Zero retinal vein pulsation amplitude extrapolated model in non-invasive intracranial pressure estimation.

Intracranial pressure (ICP) includes the brain, optic nerve, and spinal cord pressures; it influences blood flow to those structures. Pathological elevation in ICP results in structural damage through various mechanisms, which adversely affects outcomes in traumatic brain injury and stroke. Currently, invasive procedures which tap directly into the cerebrospinal fluid are required to measure this pressure. Recent fluidic engineering modelling analogous to the ocular vascular flow suggests that retinal venous pulse amplitudes are predictably influenced by downstream pressures, suggesting that ICP could be estimated by analysing this pulse signal. We used this modelling theory and our photoplethysmographic (PPG) retinal venous pulse amplitude measurement system to measure amplitudes in 30 subjects undergoing invasive ICP measurements by lumbar puncture (LP) or external ventricular drain (EVD). We estimated ICP from these amplitudes using this modelling and found it to be accurate with a mean absolute error of 3.0 mmHg and a slope of 1.00 (r = 0.91). Ninety-four percent of differences between the PPG and invasive method were between - 5.5 and + 4.0 mmHg, which compares favourably to comparisons between LP and EVD. This type of modelling may be useful for understanding retinal vessel pulsatile fluid dynamics and may provide a method for non-invasive ICP measurement.

Are viruses associated with disc herniation? A clinical case series.

BACKGROUND: There is some limited evidence for the presence of viruses in herniated disc material including a previous case series that claimed to provide "unequivocal evidence of the presence of herpes virus DNA in intervertebral disc specimens of patients with lumbar disc herniation suggesting the potential role of herpes viruses as a contributing factor to the pathogenesis of degenerative disc disease". This study has not been replicated. The objective of our study was to determine if viruses were present in herniated disc fragments in participants with a prior history of back pain. METHODS: We recruited fifteen participants with a history of prior low-back pain prior to undergoing disc herniation surgery in the lumbar spine. Harvested disc samples were subject to next generation sequencing for detection of both RNA and DNA viral pathogens. Additionally, samples were analysed by a broadly reactive PCR targeting herpesviral DNA. Ethics approval was granted by the Human Research Ethics Committees of both Murdoch University, and St John of God Hospital, Western Australia. RESULTS: Of the fifteen research participants, 8 were female. Mean age was 49.4 years (SD 14.5 yrs) with a range of 24-70 years. All participants had prior back pain with mean time since first ever attack being 8.8 years (SD 8.8 yrs). No samples contained significant DNA sequences relating to known human viral agents. Inconsequential retroviral sequences were commonly found and were a mixture of putative animal and human retroviral protein coding segments. All samples were negative for herpesvirus DNA when analysed by pan-herpesvirus PCR. CONCLUSIONS: This study found no viral pathogens in any intervertebral disc fragments of patients who had previous back pain and underwent discectomy for disc herniation and thus it is unlikely that viruses are associated with disc herniation, however given the contradiction between key studies enhanced replication of this experiment is recommended.

The current role of decompressive craniectomy for severe traumatic brain injury.

There is little doubt that decompressive craniectomy can reduce mortality however, the results of a recent study has provided more evidence to inform the debate regarding clinical and ethical concerns that it merely converts death into survival with severe disability or in a vegetative state. The recently published RESCUEicp trial compared last-tier secondary decompressive craniectomy with continued medical management for refractory intracranial hypertension after severe traumatic brain injury. Patients were randomly assigned to decompressive craniectomy with medical therapy or to receive continued medical therapy with the option of adding barbiturates. The results of the study support the findings of the stroke studies in that the reduction in mortality was almost directly translatable into survival with either severe disability or in a vegetative state. The question remains as to whether there is a subset of patients who obtain benefit from surgical decompression and it is in this regard that the use of observational cohort studies and sophisticated outcome prediction models may be of use. Comparing the percentage prediction with the observed long outcome provides an objective assessment of the most likely outcome can be obtained for patients thought to require surgical intervention. Whilst there will always be limitations when using this type of data they may help prompt appropriate patient-centred discussions regarding realistic outcome expectations. A broader debate is also needed regarding use of a medical intervention that may leave a person in a condition that they may feel to be unacceptable and also places a considerable burden on society.

Malignant cerebral swelling following cranioplasty.

