What is a syrinx (syringomyelia)?

From the Guidelines

A syrinx, particularly when associated with scoliosis, should be evaluated with MRI to assess for underlying neural axis anomalies, as early intervention can be crucial in preventing progression and improving outcomes, as suggested by Krieger et al 1. When considering the management of a syrinx, it's essential to understand that this condition can be asymptomatic or associated with significant morbidity, including pain, weakness, and sensory disturbances. The presence of a syrinx in patients with scoliosis may indicate an underlying condition such as Chiari I malformation, which can have implications for treatment and prognosis.

Key Considerations

• The diagnosis of a syrinx is typically made using MRI, which can also help identify associated conditions like Chiari malformation or spinal cord tethering.
• Treatment of a syrinx depends on the underlying cause, symptom severity, and the presence of associated conditions.
• For patients with scoliosis and a syrinx, particularly those with curves greater than 20 degrees, early intervention with surgical decompression may be beneficial in preventing curve progression and reducing syrinx size, as noted in the study by Krieger et al 1.
• Regular monitoring with MRI scans is crucial for managing asymptomatic or mildly symptomatic cases, allowing for the detection of any changes in syrinx size or the development of new symptoms.
• Physical therapy can play a role in managing symptoms and maintaining spinal function, especially in patients with significant curvature or those undergoing surgical intervention.

Management Approach

• For symptomatic patients or those with significant curvature, surgical intervention should be considered to address the underlying cause of the syrinx, such as decompression surgery for Chiari malformation or shunt placement to drain the syrinx, as these interventions can improve outcomes and prevent further neurological deterioration 1.
• In asymptomatic patients with a syrinx and minimal curvature, regular follow-up with MRI scans and clinical evaluation is recommended to monitor for any changes in the syrinx or the development of symptoms.
• The presence of risk factors such as left thoracic curve, short segment curve, absence of apical segment lordosis/kyphosis, and rapid curve progression should prompt further evaluation with MRI to assess for neural axis anomalies, as these factors can increase the likelihood of underlying conditions that may require intervention 1.

From the Research

Definition and Causes of Syrinx

• Syrinx refers to a fluid cavity extending beyond several segments within the spinal cord, which is a condition with many possible causes 2.
• The most common cause of syrinx is hindbrain herniation with or without associated arachnoid thickening, followed by spinal arachnoiditis, especially with paraplegia, and intraspinal tumors 2.

Treatment Options for Syrinx

• Posterior fossa decompression with expansive duraplasty is the first-line surgical approach for the treatment of symptomatic syringomyelia associated with Chiari malformation 3, 4.
• A syringosubarachnoid (S-S) shunt may be used as a secondary option for patients who do not improve with posterior fossa decompression 3.
• Syringoperitoneal and syringopleural shunts are also accepted treatment options for patients with persistent syringomyelia 5.

Outcomes of Treatment Options

• Posterior fossa decompression has a considerable chance of clinical improvement, with 76% of patients experiencing improvement in the early follow-up period and 68% in the late follow-up period 4.
• The use of a syringosubarachnoid shunt has been shown to be effective in reducing the size of the syrinx and improving neurological deficits 3.
• A systematic review and meta-analysis found that syringopleural shunts may offer the best rate of clinical improvement with the lowest rate of reoperation, while syringoperitoneal shunts have a greater rate of malfunction requiring surgical revision 5.

Challenges in Management

• The management of patients with persistent syringomyelia after posterior fossa decompression is problematic, with high failure rates of reoperation and syrinx shunting 6.
• Despite "radiographic failure," good symptom control can be achieved in some patients, supporting a conservative approach in this population 6.