Ahn, Edward S.

Spinal cord intramedullary arteriovenous malformations (AVMs) have classically been considered congenital lesions that are present from birth. The reason for this dogmatic principal is the fact that a vast majority of these lesions present in pediatric and young adult patients. Interestingly, while many authors have demonstrated the development of de novo nidus-type brain AVMs, there have been no reported cases of a de novo intramedullary or perimedullary AVM of the spine. In this paper the authors describe what they believe to be the first reported case of a de novo AVM of the spinal cord in a young patient who underwent serial imaging from birth for evaluation of a syrinx. Potential pathophysiological mechanisms for the development of de novo vascular malformations of the spinal cord are discussed.

OBJECTIVE Phenotypic differences between moyamoya disease (MMD) and moyamoya syndrome (MMS) remain unclear. The purpose of this study was to evaluate whether such differences exist when presentation, procedure-related, and outcome variables are compared quantitatively. METHODS The study cohort included 185 patients with moyamoya presenting to the Johns Hopkins Medical Institutions between 1994 and 2015. Baseline demographic, angiographic, and clinical characteristics were compared between patients with MMS and MMD, in addition to procedure-related complications and length of stay (LOS) after surgery. Stroke-free survival was compared between both disease variants after diagnosis. Kaplan-Meier analysis and Cox proportional hazards regression were used to compare stroke-free survival between surgically treated and conservatively managed hemispheres in both types of disease, while evaluating interaction between disease variant and management. RESULTS The cohort consisted of 137 patients with MMD (74%) with a bimodal age distribution and 48 patients with MMS (26%) who were mostly under 18 years of age (75%). Underlying diseases included sickle cell disease (48%), trisomy 21 (12%), neurofibromatosis (23%), and other disorders (17%). Patients with MMS were younger (p < 0.001) and less likely to be female (p = 0.034). Otherwise, baseline characteristics were statistically comparable. The rate of surgical complications was 33% in patients with MMD and 16% in patients with MMS (p = 0.097). Both groups of patients had a similar LOS after surgery (p = 0.823). Survival analysis (n = 330 hemispheres) showed similar stroke-free survival after diagnosis (p = 0.856) and lower stroke hazard in surgically managed patients in both MMD (hazard ratio [HR] 0.29, p = 0.028) and MMS (HR 0.62, p = 0.586). The disease variant (MMD vs MMS) did not affect the relationship between management approach (surgery vs conservative) and stroke hazard (p = 0.787). CONCLUSIONS MMD and MMS have largely comparable clinical and angiographic phenotypes with analogously favorable responses to surgical revascularization.

OBJECTIVE Open prenatal myelomeningocele (MMC) repair is typically associated with reversal of in utero hindbrain herniation (HBH) and has been posited to be associated with a reduction in both postoperative prenatal and immediate postnatal hydrocephalus (HCP) risks. However, the long-term postnatal risk of HCP following HBH reversal in these cases has not been well defined. The authors describe the results of a long-term HCP surveillance in a cohort of patients who underwent prenatal MMC repair at their institution. METHODS A retrospective review of all prenatal MMC repair operations performed at the Mayo Clinic between 2012 and 2017 was conducted. Pertinent data regarding the clinical courses of these patients before and after MMC repair were summarized. Outcomes of interest were occurrences of HBH and HCP and the need for intervention. RESULTS A total of 9 prenatal MMC repair cases were identified. There were 7 cases in which MRI clearly demonstrated prenatal HBH, and of these 86% (6/7) had evidence of HBH reversal after repair and prior to delivery. After a mean postnatal follow-up of 20 months, there were 3 cases of postnatal HCP requiring intervention. One case that failed to show complete HBH reversal after MMC repair required early ventriculoperitoneal shunting. The other 2 cases were of progressive, gradual-onset HCP despite complete prenatal HBH reversal, requiring endoscopic third ventriculostomy with choroid plexus cauterization at ages 5 and 7 months. CONCLUSIONS Although prenatal MMC repair can achieve HBH reversal in a majority of well-selected cases, the prevention of postnatal HCP requiring intervention appears not to be predicated on this outcome alone. In fact, it appears that in a subset of cases in which HBH reversal is achieved, patients can experience a progressive, gradual-onset HCP within the 1st year of life. These findings support continued rigorous postnatal surveillance of all prenatal MMC repair patients, irrespective of postoperative HBH outcome.