What is the appropriate management and treatment for a patient with a thoracic syrinx?

Management and Treatment of Thoracic Syrinx

What is a Thoracic Syrinx?

A thoracic syrinx (syringomyelia) is a fluid-filled cavity within the thoracic spinal cord that can cause progressive neurological dysfunction through compression of neural tissue and disruption of cerebrospinal fluid (CSF) flow 1. The most common underlying cause is Chiari malformation type I, which is present in 25-50% of patients with syringomyelia 1, 2.

Immediate Diagnostic Evaluation

MRI of the entire spine and brain is mandatory—not just the symptomatic thoracic region—because syringes frequently extend beyond the initially suspected area 1, 2. The American College of Radiology recommends comprehensive MRI sequences including T1-weighted, T2-weighted, FLAIR imaging, T2*-weighted gradient echo, and high-resolution heavily T2-weighted 3D sequences 1, 2.

Brain imaging must be included to evaluate for Chiari malformation, as this finding fundamentally changes surgical management 1, 2, 3. Additionally, complete spine imaging can identify other causative pathologies such as arachnoid webs, tethered cord, or hydrocephalus 3, 4, 5.

Surgical Management: The Definitive Treatment

For Chiari Malformation-Associated Syrinx

Posterior fossa decompression (PFD) with or without duraplasty (PFDD) is the first-line surgical treatment for symptomatic Chiari malformation-associated thoracic syrinx 6, 1, 3. The Congress of Neurological Surgeons provides Grade C evidence that both approaches provide benefit for symptom relief and syrinx reduction 6.

• Duraplasty may provide superior syrinx resolution compared to bone decompression alone, though the evidence is not definitive enough to mandate it in all cases 6, 1, 3
• Cerebellar tonsil reduction may be performed during decompression surgery to improve syrinx and symptoms (Grade C recommendation) 6, 1, 3
• The goal is to re-establish physiological CSF flow in the subarachnoid spaces at the craniocervical junction 2

For Non-Chiari Syrinx (Idiopathic, Arachnoid Web, Post-Infectious)

When no Chiari malformation is present, direct surgical treatment of the causative pathology is required 4, 5, 7:

• For arachnoid webs: Laminectomy with resection of the web to decompress the subarachnoid space and restore normal CSF flow 4, 5
• For idiopathic syrinx with focal CSF flow block: Laminectomy, lysis of adhesions, untethering of spinal cord, fenestration of syrinx, and duraplasty 7
• Concomitant midline myelotomy for syrinx drainage can be considered if the patient is symptomatic from the syrinx itself, particularly with rapid symptom onset 4

Critical Timing Considerations

Allow 6-12 months for syrinx reduction after initial surgery before considering additional neurosurgical intervention (Grade B recommendation) 6, 1, 2, 3. This is crucial because:

• Symptom resolution and syrinx resolution do not correlate directly 6, 3
• Radiographic improvement often lags behind clinical improvement 4, 5
• Reoperation is only potentially beneficial if the syrinx has not demonstrated radiographic improvement after 6-12 months 6, 1

Common Clinical Pitfalls to Avoid

Do not assume the syrinx is limited to the thoracic region based on symptoms alone—syringes commonly extend into cervical or lumbar regions and require complete spine imaging 1, 2, 5. One case report documented a thoracic arachnoid web causing syrinx extending rostrally to C1, presenting with upper extremity symptoms 5.

Do not rush to reoperation if symptoms persist immediately post-surgery—the Congress of Neurological Surgeons explicitly recommends waiting 6-12 months for improvement 6, 1, 2, 3.

Do not equate syrinx size with symptom severity—complete collapse of the syrinx does not eradicate all symptoms, and conversely, significant clinical improvement can occur with persistent radiographic syrinx 8, 7.

For patients presenting with unusual pain patterns (such as nipple pain from T5-T6 syrinx), recognize this as referred neuropathic pain from spinal nerve root involvement rather than a primary breast problem 2. Avoid unnecessary breast-focused workup unless additional breast-specific findings are present 2.

Prognosis and Expected Outcomes

Surgical outcomes vary by etiology and surgical approach 6, 4, 5, 7:

• Arachnoid web resection: Can result in complete resolution of symptoms and near-complete syrinx resolution when performed early 4, 5
• Chiari decompression: Provides symptom relief in the majority of patients, though syrinx resolution is variable 6
• Idiopathic syrinx surgery: Can arrest deterioration or provide improvement, though long-term follow-up is required to determine durability 7

Multifocal loculations and arachnoid adhesions are associated with treatment failures and poor prognosis, particularly in post-infectious cases 9.