[Non-traumatic arachnoiditis and syringomyelia. A series of 32 cases]

We conducted a retrospective study of 32 patients treated for syringomyelia associated with non-traumatic arachnoid scarring. We selected the cases with documented history of arachnoiditis with pre and post-operative clinical evaluation of the neurological status and anatomical study on MRI with a minimal follow-up of one year. Extensive arachnoid scarring (Group I) was noted in 18 cases, after spinal meningitis in 15 cases (tuberculosis in 9 cases, listeria in 3 cases, pyogenic meningitis in 3 cases), subarachnoid hemorrhage in 3 cases. Focal arachnoid scarring (Group II) occurred in 10 cases, related to spinal surgery in 5 cases (meningiomas: 2, neurinomas: 2, thoracic discectomy: 1), to peridural anesthesia in 1 case, thoracic disc herniation in 1 case, Pott's disease in 1 case, no obvious cause in 2 cases. Basal arachnoid scarring without hindbrain herniation (Group III) was associated with birth injuries in 4 cases. Shunting of the syrinx to the subarachnoid or peritoneal cavity was associated with a recurrence rate of 60% whereas microsurgical dissection of the arachnoid scar and decompression of the subarachnoid space with a recurrence rate of 33%, with a mean follow-up period of 28 months. Successful long-term management of the syrinx was associated with basal or focal spinal arachnoid scarring, no history of spinal meningitis, microsurgical dissection of the arachnoid scar and decompression of the subarachnoid space.