Daniel Hansen

Chiari malformation Type I in children younger than age 6 years: presentation and surgical outcome

OBJECT The authors conducted a study to evaluate the unique presenting signs and symptoms of Chiari malformation Type I (CM-I) in children younger than 6 years of age and highlight the benefits of early surgical treatment in this patient population. METHODS The authors reviewed the medical records of patients who presented to the neurosurgery department before their 6th birthday and subsequently underwent surgery for CM-I. They identified 39 patients who had been evaluated between 1984 and 2007 and examined the medical records for presentation, surgical intervention, and outcome. RESULTS Children aged 0-2 years commonly presented with oropharyngeal dysfunction (77.8%). Children aged 3-5 years more frequently presented with syringomyelia (85.7%), scoliosis (38.1%), and/or headache (57.1%). All patients underwent posterior fossa craniectomy. Additionally, in many patients cervical laminectomy and/or duraplasty was performed. A few patients required transoral decompression and occipitocervical fusion. In most cases, surgery led to resolution or dramatic improvement of initial symptoms. CONCLUSIONS Early recognition and surgical treatment of CM-I in young children leads to good outcomes in the majority of patients. Additional therapies for oropharyngeal dysfunction, syringomyelia, and scoliosis can frequently be avoided.

Sensory-motor networks involved in speech production and motor control: An fMRI study

Speaking is one of the most complex motor behaviors developed to facilitate human communication. The underlying neural mechanisms of speech involve sensory-motor interactions that incorporate feedback information for online monitoring and control of produced speech sounds. In the present study, we adopted an auditory feedback pitch perturbation paradigm and combined it with functional magnetic resonance imaging (fMRI) recordings in order to identify brain areas involved in speech production and motor control. Subjects underwent fMRI scanning while they produced a steady vowel sound /a/ (speaking) or listened to the playback of their own vowel production (playback). During each condition, the auditory feedback from vowel production was either normal (no perturbation) or perturbed by an upward (+600 cents) pitch-shift stimulus randomly. Analysis of BOLD responses during speaking (with and without shift) vs. rest revealed activation of a complex network including bilateral superior temporal gyrus (STG), Heschls gyrus, precentral gyrus, supplementary motor area (SMA), Rolandic operculum, postcentral gyrus and right inferior frontal gyrus (IFG). Performance correlation analysis showed that the subjects produced compensatory vocal responses that significantly correlated with BOLD response increases in bilateral STG and left precentral gyrus. However, during playback, the activation network was limited to cortical auditory areas including bilateral STG and Heschls gyrus. Moreover, the contrast between speaking vs. playback highlighted a distinct functional network that included bilateral precentral gyrus, SMA, IFG, postcentral gyrus and insula. These findings suggest that speech motor control involves feedback error detection in sensory (e.g. auditory) cortices that subsequently activate motor-related areas for the adjustment of speech parameters during speaking.

Sensory-Motor Interactions for Vocal Pitch Monitoring in Non-Primary Human Auditory Cortex

The neural mechanisms underlying processing of auditory feedback during self-vocalization are poorly understood. One technique used to study the role of auditory feedback involves shifting the pitch of the feedback that a speaker receives, known as pitch-shifted feedback. We utilized a pitch shift self-vocalization and playback paradigm to investigate the underlying neural mechanisms of audio-vocal interaction. High-resolution electrocorticography (ECoG) signals were recorded directly from auditory cortex of 10 human subjects while they vocalized and received brief downward (−100 cents) pitch perturbations in their voice auditory feedback (speaking task). ECoG was also recorded when subjects passively listened to playback of their own pitch-shifted vocalizations. Feedback pitch perturbations elicited average evoked potential (AEP) and event-related band power (ERBP) responses, primarily in the high gamma (70–150 Hz) range, in focal areas of non-primary auditory cortex on superior temporal gyrus (STG). The AEPs and high gamma responses were both modulated by speaking compared with playback in a subset of STG contacts. From these contacts, a majority showed significant enhancement of high gamma power and AEP responses during speaking while the remaining contacts showed attenuated response amplitudes. The speaking-induced enhancement effect suggests that engaging the vocal motor system can modulate auditory cortical processing of self-produced sounds in such a way as to increase neural sensitivity for feedback pitch error detection. It is likely that mechanisms such as efference copies may be involved in this process, and modulation of AEP and high gamma responses imply that such modulatory effects may affect different cortical generators within distinctive functional networks that drive voice production and control.

