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Christopher R. P. Lind, Christina J. Lind and Edward W. Mee

Object. The aim of this study was to determine the influence of closed-system subdural drainage on repeated operation rates after burr hole evacuation of subacute and chronic subdural hematomas (SDHs).

Methods. Five hundred consecutive operations for the treatment of SDH via burr holes were performed between January 1, 1996, and April 15, 2002, at the Auckland Hospital. Hospital records were used to ascertain demographic data, operation, and repeated operation details. Rates of repeated surgeries were compared in patients with and without subdural drains.

Repeated operations were performed less frequently in patients with subdural drains, occurring in 31 (10%) of 310 cases involving drains and in 35 (19%) of 188 cases without drains (p < 0.01). Demographics between the two groups were not significantly different except for mean patient age, which was higher among patients with a subdural drain. A lower rate of repeated operation was observed in patients who had undergone drain placement, regardless of whether there was visible evidence of brain reexpansion.

Conclusions. Patients have lower rates of repeated surgeries if subdural drains are placed following evacuation of an SDH via a burr hole. To reach high clinical significance, 12 patients must undergo this simple intervention. If technically feasible, subdural drains should be inserted regardless of any occurrence of brain expansion during surgery.

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Arjun S. Chandran, Michael Bynevelt and Christopher R. P. Lind

The subthalamic nucleus (STN) is one of the most important stereotactic targets in neurosurgery, and its accurate imaging is crucial. With improving MRI sequences there is impetus for direct targeting of the STN. High-quality, distortion-free images are paramount. Image reconstruction techniques appear to show the greatest promise in balancing the issue of geometrical distortion and STN edge detection. Existing spin echo- and susceptibility-based MRI sequences are compared with new image reconstruction methods. Quantitative susceptibility mapping is the most promising technique for stereotactic imaging of the STN.

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Alex J. Koefman, Melissa Licari, Michael Bynevelt and Christopher R. P. Lind

OBJECTIVE

An objective biomarker for pain is yet to be established. Functional MRI (fMRI) is a promising neuroimaging technique that may reveal an objective radiological biomarker. The purpose of this study was to evaluate fMRI technology in the setting of lumbosacral radiculopathy and discuss its application in revealing a biomarker for pain in the future.

METHODS

A prospective, within-participant control study was conducted. Twenty participants with painful lumbosacral radiculopathy from intervertebral disc pathology were recruited. Functional imaging of the brain was performed during a randomly generated series of nonprovocative and provocative straight leg raise maneuvers.

RESULTS

With a statistical threshold set at p < 0.000001, 3 areas showed significant blood oxygen level–dependent (BOLD) signal change: right superior frontal gyrus (x = 2, y = 13, z = 48, k = 29, Brodmann area 6 [BA6]), left supramarginal cortex (x = −37, y = −44, z = 33, k = 1084, BA40), and left parietal cortex (x = −19, y = −41, z = 63, k = 354, BA5). With a statistical threshold set at p < 0.0002, 2 structures showed significant BOLD signal change: right putamen (x = 29, y = −11, z = 6, k = 72) and bilateral thalami (right: x = 23, y = −11, z = 21, k = 29; x = 8, y = −11, z = 9, k = 274; and left: x = −28, y = −32, z = 6, k = 21).

CONCLUSIONS

The results in this study compare with those in previous studies and suggest that fMRI technology can provide an objective assessment of the pain experience.

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Arjun S. Chandran, Stuti Joshi, Megan Thorburn, Rick Stell and Christopher R. P. Lind

OBJECTIVE

The posterior subthalamic area (PSA) is a promising target of deep brain stimulation (DBS) for medication-refractory essential tremor (ET). This case series describes a novel adverse effect manifesting as dystonic tics in patients with ET undergoing DBS of the PSA.

METHODS

Six patients with ET received electrode implants for DBS of the dorsal and caudal zona incerta subregions of the PSA.

RESULTS

Five of the 6 patients developed dystonic tics soon after clinical programming. These tics were of varying severity and required reduction of the electrical stimulation amplitude. This reduction resolved tic occurrence without significantly affecting ET control. Dystonic tics were not observed in 39 additional patients who underwent DBS of the same brain regions for controlling non-ET movement disorders.

