Origin of Syrinx Fluid in Syringomyelia: A Physiological Study

Area of Science:

• Neurosurgery
• Neurology
• Radiology

Background:

• The origin of fluid within syrinxes (syrinx fluid) in syringomyelia is a subject of ongoing debate.
• Understanding syrinx fluid origin is crucial for effective treatment strategies.

Purpose of the Study:

• To investigate the mechanisms of syringomyelia, particularly in cases associated with cerebrospinal fluid (CSF) pathway obstruction and intramedullary tumors.
• To evaluate contrast transport from the spinal subarachnoid space (SAS) into the syrinx in patients with syringomyelia.

Main Methods:

• Prospective study of 3 groups of syringomyelia patients: Chiari I malformation (n=22), SAS obstruction (n=16, pre- and post-surgery), and tumor-related (n=9, pre-surgery only).
• Computed tomography-myelography was used to quantify contrast transport into the syrinx by measuring contrast density (Hounsfield units, HU) over 22 hours.
• Key metrics included maximum syrinx HU, area under the concentration-time curve (AUC) for syrinx and SAS, and their ratios.

Main Results:

• Significantly more contrast entered the syrinx in Chiari I malformation and SAS obstruction-related syringomyelia compared to tumor-related cases before surgery.
• The accumulation of contrast (AUC) in both the syrinx and SAS was greater before than after surgical intervention.
• Contrast transport into the syrinx was reduced after decompressive surgery that addressed CSF pathway obstruction.

Conclusions:

• Evidence suggests transparenchymal bulk flow of CSF from the SAS to the syrinx occurs in Chiari I malformation and SAS obstruction-related syringomyelia.
• These findings support the origin of syrinx fluid from the SAS in these conditions, contrasting with tumor-related syringomyelia.
• Surgical decompression effectively restores SAS CSF pathways, diminishing abnormal contrast entry into the syrinx.