A method for placing Heschl gyrus depth electrodes

A wide range of devices is used to obtain intracranial electrocorticography recordings in patients with medically refractory epilepsy, including subdural strip and grid electrodes and depth electrodes. Penetrating depth electrodes are required to access some brain regions, and 1 target site that presents a particular technical challenge is the first transverse temporal gyrus, or Heschl gyrus (HG). The HG is located within the supratemporal plane and has an oblique orientation relative to the sagittal and coronal planes. Large and small branches of the middle cerebral artery abut the pial surface of the HG and must be avoided when planning the electrode trajectory. Auditory cortex is located within the HG, and there are functional connections between this dorsal temporal lobe region and medial sites commonly implicated in the pathophysiology of temporal lobe epilepsy. At some surgical centers, depth electrodes are routinely placed within the supratemporal plane, and the HG, in patients who require intracranial electrocorticography monitoring for presumed temporal lobe epilepsy. Information from these recordings is reported to facilitate the identification of seizure patterns in patients with or without auditory auras. To date, only one implantation method has been reported to be safe and effective for placing HG electrodes in a large series of patients undergoing epilepsy surgery. This well-established approach involves inserting the electrodes from a lateral trajectory while using stereoscopic stereotactic angiography to avoid vascular injury. In this report, the authors describe an alternative method for implantation. They use frameless stereotaxy and an oblique insertion trajectory that does not require angiography and allows for the simultaneous placement of subdural grid arrays. Results in 19 patients demonstrate the safety and efficacy of the method.

Postoperative radiographic findings in patients undergoing intracranial electrode monitoring for medically refractory epilepsy

OBJECT In this study the authors sought to determine whether any correlations existed between postimplantation head CT findings and the need to perform decompression surgery in patients with grid electrodes. METHODS The authors identified 74 patients who underwent intracranial electrode monitoring for medically refractory epilepsy from January 2000 through June 2008. Only the 46 patients who had head CT scans available for review were included in the study. The authors were able to determine the number and types of electrodes placed as well as complications experienced. They reviewed the CT scans for abnormal findings including extraaxial fluid collections, intracranial hemorrhages, and signs of mass effect. RESULTS All patients developed some degree of extraaxial fluid collection following the placement of intracranial electrodes. The maximum width of the extraaxial fluid collection and the degree of midline shift were not predictive of the need for decompressive surgery. The presence, but not degree, of midline shift was associated with the need for decompressive surgery. Likewise, the presence of ventricular asymmetry was correlated with the need for removal of the electrodes and bone flap. Patients without midline shift or ventricular asymmetry on CT did not require decompressive surgery. CONCLUSIONS After undergoing placement of intracranial electrodes all patients develop extraaxial fluid collections. In addition, many patients develop signs of mass effect including midline shift and ventricular asymmetry. When these findings are absent it is highly unlikely that surgical decompression is required.

Patient-reported outcomes of occipitocervical and atlantoaxial fusions in children

