Infrared neural stimulation of human spinal nerve roots in vivo.

Infrared neural stimulation (INS) is a neurostimulation modality that uses pulsed infrared light to evoke artifact-free, spatially precise neural activity with a noncontact interface; however, the technique has not been demonstrated in humans. The objective of this study is to demonstrate the safety and efficacy of INS in humans in vivo. The feasibility of INS in humans was assessed in patients ([Formula: see text]) undergoing selective dorsal root rhizotomy, where hyperactive dorsal roots, identified for transection, were stimulated in vivo with INS on two to three sites per nerve with electromyogram recordings acquired throughout the stimulation. The stimulated dorsal root was removed and histology was performed to determine thermal damage thresholds of INS. Threshold activation of human dorsal rootlets occurred in 63% of nerves for radiant exposures between 0.53 and [Formula: see text]. In all cases, only one or two monitored muscle groups were activated from INS stimulation of a hyperactive spinal root identified by electrical stimulation. Thermal damage was first noted at [Formula: see text] and a [Formula: see text] safety ratio was identified. These findings demonstrate the success of INS as a fresh approach for activating human nerves in vivo and providing the necessary safety data needed to pursue clinically driven therapeutic and diagnostic applications of INS in humans.

Repairing Fetal Membranes with a Self-adhesive Ultrathin Polymeric Film: Evaluation in Mid-gestational Rabbit Model.

Preterm premature rupture of membranes causes 40% of all preterm births, affecting 150000 women each year in the United States. Prenatal diagnostic procedures and surgical interventions increase incidence of adverse events, leading to iatrogenic membrane rupture after a fetoscopic procedure in 45% of cases. We propose an ultrathin, self-adherent, poly-L-lactic acid patch ("nanofilm") as a reparative wound closure after endoscopic/fetoscopic procedures. These nanofilms are compatible with application in wet conditions and with minimally invasive instrumentation. Ex vivo studies to evaluate the nanofilm were conducted using human chorion-amnion (CA) membranes. A custom-built inflation device was used for mechanical characterization of CA membranes and for assessment of nanofilm adhesion and sealing of membrane defects up to 3 mm in size. These ex vivo tests demonstrated the ability of the nanofilm to seal human CA defects ranging in size from 1 to 3 mm in diameter. In vivo survival studies were conducted in 25 mid-gestational rabbits, defects were created by perforating the uterus and the CA membranes and subsequently using the nanofilm to seal these wounds. These in vivo studies confirmed the successful sealing of defects smaller than 3 mm observed ex vivo. Histological analysis of whole harvested uteri 7 days after surgery showed intact uterine walls in 59% of the nanofilm repaired fetuses, along with increased uterine size and intrauterine development in 63% of the cases. In summary, we have developed an ultrathin, self-adhesive nanofilm for repair of uterine membrane defects.

Reducing perinatal complications and preterm delivery for patients undergoing in utero closure of fetal myelomeningocele: further modifications to the multidisciplinary surgical technique.

UNLABELLED: OBJECT.: As more pediatric neurosurgeons become involved with fetal myelomeningocele closure efforts, examining refined techniques in the overall surgical approach that could maximize beneficial outcomes becomes critical. The authors compared outcomes for patients who had undergone a modified technique with those for patients who had undergone fetal repair as part of the earlier Management of Myelomeningocele Study (MOMS). METHODS: Demographic and outcomes data were collected for a series of 43 delivered patients who had undergone in utero myelomeningocele closure at the Fetal Center at Vanderbilt from March 2011 through January 2013 (the study cohort) and were compared with data for 78 patients who had undergone fetal repair as part of MOMS (the MOMS cohort). For the study cohort, no uterine trocar was used, and uterine entry, manipulation, and closure were modified to minimize separation of the amniotic membrane. Weekly ultrasound reports were obtained from primary maternal-fetal medicine providers and reviewed. A test for normality revealed that distribution for the study cohort was normal; therefore, parametric statistics were used for comparisons. RESULTS: The incidence of premature rupture of membranes (22% vs 46%, p = 0.011) and chorioamnion separation (0% vs 26%, p < 0.001) were lower for the study cohort than for the MOMS cohort. Incidence of oligohydramnios did not differ between the cohorts. The mean (± SD) gestational age of 34.4 (± 6.6) weeks for the study cohort was similar to that for the MOMS cohort (34.1 ± 3.1 weeks). However, the proportion of infants born at term (37 weeks or greater) was significantly higher for the study cohort (16 of 41; 39%) than for the MOMS cohort (16 of 78; 21%) (p = 0.030). Compared with 10 (13%) of 78 patients in the MOMS cohort, only 2 (4%) of 41 infants in the study cohort were delivered earlier than 30 weeks of gestation (p = 0.084, approaching significance). For the study cohort, 2 fetal deaths were attributed to the intervention, and both were believed to be associated with placental disruption; one of these mothers had previously unidentified thrombophilia. Mortality rates did not statistically differ between the cohorts. CONCLUSIONS: These early results suggest that careful attention to uterine entry, manipulation, and closure by the surgical team can result in a decreased rate of premature rupture of membranes and chorioamnion separation and can reduce early preterm delivery. Although these results are promising, their confirmation will require further study of a larger series of patients.