CONCLUSIONS

The pathophysiology of tic disorders is poorly understood and may involve the basal ganglia and related cortico-striato-thalamo-cortical circuits. This series is the first report of DBS-induced tics after stimulation of any brain target. Although the PSA has not previously been implicated in tic pathophysiology, it may be a candidate region for future studies.

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Stephen Honeybul, David Anthony Morrison, Kwok M. Ho, Christopher R. P. Lind and Elizabeth Geelhoed

OBJECTIVE

Autologous bone is usually used to reconstruct skull defects following decompressive surgery. However, it is associated with a high failure rate due to infection and resorption. The aim of this study was to see whether it would be cost-effective to use titanium as a primary reconstructive material.

METHODS

Sixty-four patients were enrolled and randomized to receive either their own bone or a primary titanium cranioplasty. All surgical procedures were performed by the senior surgeon. Primary and secondary outcome measures were assessed at 1 year after cranioplasty.

RESULTS

There were no primary infections in either arm of the trial. There was one secondary infection of a titanium cranioplasty that had replaced a resorbed autologous cranioplasty. In the titanium group, no patient was considered to have partial or complete cranioplasty failure at 12 months of follow-up (p = 0.002) and none needed revision (p = 0.053). There were 2 deaths unrelated to the cranioplasty, one in each arm of the trial. Among the 31 patients who had an autologous cranioplasty, 7 patients (22%) had complete resorption of the autologous bone such that it was deemed a complete failure. Partial or complete autologous bone resorption appeared to be more common among young patients than older patients (32 vs 45 years old, p = 0.013). The total cumulative cost between the 2 groups was not significantly different (mean difference A$3281, 95% CI $−9869 to $3308; p = 0.327).

CONCLUSIONS

Primary titanium cranioplasty should be seriously considered for young patients who require reconstruction of the skull vault following decompressive craniectomy.

Clinical trial registration no.: ACTRN12612000353897 (anzctr.org.au)

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Christopher R. P. Lind, Amy M. C. Tsai, Andrew J. J. Law, Hui Lau and Kavitha Muthiah

Object

The purpose of this study was to compare the margins of error of different shunt catheter approaches to the lateral ventricle and assess surface anatomical aiming landmarks for free-hand ventricular catheter insertion in adult patients with hydrocephalus.

Methods

Four adults who had undergone stereotactic brain magnetic resonance (MR) imaging and had normal ventricles, and 7 prospectively recruited adult patients with acute hydrocephalus were selected for inclusion in this study. Reconstructed MR images obtained prior to surgical intervention were geometrically analyzed with regard to frontal, parietal, and parietooccipital (occipital) approaches in both hemispheres.

Results

The ventricular target zones were as follows: the frontal horn for frontal and occipital approaches, and the atrium/ posterior horn for parietal approaches. The range of possible angles for successful catheter insertion was smallest for the occipital approach (8° in the sagittal plane and 11° in the coronal plane), greater for parietal catheters (23 and 36°), and greatest for the frontal approach in models of hydrocephalic brains (42 and 30°; p < 0.001 for all comparisons except frontal vs parietal, which did not reach statistical significance). There was no single landmark for aiming occipital or parietal catheters that achieved ventricular target cannulation in every case. Success was achieved in only 86% of procedures using occipital trajectories and in 66% of those using parietal trajectories.

Conclusions

The occipital approach to ventricular catheter insertion provides the narrowest margin of error with regard to trajectory but has less aiming point variability than the parietal approach. The use of patient-specific stereotaxy rather than generic guides is required for totally reliable, first-pass ventricular catheterization via a posterior approach to shunt placement surgery in adults.

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Stephen Honeybul, Kwok M. Ho, Christopher R. P. Lind and Grant R. Gillett

Object

The goal in this study was to assess the validity of the corticosteroid randomization after significant head injury (CRASH) collaborators prediction model in predicting mortality and unfavorable outcome at 18 months in patients with severe traumatic brain injury (TBI) requiring decompressive craniectomy. In addition, the authors aimed to assess whether this model was well calibrated in predicting outcome across a wide spectrum of severity of TBI requiring decompressive craniectomy.