Over the past few years there have been a number of case reports and small cohort studies that have described so called "malignant" cerebral swelling following an uneventful cranioplasty procedure. The pathophysiology remains to be established however it has been suggested that it may be related to a combination of failure of autoregulation and the use of closed vacuum suction drainage. The current study presents three further patients who had had a decompressive hemicraniectomy for ischaemic stroke. If decompressive craniectomy is utilised in the management of neurological emergencies, close attention and wider reporting of this type of complication is required not only to focus attention on possible management strategies, but also to determine which patients are at most risk of this devastating complication.

Atlanto-axial infection after acupuncture.

A 67-year-old man presented with neck cellulitis following acupuncture for cervical spondylosis. Blood cultures were positive for methicillin-sensitive Staphylococcus aureus Increased neck pain and bacteraemia prompted MRI, which showed atlanto-axial septic arthritis without signs of infection of the tissues between the superficial cellulitic area and the atlanto-axial joint, thus making direct extension of infection unlikely. It is more likely that haematogenous spread of infection resulted in seeding in the atlanto-axial joint, with the proximity of the arthritis and acupuncture site being coincidental. Acupuncture is a treatment option for some indolent pain conditions. As such, acupuncture services are likely to be more frequently utilised. A history of acupuncture is rarely requested by the admitting doctor and seldom offered voluntarily by the patient, especially where the site of infection due to haematogenous spread is distant from the needling location. Awareness of infectious complications following acupuncture can reduce morbidity through early intervention.

Computer-aided combined movement examination of the lumbar spine and manual therapy implications: Case report.

Combined movement examination (CME) of the lumbar spine has been recommended for clinical examination as it confers information about mechanical pain patterns. However, little quantitative study has been undertaken to validate its use in manual therapy practice. This study used computer aided CME to develop a normal reference range, and to guide provisional diagnosis and management. Two cases were assessed, before and after manual therapy using CME, a pain Visual Analogue Scale, the Roland Morris Low Back Pain and Disability Questionnaire and the Short Form (SF-12) Health Survey. Diagnosis and management were guided by comparing each CME pattern with the age and gender matched reference range. Self-reports data and CME total change scores were markedly improved for both cases, particularly for the most painful and restricted CME directions. This report describes how computer-aided CME and a normal reference range may be used objectively to inform a diagnosis and as an outcome measure in cases of mechanical LBP. Future investigations of cases with specific lumbar pathologies are required to validate this concept.

Atlanto-axial infection after acupuncture.

A 67-year-old man presented with neck cellulitis following acupuncture for cervical spondylosis. Blood cultures were positive for methicillin-sensitive Staphylococcus aureus. Increased neck pain and bacteraemia prompted MRI, which showed atlanto-axial septic arthritis without signs of infection of the tissues between the superficial cellulitic area and the atlanto-axial joint, thus making direct extension of infection unlikely. It is more likely that haematogenous spread of infection resulted in seeding in the atlanto-axial joint, with the proximity of the arthritis and acupuncture site being coincidental. Acupuncture is a treatment option for some indolent pain conditions. As such, acupuncture services are likely to be more frequently utilised. A history of acupuncture is rarely requested by the admitting doctor and seldom offered voluntarily by the patient, especially where the site of infection due to haematogenous spread is distant from the needling location. Awareness of infectious complications following acupuncture can reduce morbidity through early intervention.

Assessing the clinical utility of combined movement examination in symptomatic degenerative lumbar spondylosis.

OBJECTIVES: The aim of this study is to report the development and validation of a low back computer-aided combined movement examination protocol in normal individuals and record treatment outcomes of cases with symptomatic degenerative lumbar spondylosis. DESIGN: Test-retest, following intervention. BACKGROUND: Self-report assessments and combined movement examination were used to record composite spinal motion, before and following neurosurgical and pain medicine interventions. METHODS: 151 normal individuals aged from 20 years to 69 years were assessed using combined movement examination between L1 and S1 spinal levels to establish a reference range. Cases with degenerative low back pain and sciatica were assessed before and after therapeutic interventions with combined movement examination and a battery of self-report pain and disability questionnaires. Change scores for combined movement examination and all outcome measures were derived. FINDINGS: Computer-aided combined movement examination validation and intraclass correlation coefficient with 95% confidence interval and least significant change scores indicated acceptable reliability of combined movement examination when recording lumbar movement in normal subjects. In both clinical cases lumbar spine movement restrictions corresponded with self-report scores for pain and disability. Post-intervention outcomes all showed significant improvement, particularly in the most restricted combined movement examination direction. INTERPRETATION: This study provides normative reference data for combined movement examination that may inform future clinical studies of the technique as a convenient objective surrogate for important clinical outcomes in lumbar degenerative spondylosis. It can be used with good reliability, may be well tolerated by individuals in pain and appears to change in concert with validated measures of lumbar spinal pain, functional limitation and quality of life.

