[Chronic fibroplastic leptomeningitis of the spinal cord and cauda equina]

Chronic (seldom subacute) low-grade spinal leptomeningitis, cystic and adhesive in natura, is a clinicopathologic condition known by several names in medical literature (arachnoiditis, arachnoditis adhesiva circumscripta, a.s.o.). The cystic structures are not cysts in the true sense of the word. They are in reality collections of cerebrospinal fluid walled off by meningeal adhesions. The extent of the leptomeningitis varies from a well-localized lesion to a diffused process involving the entire cereprospinal axis. In some cases the chronic proliferative changes lead to calcification and ossification of the leptomeninx. As well the circumscribed adhesive as the cystic form can produce a spinal cord compression syndrome similar to a tumor or a hydro-syringomyelia. Progressive paraparesis with difficulties of bladder and bowel function may nevertheless be arrested, or spontaneous remission may occur, perhaps due to temporary improvement of the local circulation of spinal fluid. An almost typical sciatic syndrome can be occasionally associated with a thickening of the leptomeninx and cystic spinal fluid collection in the region of the cauda equina. The lumbar adhesive and cystic form is as a rule a more benign disease then leptomeningitis occurring at thoracic or cervical levels. The etiological factors are trauma, spinal anesthesia, myelography, blood in the subarachnoid space, previous operations and infections. When the origin of the illness remains unidentified, low grade bacterial or viral infections can be presumed. We operated 2 patients with circumscribed severe leptomeningitis several segments far away from an intradural meningeoma. Such illness is uncommon, but not very rare. From 1970 until the end of 1986 we have carried out 33 laminectomies on 26 patients because of spinal leptomeningitis among 603 patients operated because of spinal cord compression (4.31%). Our cases are presented and literature is discussed. The dilemma what we have to do with a patient with symptomatic spinal leptomeningitis is open: the microsurgery can help the patient significantly, even if complete recovery is rare. In view of the extreme variety of these lesions a circumspect, sometime skeptical analysis of each patient must precede decision about surgery. We try to give some indications for microsurgery.