Update: Dural ectasia

Dural ectasia is widening or ballooning of the dural sac surrounding the spinal cord. This usually occurs in the lumbosacral region, as this is where the cerebrospinal fluid pressure is greatest, but the spinal canal can be affected in any plane.

Case courtesy of Dr Franco Ruales, Radiopaedia.org. From the case rID: 16114

Most common symptoms include low back painheadaches, weaknessnumbness above and below the involved limb, leg pain, and sometimes there can be rectal and genital pain. Bowel and bladder dysfunction, urinary retention or even incontinence may occur.

The symptoms are usually exacerbated by upright posture and often but not always relieved by lying down. However, in many patients it is asymptomatic.

It is common in Marfan syndrome, occurring in 63–92% of people with the syndrome. Dural ectasia may also occur in Ehlers-Danlos Syndrome, neurofibromatosis type I, ankylosing spondylitis, and trauma.

A “classic” picture of dural ectasia in the Marfan patient may consist of low back pain, headache, proximal leg pain, weakness and numbness above and below the knee, and genital/rectal pain. Symptoms, when present, are typically moderate to severe, occur several times per week (often daily), are commonly exacerbated by upright posture, and are not always relieved by recumbency 1).

Radiographic features

Dural ectasia is dilation of the dural sac. Anteroposterior diameter of the thecal sac at the S1 level greater than that of the thecal sac at the L4 level ref required.

Plain radiograph

Posterior vertebral scalloping may be an indirect indicator 2) 3). However, this is not specific, as it is seen in a significant percentage of the normal population and is also associated with several other conditions.

MRI

Increase in the AP diameter of the dural sac, usually in the lumbar region.

Differential diagnosis

Pathology

Among 1519 patients with spinal space-occupying lesions, 66 patients demonstrated spinal dura mater pathologies. Neuroradiological and surgical features were reviewed and clinical data analyzed.

Saccular dural diverticula (type I, n = 28) caused by defects of both dural layers, dissections between dural layers (type II, n = 29) due to defects of the inner layer, and dural ectasias (type III, n = 9) related to structural changes of the dura were distinguished. For all types, symptoms consisted of local pain followed by signs of radiculopathy or myelopathy, while one patient with dural ectasia presented a low-pressure syndrome and 10 patients with dural dissections additional spinal cord herniation. Type I and type II pathologies required occlusion of their dural defects via extradural (type I) or intradural (type II) approaches. For type III pathologies of the dural sac no surgery was recommended. Favorable results were obtained in all 14 patients with type I and 13 of 15 patients with type II pathologies undergoing surgery.

The majority of dural pathologies involving nerve root sleeves remain asymptomatic, while those of the dural sac commonly lead to pain and neurological symptoms. Saccular dural diverticula (type I) and dissections between dural layers (type II) pathologies were treated with good long-term results occluding their dural defects, while dural ectasias (type III) were managed conservatively 4).

Complications

Dural ectasia is one of the likely causes of incomplete or failed spinal anaesthesia. Its association with diseases like Marfans syndrome, neurofibromatosis, osteogenesis imperfecta, vertebral fracture, postopertative adhesions, trauma etc., is often overlooked as a reason for inadequate spinal anaesthesia. Greater than normal volume of cerebrospinal fluid in the lumber theca in dural ectasia is postulated to restrict the spread of intrathecally injected Local anaesthetic 5).

1)

Foran JR, Pyeritz RE, Dietz HC, Sponseller PD. Characterization of the symptoms associated with dural ectasia in the Marfan patient. Am J Med Genet A. 2005 Apr 1;134A(1):58-65. PubMed PMID: 15690402.
2)

Habermann CR, Weiss F, Schoder V et-al. MR evaluation of dural ectasia in Marfan syndrome: reassessment of the established criteria in children, adolescents, and young adults. Radiology. 2005;234 (2): 535-41. doi:10.1148/radiol.2342031497
3)

Wakely SL. The posterior vertebral scalloping sign. Radiology. 2006;239 (2): 607-9. doi:10.1148/radiol.2392040224
4)

Klekamp J. A New Classification for Pathologies of Spinal Meninges, Part 1: Dural Cysts, Dissections, and Ectasias. Neurosurgery. 2017 Mar 17. doi: 10.1093/neuros/nyx049. [Epub ahead of print] PubMed PMID: 28327939.
5)

Gupta N, Gupta V, Kumar A, Kumar G. Dural ectasia. Indian Journal of Anaesthesia. 2014;58(2):199-201. doi:10.4103/0019-5049.130829.

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