The Cape Town Stereotactic pointer clinical development and Applications

This dissertation describes the development and clinical use of a novel stereotactic neurosurgical system, the Cape Town Stereotactic Pointer (CTSP). This system has four main components; a halo containing three fiducials also serves as the platform for a tripod pointing device which is set with the aid of a 3D phantom or a printed setting diagram, and software which enables transformation of imaging space into patient space. Laboratory tests indicated an application accuracy of 1.9 +/- 0.6mm using the 3D phantom to set the tripod. From the first clinical application, the system underwent a series of iterations which could broadly be divided into four successive phases of refinement. This took place over a six year period, encompassing one hundred patients who underwent 115 stereotactic procedures. Indications for surgery included biopsy (62.6%), aspiration (15.7%) and cannulation (21.7%) and the surgical objective was realized in 101/109 cases (92.7%). Given the fact that six of the eight failures represented errors of surgical judgment that could not be ascribed to the device, and each of two system errors resulted in a significant modification to the system, the CTSP demonstrated a satisfactory level of accuracy in the clinical setting. This was accomplished at an acceptable complication rate, with one death five days after surgery attributable to a stereotactic procedure (mortality 0.9%) and major morbidity in two cases (1.7%); thirteen patients experienced minor complications, all of which proved to be transient (11.3%). A simple protocol for use of the CTSP evolved over the course of this study, making it easier for neurosurgeons from varying backgrounds to introduce stereotaxis into their practice with the help of this system. In addition to satisfactory levels of clinical reliability and safety, the system was versatile and also well tolerated by patients. It is hoped that the CTSP provides a costeffective alternative for neurosurgeons working in under-resourced settings. Sixty units of the production version of the CTSP have been sold and the system is now in use in ten countries

Transition from child- to adult-orientated care for children with long-term health conditions: A process, not an event

This issue of CME contains the second of a two-part series of continuing medical education articles on various aspects of spina bifida, with the focus on some of the longer-term management issues such as hydrocephalus and limb deformity, as well as quality of life.

Transcranial Doppler pulsatility index is not a reliable indicator of intracranial pressure in children with severe traumatic brain injury

Background: The TCD-derived PI has been associated with ICP in adult studies but has not been well investigated in children. We examined the relationship between PI and ICP and CPP in children with severe TBI. Methods: Data were prospectively collected from consecutive TCD studies in children with severe TBI undergoing ICP monitoring. Ipsilateral ICP and CPP values were examined with Spearman correlation coefficient (mean values and raw observations), with a GEE, and as binary values (1 and 20 mm Hg, respectively). Results: Thirty-four children underwent 275 TCD studies. There was a weak relationship between mean values of ICP and PI (P = .04, r = 0.36), but not when raw observations (P = .54) or GEE (P = .23) were used. Pulsatility index was 0.76 when ICP was lower than 20 mm Hg and 0.86 when ICP was 20 mm Hg or higher. When PI was 1 or higher, ICP was lower than 20 mm Hg in 62.5% (25 of 40 studies), and when ICP was 20 mm Hg or higher, PI was lower than 1 in 75% (46 of 61 studies). The sensitivity and specificity of a PI threshold of 1 for examining the ICP threshold of 20 mm Hg were 25% and 88%, respectively. The relationship between CPP and PI was stronger (P = .001, r -0.41), but there were too few observations below 50 mm Hg to examine PI at this threshold. Conclusion: The absolute value of the PI is not a reliable noninvasive indicator of ICP in children with severe TBI. Further study is required to examine the relationship between PI and a CPP threshold of 50 mm Hg. (C) 2009 Elsevier Inc. All rights reserved

Pressure autoregulation, intracranial pressure, and brain tissue oxygenation in children with severe traumatic brain injury

Object. Cerebral pressure autoregulation is an important neuroprotective mechanism that stabilizes cerebral blood flow when blood pressure (BP) changes In this study the authors examined the association between autoregulation and clinical factors. BR. intracranial pressure (ICP), brain tissue oxygen tension (PbtO(2)), and outcome after pediatric severe traumatic brain injury (TBI). In particular we examined how the Status 01: autoregulation influenced the effect of BP changes on ICP and PbtO(2) Methods In this prospective observational study. 52 autoregulation tests were performed in 24 patients with severe. TBI. The patients had a mean age of 6.3 +/- 3.2 years. and a postresuscitation Glasgow Coma Scale score of 6 (range 3-8). All patients underwent continuous ICP and MID, monitoring. and transcranial Doppler ultrasonography was, used to examine the autoregulatory index (ARI) based on blood flow velocity of the middle cerebral artery after increasing mean arterial pressure by 20% of the baseline value Impaired autoregulation was defined as an ARI = 0 4 The relationships between autoregulation (measured as both a Continuous and dichotomous variable), outcome, and clinical and physiological variables were examined using Multiple logistic regression analysis Results. Autoregulation was impaired (ART < 0 4) in 29% of patients (7 patients). The initial Glasgow Coma Scale score was significantly associated with the ARI (p = 0.02, r = 0.32) but no other clinical factors were associated with autoregulation Status. Baseline values at the time of testing for ICP, PbtO(2), the ratio PbtO(2)/PaO2, mean arterial pressure, and middle cerebral artery blood flow velocity were similar in the patients with impaired or intact autoregulation. There was an inverse relationship between ART (continuous and dichotomous) with a chancle in ICP (continuous ARI, p 0.005, dichotomous ARI, p = 0 02): that is. ICP increased with the BP increase when ARI was low (weak autoregulation) The ART (continuous and dichotomous) was also inversely associated with a change in PbtO(2). (continuous ART. p 0.002. dichotomous ARI, p = 0 02). The PbtO(2) increased when BP was increased in most patients, even when the ARI was relatively high (stronger autoregulation). but the magnitude of this response was still associated with the ART. There was no relationship between the ART and Outcome Conclusion. These data demonstrate the influence of the strength of autoregulation on the response of ICP and MO. to BP changes and the variability of this response between individuals The findings suggest that autoregulation testing may assist clinical decision-making in pediatric severe TBI and help better define optimal BP or cerebral perfusion pressure targets for individual patients. (DOI: 10.3171/2009.6.PEDS096