Lumbar Disc Herniation and Cauda Equina Syndrome

Lumbar Disc Herniation and Cauda Equina Syndrome

Lumbar disc herniation (LDH) is a condition in which the nucleus pulposus of an intervertebral disc protrudes beyond its normal boundaries, typically into the spinal canal.

Anatomy of the intervertebral disc:

• Nerves: Luschka’s recurrent nerve (a branch of the spinal nerve originating from the spinal ganglion).

• Blood vessels: No blood vessels, nourished by osmosis.

Ligament system of the lumbar spine:

• Anterior to the vertebrae: Anterior longitudinal ligament.

• Posterior to the vertebrae: Posterior longitudinal ligament -> dura mater -> yellow ligament -> interspinous ligament -> supraspinous ligament.

Causes of LDH:

• Degeneration of the intervertebral disc combined with trauma or strenuous activity.

• Normal intervertebral disc but subjected to strong impact forces.

Clinical presentations of LDH:

1. Anterior LDH: Spinal syndrome (because there are no nerves at this location).

2. Central posterior LDH: Spinal syndrome.

3. Posterolateral LDH: Spinal syndrome + nerve root syndrome.

4. Foraminal LDH: Severe pain (due to direct nerve compression).

5. Pseudotumor type LDH: Herniated disc enters the spinal canal (due to strong impact force) -> cauda equina syndrome.

6. Multilevel LDH: Multiple nerve root damage.

7. Intravertebral LDH: Due to strong impact force -> spinal syndrome.

8. Bilateral LDH: Bilateral disc herniation syndrome.

Clinical symptoms of LDH:

• Spinal syndrome:

• Corresponding spinal pain point.

• Spasm of the paravertebral muscle mass.

• Restricted spinal movement in all directions: bending, hyperextension, lateral flexion, rotation, Schober (< 14/10), fingertip touching the ground (-).

• Nerve root syndrome:

• Nerve root tension syndrome:

• Pain at the edge of the spine.

• Valleix’s, Dejerine’s, Lasegue’s, percussion, Neri’s, Siccar’s, Bonnet’s pain points (+), ….

• Nerve root damage syndrome (L4/L5/S1): Motor, sensory, reflex, nutritional symptoms.

Assessment of functional damage to the nerve roots:

• Motor:

• L5: Controls the movement of the anterior tibial muscle group -> dorsiflexion of the foot and flexion of toes 1, 2 towards the dorsum. Examination: Patient dorsiflexes the foot/flexes the big toe/stands on the heel -> if damaged, the patient cannot do this.

• S1: Controls the movement of the posterior calf muscle -> plantar flexion of the foot. Examination: Patient plantar flexes the foot/flexes the big toe/stands on tiptoes -> if damaged, the patient cannot do this.

• Reflexes: Patellar tendon reflex (L3, L4 nerve roots) and Achilles tendon reflex (S1 nerve root).

• Sensation:

• L4: Anterior and lateral thigh -> anterior medial leg.

• L5: Along the posterior thigh -> anterolateral leg.

• S1: Along the posterior thigh, leg, heel, sole of the foot.

• Nutrition: Similar.

Why does LDH cause spinal deviation?

• Patients with LDH often tilt their spine towards the healthy side to reduce pressure on the injured side, helping to reduce pain. This is a sign that helps with diagnosis.

Barr’s triad on X-ray of LDH patients:

1. Reduced height of the intervertebral space.

2. Reduced lumbar lordosis.

3. Deviation, scoliosis of the lumbar spine.

Why is the intervertebral disc not visible on X-ray?

• Because the intervertebral disc is 80-85% water, and water does not block X-rays -> the intervertebral disc is not visible on X-ray.

Significance of MRI in LDH:

• Provides 4 diagnoses: definitive diagnosis, severity, type, localization.

• Does not provide a stage diagnosis.

Method of lumbar spine myelography:

• Procedure: Inject contrast agent into the cancellous bone of the lumbar spine -> the agent enters the vascular system of the spinal canal.

• Interpretation of results: The vascular system of the normal spinal canal will have a certain shape. When the patient has LDH, it will compress the vascular system of the spinal canal, creating pathological images such as: dilated blood vessels, compression, blurring,….

Diagnostic criteria based on LDH clinical presentation:

• According to Saporta (1970): Determined when there are 4/6 of the following symptoms:

1. Presence of trauma factor.

2. Pain in the lumbar spine radiating along the sciatic nerve.

3. Pain with a mechanical nature.

4. Spinal deviation.

5. Percussion test (+).

6. Lasegue test (+).

Diagnosis of the degree of nerve root compression (NRC) on nerve root compression imaging (contrast agent injection into the spinal cord):

• According to H? H?u L??ng:

• Degree I: NRC <= 1/4 of the NRC diameter.

• Degree II: 1/4 < NRC <= 1/2.

• Degree III: 1/2 < NRC < 3/4.

