STARTING POINT – THE HEALTHY SPINE
The spine consists of vertebral bodies stacked on top of one another with a cartilaginous disc between each of the bony vertebral bodies. The disc is in front and on the posterior side there are two joints (facet joints), one on either side of the spine. These three structures – disc and facet joints – support the spine and allow movement. The spinal canal contains spinal fluid and nerves that lie in a triangular space surrounded by the disc or vertebral bodies in front, and the facet joints in back.
CAUSE OF STENOSIS – NARROWING OF THE SPINAL CANAL
When something protrudes into the triangular spinal canal structure, effectively narrowing it, it is called spinal stenosis. This narrowing may place pressure on the spinal nerves causing pain down the leg, numbness and weakness, and preventing the nerves from functioning properly.
Why does the spinal canal narrow:
- Age-related degeneration
- Herniated discs
- Thickening of ligaments
- Bone spurs
Stenosis can occur in all areas of the spine, but it is most common in the lumbar spine. It usually affects people over 60 years of age and those who have experienced more demanding physical lives with hard labor and whose facet joints have become arthritic and enlarged as a result. However, it can also occur in younger people who have abnormally small spinal canals from birth.
STENOSIS SYMPTOMS – PAIN, NUMBNESS, WEAKNESS
When lumbar spinal nerves are compressed, pain, numbness, and weakness in the legs often results. Areas of discomfort may include thigh, buttocks, and even calves. The sufferer may also experience leg cramping, fatigue and a feeling of heaviness. Usually the leg pain is in both legs but may be in only one. With lumbar spinal stenosis, the pressure on the nerves is from behind so activities where the body is upright (walking, standing) may produce the symptoms. The pressure on the nerves can often be relieved by bending forward or sitting and bending backward. These actions open the spinal canal and relieve the pressure. That is why those suffering from lumbar spinal stenosis can walk farther when shopping if they can lean on a grocery cart.
Lumbar spinal stenosis can lead to a condition called lumbar spondylolisthesis. When arthritic facet joints have degenerated to the point that they crack, the vertebral body can slip forward on top of the vertebrae below it further narrowing the spinal canal.
With cervical stenosis, there can be numbness, weakness or tingling in a leg, foot, arm or hand. In severe cases, nerves to the bladder or bowel may be affected, leading to incontinence.
Wherever the stenosis is located, the symptoms usually worsen with time as the joints slowly enlarge and compress the spinal canal more and more.
NOTE: There is another syndrome that produces leg pain when walking called “Vascular Claudication.” It is caused by blocked arteries in the legs. At rest there may be enough blood to feed the leg muscles, but when the muscles are exercised (when walking) and need more blood and oxygen, the arteries can’t open up to supply the needed blood and the muscles start hurting. Your doctor can distinguish between these by getting a Lumbar MRI and/or Vascular studies of the arteries.
Non-surgical treatment may be advised for very mild stenosis including medication and spinal injections. Pain medication may mask the pain and injections may help alleviate some of the symptoms, but these non-surgical methods will not change the underlying stenotic condition. Physical therapy may also provide some relief from symptoms. However, the spine will continue to degenerate and the symptoms will likely worsen over time.
Lumbar Laminectomy (lumbar decompression surgery)
When the non-surgical treatments fail to produce the desired results, surgery may be recommended and id generally effective. The goal of surgery is to remove the bone overlying the lamina to give the nerves more room.
Laminectomy with Fusion
When the spinal stenosis is accompanied by a slip of one vertebra on another (spondylolisthesis), those two spinal levels are fused together so they won’t slip further after surgery. The fusion is done in conjunction with the laminectomy.
X-STOP- interspinous implant
Another way of opening the space between compressed vertebrae that are impinging on spinal nerves is to add an interspinous device that opens up that space. The X-STOP is essentially a titanium spacer that fits between two spinous processes at the back of the spine lifting the verterbra off the pinched nerve. It is recommended in cases of moderate stenosis. This is considered a minimally invasive surgery.