Myelopathy – Lumbar Disc Herniation

Myelopathy – Lumbar Disc Herniation

Transverse Myelopathy

• Common Location: Transverse myelopathy often occurs in the lumbar and thoracic spinal cord enlargements.

• MRI Findings: Increased signal intensity on T2-weighted images and an increase in the spinal cord diameter.

• Differentiation from Polyneuropathy: Transverse myelopathy usually presents with bowel and bladder dysfunction, muscle atrophy, and faster onset of these symptoms.

• Recovery Process: Typically follows a sequence: motor function -> bowel and bladder -> sensation.

Nerve Root Compression

• L5 Root:

• Sign: Positive heel-walk test.

• Sensory Disturbances: Anterolateral aspect of the lower leg, dorsum of the foot, and the first and second toes.

• S1 Root:

• Sign: Positive toe-walk test.

• Sensory Disturbances: Posterior aspect of the thigh and leg, heel, sole of the foot, and the third to fifth toes.

Disc Herniation

• Types of Herniation:

• Schmorl’s node: Herniation into the vertebral body.

• Protrusion: Disc bulges out without rupture.

• Extrusion: Disc ruptures and some of the nucleus pulposus material escapes.

• Sequestration: A fragment of the disc breaks off and migrates away.

• Multilevel: Herniation at multiple levels.

• Saporta Diagnostic Criteria:

• 4 out of 6 criteria:

• Traumatic event

• Lumbar back pain radiating down the sciatic nerve

• Mechanical pain pattern

• Spinal deviation

• Positive percussion sign

• Positive Lasegue sign

• Barr Triad:

• Reduced disc space height

• Decreased lumbar lordosis

• Deviation and scoliosis of the lumbar spine

• Albumin-Cellular Dissociation: Present in severe disc herniation, particularly with a sequestered fragment.

Nerve Root Compression on X-Ray

• Grade 1: Compression <= 1/4 of the nerve root diameter.

• Grade 2: 1/4 < compression <= 1/2.

• Grade 3: > 1/2 – 3/4.

• Grade 4: Complete compression > 3/4.

Modic Classification

• Type 1: Decreased signal on T1, increased signal on T2.

• Type 2: Increased signal on T1, equal or increased signal on T2.

• Type 3: Decreased signal on both T1 and T2.

Stages of Disc Herniation

• Stage 1: Disc bulge causing pain.

• Stage 2: Nerve root irritation.

• Stage 3: Nerve root compression:

• 3a: Partial conduction loss.

• 3b: Complete conduction loss.

• Stage 4: Disc degeneration.

Principles of Treatment

• Triad of Therapy:

• Epidural injections

• Spinal traction, physical therapy

• Medications

• Surgical Indications:

• Absolute: Sequestered fragment causing cauda equina syndrome or spinal cord compression.

• Relative: Stage 3b or Stage 2 where conservative treatment has been ineffective after 2 months.