What is sacral ductal ectasia?

Sacral Dural Ectasia

Sacral dural ectasia is a ballooning or widening of the dural sac (the membrane covering the spinal cord) in the lower spine, most commonly occurring in the lumbosacral region, and is strongly associated with connective tissue disorders, particularly Marfan syndrome. 1, 2

Definition and Pathophysiology

Dural ectasia represents an abnormal expansion of the dural membrane that can extend into the sacral region, creating enlarged cerebrospinal fluid-filled spaces. 2 This occurs due to errors in collagen biosynthesis, particularly in patients with Marfan syndrome and other connective tissue disorders. 3

Clinical Significance

Association with Marfan Syndrome

• Dural ectasia is considered a major diagnostic criterion for Marfan syndrome in the Ghent nosology, reflecting its strong association with this condition. 1
• The condition occurs very rarely outside of systemic connective tissue disorders, making it diagnostically significant when identified. 1

Clinical Presentations

Sacral dural ectasia can present in several ways:

• Many patients remain completely asymptomatic despite significant radiographic findings, as demonstrated in case reports of large anterior sacral meningoceles without associated symptoms. 2
• When symptomatic, patients may experience back pain, headaches (particularly postural headaches from CSF leak), radiculopathies, or incontinence. 2, 4
• In rare cases, large sacral meningoceles can cause compression of adjacent structures, including bilateral ureteric obstruction leading to hydroureteronephrosis, acute renal failure, or urosepsis. 3, 4

Diagnostic Considerations

Imaging Characteristics

• The severity of dural ectasia is age-dependent, with radiographic features becoming more pronounced over time. 1
• MRI is the imaging modality of choice for evaluating the extent of dural ectasia and any associated complications. 4

When to Image

• If the diagnosis of Marfan syndrome is already established and the patient has no back pain or radicular symptoms, routine imaging of the lower spine is not necessary. 1
• However, if the diagnosis of Marfan syndrome is uncertain and depends on whether dural ectasia is present, then imaging is warranted despite the effort, expense, and potential radiation exposure. 1

Management Approach

Conservative Management

• Asymptomatic patients with Marfan syndrome and dural ectasia should be closely observed without immediate surgical intervention. 2
• This recommendation is based on the recognition that many patients with significant radiographic findings remain symptom-free. 2

Surgical Intervention

Surgical treatment is reserved for specific complications:

• Progressive hydroureteronephrosis from ureteric compression may require combined neurosurgical and urologic intervention. 4
• Symptomatic cases with postural headaches from CSF leak and progressive compression of adjacent structures warrant surgical consideration. 4
• Large pelvic meningoceles causing acute ureteric obstruction and urosepsis require urgent surgical decompression. 3

Important Distinctions

Do not confuse sacral dural ectasia with other conditions:

• This is distinct from cauda equina syndrome, which involves compression of nerve roots rather than dural expansion. 1
• It differs from the Currarino triad, which includes sacral bony defects, anorectal malformations, and presacral masses. 1
• Sacral dural ectasia should not be confused with ductal ectasia in other organ systems (such as mammary or pancreatic ductal ectasia), which are entirely different pathologic entities. 5, 6

Clinical Pitfalls to Avoid

• Do not assume all patients with radiographic dural ectasia require intervention—many remain asymptomatic throughout life. 2
• Do not overlook the possibility of ureteric obstruction in symptomatic patients, as this can lead to serious renal complications if unrecognized. 3, 4
• Maintain awareness that dural ectasia has diagnostic value for Marfan syndrome, particularly when other features are equivocal. 1