Effect of symptomatic pseudomeningocele on improvement in pain, disability, and quality of life following suboccipital decompression for adult Chiari malformation type I.

OBJECT: Suboccipital decompression is a common procedure for patients with Chiari malformation Type I (CMI). Published studies have reported complication rates ranging from 3% to 40%, with pseudomeningocele being one of the most common complications. To date, there are no studies assessing the effect of this complication on long-term outcome. Therefore, the authors set out to assess the effect of symptomatic pseudomeningocele on patient outcomes following suboccipital decompression for CM-I. METHODS: The study comprised 50 adult patients with CM-I who underwent suboccipital craniectomy and C-1 laminectomy with or without duraplasty. Clinical presentation, radiological studies, operative variables, and complications were assessed for each case. Baseline and 1-year postoperative patient-reported outcomes were assessed to determine improvement in pain, disability, and quality of life. The extent of improvement was compared for patients with and without development of a postoperative symptomatic pseudomeningocele. RESULTS: A symptomatic pseudomeningocele developed postoperatively in 9 patients (18%). There was no difference with regard to clinical, radiological, or operative variables for patients with or without a postoperative pseudomeningocele. Patients without a pseudomeningocele had significant improvement in all 9 patient-reported outcome measures assessed. On the other hand, patients with pseudomeningocele only had significant improvement in headache (as measured on the Numeric Rating Scale) and headache-related disability (as measured on the Headache Disability Index) but no improvement in quality of life. Twenty-nine (71%) of 41 patients without a pseudomeningocele reported improvement in health status postoperatively compared with only 3 (33%) of 9 patients with a postoperative pseudomeningocele (p = 0.05). CONCLUSIONS: Surgical management of CM-I in adults provides significant and sustained improvement in pain, disability, general health, and quality of life. Development of a postoperative symptomatic pseudomeningocele has lingering effects at 1 year, and it significantly diminishes the overall benefit of suboccipital decompression for CM-related symptoms. Further research is needed to accurately predict which patients may benefit from decompression alone without duraplasty.

A randomized trial of prenatal versus postnatal repair of myelomeningocele.

BACKGROUND: Prenatal repair of myelomeningocele, the most common form of spina bifida, may result in better neurologic function than repair deferred until after delivery. We compared outcomes of in utero repair with standard postnatal repair. METHODS: We randomly assigned eligible women to undergo either prenatal surgery before 26 weeks of gestation or standard postnatal repair. One primary outcome was a composite of fetal or neonatal death or the need for placement of a cerebrospinal fluid shunt by the age of 12 months. Another primary outcome at 30 months was a composite of mental development and motor function. RESULTS: The trial was stopped for efficacy of prenatal surgery after the recruitment of 183 of a planned 200 patients. This report is based on results in 158 patients whose children were evaluated at 12 months. The first primary outcome occurred in 68% of the infants in the prenatal-surgery group and in 98% of those in the postnatal-surgery group (relative risk, 0.70; 97.7% confidence interval [CI], 0.58 to 0.84; P<0.001). Actual rates of shunt placement were 40% in the prenatal-surgery group and 82% in the postnatal-surgery group (relative risk, 0.48; 97.7% CI, 0.36 to 0.64; P<0.001). Prenatal surgery also resulted in improvement in the composite score for mental development and motor function at 30 months (P=0.007) and in improvement in several secondary outcomes, including hindbrain herniation by 12 months and ambulation by 30 months. However, prenatal surgery was associated with an increased risk of preterm delivery and uterine dehiscence at delivery. CONCLUSIONS: Prenatal surgery for myelomeningocele reduced the need for shunting and improved motor outcomes at 30 months but was associated with maternal and fetal risks. (Funded by the National Institutes of Health; ClinicalTrials.gov number, NCT00060606.).

