Syringomyelia¶

Definition¶

Syringomyelia (syrinx) is a fluid-filled cavity within the spinal cord parenchyma. It is not a disease itself but a finding associated with various underlying conditions. The cavity is lined by glial tissue (unlike hydromyelia, which is dilation of the central canal lined by ependyma — in practice, the terms are often used interchangeably).

Etiology¶

Chiari I malformation — Most common cause; impaired CSF flow at the foramen magnum creates a pressure gradient that drives CSF into the cord
Post-traumatic — Develops months to years after spinal cord injury
Tumor-associated — Intramedullary tumors (ependymoma, hemangioblastoma) can produce a reactive syrinx
Post-inflammatory — After meningitis or arachnoiditis
Tethered cord
Idiopathic — No identifiable cause

Imaging Findings¶

MRI¶

T1-weighted — Low signal (CSF-equivalent) tubular cavity within the cord
T2-weighted — High signal (CSF-equivalent) cavity, often spanning multiple segments
Location — Central within the cord, most commonly cervicothoracic
Cord expansion — The cord is expanded at the level of the syrinx
No enhancement — A non-neoplastic syrinx does not enhance. Enhancement within or adjacent to a syrinx should raise concern for an associated tumor.
Evaluate the craniocervical junction — Look for Chiari I malformation
Evaluate the entire cord — Look for associated tumors, tethered cord, or arachnoid webs

Clinical Pearl

When you identify a syrinx, always search for the cause — the most important step is evaluating the craniocervical junction for Chiari I and the cord itself for an associated tumor. An enhancing nodule adjacent to a syrinx suggests hemangioblastoma or ependymoma. A syrinx that is disproportionately large relative to a small enhancing nodule is characteristic of hemangioblastoma.

Key Points¶

Syringomyelia is a fluid-filled cavity within the cord — always search for the underlying cause
Chiari I malformation is the most common cause
CSF-signal cavity on T1 and T2, central within the cord
No enhancement in a simple syrinx — enhancement suggests tumor
Post-traumatic syrinx can develop months to years after spinal cord injury
Treatment targets the underlying cause (e.g., Chiari decompression)

References¶

Shenoy VS, Munakomi S, Sampath R. Syringomyelia. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537110/
Goetz LL, De Jesus O, Munakomi S, McAvoy SM. Posttraumatic Syringomyelia. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470405/
Syringomyelia. Radiopaedia.org. Available from: https://radiopaedia.org/articles/syringomyelia
Heiss JD, Patronas N, DeVroom HL, et al. Elucidating the pathophysiology of syringomyelia. J Neurosurg. 1999;91(4):553-62.
Schurch B, Wichmann W, Rossier AB. Post-traumatic syringomyelia (cystic myelopathy): a prospective study of 449 patients with spinal cord injury. J Neurol Neurosurg Psychiatry. 1996;60(1):61-7.
Kleindienst A, Laut FM, Roeckelein V, Buchfelder M, Dodoo-Schittko F. Treatment of posttraumatic syringomyelia: evidence from a systematic review. Acta Neurochir (Wien). 2020;162(10):2541-2556.