Phase 1 evaluation of an elastomeric nucleus pulposus device as an option to augment disc at microdiscectomy: Experimental results from biomechanical and biocompatibility testing and first in human.

Objective: Whilst microdiscectomy is an excellent reliever of pain for recalcitrant lumbar disc herniation (LDH), it has a high failure rate over time due to the ensuing reduction in mechanical stabilization and support of the spine. One option is to clear the disc and replace it with a nonhygroscopic elastomer. Here, we present the evaluation of biomechanical and biological behavior of a novel elastomeric nucleus device (Kunovus disc device [KDD]), consisting of a silicone jacket and a two-part in situ curing silicone polymer filler. Materials and Methods: ISO 10993 and American Society for Testing and Materials (ASTM) standards were used to evaluate the biocompatibility and mechanics of KDD. Sensitization, intracutaneous reactivity, acute systemic toxicity, genotoxicity, muscle implantation study, direct contact matrix toxicity assay, and cell growth inhibition assay were performed. Fatigue test, static compression creep testing, expulsion testing, swell testing, shock testing, and aged fatigue testing were conducted to characterize the mechanical and wear behavior of the device. Cadaveric studies to develop a surgical manual and evaluate feasibility were conducted. Finally, a first-in-human implantation was conducted to complete the proof of principle. Results: The KDD demonstrated exceptional biocompatibility and biodurability. Mechanical tests showed no Barium-containing particles in fatigue test, no fracture of nucleus in static compression creep testing, no extrusion and swelling, and no material failure in shock and aged fatigue testing. Cadaver training sessions showed that KDD was deemed implantable during microdiscectomy procedures in a minimally invasive manner. Following IRB approval, the first implantation in a human showed no intraoperative vascular and neurological complications and demonstrated feasibility. This successfully completed Phase 1 development of the device. Conclusion: The elastomeric nucleus device may mimic native disc behavior in mechanical tests, offering an effective way for treating LDH by way of Phase 2 and subsequent clinical trials or postmarket surveillance in the future.

Accurate placement of parieto-occipital shunt ventricular catheter: use of craniometrics and technical note.

PURPOSE: Ventriculoperitoneal shunt insertion is one of the most commonly performed procedures in neurosurgery but has a relatively high complication rate. One important source of complications is shunt malposition from erroneous placement of the parieto-occipital burr hole or poor shunt trajectory. There are significant variations in the freehand parieto-occipital approach amongst neurosurgeons that are derived from variations in technique or experience. The patient's skull shape or size is also often not taken into consideration if fixed measurements are used to define the burr hole entry point. The authors suggest a variation to the technique of ventricular catheter placement by relying on the patient's own craniometrics and skull landmarks. METHODS: The technique is illustrated and supported by analysis of a case series of 25 patients undergoing shunt placement. RESULTS: By this method, all shunts were positioned in the lateral ventricle. Using a 3-point scale, the catheter position was evaluated: grade 1, free floating in cerebrospinal fluid; grade 2, touching the choroid plexus or ventricular wall; and grade 3, tip within the parenchyma. The catheter position was grade 1 in sixteen (64%) cases and grade 2 in nine (36%) cases; none was grade 3. Only one shunt malfunction occurred from proximal shunt obstruction in the series. CONCLUSION: The use of this technique aims to reduce operator and patient variability as contributors to shunt malposition, to increase user reproducibility and decrease the learning curve for trainees. Further prospective study could be designed to validate the technique.

Radiological predictors of recurrent lumbar disc herniation: a systematic review and meta-analysis.

OBJECTIVE: Lumbar discectomy for the management of lumbar radiculopathy is a commonly performed procedure with generally excellent patient outcomes. However, recurrent lumbar disc herniation (rLDH) remains one of the most common complications of the procedure, often necessitating repeat surgery. rLDH is known to be influenced by a variety of factors, and in this systematic review the authors aimed to explore the radiological predictors of recurrence. METHODS: A systematic review and meta-analysis was conducted to identify studies analyzing radiological predictors of recurrent herniation, both ipsilateral and contralateral. A search was conducted on Medline and EMBASE. Both retrospective and prospective comparative studies were included, measuring radiological parameters of lumbar discectomy patients. All factors were considered irrespective of imaging modality, and a meta-analysis of the data was performed in which 5 or more studies were identified analyzing the same parameter. RESULTS: In total, 1626 reported studies were screened, with 23 being included in this review, of which 13 were appropriate for meta-analysis. Three factors, namely disc height index, Modic changes, and sagittal range of motion, were determined to be significantly correlated with an increased rate of rLDH. Some variables were considered in only 1 or 2 different studies, and the authors have included a narrative review of these novel findings. CONCLUSIONS: The findings of associations between the radiological parameters and rLDH implicates the role of instability in the development of recurrence. Understanding the physiological factors associated with instability is important, because although early degenerative disc changes may predispose patients to herniation recurrence, more advanced degeneration likely reduces segmental motion and concurrently risk of recurrence.

