Neurofibromatosis with dural ectasia and bilateral symmetrical pedicular clefts: report of two cases.

We present two cases of bilateral, symmetrical pedicular clefts associated with dural ectasia in von Recklinghausen's disease (neurofibromatosis). In one case the pedicular cleft was at the T12 level, while in the other it was at L4, and was responsible for spondylolisthesis. Two hypotheses are advanced to explain the cleft: (1) a congenital, dysplastic osseous defect and (2) bilateral stress fractures related to thinning of the pedicle caused by dural ectasia.