Lumbar Canal Stenosis
Lumbar canal stenosis means decreased space in the spinal canal of the lumbar spine. The space for the nerve roots in the lumbar spine region is compromised leading to compression of these nerve roots and its symptomatology.
This stenosis can be either central, lateral or foraminal. Lumbar canal stenosis can be present at one or more than one level. Depending on its location and number of levels involved, it may have varied presentations.
CAUSES OF LUMBAR CANAL STENOSIS/ETIOLOGY
Most common cause of lumbar canal stenosis is wear and tear or aging aka degeneration. This leads to dehydration of the intervertebral disc with subsequent changes leading to bulging, herniation, extrusion or sequestration of a disc fragment, degenerative changes in the facet joints with hypertrophy, osteophytes formation around the back of the vertebral body as well as the facet joints, thickening and crumpling as well as ossification of the ligament around the back of the spinal nerves in the spinal canal. Depending on the location of these changes, patients may have presentations of a central, lateral foraminal lumbar canal stenosis.
Presentation of lumbar canal stenosis can be aggravated or occasionally solely caused due to traumatic injury of the lumbar spine leading to fracture, subluxation, dislocation, and injury to the facet of the intervertebral disk. Also patients with congenital lumbar canal stenosis are at increased risk of presentation or symptoms of lumbar canal stenosis.
SYMPTOMS OR PRESENTATIONS OF LUMBAR CANAL STENOSIS
Most common symptom of lumbar canal stenosis is radicular pain in either of the two lower extremities. This pain may be associated with tingling, numbness and rarely weakness of the extremity. Rarely, patients may have involvement of bowel, bladder as well as gait.
Patients with central stenosis usually present with symptoms of neurologic claudication in the form of pain, heaviness of both lower extremities with or without tingling, numbness in both lower extremities.
The presentation is aggravated with prolonged standing or walking certain amount of distance (called Claudication distance), which is usually fixed and may be decreasing with worsening condition. These patients tend to improve with bending forwards and can be seen leaning over a grocery cart in a departmental store (Grocery cart sign) or making frequent stops and stooping forwards to relieve their pain.
Also these patients can go for longer distances on a bicycle and paradoxically going uphill is easier for them than going downhill on a slope. Forward bending helps in decreasing the symptoms while bending backwards can worsen their symptoms.
Rarely these patients can present with acute symptomatology or worsening of neurological status, weakness with or without bowel or bladder involvement. This presentation is termed as cauda equina syndrome that may need immediate and urgent intervention.
NATURAL HISTORY OF LUMBAR CANAL STENOSIS
Most patients with radicular symptoms improve over a span of 4 to 6 weeks and may have complete resolution of their symptoms with conservative treatment. Patients with central canal stenosis especially that of multiple levels and presenting with neurologic claudication usually have mixed prognosis. Studies have shown that a third of these patients will improve over time, a third will stay stable on same presentation while the third will worsen over time. The presentations may be interspersed with episodic worsening and improvement, which can last 4 to 6 weeks. Conservative means with occasional minimally invasive treatments may be required for management of symptoms in most of these patients.
WARNING SIGNS OR RED FLAGS IN LUMBAR CANAL STENOSIS
The patients who have back pain with any of these following conditions should seek medical attention as soon as possible.
- Cancer, neoplasia or malignancy.
- Unexplained weight loss of more than 10 pounds in the last 6 months.
- Immunocompromised comorbidities like on chemo or radiotherapy or having disease like HIV or AIDS or being on prolonged corticosteroid therapy.
- IV drug users.
- Urinary tract infection.
- Fever of more than 100 degrees centigrade.
- Significant trauma from a fall or accident.
- Bowel or bladder involvement in the form of incontinence or retention.
- Weakness in the major joint of the leg.
MANAGEMENT OF LUMBAR CANAL STENOSIS
Most of the patients with lumbar canal stenosis presenting with radicular symptoms or claudication can be treated conservatively. All patients except those who present with red flags should be tried with conservative treatment, which includes medications, physical therapy, change in lifestyle, control of predisposing factors.
If the patients are not improved with these measures then cortisone injection to the back may help in vast majority of these patients. In patients who fail conservative treatment, surgical options should be explored to improve their symptoms and give them a better quality of life.
