Richard J. Nelson

Advances in image-directed neurosurgery: preliminary experience with the ISG Viewing Wand compared with the Leksell G frame

Because of the limited application of frame-based stereotaxy to general neurosurgical procedures, we have carried out a preliminary evaluation of the ISG Viewing Wand, a frameless image-directed surgical system that is based on the rapid reformat and accurate three-dimensional reconstruction capability of parallel processor-based computer technology. We have compared the first 36 cases carried out with the system in the Frenchay Neurosurgery Department with a retrospective analysis of the previous 36 cases carried out using the Leksell G frame. The stereotactic cases were completed over a period of 15 months, representing 2.8% of intracranial procedures. The wand cases were completed in 3 months, 13% of the intracranial practice during that time. The wand was used for 28 supratentorial craniotomies (76%), four infratentorial procedures (11%) and five biopsy procedures (13%). Conventional stereotaxy was not used for posterior fossa or skull base procedures. Supratentorial craniotomy was carried out in nine cases (25%), while the remaining 27 cases involved point source localization within the cranium (75%). The mean preparation time prior to surgery was 65 min for the stereotactic cases and 37 min for the wand cases. We therefore conclude that the indications for frame-based stereotaxy and Viewing Wand use are mutually exclusive. Leksell stereotaxy remains the method of choice for point source localization deep within the cranium. All other procedures requiring an image-directed minimally invasive surgical approach are more appropriately carried out using the Viewing Wand. The system has potential immediate application in supratentorial, skull base and infratentorial tumour surgery, vascular surgery, epilepsy surgery and upper cervical spine surgery.

Reduction in mortality from severe head injury following introduction of a protocol for intensive care management

BACKGROUND To determine the effect of an intensive care management protocol on the intensive care unit (ICU) and hospital mortality of severely head-injured patients, we designed a longitudinal observational study of all patients admitted with a head injury between 1992 and 2000. METHODS A computerized patient database was used to identify all patients with severe head injury admitted to the ICU at Frenchay Hospital, Bristol, UK: a tertiary referral centre for the clinical neurosciences. We compared the ICU and hospital mortality and length of stay in patients before and after implementation of a protocol for their ICU management in 1997. RESULTS Implementation of the protocol was associated with a significant reduction in ICU mortality from 19.95% to 13.5% (odds ratio 0.47; 95% CI 0.29-0.75), and in hospital mortality from 24.55% to 20.8% (odds ratio 0.48; 95% CI 0.31-0.74). This was achieved despite a significant increase in the median APACHE II score (14 vs 18) of patients admitted after implementation of the protocol. The median ICU and hospital length of stay remained constant over the study period. CONCLUSIONS The introduction of an evidence-based protocol to guide the ICU management of patients with severe head injury has been associated with a significant reduction in both ICU and hospital mortality.

Nonautologous interbody fusion materials in cervical spine surgery: how strong is the evidence to justify their use?

Study Design. A review of the literature concerning the use of interbody fusion devices and materials in anterior cervical surgery. Objectives. To examine the evidence supporting the use of interbody fusion devices as an alternative to autologous bone after anterior cervical discectomy. Summary of Background Data. Concerns over the morbidity associated with harvesting autologous bone and the risk of transmissible infectious from allografts and xenografts have prompted the search for alternative methods of achieving interbody fusion. Several of these methods have been associated with an unacceptable rate of complications. The clinical and health economic implications of the widespread introduction of interbody fusion devices in the absence of sound evidence cannot be ignored. Methods. A systematic review of the literature relating to cervical interbody fusion was undertaken. Studies were assessed critically with respect to their methodology, results, and conclusions. Results. Thirty-two clinical studies and 10 laboratory studies were analyzed. Methodologic weaknesses were identified in the majority. Only four clinical reports were either randomized or blinded or involved independent assessment of their outcomes. Fewer than half of the studies included a valid statistical analysis. Radiologic evidence of fusion was limited in many cases. There was little evidence that nonautologous fusion devices offered a reduction in the length of hospital stay. Autologous bone was as effective as, or superior to, many other fusion devices. The early results of some new fusion techniques used alone or in combination showed promise. Conclusions. There is limited evidence supporting the use of a cervical interbody fusion device in place of autologous bone. There is a need to standardize the testing of implants with good quality laboratory work preceding clinical use. Certain devices including cages, some forms of hydroxyapatite, and bone morphogenic proteins merit further study.