Methods

This prospective observational cohort study included all patients who underwent a decompressive craniectomy following severe TBI at the two major trauma hospitals in Western Australia between 2004 and 2012 and for whom 18-month follow-up data were available. Clinical and radiological data on initial presentation were entered into the Web-based model and the predicted outcome was compared with the observed outcome. In validating the CRASH model, the authors used area under the receiver operating characteristic curve to assess the ability of the CRASH model to differentiate between favorable and unfavorable outcomes.

Results

The ability of the CRASH 6-month unfavorable prediction model to differentiate between unfavorable and favorable outcomes at 18 months after decompressive craniectomy was good (area under the receiver operating characteristic curve 0.85, 95% CI 0.80–0.90). However, the model's calibration was not perfect. The slope and the intercept of the calibration curve were 1.66 (SE 0.21) and −1.11 (SE 0.14), respectively, suggesting that the predicted risks of unfavorable outcomes were not sufficiently extreme or different across different risk strata and were systematically too high (or overly pessimistic), respectively.

Conclusions

The CRASH collaborators prediction model can be used as a surrogate index of injury severity to stratify patients according to injury severity. However, clinical decisions should not be based solely on the predicted risks derived from the model, because the number of patients in each predicted risk stratum was still relatively small and hence the results were relatively imprecise. Notwithstanding these limitations, the model may add to a clinician's ability to have better-informed conversations with colleagues and patients' relatives about prognosis.

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Omar K. Bangash, Megan Thorburn, Jimena Garcia-Vega, Susan Walters, Rick Stell, Sergio E. Starkstein and Christopher R. P. Lind

The caudal zona incerta target within the posterior subthalamic area is an investigational site for deep brain stimulation (DBS) in Parkinson disease (PD) and tremor. The authors report on a patient with tremor-predominant PD who, despite excellent tremor control and an otherwise normal neurological examination, exhibited profound difficulty swimming during stimulation. Over the last 20 years, anecdotal reports have been received of 3 other patients with PD who underwent thalamic or pallidal lesioning or DBS surgery performed at the authors’ center and subsequently drowned. It may be that DBS puts patients at risk for drowning by specifically impairing their ability to swim. Until this finding can be further examined in larger cohorts, patients should be warned to swim under close supervision soon after DBS surgery.

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Omar K. Bangash, Arosha S. Dissanayake, Shirley Knight, John Murray, Megan Thorburn, Nova Thani, Arul Bala, Rick Stell and Christopher R. P. Lind

OBJECTIVE

Posterior subthalamic area (PSA) deep brain stimulation (DBS) targeting the zona incerta (ZI) is an emerging treatment for tremor syndromes, including Parkinson’s disease (PD) and essential tremor (ET). Evidence from animal studies has indicated that the ZI may play a role in saccadic eye movements via pathways between the ZI and superior colliculus (incerto-collicular pathways). PSA DBS permitted testing this hypothesis in humans.

METHODS

Sixteen patients (12 with PD and 4 with ET) underwent DBS using the MRI-directed implantable guide tube technique. Active electrode positions were confirmed at the caudal ZI. Eye movements were tested using direct current electrooculography (EOG) in the medicated state pre- and postoperatively on a horizontal predictive task subtending 30°. Postoperative assessments consisted of stimulation-off, constituting a microlesion (ML) condition, and high-frequency stimulation (HFS; frequency = 130 Hz) up to 3 V.

RESULTS

With PSA HFS, the first saccade amplitude was significantly reduced by 10.4% (95% CI 8.68%–12.2%) and 12.6% (95% CI 10.0%–15.9%) in the PD and ET groups, respectively. With HFS, peak velocity was reduced by 14.7% (95% CI 11.7%–17.6%) in the PD group and 27.7% (95% CI 23.7%–31.7%) in the ET group. HFS led to PD patients performing 21% (95% CI 16%–26%) and ET patients 31% (95% CI 19%–38%) more saccadic steps to reach the target.

CONCLUSIONS

PSA DBS in patients with PD and ET leads to hypometric, slowed saccades with an increase in the number of steps taken to reach the target. These effects contrast with the saccadometric findings observed with subthalamic nucleus DBS. Given the location of the active contacts, incerto-collicular pathways are likely responsible. Whether the acute finding of saccadic impairment persists with chronic PSA stimulation is unknown.