OBJECTIVE There is limited literature on patient-reported outcomes (PROs) and health-related quality of life (HRQOL) outcomes in pediatric patients undergoing surgery for craniovertebral junction pathology. The aim of the present study was to assess surgical and quality of life outcomes in children who had undergone occipitocervical or atlantoaxial fusion. METHODS The authors retrospectively reviewed the demographics, procedural data, and outcomes of 77 consecutive pediatric patients who underwent posterior occipitocervical or atlantoaxial fusion between 2008 and 2015 at Texas Childrens Hospital. Outcome measures (collected at last follow-up) included mortality, neurological improvement, complications, Scoliosis Research Society Outcomes Measure-22 (SRS-22) score, SF-36 score, Neck Disability Index (NDI), and Pediatric Quality of Life Inventory (PedsQL). Multivariate linear regression analysis was performed to identify factors affecting PROs and HRQOL scores at follow-up. RESULTS The average age in this series was 10.6 ± 4.5 years. The median follow-up was 13.9 months (range 0.5-121.5 months). Sixty-three patients (81.8%) were treated with occipitocervical fusion, and 14 patients (18.1%) were treated with atlantoaxial fusion. The American Spinal Injury Association (ASIA) grade at discharge was unchanged in 73 patients (94.8%). The average PRO metrics at the time of last follow-up were as follows: SRS-22 score, 4.2 ± 0.8; NDI, 3.0 ± 2.6; the parents PedsQL (ParentPedsQL) score, 69.6 ± 22.7, and childs PedsQL score, 75.5 ± 18.7. Multivariate linear regression analysis revealed that older age at surgery was significantly associated with lower SRS-22 scores at follow-up (B = -0.06, p = 0.03), and the presence of comorbidities was associated with poorer ParentPedsQL scores at follow-up (B = -19.68, p = 0.03). CONCLUSIONS This study indicates that occipitocervical and atlantoaxial fusions in children preserve neurological function and are associated with acceptable PROs and ParentPedsQL scores, considering the serious nature and potential for morbidity in this patient population. However, longer follow-up and disease-specific scales are necessary to fully elucidate the impact of occipitocervical and atlantoaxial fusions on children.

Syringohydromyelia in association with syringobulbia and syringocephaly: case report

The authors present the case of a 14-year-old boy with holocord syringohydromyelia extending into the brainstem, cerebral peduncle, internal capsule, and cerebral cortex. At the posterior fossa exploration, an opaque thickened arachnoid with occlusion of the foramen of Magendie was encountered. Careful documentation of postoperative regression of the syringocephaly, syringobulbia, and syringohydromyelia was made. The pathophysiology is discussed.

Treatment options for pediatric craniopharyngioma.

Case 1 A 13‐year‐old female with intermittent headaches evaluated by an ophthalmologist was noted to have a retinal abnormality, prompting a magnetic resonance imaging (MRI) scan and referral to the neurosurgery service. On initial exam, the patient was neurologically intact and without headache. Imaging revealed a complex heterogeneous cystic mass, arising from a suprasellar location, invading into the third ventricle, and closely apposed to the hypothalamus bilaterally. There was mild contrast enhancement peripherally and inferiorly. Of note, the initial MRI and clinical presentation [Figure 1] showed no hydrocephalus. Likewise, initial endocrine evaluation was normal. On follow‐up imaging, however, the ventricular system was noted to be enlarging. After extensive discussion of the risks, benefits, and alternatives to surgery, a right frontal endoscopic transventricular resection was planned with a goal of gross total resection (GTR). Intraoperatively, the tumor was found to be densely adherent to the walls of the third ventricle. Approximately 50% of the tumor could be safely debulked. Postoperatively, she was noted to have hypopituitarism and required hormonal replacement with desmopressin, hydrocortisone, and levothyroxine. The patient was discharged in stable condition but returned soon after with symptoms and imaging consistent with a trapped right ventricle for which she underwent a septostomy and eventual ventriculoperitoneal shunt placement. She subsequently completed proton radiation for the residual tumor, which has remained stable over 4‐year follow‐up. After radiation, she developed hypothalamic obesity and suffered a gradual decline in her vision bilaterally. At last follow‐up, she could count fingers on the right and could only detect motion on the left. Since completing her treatments, she has required 24‐h care. The patient has had multiple emergency room visits and hospital admissions for sodium fluctuations. She has also suffered multiple bone fractures secondary to osteoporosis from chronic steroid use.

