I. Causes
1, congenital spinal stenosis: congenital development process, the lumbar arch root is short and the sagittal diameter of the spinal canal is short. This condition is very rare clinically.
2, degenerative spinal stenosis: the most common clinical, is the result of lumbar spine degeneration, with age, degenerative degeneration include.
(1) The lumbar intervertebral disc degenerates first.
(2) This is followed by vertebral lip-like hyperplasia.
(3) The small posterior joints also proliferate, hypertrophy, coalesce, and protrude into the vertebral canal, and in the case of hypertrophy and hyperplasia of the upper articular processes, narrowing occurs in the lateral saphenous fossa consisting of the back of the upper articular processes and the posterior margin of the vertebral body in the lower lumbar spine (lumbar 4, lumbar 5 or lumbar 3, lumbar 4, lumbar 5), which is passed by the nerve roots and thus can be compressed.
(4) Thickening of the vertebral plate.
(5) Thickening or even ossification of the ligamentum flavum, all of which occupy a certain space in the spinal canal and together become degenerative lumbar spinal stenosis.
The sagittal diameter of the lumbar spinal canal varies greatly among individuals, as do the cervical and thoracic spinal canals, and the sagittal diameter varies. It is the difference between individuals.
3. Other causes.
(1) slipped lumbar spine, the plane of the spinal canal sagittal diameter is reduced.
(2) Central lumbar disc herniation, which occupies the space of the lumbar spinal canal and can produce spinal stenosis symptoms. Both of these conditions have a clear diagnosis and are not clinically referred to as lumbar spinal stenosis.
(3) Secondary, such as scar formation after total laminectomy, which then stenoses the spinal canal, or the relative thickening of the lamina after fusion of the lamina, resulting in local spinal canal stenosis. These cases are rare.
(4) Burst fracture of the lumbar spine, displacement of the vertebral body into the spinal canal, rest during the acute period, asymptomatic, after getting up and moving or after increased activity, symptoms of spinal stenosis may appear.
II. Pathogenesis
1.Intermittent claudication
(1) Clinical manifestations: that is, when the patient walks a few hundred meters (only tens of steps in severe cases), one or both sides of lumbago, leg pain and lower limbs numbness, weakness, and even claudication appear. However, when slightly squatting or sitting down to rest for a few minutes, they can continue to walk again, because there is an interval, so the name is intermittent claudication.
(2) Pathophysiological basis: The appearance of the above clinical symptoms is mainly due to the diastolic contraction of the muscles of the lower limbs, which causes physiological congestion of the vascular plexus of the nerve root in the corresponding spinal canal, followed by venous stasis, causing ischemic radiculitis due to the obstruction of microcirculation here. After a little squatting or sitting or lying down, the symptoms are alleviated or disappear as the source of stimulation from muscle activity is eliminated and the stagnant vascular plexus returns to its normal state, thereby also restoring the normal width of the spinal canal.
2.Contradiction between subjective complaints and objective examination
(1) Clinical manifestations: In all stages of the disease, there are many complaints, especially when the patient walks long distances or is in various forced positions that increase the pressure in the spinal canal, there are more complaints, and there may even be typical manifestations of radiating pain in the sciatic nerve, but there are no positive findings in the examination, and the straight leg elevation test is often negative.
(2) Pathophysiological basis: This is mainly due to the increase of the internal volume of the spinal canal and the return of the internal pressure to the original state due to the short rest and resumption of the forward flexion position before the consultation. At the same time, the rapid restoration of venous plexus stasis in the root canal also helps to eliminate symptoms. This inconsistency between complaints and physical examination can be mistaken for “exaggerated complaints” or “fraudulent disease”. However, in the later stages of the disease, due to various additional factors, such as combined disc prolapse, osteophytes and intracanal adhesions, there may be positive signs due to persistent occupying lesions in the vertebral canal; however, there is a characteristic increase in dynamics.
3.Lumbar posterior extension restriction and pain
(1) Clinical manifestations: The patient complains of local pain when the lumbar spine is extended backward, and it may radiate to bilateral or unilateral lower limbs; however, as long as the position is changed, such as bending the body forward or squatting, and walking or cycling on the road, the symptoms disappear immediately. This phenomenon can also be called “postural claudication”.
(2) Pathophysiological basis: The occurrence of this group of symptoms is mainly due to the reduction or disappearance of the effective space in the canal lumen. This is because when the lumbar spine is changed from neutral to posterior extension position, the length of the spinal canal is shortened by 2.2 mm, the intervertebral foramen is narrowed accordingly, the intervertebral disc protrudes into the spinal canal, and the nerve root cross-section is thickened, resulting in a rapid increase in the pressure in the canal. As a result, the patient’s posterior extension is inevitably limited, and various symptoms occur as a result. However, when the lumbar region is restored to a straightened position or slightly flexed forward, the symptoms are immediately eliminated or relieved as the spinal canal returns to its original width. Therefore, although these patients cannot stand with their chests up, they can walk with their backs bent and can ride a bicycle (i.e., postural type). However, if lumbar disc prolapse is also combined, the symptoms of lumbago and sciatica also appear when the lumbar region cannot continue to be flexed forward or even slightly flexed.
In addition to the three major clinical manifestations mentioned above, other clinical manifestations can also be seen in this pathophysiology, mainly as follows
1, lumbar symptoms: manifested as general lumbar symptoms such as lumbar pain, weakness and easy fatigue, which are mainly due to the stimulation of sinus nerve in the spinal canal; however, the flexion test is negative, which is different from lumbar disc herniation.
2, lower extremity radicular symptoms: mostly bilateral, similar to lumbar disc herniation, characterized by walking, but relieved or disappeared after rest, so the straight leg raise test is mostly negative. This group of symptoms is also due to narrowing of the spinal canal and/or root canal.
Reflex abnormalities: Achilles tendon reflex is easily affected and weakened, mainly because the lower the lumbar vertebral area, the narrower the spinal canal is, so the lumbar 5-sacral 1 segment is easily affected and affects the Achilles tendon reflex; while the knee tendon reflex is mostly normal.
Treatment
Intervertebral foraminoscopy has the advantages of less trauma, higher safety, faster recovery, and a wider range of indications than discoscopy, making it the most advanced treatment technology for minimally invasive spine treatment today.