[Intraforaminal lumbosacral neurinoma]

Twelve cases of intra-foraminal localization of lumbosacral neurinoma are reported including 9 schwannomas, 2 neurifibromas and 1 melanotic schannoma. According to their extension, they are classified in type II strictly intra-foraminal and extra-arachnoïdal: N = 6, type I-II, extending into the subarachnoïdal space; N = 5, type II-III, extending out of the spine. There were 7 men and 5 women with mean age of 49.5 years and a 5.2 years delay before diagnosis. The most common, though not permanent, symptom was radiculalgia; a generally weak sensorimotor deficit was noticed in 4 cases and hypoesthesia in two cases. Diagnosis was sometimes doubtful using myelography for the oldest cases, but is now made easily with CT scan and M.R.I. Microsurgery allows to dissect out the tumor inside the perineural sheath and to preserve the nervous root in most cases even in extra-arachnoïdal forms (N = 8). However, in cases of neurofibromas and of large tumors, the root had to be divided (N = 4) with rather surprisingly no new post-operative deficits. Intra-foraminal localization of lombo-sacral neurinomas is rare but now easily identified; it should be cured surgically with the goal, often reached, of maximum preservation of the nervous root.