Neurotrauma and the rule of rescue.

The rule of rescue describes the powerful human proclivity to rescue identified endangered lives, regardless of cost or risk. Deciding whether or not to perform a decompressive craniectomy as a life-saving or 'rescue' procedure for a young person with a severe traumatic brain injury provides a good example of the ethical tensions that occur in these situations. Unfortunately, there comes a point when the primary brain injury is so severe that if the patient survives they are likely to remain severely disabled and fully dependent. The health resource implications of this outcome are significant. By using a web-based outcome prediction model this study compares the long-term outcome and designation of two groups of patients. One group had a very severe injury as adjudged by the model and the other group a less severe injury. At 18 month follow-up there were significant differences in outcome and healthcare requirements. This raises important ethical issues when considering life-saving but non-restorative surgical intervention. The discussion about realistic outcome cannot be dichotomised into simply life or death so that the outcome for the patient must enter the equation. As in other 'rescue situations', the utility of the procedure cannot be rationalised on a mere cost-benefit analysis. A compromise has to be reached to determine at what point either the likely outcome would be unacceptable to the person on whom the procedure is being performed or the social utility gained from the rule of rescue intervention fails to justify the utilitarian value and justice of equitable resource allocation.

Intramedullary conus medullaris metastasis of periurethral adenocarcinoma.

Intramedullary spinal cord metastasis to the conus medullaris is very rare. We report a 44-year-old woman with an intra-axial conus medullaris metastasis from periurethral adenocarcinoma. To our knowledge, this is the first report in the literature. We also discuss the clinical features, possible pathophysiological mechanisms and treatment options for intramedullary spinal cord metastasis to the conus medullaris.

Neurotrauma and the RUB: where tragedy meets ethics and science.

Decompressive craniectomy is a technically straightforward procedure whereby a large section of the cranium is temporarily removed in cases where the intracranial pressure is dangerously high. While its use has been described for a number of conditions, it is increasingly used in the context of severe head injury. As the use of the procedure increases, a significant number of patients may survive a severe head injury who otherwise would have died. Unfortunately some of these patients will be left severely disabled; a condition likened to the RUB, an acronym for the Risk of Unacceptable Badness. Until recently it has been difficult to predict this outcome, however an accurate prediction model has been developed and this has been applied to a large cohort of patients in Western Australia. It is possible to compare the predicted outcome with the observed outcome at 18 months within this cohort. By using predicted and observed outcome data this paper considers the ethical implications in three cases of differing severity of head injury in view of the fact that it is possible to calculate the RUB for each case.

P-POSSUM scoring system for mortality prediction in general neurosurgery.

The Physiological and Operative Severity Score for enUmeration of Mortality and morbidity (POSSUM) scoring systems have been designed for comparative audit and have been well validated in general and vascular surgery. The Portsmouth predictor equation (P-POSSUM) was highly predictive of mortality in a study of elective craniotomies for neurosurgery but has yet to be validated in spinal, peripheral nerve or acute cranial neurosurgery. The West Australian Categorisation of Operative Severity (WA classification) was created for all neurosurgical procedures. Case notes and laboratory results of 531 consecutive patients undergoing neurosurgery were reviewed retrospectively. All POSSUM variables were collected and the POSSUM and P-POSSUM mortality equations were applied. The observed mortality rate was 4.52% and the WA P-POSSUM predicted mortality rate was 4.58% (p>0.951). The WA P-POSSUM rate was more predictive than either the WA POSSUM rate (10.9%, p<0.0001) or the previously proposed elective craniotomy P-POSSUM classification (5.8%, p<0.198). We concluded that the P-POSSUM model with WA classification has the potential to be used in mortality audits for general neurosurgery. By quantifying preoperative risk, P-POSSUM might provide a useful denominator to observed death rates for meaningful comparison of individual neurosurgeons and between departments.