Can exercise therapy improve the outcome of microdiscectomy

Study Design. A prospective randomized controlled trial of exercise therapy in patients who underwent microdiscectomy for prolapsed lumbar intervertebral disc. Results of a pilot study are presented. Objective. To determine the effects of a postoperative exercise program on pain, disability, psychological status, and spinal function. Summary of Background Data. Microdiscectomy is often used successfully to treat prolapsed lumbar intervertebral disc. However, some patients do not have a good outcome and many continue to have low back pain. The reasons for this are unclear but impairment of back muscle function due to months of inactivity before surgery may be a contributing factor. A postoperative exercise program may improve outcome in such patients. Methods. Twenty patients who underwent lumbar microdiscectomy were randomized into EXERCISE and CONTROL groups. After surgery, all patients received normal postoperative care that included advice from a physiotherapist about exercise and a return to normal activities. Six weeks after surgery, patients in the EXERCISE group undertook a 4-week exercise program that concentrated on improving strength and endurance of the back and abdominal muscles and mobility of the spine and hips. Assessments of spinal function were performed in all patients during the week before surgery and at 6, 10, 26, and 52 weeks after. The assessment included measures of posture, hip and lumbar mobility, back muscle endurance capacity and electromyographic measures of back muscle fatigue. On each occasion, patients completed questionnaires inquiring about pain, disability and psychological status. Results. Surgery improved pain, disability, back muscle endurance capacity and hip and lumbar mobility in both groups of patients. After the exercise program, the EXERCISE group showed further improvements in these measures and also in electromyographic measures of back muscle fatigability. All these improvements were maintained 12 months after surgery. The only further improvement showed by the CONTROL group between 6 and 52 weeks was an increase in back muscle endurance capacity. Conclusion. A 4-week postoperative exercise program can improve pain, disability, and spinal function inpatients who undergo microdiscectomy.

Clinical experience with porous tantalum cervical interbody implants in a prospective randomized controlled trial

A prospective randomized study was undertaken to evaluate the radiological appearance and clinical effectiveness of two porous tantalum (Hedrocel) implants in achieving a stable cervical interbody fusion. A prerandomization protocol was used to allocate patients to the three arms of the study: a ring implant containing autologous cancellous bone graft, a solid block implant or autologous tricortical iliac crest bone graft. Patients were followed for 2 years with plain radiological studies, SF-36, and Neck Disability Index questionnaires and neurological assessment. Early in the study the postoperative radiographs of four patients receiving Hedrocel implants showed inferior end-plate lucency raising concerns about delayed or non-fusion. Recruitment to the study was halted by the investigators to allow longer-term follow-up of the implanted patients when only 24 patients had been recruited to the study. Although fusion was subsequently noted in all patients at 12 months there was no further enrolment to the study. At 2 years the radiological and clinical outcomes of the three groups appeared comparable, but the study numbers were too small for any statistical analysis. This study highlights the difficulties that can arise when clinical caution takes precedence over objective measures of clinical progress during a study. In the absence of an independent safety monitoring committee, the investigators were under an ethical obligation to suspend recruitment to this study, until it was clear that the radiological features were not associated with poor clinical outcomes. The use of safety monitoring committees and the clarification of stopping criteria in relation to outcome measures should be considered in open randomized trials of spinal surgical techniques and implants.

Sensitivity of near infrared spectroscopy to cerebral and extra-cerebral oxygenation changes is determined by emitter-detector separation.

Objective. To examine the effect of two emitter-detector separations (2.7 and 5.5 cm) on the detection of changes in cerebral and extra-cerebral tissue oxygenation using near infrared spectroscopy (NIRS). Methods. Two NIR detectors were placed on the scalp 2.7 and 5.5 cm from a single NIR emitter. Changes in deoxyhaemoglobin (HHb), oxyhaemoglobin (O2Hb),oxidised cytochrome C oxidase (Cyt) and total haemoglobin (tHb) were recorded from each detector during the induction of cerebral oligaemia (transition from hypercapnia to hypocapnia) and scalp hyperaemia (following release of a scalp tourniquet). Results. Cerebral oligaemia (mean decrease in middle cerebral artery blood flow velocity of 44%) induced by a mean reduction in end tidal CO2 of 18 mmHg was accompanied by a significant increase in the spectroscopic signal for HHb and a decrease in the O2Hb signal. The signal change per unit photon path length detected at 5.5 cm was significantly greater for HHb (p = 0.007) than that detected at 2.7 cm. In contrast, the increase in all chromophores detected at 5.5 cm during scalp hyperaemia was significantly less than that detected at 2.7 cm (p < 0.001). Conclusions. The differing sensitivity of the proximal and distal channels to changes in cerebral and extra-cerebral oxygenation is compatible with theoretical models of NIR light transmission in the adult head and may provide a basis for spatially resolving these changes. The optimal emitter-detector separation for adult NIRS requires further investigation and may differ between individuals.