• Degree IV: NRC > 3/4.

Diagnosis of LDH stage:

• According to Arseni K (1973):

• Stage 1: Disc bulge causing localized low back pain.

• Stage 2: Nerve root irritation (nerve root tension): Pain at the edge of the spine, Lasegue/Siccar,….

• Stage 3: Nerve root compression.

• 3a: Loss of a part of the nerve area.

• 3b: Complete loss of nerve area: Patient loses sensation, atrophy, and paralysis of the corresponding muscles.

• Stage 4: Disc-joint degeneration, disc degeneration, secondary vertebral joint degeneration, persistent low back pain difficult to recover.

Treatment of LDH:

• 90-95% of patients with LDH are treated conservatively, only about 5-10% need surgery.

Principles of conservative treatment:

• The success of treatment is determined by the combined application of 3 therapies:

1. Epidural injection.

2. Spinal traction, physiotherapy.

3. Medication: NSAID pain relievers, muscle relaxants, vitamins, etc.

Conservative treatment for patients with LDH:

• Immobilization:

• Lie on a hard bed for 5-7 days during the acute phase.

• Relative immobilization when the patient feels pain.

• Pain relievers and anti-inflammatory drugs: Aspirin, celecoxib,….

• Muscle relaxants: Mydocalm.

• Sedatives and high-dose B vitamins.

• Corticosteroid therapy.

• Spinal traction.

• Physiotherapy, acupuncture, acupressure.

• Combine some special methods: Nucleus pulposus dissolution, intradiscal injection, percutaneous aspiration, laser treatment.

• Epidural injection therapy.

Epidural injection therapy for patients with LDH:

• Indication: LDH and lumbosacral syndrome due to spinal degeneration.

• Contraindication:

• Severe systemic diseases (heart, kidney,…).

• Infection of the skin at the site of the procedure.

• Contraindication to corticosteroids and anesthetics.

• Medication:

• Corticosteroids 1-2 ml.

• Local anesthetics (lidocaine, novocain,…): 3-5 ml.

• Treatment regimen: Inject once every 2-3 days, inject for 5-6 times.

Some minimally invasive disc intervention methods:

• Percutaneous laser-assisted reduction of intradiscal pressure: Use a laser to vaporize a portion of the nucleus pulposus (which contains 80% water).

• Percutaneous thermal intradiscal intervention: Use heat to cut away a portion of the nucleus pulposus.

• Manual-controlled percutaneous removal of a portion of the intervertebral disc.

Absolute indications for LDH surgery:

• Cauda equina syndrome.

• Spinal cord compression syndrome.

Relative indications for LDH surgery:

• Stage 3b.

• Stage 2, 3a but conservative treatment fails within 2 months.

Cauda equina syndrome:

• Cauda equina syndrome is caused by compression of a bundle of nerve roots called the cauda equina. These nerves are located at the end of the spinal cord in the lumbosacral spine. They send and receive signals to and from the legs, feet, and pelvic organs.

• Cauda equina syndrome is a complex neurosurgical emergency. If not detected and treated promptly, the patient will experience motor paralysis with sensory, nutritional disturbances in one or both legs and the anorectal area, and dysfunction of the bladder sphincter.

• Symptoms of cauda equina syndrome appear quickly and often in combination with each other at various levels: pain in the lumbosacral area, lower extremities, sensory and motor disturbances,….

Causes of cauda equina syndrome:

• Lumbar disc herniation: Most common.

• Spinal stenosis: Approximately 15% of cases of low back pain are related to spinal stenosis. Normally, the anteroposterior dimension of the lumbar spinal canal is about 13-15mm. If the anteroposterior dimension is less than 13mm, it is considered spinal stenosis.

• Nerve root tumor in the cauda equina: This is the most common cause of cauda equina syndrome within the dura mater.

• Intramedullary tumor in the cauda equina: This is a type of tumor that originates from the end of the spinal cord and progressively damages the entire lumbosacral sac, making surgery difficult.

Symptoms of cauda equina syndrome:

• Severe low back pain.

• Muscle weakness, loss of sensation, or pain in one or both legs, more commonly in both legs. Loss of reflexes in the legs.

• Loss of sensation in the saddle area.

• Bladder dysfunction: Urinary incontinence.

• Loss of sensation in the bladder or rectum.

• Newly-onset sexual dysfunction.

Treatment of cauda equina syndrome:

• Surgery should be performed promptly to prevent permanent damage, such as paralysis of both legs, loss of bladder and bowel control, sexual function or other problems.

Treatment measures for cauda equina syndrome:

• Best treatment is within 48 hours of the onset of symptoms.

• Surgery should be performed promptly.

• High-dose corticosteroids.

• If infection is diagnosed, antibiotics may be necessary.

• If the cause is a tumor, radiation therapy or chemotherapy may be necessary after surgery.

• Treatment of neuropathic pain.

• Sexual rehabilitation.