Is a T8-9 fusion medically necessary for a 43-year-old female patient with a history of degenerative disc disease, presenting with progressive thoracic myelopathy, worsening numbness and tingling, pain, and weakness in her lower extremities, due to a T8-9 thoracic disc herniation compressing the spinal cord, despite failed conservative therapy with medications?

T8-9 Fusion is Medically Necessary for This Patient

Surgical decompression with fusion is medically necessary for this 43-year-old female with progressive thoracic myelopathy from T8-9 disc herniation causing spinal cord compression, given her failed conservative management and worsening neurological symptoms. 1, 2

Surgical Indication for Thoracic Myelopathy

Clear Evidence of Cord Compression Requiring Surgery

• Surgery is indicated for patients with thoracic disc herniation causing progressive neurologic deficit with signs or symptoms of thoracic spinal cord myelopathy. 2
• This patient demonstrates progressive thoracic myelopathy with worsening numbness, tingling, pain, and weakness in lower extremities, along with balance difficulties and hand paresthesias—all consistent with cord compression. 1
• MRI confirms a 15 mm craniocaudad dimension central-right paracentral disc extrusion abutting the spinal cord with mild cord deformation at T8-9. 1
• The presence of myelomalacia or cord deformation on imaging, combined with progressive symptoms, strongly supports surgical intervention. 1

Failed Conservative Management

• Conservative therapy with medications has failed to control her progressive symptoms. 2
• The patient's symptoms have been progressively worsening despite medical management, with episodes of leg numbness after standing, severe dorsalgia after sitting, and difficulty standing from seated position. 1

Fusion Component is Medically Necessary

Instability Considerations in Thoracic Disc Disease

• While the provider notes uncertainty about instability, the presence of degenerative disc disease with thoracic disc herniation causing myelopathy warrants fusion when decompression is performed. 3, 4
• Thoracic degenerative spondylolisthesis develops secondary to intervertebral disc degeneration, and micromotion due to facet joint laxity and disc degeneration causes progressive myelopathy. 3
• Posterior decompression with fixation/fusion is appropriate for thoracic disc herniation secondary to thoracic disc degeneration. 3
• In cases of thoracic myelopathy with degenerative changes, segmental instability may be present even without obvious spondylolisthesis on static imaging. 4

Evidence Supporting Fusion with Decompression

• Posterior thoracic interbody fusion (PTIF) by bilateral total facetectomies with pedicle screw fixation has produced satisfactory outcomes for myelopathy due to thoracic disc herniation, with average recovery rates of 61% and improvement in modified Frankel grades. 5
• Bony union was observed in 91% of cases (10 of 11 patients) treated with PTIF for thoracic disc herniation with myelopathy. 5
• The extensive decompression required to adequately address central-right paracentral disc extrusion at T8-9 will necessitate facet joint removal, creating iatrogenic instability that requires fusion. 5

Surgical Approach and Timing

Urgency of Intervention

• Approximately 4% of thoracic disc herniations present with acute or progressive myelopathy, and remarkable recovery is possible even with profound neurological deficit and delay of several days, provided the spinal cord is adequately decompressed. 1
• The patient's progressive symptoms with cord compression warrant prompt surgical intervention to prevent irreversible neurological damage. 1, 2

Technical Considerations

• Posterior laminectomy has largely been abandoned for treatment of symptomatic thoracic disc protrusions; surgeons must choose among anterior, lateral, and posterior approaches based on the level, anatomic location, and morphology of the herniation. 2
• For T8-9 level with central-right paracentral disc extrusion, posterior approach with decompression and fusion is appropriate. 5
• Intraoperative hypotension must be strictly avoided, and careful blood pressure monitoring is essential during thoracic myelopathy surgery. 1

Critical Pitfalls to Avoid

• Do not delay surgery in patients with progressive thoracic myelopathy, as neurological deterioration may become irreversible. 1, 2
• Inadequate decompression or failure to stabilize after extensive facetectomy can lead to poor outcomes. 3, 5
• The patient's history of degenerative disc disease for 10 years, combined with current progressive myelopathy, indicates that conservative management is no longer appropriate. 3

Distinction from Lumbar Fusion Guidelines

• The guidelines cited regarding lumbar fusion requiring documented instability, chronic axial pain, or deformity 6, 7 do not apply to thoracic myelopathy from disc herniation with cord compression.
• Thoracic spine pathology causing myelopathy has different surgical indications than lumbar radiculopathy. 1, 2
• The presence of cord compression with progressive myelopathy is itself an absolute indication for surgery, regardless of whether instability is definitively documented on dynamic imaging. 1, 2