Outcome Following Surgical Evacuation of Traumatic Intracranial Haematomas in the Elderly

In order to determine the factors influencing outcome following craniotomy for trauma in patients over the age of 65 and to establish criteria for surgical intervention, the authors carried out a retrospective analysis of the hospital and general practice records of all head injury patients over the age of 65 who underwent a craniotomy for evacuation of a post-traumatic haematoma within 7 days of injury at Frenchay Hospital during a 10-year period (1980-89). Outcome was measured using the Glasgow Outcome Scale and patients were allotted to a good outcome group (good recovery or moderate disability but independent) or a poor outcome group (severe disability, vegetative state of death). There were 35 men and 31 women with a mean age of 72.5 years (range 65-85 years). The mortality rate was 61% and 9% of patients survived in a severely disabled or vegetative state. All 20 (30%) patients with a good outcome had a Glasgow Coma Score (GCS) of 5 or more immediately before surgery. All 18 (27%) patients with a GCS of 4 or less and all 22 (33%) patients with unilateral or bilateral pupillary dilatation had a poor outcome. Outcome was significantly worse in the older patients (75-85 years) compared with the younger patients (65-74 years) and in those patients requiring craniotomy within 24 hours of injury, but the mechanism of injury (fall or road traffic accident), the presence or absence of skull fractures and limb fractures and the pre-operative CT scan appearances did not influence outcome. This study confirms the high probability of poor outcome following surgical evacuation of traumatic intracranial haematomas for elderly head-injured patients with pupillary dilatation or extensor motor responses. Craniotomy under these circumstances is not justified.

Proposal for a prospective multi-centre audit of chronic subdural haematoma management in the United Kingdom and Ireland

Abstract Background. Chronic subdural haematoma (CSDH) is a common condition that increases in incidence with rising age. Evacuation of a CSDH is one of the commonest neurosurgical procedures; however the optimal peri-operative management, surgical technique, post-operative care and the role of adjuvant therapies remain controversial. Aim. We propose a prospective multi-centre audit in order to establish current practices, outcomes and national benchmarks for future studies. Methods. Neurosurgical units (NSU) in the United Kingdom and Ireland will be invited to enrol patients to this audit. All adult patients aged 16 years and over with a primary or recurrent CSDH will be eligible for inclusion. Outcome measures and analysis. The proposed outcome measures are (1) clinical recurrence requiring re-operation within 60 days; (2) modified Rankin scale (mRS) score at discharge from NSU; (3) morbidity and mortality in the NSU; (4) destination at discharge from NSU and (5) length of stay in the NSU. Audit standards have been derived from published systematic reviews and a recent randomised trial. The proposed standards are clinical recurrence rate < 20%; unfavourable mRS (4–6) at discharge from NSU < 30%; mortality rate in NSU < 5%; morbidity rate in NSU < 10%. Data will be submitted directly into a secure online database and analysed by the studys management group. Conclusions. The audit will determine the contemporary management and outcomes of patients with CSDH in the United Kingdom and Ireland. It will inform national guidelines, clinical practice and future studies in order to improve the outcome of patients with CSDH.

A report from the inaugural meeting of the British Neurosurgical Trainee Research Collaborative held in the Royal College of Surgeons of England, 19 October 2012.

Abstract Clinical research, which is essential for improving patient outcomes, is increasingly carried out in the context of networks established between multiple institutions. Research is also considered an important component of training curricula. The recent successful completion of a randomised trial (ROSSINI), which was led by general surgical trainees of the West Midlands Research Collaborative, has established the feasibility of trainee collaborative research networks. A research network for neurosurgical trainees in the UK and Ireland was, therefore, established following the meeting of the British Neurosurgical Trainee Association (BNTA) in Aberdeen on 19 April 2012. This BNTA initiative quickly gained the full support from the Society of British Neurological Surgeons and the UK Neurosurgical Research Network. The inaugural meeting of the British Neurosurgical Trainee Research Collaborative took place at the Royal College of Surgeons of England, London, on 19 October 2012. The purpose of this report is both to record progress to date and to promote this concept.

Spontaneous cerebral haemorrhage from cerebral amyloid angiopathy

Three cases of spontaneous intracerebral haemorrhage treated by acute evacuation of haematoma are described. All cases proved to have cerebral amyloid angiopathy as the primary cause of the haemorrhage. Only one patient survived. Previous reports are discussed.