The mitogen-activated/extracellular signal-regulated kinase kinase 1/2 inhibitor U0126 induces glial fibrillary acidic protein expression and reduces the proliferation and migration of C6 glioma cells.

The extracellular signal-regulated kinase (ERK) signaling pathway has been implicated in diverse cellular functions. ERK and its activating kinase, mitogen-activated/extracellular signal-regulated kinase kinase (MEK), are downstream of cell surface receptors known to be up-regulated in many malignant gliomas. We sought to investigate the role of ERK in glioma cell migration, proliferation and differentiation using the rat-derived C6 glioma cell line and the MEK inhibitor, U0126. Treatment of C6 cells with U0126 caused a significant concentration-dependent reduction in cell proliferation and migration and also induced expression of glial fibrillary acidic protein, a marker of astrocytic differentiation. These results suggest that the ERK pathway regulates glioma cell proliferation, migration and differentiation.

Stereotactic radiosurgery in New Zealand.

AIMS: To explain the use of Stereotactic Radiosurgery for intracranial lesions and report Dunedin Hospital's early experience with this treatment. METHODS: Review of a prospective computer database and departmental clinical files. RESULTS: 74 patients underwent 78 radiosurgical procedures between 30 July 1994 to 18 December 1997. 28 patients with arteriovenous malformations were treated with an obliteration rate of 82% (95% CI: 48% to 98%) at two years. Seventeen vestibular schwannomas (acoustic neuroma's) were treated, with follow-up magnetic resonance imaging available in eleven in whom there was no tumour progression after a mean period of twelve months. There was preservation of some hearing in all patients not already deaf, but one developed a new facial palsy and another had worsening palsy as late side effects. Other tumours, including selected metastases, gliomas and skull base tumours have been treated in smaller numbers. CONCLUSION: Rates of arteriovenous malformation obliteration, vestibular schwannoma control, and side effects of radiosurgery in Dunedin are comparable to those reported in other uncontrolled series. Radiosurgery is quick and has a low procedure-related morbidity but does have important limitations and delayed side effects, which means the decision to treat needs to be based on thorough multidisciplinary review.

CG-clip expansive open-door laminoplasty: a technical note.

The CG clip is a device designed for use in expansive open-door laminoplasty with both a spacer and means of attachment in a single unit. It provides an effective technique for open-door laminoplasty, which obviates the need for bone grafting or complex internal fixation by providing dynamic stabilization of the open laminae. A number of techniques for expansive open-door laminoplasty have been devised for the decompression of the spinal cord and nerve roots in cervical spondylotic myeloradiculopathy. Each of these techniques requires some degree of internal fixation and/or bone grafting. The CG clip is a single device which is composed of both a spacer and a spring clip for attachment. The spacer ensures a 4-5-mm sagittal expansion of the cervical spinal canal. The spacer is held in place along the lateral cut margin of the laminae by a spring-wound titanium clip, which folds over the central spinous process of the unilaterally elevated laminar block. In all respects except for grafting and internal fixation, the surgery is performed as for a standard expansive open-door laminoplasty. Sixteen of the first 24 patients to undergo this procedure improved at least one point on the Neurosurgical Cervical Spine Scale. Of the remaining eight patients, four remained the same and four deteriorated. The authors have found the CG-clip laminoplasty technique quick and easy to perform, with early results in the treatment of cervical spondylotic myeloradiculopathy consistent with those of other decompressive procedures.

An audit of carotid endarterectomy for internal carotid artery disease at Dunedin Hospital.

Carotid endarterectomy, mostly for symptomatic internal carotid artery stenosis, has been successfully performed in both the vascular and neurological surgery units at Dunedin Hospital. This study was performed to compare our results with those of the North American Symptomatic Carotid Endarterectomy Trial and the European Carotid Surgery Trial. The 30-day perioperative morbidity and mortality rate was 4.3% (1.2% < 95% Cl > 7.4%) which compares favourably with an estimated upper limit of 5.5% based on recent trial reports. The present study highlights the difficulty in modelling local clinical practice on results of major trials when standards of patient evaluation and surgical skill may differ from those of the large studies. To justify generalization of indications for intervention based on the multicentre trials, there must be continual monitoring of local surgical results, and standardized use of diagnostic investigations.