can occur.
When the high lumbar intervertebral disc is herniated, the sacral medulla 3 5 segment and the caudal medulla 1 segment are compressed, the perineum and the surrounding ** sensory loss is produced;If Sacrium 2 is affected, numbness will occur in the posterior thigh, known as "saddle zone numbness." Muscle paralysis at the pelvic outlet, causing flaccid paralysis including bladder smooth muscles (no bladder filling sensation,** and signs of non-emptying. Due to the loss of control of the striated muscle system over the external sphincter, fecal incontinence or inability to defecate spontaneously when abdominal pressure increases. Complete loss of erection and function is called conus medullaris syndrome.
Low back pain and anterior thigh pain are typical symptoms of high lumbar disc herniation, and the cause of low back pain may be caused by tension stimulation of the annulus fibrous and posterior longitudinal ligaments. Pain may radiate to the groin, anterior femor, hip, and, rarely, in a lower prominence, may involve the medial calf. 29.4% present with sudden paraplegia.
Examination shows atrophy of the quadriceps muscles and weakness of knee extension. There may be sensory disturbances in the front of the thighs and the inner calves. The straight leg raise test is negative for lumbar 12 and lumbar 23 protrusion, and the straight leg raise test may be positive for a few patients with lumbar 34 protrusion, and the femoral nerve traction test is positive. The significance of the high herniated femoral nerve traction test is similar to that of low sciatic nerve traction pain. The knee reflex is usually diminished or absent. Large protrusions may have varying degrees of cauda equina syndrome and conus myeloides.
High lumbar disc herniation is easily ignored, and it is necessary to improve the understanding of the symptomatic mechanism of high herniation, and to consider the possibility of high herniation when it cannot be explained by low disc herniation, and then select appropriate imaging tests. MRI should be the first choice for testing, especially when high and multi-space protrusions, to determine the location, size, pathologic type, and degree of compression of the dural sac.
In cases of multiple protrusions, or cases of both high and low prominence, the staggering intervertebral space, commonly referred to as the "responsible" intervertebral space, should be identified.
The clinical manifestations of high lumbar intervertebral disc herniation are diverse, and attention should be paid to the differentiation of atypical cases, both from neuraxial tumors and from general low back pain. It must be ascertained that the low back pain is due to a high protrusion and not to general strain or degeneration.
When the herniated disc in the high lumbar spine is small, no symptoms occur;When symptoms are mild, the symptoms can be conservative**. However, if the symptoms are obvious, reversed, or accompanied by cauda equina nerve symptoms, surgery should be performed. Note that in lumbar 1-2 intervertebral disc herniation, the dural sac is stretched to prevent injury to the conus medullaris. With the development of minimally invasive technology, spinal endoscopy under awake local anesthesia provides the best solution for high lumbar disc herniation.