Management of spinal dural arteriovenous fistula in a child with myelopathy.

BACKGROUND: Spinal dural arteriovenous fistulas (DAVF) are rare intradural spinal lesions. Patients with DAVF are typically in the 40's or 50's, and classically present with acute neurological deterioration. Notably, these lesions are exceedingly rare in the pediatric age group. CASE DESCRIPTION: A 2-year-old child presented with the sudden onset of lethargy, and 4/5 weakness of the left lower extremity with accompanying ataxia. The cervicothoracic MR scan revealed central cord edema from C5 to T4. A DAVF was diagnosed based on the multiple dilated intradural perimedullary veins. Following endovascular treatment, the child markedly recovered and remained stable 2 years later. CONCLUSION: DAVFs are treatable lesions that rarely occur in the pediatric age group. They are associated with serious neurological morbidity. When suspected, they should be immediately diagnosed with magnetic resonance imaging/magnetic resonance angiography, and formal angiography. Prompt neurosurgical and neuroradiological/ endovascular opinions and intervention should be sought to provide and the best treatment strategy.

Os odontoideum: a rare cause of syncope.

Syncopal events are a concerning presentation and timely evaluation is warranted. Common aetiologies include cardiac and neurological pathology such as arrhythmias, vertebrobasilar arterial disease and vasovagal syncope. We describe the case of a 65-year-old man who presented to our emergency department with symptoms of vertigo and syncope. He was investigated extensively for both cardiac and neurological causes of his symptoms which returned negative results. An outpatient CT scan demonstrated the presence of Os odontoideum and dynamic instability of the atlantoaxial junction, with presumed dynamic obstruction of the vertebral arterial system. This was successfully managed with a posterior atlantoaxial lateral mass fusion with resolution of syncopal symptoms.

Persistent Gram-negative Neurosurgical Meningitis in a Neonate, Successfully Treated With Intraventricular Colistin: Case Report and Review of the Literature.

We present a case of Gram-negative neurosurgical meningitis in a neonate, refractory to optimal intravenous therapy and removal of ventriculoperitoneal shunt. Cerebrospinal fluid was sterilized within 24 hours using intraventricular colistin. This is the first report of intraventricular colistin use in neonatal meningitis caused by Enterobacter cloacae.

Analysis of endoscopic third ventriculostomy patency by MRI: value of different pulse sequences, the sequence parameters, and the imaging planes for investigation of flow void.

PURPOSE: The aim of the study is to evaluate the efficiency of turbo spin-echo (TSE), three-dimensional constructive interference in the steady state (3D CISS) and cine phase contrast (Cine PC) sequences in determining flow through the endoscopic third ventriculostomy (ETV) fenestration, and to determine the effect of various TSE sequence parameters. MATERIALS AND METHODS: The study was approved by our institutional review board and informed consent from all patients was obtained. Two groups of patients were included: group I (24 patients with good clinical outcome after ETV) and group II (22 patients with hydrocephalus evaluated preoperatively). The imaging protocol for both groups was identical. TSE T2 with various sequence parameters and imaging planes, and 3D CISS, followed by cine PC were obtained. Flow void was graded as four-point scales. The sensitivity, specificity, accuracy, positive and negative predictive values of sequences were calculated. RESULTS: Bidirectional flow through the fenestration was detected in all group I patients by cine PC. Stroke volumes through the fenestration in group I ranged 10-160.8 ml/min. There was no correlation between the presence of reversed flow and flow void grading. Also, there was no correlation between the stroke volumes and flow void grading. The sensitivity of 3D CISS was low, and 2 mm sagittal TSE T2, nearly equal to cine PC, provided best result. CONCLUSION: Cine PC and TSE T2 both have high confidence in the assessment of the flow through the fenestration. But, sequence parameters significantly affect the efficiency of TSE T2.