CT-based, fiducial-free frameless stereotaxy for difficult ventriculoperitoneal shunt insertion: experience in 26 consecutive patients.

BACKGROUND: Patients with small or dysmorphic ventricles requiring ventriculoperitoneal shunt (VPS) insertion for hydrocephalus can be challenging. The 'freehand' technique does not always provide for accurate catheter insertion, particularly in patients with slit ventricles, complex hydrocephalus or displaced ventricles. Consequently, many surgeons use stereotaxy for assistance. We have employed a frameless stereotactic technique, obviating the need for fiducials or preoperative MRI, for difficult ventricular catheter placement over the past 1.5 years with excellent results. We describe our experience with frameless stereotactic VPS insertion. METHODS: We retrospectively reviewed the charts of 26 patients who underwent frameless stereotactic VPS insertion. All patients had preoperative CT scans using a navigation protocol and were registered into the Stealth Station via the face tracer program. Catheters were inserted using the Medtronic frameless trajectory guide kit. We recorded demographic data, operative time, complications and follow-up. RESULTS: The mean patient age was 31 years. The average operative time was 46 min. There were 3 complications. The average follow-up was 5 months. Twenty-one patients had postoperative imaging, with 20 having excellent catheter positioning. CONCLUSIONS: Our results confirm that frameless stereotactic VPS without fiducial marker placement is a feasible technique for catheter insertion in patients who have small/dysmorphic ventricles. In experienced hands, there is negligible added operative time and a low complication rate.

Myelomeningocele: prenatal evaluation--comparison between transabdominal US and MR imaging.

PURPOSE: To compare transabdominal ultrasonography (US) with fetal magnetic resonance (MR) imaging in the prenatal evaluation of myelomeningocele lesion level. MATERIALS AND METHODS: Prenatal US images, pre- and postnatal MR images, and postnatal spinal radiographs obtained in the first 100 fetuses who underwent intrauterine myelomeningocele repair were the basis for this study. Each image was used to assign a lesion level. The assigned levels were compared by means of the kappa statistic, as an index of agreement. RESULTS: All fetuses underwent prenatal US. Sixty-one fetuses underwent prenatal MR imaging. Fifty fetuses underwent both postnatal spinal radiography and postnatal MR imaging, and an additional 34 fetuses underwent one postnatal study but not the other. When findings on prenatal US images were compared with those on postnatal radiographs, the findings agreed within one spinal level in 79% (55 of 70, kappa = 0.60) of cases. When findings on prenatal MR images were compared with those on postnatal radiographs, the findings agreed in 82% (31 of 38, kappa = 0.63) of cases. Findings on postnatal MR images and those on postnatal spinal radiographs agreed within one spinal level in 100% (50 of 50, kappa = 1.0) of cases. CONCLUSION: Findings at prenatal MR imaging and prenatal US are equally accurate for the assignment of a lesion level in a fetus with myelomeningocele. Given that findings with both modalities will lead to misdiagnosis of the spinal level by two or more segments in at least 20% of cases, care should be exercised when neurologic outcome is predicted on the basis of these studies alone.

Robot-assisted endoscopic intrauterine myelomeningocele repair: a feasibility study.

BACKGROUND: Animal experiments have suggested that the intrauterine environment causes secondary injury to the congenitally dysplastic spinal cord. This in turn suggests that early closure of the myelomeningocele sac might prevent secondary injury and therefore improve neurologic outcome. This study was designed to examine the technical feasibility of performing intrauterine myelomeningocele repair using a robot-assisted endoscopic system in an animal model. METHODS: Six fetal sheep underwent creation and repair of a full-thickness skin lesion using the da Vinci system. RESULTS: With the device's advanced articulated instruments and three-dimensional optics, it was possible to endoscopically repair the induced skin defects. CONCLUSION: We conclude that, with the recent evolution in robotics and minimally invasive techniques, intrauterine endoscopic surgery has become a realistic goal that promises to reduce the associated risks of fetal surgery and extend the indications for its use.