Assessing calvarial vault constriction associated with helmet therapy in deformational plagiocephaly.

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Assessing calvarial vault constriction associated with helmet therapy in deformational plagiocephaly.

J Neurosurg Pediatr. 2018 May 11;:1-7

Authors: Peterson EC, Patel KB, Skolnick GB, Pfeifauf KD, Davidson KN, Smyth MD, Naidoo SD

Abstract
OBJECTIVE Deformational plagiocephaly and/or brachycephaly (DPB) is a cranial flattening frequently treated in pediatric craniofacial centers. The standard of care for DPB involves patient positioning or helmet therapy. Orthotic therapy successfully reduces cranial asymmetry, but there is concern over whether the orthotics have the potential to restrict cranial growth. Previous research addressing helmet safety was limited by lack of volume measurements and serial data. The purpose of this study was to directly compare head growth data in patients with DPB between those who underwent helmet therapy and those who received repositioning therapy. METHODS This retrospective cohort study analyzed pre- and posttherapy 3D photographs of 57 patients with DPB who had helmet therapy and a control group of 57 patients with DPB who underwent repositioning therapy. The authors determined the change in cranial vault volume and cranial circumference between each patient's photographs using 3D photogrammetry. They also computed a cubic volume calculated by multiplying anterior-posterior diameter, biparietal diameter, and height. Linear regressions were used to quantify effects of age and therapy type on these quantities. RESULTS A comparison of the following variables between the two groups yielded nonsignificant results: age at the beginning (p = 0.861) and end (p = 0.539) of therapy, therapy duration (p = 0.161), and the ratio of males to females (p = 0.689). There was no significant difference between patients who underwent helmeting versus positioning therapy with respect to change in either volume calculation or head circumference z-score (p ≥ 0.545). Pretherapy photograph age was a significant predictor of cranial growth (p ≤ 0.001), but therapy type was not predictive of the change in the study measurements (p ≤ 0.210). CONCLUSIONS The authors found no evidence that helmet therapy was associated with cranial constriction in the study population of patients with DPB. These results strengthen previous research supporting helmet safety and should allow health care providers and families to choose the appropriate therapy without concern for potential negative effects on cranial growth.

PMID: 29749885 [PubMed - as supplied by publisher]

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Perioperative complications and risk factors in neuromuscular scoliosis surgery.

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Perioperative complications and risk factors in neuromuscular scoliosis surgery.

J Neurosurg Pediatr. 2018 May 11;:1-7

Authors: Toll BJ, Samdani AF, Janjua MB, Gandhi S, Pahys JM, Hwang SW

Abstract
OBJECTIVE High rates of perioperative complications are associated with deformity correction in neuromuscular scoliosis. The current study aimed to evaluate complications associated with surgical correction of neuromuscular scoliosis and to characterize potential risk factors. METHODS Data were retrospectively collected from a single-center cohort of 102 consecutive patients who underwent spinal fusions for neuromuscular scoliosis between January 2008 and December 2016 and who had a minimum of 6 months of follow-up. A subgroup analysis was performed on data from patients who had at least 2 years of follow-up. Univariate and multivariate regression analyses, as well as binary correlational models and Student t-tests, were employed for further statistical analysis. RESULTS The present cohort had 53 boys and 49 girls with a mean age at surgery of 14.0 years (± 2.7 SD, range 7.5-19.5 years). The most prevalent diagnoses were cerebral palsy (26.5%), spinal cord injury (24.5%), and neurofibromatosis (10.8%). Analysis reflected an overall perioperative complication rate of 27% (37 complications in 27 patients), 81.1% of which constituted major complications (n = 30) compared to a rate of 18.9% for minor complications (n = 7). Complications were predicted by nonambulatory status (p = 0.037), increased intraoperative blood loss (p = 0.012), increased intraoperative time (p = 0.046), greater pelvic obliquity at follow-up (p = 0.028), and greater magnitude of sagittal profile at follow-up (p = 0.048). Pulmonary comorbidity (p = 0.001), previous operations (p = 0.013), history of seizures (p = 0.046), diagnosis of myelomeningocele (p = 0.046), increase in weight postoperatively (p < 0.005), and increased lumbar lordosis at follow-up (p = 0.015) were identified as risk factors for perioperative infection. CONCLUSIONS These results suggest that in neuromuscular scoliosis, patients with preexisting pulmonary compromise and greater intraoperative blood loss have the greatest risk of experiencing a major perioperative complication following surgical deformity correction.

PMID: 29749884 [PubMed - as supplied by publisher]

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Rapid-sequence brain magnetic resonance imaging for Chiari I abnormality.

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Rapid-sequence brain magnetic resonance imaging for Chiari I abnormality.

