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Spinal Idiopathic Hypertrophic Pachymeningitis: two cases 2005

General Spine

Zoran J Rumboldt, M.D.
Cynthia A Welsh , M.D., Non ASSR Member
Suhas Pai , M.D., Non ASSR Member

Excerpta

A 47-year-old female presented with a 2-year history of truncal and lower extremity weakness and paresthesias, bowel and bladder incontinence and increased reflexes in her lower extremities. The symptoms almost completely resolved after a year, but then started progressing during the past month. MR imaging demonstrated an anterior extramedullary mass of low T1 and T2 signal extending from T1 to T6 (Image 1 and 2). The lesion compressed the spinal cord and showed strong predominantly peripheral contrast enhancement (Image 3). Following T1 to T6 laminectomy, an induration of the dura was found intraoperatively. Multiple biopsy specimens were taken and demonstrated chronic dural inflammation with dense collagen fibers and lymphoplasmacytic infiltrate on histology.
A 68-year-old female presented with a 2-month history of progressive lower extremity weakness and urinary retention, decreased sensation in lower extremities bilaterally and a poor rectal tone. MR imaging showed an enhancing mass compressing the spinal cord, hypointense on T2 and isointense on T1-weighted images. The lesion was anteriorly located at C3 and C4, and encompassing the cord from C5 to T2 levels. After C6-C7 laminectomy, a large amount of thickened ligament, dura, and granular epidural tissue were evacuated from the epidural space. Histology demonstrated chronic inflammatory reaction with xanthomatous inflammation.

Idiopathic hypertrophic pachymeningitis (IHP) is an uncommon entity, which usually affects cranial meninges. It is a fibrosing inflammatory process that thickens the dura mater that is considered when no identifiable cause is found and exact etiopathogenesis is still unknown.

The spinal form is extremely rare with only a handful of cases described, none in radiological literature. It presents as a chronic progressive disease with manifestations of radiculopathy, myelopathy or a combination of the two. It either occurs alone or as a craniospinal form, usually involving the cervical and thoracic dura.

The lesions on MR images are typically hypointense on both T1 and T2-weighted images and show uniform dense enhancement of the thickened meninges. Two patterns of enhancement have been described, with linear form showing better therapeutic response compared to nodular form, possibly related to less fibrosis and more vascularity.

These findings may simulate menigioma, lymphoma, tuberculosis, and sarcoidosis, while an association with Wegener's granulomatosis has been found in some cases. It has been also proposed that Tolosa-Hunt syndrome and IHP may represent the same entity.

Surgical decompression provides relief, while steroid therapy has been considered the mainstay of therapy in this disease, and azathioprine and cyclophosphamide have been tried.

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