FIGURE 2
After two years of symptomatology and multiple interventions, MRI demonstrated worsening spinal cord edema and extension of the syrinx into the cervical spine to the level of C1( yellow arrows).
Due to rapid progression of upper extremity symptoms, the patient then underwent C6- C7 laminectomy with myelotomy, intradural lysis of adhesions, and syringo-subarachnoid shunt placement. Despite multiple surgical interventions, his quadriparesis worsened, and subsequent MRIs did not show any improvement in the spine syrinx. Given the lack of further surgical options, the patient explored clinical trials but was not deemed an appropriate candidate. He continued to participate in aggressive physical therapy but ultimately died from complications related to his neurological decline.
DISCUSSION
We present a rare and complex case of syringomyelia developing nearly six years after SAH, secondary to adhesive arachnoiditis. Despite multiple surgical interventions, including intradural lysis of adhesions, tethered cord release, and both syringo-peritoneal and syringo-subarachnoid shunt placements, the syrinx and associated symptoms continued to progress. This case illustrates the challenges in managing delayed post-SAH syringomyelia and highlights the urgent need for more effective therapeutic strategies.
Syringomyelia caused by adhesive arachnoiditis following SAH is an uncommon but clinically significant phenomenon. While numerous reports describe syringomyelia resulting from spinal arachnoiditis or arachnoid scarring, 3-10 its incidence remains low, estimated at two to four cases per 100,000 individuals. 11 A subset of the literature specifically linked arachnoiditis and syringomyelia to prior SAH. 4, 5, 8
Although various theories have been proposed to explain the pathophysiology of syringomyelia secondary to arachnoiditis 12, 13, a definitive mechanism has not been established. These hypotheses converge on a common pathway: an inciting event( e. g., SAH, trauma, surgery, infections, or tumor) initiates an inflammatory response within the subarachnoid space, leading to leptomeningeal fibrosis, dural adhesions, and scar formation. These structural changes can encapsulate nerve roots and obstruct CSF flow, resulting in chronic adhesive arachnoiditis and subsequent syringomyelia. 13-15 These changes give rise to distinct radiologic findings, including central clumping of nerve roots within the dural sac, peripheral adhesions, tethering, obliteration of the subarachnoid space by soft tissue, pial and dural enhancement, canal enlargement, and signal abnormalities in the spinal cord and CSF. 14 MRI has proved highly effective in diagnosing chronic adhesive arachnoiditis, with reported sensitivity of 92 %, specificity of 100 %, and accuracy of 99 %. 16
CSF dynamics are typically disrupted at the level of the adhesive arachnoiditis. The exact composition of syrinx fluid, whether CSF or extracellular fluid, remains unclear. Recent studies suggest that altered flow dynamics and pressure gradients involving CSF and extracellular fluid contribute to edema and syrinx formation, with fluid accumulation arising from the spinal cord’ s microcirculation. 9, 14 The resulting syrinx associated with adhesive arachnoiditis is usually distal to the site of CSF blockage. 17 Blocked CSF flow may also result in hydrocephalus, as was observed in our patient. 15
Rupture of aneurysms in the posterior fossa is the most common cause of SAH and may be associated with a higher risk of adhesive arachnoiditis than aneurysms in the anterior circulation. 5 Although rare, arachnoiditis secondary to SAH often localizes to the thoracic spine, the region most vulnerable to scarring. 8 Clinically, patients typically present with signs of myelopathy and radiculopathy, such as paraparesis, lower extremity spasticity, and bladder dysfunction. 14 However, subclinical presentations are also possible.
Our patient initially presented with paraparesis, which gradually progressed to tetraplegia, dysesthesia, and neurogenic bowel and bladder. Imaging revealed extensive arachnoiditis and scarring throughout the thoracic spinal cord with a thoracic syrinx that later extended to the C1 level. In published cases where both the syrinx and arachnoiditis were reported, they generally co-localized at the same spinal cord region as the adhesive arachnoiditis( i. e., cervical syrinx and cervical arachnoid scar or thoracic syrinx and thoracic arachnoiditis). 9 The latency period between SAH and syrinx onset is variable, ranging from one month to 12 years. 2, 18 In our case, the interval between SAH and syrinx presentation was nearly six years, signifying the importance of vigilance and follow-up on post- SAH patients.
Several surgical treatments for adhesive arachnoiditis have been described. 6, 7, 9 Syrinx shunting, subarachnoid bypass, and foramen magnum decompression have been proposed as options to normalize pressure gradients and CSF flow. 1, 9, 12 Syrinx shunting may be particularly useful in cases where arachnoiditis spans multiple spine levels. 6 However, long-term outcomes are often unsatisfactory, with many shunts failing due to ingrowth of glial tissue, cord tethering, infections, or, in our case, extensive syrinx septation. 6, 16 Another treatment option is direct microsurgical dissection of the arachnoid scar and release of tethered cord. 19 Albeit dangerous in certain instances, this procedure has been shown to be successful. 6, 7 However, postoperative recurrence of scar tissue after microlysis remains a concern, thus meticulous surgical technique should be emphasized as a preventive strategy. 10 In cases involving arachnoid webs, surgical division of the webbing, with or without shunting, has been employed successfully. 3 As a last resort, cordectomy may be considered for patients with progressive, end-stage myelopathy marked by severe spasticity or neurogenic decline. 20
Ultimately, no best treatment strategies have been identified. Nonetheless, the management must be individualized based on clinical presentation, radiologic findings, and disease progression.
West Virginia Medical Journal • June 2026 • 17