Surgical treatment essentially involves decompression of the nerve roots and allowing more space to help the nerve roots heal and patient to improve in its symptomatology. This decompression can be done in various ways and from various directions namely front, side and back. Decompression from the back is the most common way especially in patients who do not have the need for concomitant fusion.
Decompression from the back can be performed in a customary open or minimal invasive fashion depending on the patient’s characteristic and presentation. Patients who need fusion surgery along with decompression can be treated from the back, from the side or from the front. A decision as to what procedure and what approach needs to be undertaken is decided based on patient’s characteristic, presentation and decided in discussion with the patient prior to the surgery.
SURGICAL PROCEDURES FOR LUMBAR CANAL STENOSIS
Surgical procedures for lumbar canal stenosis include decompression laminectomy in which the back or the lamina of the vertebral body is removed along with removal of the ligament on the back of the levels to give more space.
This is associated with foraminotomy that is to clean up off the foramens through which the nerve roots pass and freeing the nerve root from the adhesions along its sides while the nerve root passes through the foramen.
Other notable procedures include laminotomy, foraminotomy among others. Occasionally, patient may be a good candidate for lumbar laminoplasty in which the lamina is pried open and held in its place with the mechanical block so as to give more space for the nerve roots in the spinal canal. Patients who need fusion surgery may need surgeries like anterior lumbar interbody fusion, lateral lumbar interbody fusion, posterior lumbar fusion, posterior lumbar interbody fusion, transforaminal interbody fusion. These fusion surgeries can lead to indirect or direct decompression of the nerve roots.
The image shows a lumbar fusion done with transforaminal technique. The fusion is aided by the bone cage which is filled with bone graft. The fusion of the segment results relief from symptoms of lumbar canal stenosis.
SUCCESS RATE FOR LUMBAR CANAL STENOSIS SURGERY
Surgeries for lumbar canal stenosis are usually associated with high success rate. The results are usually gratifying with alleviation of the symptoms of radiculopathy or neurologic claudication. Patients with associated back pain who usually undergo a fusion surgery also have good results.
RISKS AND COMPLICATIONS OF SURGERY FOR LUMBAR CANAL STENOSIS
As for all surgeries there are certain but rare risks for anesthesia including cardiac arrest, stroke, paralysis, and rarely death.
Risks of Lumbar spine surgery may include though not limited to:
- Hematoma or hemorrhage
- Damage to the major vessels which may result in a excessive bleeding, even death
- Damage to the dura, resulting in a cerebrospinal fluid leak
- Failure, loosening or pull out of the graft, cage, implant or plate
- Wound infection
- Failure of fusion to happen
- Damage to the nerve root(s) resulting in new onset or deterioration of preexisting pain, weakness, paralysis, loss of sensation, loss of bowel or bladder function, impaired sexual function, etc., which may or may not recover.
- A few of these conditions may warrant repeat surgery
Certain patient population is at a higher risk for complication which include but are not limited to:
- Obstructive sleep apnea
- High blood pressure
- Other medical conditions involving your heart, lungs or kidneys
- Medications, such as aspirin, that can increase bleeding
- History of heavy alcohol use
- Drug allergies
- History of adverse reactions to anesthesia
WHO ARE GOOD CANDIDATE FOR LUMBAR CANAL STENOSIS SURGERY?
Patients who have radicular symptoms, especially pain or patients who have neurologic claudication and have failed nonsurgical or conservative treatment over a period of more than 6 weeks are usually good candidate for surgical management of lumbar canal stenosis. Patients who also have concomitant back pain should fail a conservative treatment for more than 3 months before going for surgical management of lumbar canal stenosis and back pain.
EXERCISES THAT HELP IN LUMBAR CANAL STENOSIS
Exercises involving strengthening of the core muscles of the back that is the front and the back muscles of the back help in stabilization of the lumbar spine. These should usually be performed under the supervision of a physician or a physical therapist.
Lumbar canal stenosis is a common phenomena in aging population. Patients are asymptomatic in vast majority of population and do not need any treatment. Patients who are symptomatic can usually be treated with conservative means with a successful outcome. Patients who have failed conservative measures and patients with sudden or rapid onset or deterioration of neurological symptoms can be treated with surgery with good results. Patients who have profound neurological involvement may have guarded recovery even after surgical management.