J Neurosurg Pediatr. 2018 May 11;:1-7

Authors: Pan J, Quon JL, Johnson E, Lanzman B, Chukus A, Ho AL, Edwards MSB, Grant GA, Yeom KW

Abstract
OBJECTIVE Fast magnetic resonance imaging (fsMRI) sequences are single-shot spin echo images with fast acquisition times that have replaced CT scans for many conditions. Introduced as a means of evaluating children with hydrocephalus and macrocephaly, these sequences reduce the need for anesthesia and can be more cost-effective, especially for children who require multiple surveillance scans. However, the role of fsMRI has yet to be investigated in evaluating the posterior fossa in patients with Chiari I abnormality (CM-I). The goal of this study was to examine the diagnostic performance of fsMRI in evaluating the cerebellar tonsils in comparison to conventional MRI. METHODS The authors performed a retrospective analysis of 18 pediatric patients with a confirmed diagnosis of CM-I based on gold-standard conventional brain MRI and 30 controls without CM-I who had presented with various neurosurgical conditions. The CM-I patients were included if fsMRI studies had been obtained within 1 year of conventional MRI with no surgical intervention between the studies. Two neuroradiologists reviewed the studies in a blinded fashion to determine the diagnostic performance of fsMRI in detecting CM-I. For the CM-I cohort, the fsMRI and T2-weighted MRI exams were randomized, and the blinded reviewers performed tonsillar measurements on both scans. RESULTS The mean age of the CM-I cohort was 7.39 years, and 50% of these subjects were male. The mean time interval between fsMRI and conventional T2-weighted MRI was 97.8 days. Forty-four percent of the subjects had undergone imaging after posterior fossa decompression. The sensitivity and specificity of fsMRI in detecting CM-I was 100% (95% CI 71.51%-100%) and 92.11% (95% CI 78.62%-98.34%), respectively. If only preoperative patients are considered, both sensitivity and specificity increase to 100%. The authors also performed a cost analysis and determined that fsMRI was significantly cost-effective compared to T2-weighted MRI or CT. CONCLUSIONS Despite known limitations, fsMRI may serve as a useful diagnostic and surveillance tool for CM-I. It is more cost-effective than full conventional brain MRI and decreases the need for sedation in young children.

PMID: 29749883 [PubMed - as supplied by publisher]

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Low-cost endoscopic third ventriculostomy simulator with mimetic endoscope.

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Low-cost endoscopic third ventriculostomy simulator with mimetic endoscope.

J Neurosurg Pediatr. 2018 May 11;:1-10

Authors: Garling RJ, Jin X, Yang J, Khasawneh AH, Harris CA

Abstract
OBJECTIVE Hydrocephalus affects approximately 1 in 500 people in the US, yet ventricular shunting, the gold standard of treatment, has a nearly 85% failure rate. Endoscopic third ventriculostomy (ETV) is an alternative surgical approach for a specific subset of hydrocephalic patients, but can be limited by the inability of neurosurgical residents to practice prior to patient contact. The goal of this study was to create an affordable ETV model and endoscope for resident training. METHODS Open-source software was used to isolate the skull and brain from the CT and MR images of a 2-year-old boy with hydrocephalus. A 3D printer created the skull and a 3D mold of the brain. A mixture of silicone and silicone tactile mutator was used to cast the brain mold prior to subsequent compression and shearing modulus testing. A mimetic endoscope was then created from basic supplies and a 3D printed frame. A small cohort of neurosurgical residents and attending physicians evaluated the ETV simulator with mimetic endoscope. RESULTS The authors successfully created a mimetic endoscope and ETV simulator. After compression and shearing modulus testing, a silicone/Slacker ratio between 10:6 and 10:7 was found to be similar to that of human brain parenchyma. Eighty-seven percent of participants strongly agreed that the simulator was useful for resident training, and 93% strongly agreed that the simulator helped them understand how to orient themselves with the endoscope. CONCLUSIONS The authors created an affordable (US$123, excluding 3D printer), easy-to-use ETV simulator with endoscope. Previous models have required expensive software and costly operative endoscopes that may not be available to most residents. Instead, this attempt takes advantage of open-source software for the manipulation and fabrication of a patient-specific mold. This model can assist with resident development, allowing them to safely practice use of the endoscope in ETV.

PMID: 29749882 [PubMed - as supplied by publisher]

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Reversible ventriculoperitoneal shunt dysfunction and chronic constipation: case report.

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Reversible ventriculoperitoneal shunt dysfunction and chronic constipation: case report.

