Myelography of sacral agenesis.

In the past, neurologic deficits found in association with sacral agenesis were thought to be unamenable to surgical therapy. Recent experience and a careful review of autopsy and case reports form the literature have demonstrated that this assumption is unwarranted. Four cases of sacral agenesis are reported with description of the myelographic findings of each case. Surgical confirmation was obtained in three of these patients. Dural sac stenosis treated with duraplasty resulted in striking improvement in the neurologic status of two patients, while in the third, a 2-month-old infant, adhesive arachnoidal bands in the distal thecal sac were found at surgery and a taut and thickened filum terminale was transected. The fourth patient has a low-lying spinal cord and a posterior meningocele. The myelographic findings appear to be divisible into two categories. One group of patients may have high termination of the subarachnoid space with a dural sac stenosis and will benefit from duraplasty, while in the other, findings may include a widened or normal subarachnoid space and low-lying tethered spinal cord. It is emphasized that treatment of dural sac stenosis, tethered cord, and intrathecal or extrathecal masses that occur in some of these patients may afford significant improvement in their neurologic condition. These children deserve careful baseline neurologic evaluation and follow-up and a more aggressive approach toward adequate myelographic assessment.