Interhospital transfer of pediatric neurosurgical patients

OBJECTIVE The purpose of this study was to describe patterns of transfer, resource utilization, and clinical outcomes associated with the interhospital transfer of pediatric neurosurgical patients. METHODS All consecutive, prospectively collected requests for interhospital patient transfer to the pediatric neurosurgical service at Texas Childrens Hospital were retrospectively analyzed from October 2013 to September 2014. Demographic patient information, resource utilization, and outcomes were recorded and compared across predefined strata (low [< 5%], moderate [5%-30%], and high [> 30%]) of predicted probability of mortality using the Pediatric Risk of Mortality score. RESULTS Requests for pediatric neurosurgical care comprised 400 (3.7%) of a total of 10,833 calls. Of 400 transfer admissions, 96.5%, 2.8%, and 0.8% were in the low, moderate, and high mortality risk groups, respectively. The median age was 54 months, and 45% were female. The median transit time was 125 minutes. The majority of transfers were after-hours (69.8%); nearly a third occurred during the weekend (32.3%). The median intensive care unit stay for 103 patients was 3 days (range 1-269 days). Median length of hospital stay was 2 days (range 1-269 days). Ninety patients (22.5%) were discharged from the emergency room after transfer. Seventy-seven patients (19.3%) required neurosurgical intervention after transfer, with the majority requiring a cranial procedure (66.2%); 87.3% of patients were discharged home. CONCLUSIONS This study highlights patient characteristics, resource utilization, and outcomes among pediatric neurosurgical patients. Opportunities for quality improvement were identified in diagnosing and managing isolated skull fractures and neck pain after trauma.

Health-related quality of life outcomes and level of evidence in pediatric neurosurgery.

OBJECTIVE The emphasis on health-related quality of life (HRQOL) outcomes is increasing, along with an emphasis on evidence-based medicine. However, there is a notable paucity of validated HRQOL instruments for the pediatric population. Furthermore, no standardization or consensus currently exists concerning which HRQOL outcome measures ought to be used in pediatric neurosurgery. The authors wished to identify HRQOL outcomes used in pediatric neurosurgery research over the past 10 years, their frequency, and usage trends. METHODS Three top pediatric neurosurgical journals were reviewed for the decade from 2005 to 2014 for clinical studies of pediatric neurosurgical procedures that report HRQOL outcomes. Similar studies in the peer-reviewed journal Pediatrics were also used as a benchmark. Publication year, level of evidence, and HRQOL outcomes were collected for each article. RESULTS A total of 31 HRQOL studies were published in the pediatric neurosurgical literature over the study period. By comparison, there were 55 such articles in Pediatrics. The number of publications using HRQOL instruments showed a significant positive trend over time for Pediatrics (B = 0.62, p = 0.02) but did not increase significantly over time for the 3 neurosurgical journals (B = 0.12, p = 0.5). The authors identified a total of 46 different HRQOL instruments used across all journals. Within the neurosurgical journals, the Hydrocephalus Outcome Questionnaire (HOQ) (24%) was the most frequently used, followed by the Health Utilities Index (HUI) (16%), the Pediatric Quality of Life Inventory (PedsQL) (12%), and the 36-Item Short Form Health Survey (SF-36) (12%). Of the 55 articles identified in Pediatrics, 22 (40%) used a version of the PedsQL. No neurosurgical study reached above Level 4 on the Oxford Centre for Evidence-Based Medicine (OCEBM) system. However, multiple studies from Pediatrics achieved OCEBM Level 3, several were categorized as Level 2, and one reached Level 1. CONCLUSIONS The frequency of studies using HRQOL outcomes in pediatric neurosurgical research has not increased over the past 10 years. Within pediatric neurosurgery, high-quality studies and standardization are lacking, as compared with contemporary studies in Pediatrics. In general, although the HOQ, HUI, PedsQL, and SF-36 instruments are emerging as standards in pediatric neurosurgery, even greater standardization across the specialty is needed, along with the design and implementation of more rigorous studies.