J Neurosurg Pediatr. 2018 May 11;:1-4

Authors: Morais BA, Cardeal DD, Andrade FG, Paiva WS, Matushita H, Teixeira MJ

Abstract
Constipation can cause transient malfunction of the ventriculoperitoneal shunt (VPS). Patients with myelomeningocele or cerebral palsy are often diagnosed with hydrocephalus and constipation due to neurogenic bowel. These patients are more prone to VPS dysfunction, often requiring surgical revision. The authors report the case of a 6-year-old girl with a VPS that had been implanted due to hydrocephalus secondary to myelomeningocele. The patient was brought to the emergency department with intermittent headache, vomiting, constipation, and abdominal distension and pain. A CT scan revealed ventricular dilatation and radiography of the abdomen showed bowel loop distension. After a Fleet enema and digital maneuvers, her abdominal distension and symptoms improved. A CT scan obtained 24 hours later showed a reduction in ventricular size. The mechanism by which constipation can lead to VPS malfunction can be traced to indirect increases of intraabdominal pressure and direct obstruction of the catheter by distended intestinal loops. Treating constipation can restore the free circulation of the CSF and avoid surgical intervention. Careful neurological monitoring of these patients is essential, because some measures used to treat constipation can increase intracranial pressure. The objective of this report was to highlight constipation as a possible cause of transient VPS malfunction, thereby avoiding unnecessary surgical revisions, to which children with hydrocephalus are frequently submitted.

PMID: 29749881 [PubMed - as supplied by publisher]

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Emotional self-other voice processing in schizophrenia and its relationship with hallucinations: ERP evidence.

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Emotional self-other voice processing in schizophrenia and its relationship with hallucinations: ERP evidence.

Psychophysiology. 2017 Sep;54(9):1252-1265

Authors: Pinheiro AP, Rezaii N, Rauber A, Nestor PG, Spencer KM, Niznikiewicz M

Abstract
Abnormalities in self-other voice processing have been observed in schizophrenia, and may underlie the experience of hallucinations. More recent studies demonstrated that these impairments are enhanced for speech stimuli with negative content. Nonetheless, few studies probed the temporal dynamics of self versus nonself speech processing in schizophrenia and, particularly, the impact of semantic valence on self-other voice discrimination. In the current study, we examined these questions, and additionally probed whether impairments in these processes are associated with the experience of hallucinations. Fifteen schizophrenia patients and 16 healthy controls listened to 420 prerecorded adjectives differing in voice identity (self-generated [SGS] versus nonself speech [NSS]) and semantic valence (neutral, positive, and negative), while EEG data were recorded. The N1, P2, and late positive potential (LPP) ERP components were analyzed. ERP results revealed group differences in the interaction between voice identity and valence in the P2 and LPP components. Specifically, LPP amplitude was reduced in patients compared with healthy subjects for SGS and NSS with negative content. Further, auditory hallucinations severity was significantly predicted by LPP amplitude: the higher the SAPS "voices conversing" score, the larger the difference in LPP amplitude between negative and positive NSS. The absence of group differences in the N1 suggests that self-other voice processing abnormalities in schizophrenia are not primarily driven by disrupted sensory processing of voice acoustic information. The association between LPP amplitude and hallucination severity suggests that auditory hallucinations are associated with enhanced sustained attention to negative cues conveyed by a nonself voice.

PMID: 28474363 [PubMed - indexed for MEDLINE]

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Adaptive optimal input design and parametric estimation of nonlinear dynamical systems: application to neuronal modeling.

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Adaptive optimal input design and parametric estimation of nonlinear dynamical systems: application to neuronal modeling.

J Neural Eng. 2018 May 11;:

Authors: Madi MK, Karameh FN

Abstract
Many physical models of biological processes including neural systems are characterized by parametric nonlinear dynamical relations between driving inputs, internal states, and measured outputs of the process. Fitting such models using experimental data (data assimilation) is a challenging task since the physical process often operates in a noisy, possibly non-stationary environment; moreover, conducting multiple experiments under controlled and repeatable conditions can be impractical, time consuming or costly. The accuracy of model identification, therefore, is dictated principally by the quality and dynamic richness of collected data over single or few experimental sessions. Accordingly, it is highly desirable to design efficient experiments that, by exciting the physical process with smart inputs, yields fast convergence and increased accuracy of the model. We herein introduce an adaptive framework in which optimal input design is integrated with Square root Cubature Kalman Filters (OID-SCKF) to develop an online estimation procedure that first, converges significantly quicker, thereby permitting model fitting over shorter time windows, and second, enhances model accuracy when only few process outputs are accessible. The methodology is demonstrated on common nonlinear models and on a four-area neural mass model with noisy and limited measurements. Estimation quality (speed and accuracy) is benchmarked against high-performance SCKF-based methods that commonly employ dynamically rich informed inputs for accurate model identification. For all the tested models, simulated single-trial and ensemble averages showed that OID-SCKF exhibited (i) faster convergence of parameter estimates and (ii) lower dependence on inter-trial noise variability with gains up to around 1000 msec in speed and 81% increase in variability for the neural mass models. In terms of accuracy, OID-SCKF estimation was superior, and exhibited considerably less variability across experiments, in identifying model parameters of (a) systems with challenging model inversion dynamics and (b) systems with fewer measurable outputs that directly relate to the underlying processes. Fast and accurate identification therefore carries particular promise for modeling of transient (short-lived) neuronal network dynamics using a spatially under-sampled set of noisy measurements, as is commonly encountered in neural engineering applications.

PMID: 29749350 [PubMed - as supplied by publisher]

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