What is syringomyelia, its typical presentation, diagnostic work‑up, and management options?

Syringomyelia: Definition, Presentation, Diagnosis, and Management

What is Syringomyelia?

Syringomyelia is a fluid-filled cyst (syrinx) within the spinal cord parenchyma caused by disrupted cerebrospinal fluid (CSF) flow dynamics, most commonly associated with Chiari malformation (25-50% of cases), and requires MRI diagnosis with surgical intervention directed at restoring normal CSF flow. 1

The condition has an incidence of approximately 8.4 new cases per 100,000 people annually, with cavities typically located in the cervical cord that can extend rostrally or caudally. 2

Clinical Presentation

Sensory Symptoms

• Dysesthetic "cold burning pain" is the hallmark sensory disturbance, segmental in distribution corresponding to the spinal cord level involved 3
• Hyperesthesia and allodynia commonly accompany the pain, with exaggerated responses to normally non-painful stimuli 3
• Dissociated sensory loss (loss of pain and temperature sensation with preserved light touch and proprioception) develops as the syrinx expands 4

Motor and Progressive Symptoms

• Weakness and muscle wasting develop as the disease progresses 5
• Symptoms typically emerge during the third or fourth decade of life 4
• Natural history shows gradual, stepwise neurological deterioration over many years 4

Associated Findings

• When headache accompanies syringomyelia, evaluate for Chiari malformation first, as this is the most common form and the likely source of cephalic symptoms rather than the syrinx itself 3, 6
• Scoliosis occurs in 2-4% of adolescents with underlying syrinx 1
• In congenital scoliosis, intraspinal anomalies including syringomyelia occur in 21-43% of cases, and a negative neurologic examination does not predict normal imaging 7

Diagnostic Work-Up

Gold Standard Imaging

MRI of both brain and complete spine is the gold standard for diagnosis. 1 The American College of Radiology recommends:

• T1 and T2-weighted sequences for anatomical detail 1
• FLAIR imaging to distinguish syrinx fluid from CSF 1
• T2-weighted gradient echo or susceptibility-weighted imaging* 1
• Pre and post-contrast T1-weighted acquisitions to exclude tumors 1
• High-resolution heavily T2-weighted 3D sequences for the spine 1
• Dynamic MRI with cine-MR sequences to study CSF velocity and flow disturbances 4

Critical Imaging Principles

• Complete spine imaging is mandatory when syringomyelia is suspected, as the syrinx may extend beyond the initially imaged region 1
• Brain imaging must be included to evaluate for Chiari malformation, the most common underlying cause 1

Etiologic Classification (in descending order of frequency)

1. Chiari malformation-associated (most common: 25-50% of Chiari patients) 1, 2
2. Post-traumatic 2
3. Basilar invagination-associated 2
4. Hydrocephalus-associated 2
5. Arachnoiditis-related (infection, inflammation) 4
6. Intramedullary tumor-associated (resolves after tumor resection) 4

Management Algorithm

Indications for Surgery

Early surgical treatment is highly recommended before gross neurological deficits develop. 2 Surgery is indicated when:

• Clinical deterioration occurs 2
• Follow-up MRI shows increase in syrinx size or extension 2
• Progressive neurological dysfunction is present 8

There is no evidence for surgery in incidental asymptomatic syringomyelia or hydromyelia. 4

First-Line Surgical Treatment

Posterior fossa decompression with or without duraplasty is the first-line treatment for Chiari malformation-associated syringomyelia, showing benefit for symptom relief and syrinx reduction. 1 The surgical approach should be:

1. Directed at the underlying cause to normalize CSF flow homeostasis 2
2. Aimed at reconstructing subarachnoid space continuity at the site of CSF flow block 2, 8
3. Case-tailored based on specific pathophysiology 2

Additional Surgical Options

• Cerebellar tonsil reduction may be performed during posterior fossa decompression to improve syrinx and symptoms (Grade C recommendation) 1
• Laminectomy, lysis of adhesions, untethering, syrinx fenestration, and duraplasty for focal CSF flow blocks 8
• Shunting procedures are advocated when reestablishment of CSF pathways proves impossible or as second-line treatment 2

Post-Operative Monitoring

Monitor for syrinx reduction for 6-12 months after initial surgery (Grade B recommendation). 1 Consider additional neurosurgical intervention only if no radiographic improvement occurs after this period. 1

Medical Management

Medical treatment is necessary for chronic pain, which is the main long-lasting symptom even after successful surgery. 4 Conservative treatment alone is not recommended as surgery stops disease progression with clinical improvement being the rule. 2

Critical Pitfalls to Avoid

• Do not assume a thoracic syrinx is causing headache—look for Chiari malformation or alternative explanations first 6
• Do not rely on neurologic examination alone to exclude intraspinal anomalies in congenital scoliosis; MRI is required 7
• Do not delay surgery once progressive symptoms develop, as established neurological deficits are irreversible 2, 4
• Do not operate on asymptomatic incidental findings without evidence of progression 4