Roger Strachan

Prospective Analysis of the Trial Period for Spinal Cord Stimulation Treatment for Chronic Pain

Objective:  To determine patient preferences regarding the duration of trial period.

Do antibiotic-impregnated external ventriculostomy catheters have a low infection rate in clinical practice? A retrospective cohort study

Abstract Objective: External ventriculostomy-related infection (VRI) of cerebrospinal fluid (CSF) is a source of significant morbidity and mortality. In previous trials, antibiotic-impregnated ventricular catheters have been associated with lower incidence of CSF infections. We undertook this retrospective observational study to evaluate whether the introduction of antibiotic-impregnated external ventricular drains (EVDs) in 2004 has decreased VRI in our neurosurgical unit. Method: One hundred and fifteen patients underwent insertion of EVDs from January 2000 to March 2008. Data were collected for 99 patients with a total of 146 EVD insertions. The parameters studied were age, gender, ASA score, seniority of the surgeon, significant medical history, presence of trauma, concurrent surgeries, revisional surgery, use of peri-operative systemic antibiotic, use of antibiotic-impregnated external ventricular catheter, tunnelling of the catheter, duration of drainage and VRIs. Results: Eleven patients developed new VRI (12%). Analysis comparing infection incidence for various co-morbidities shows that systemic sepsis was associated with higher infection rates (p = 0.037). Revisional surgery (p = 0.036) and longer duration of catheterization (p = 0.001) were also found to be associated with VRI. The Standard catheters and the antibiotic-impregnated catheters had similar infection rates. The antibiotic-impregnated catheters tended to be infection-free for longer but these differences were not statistically significant. The duration of catheterization was significantly higher for the antibiotic-impregnated catheter group. In both groups, the majority of infections were caused by Gram-positive bacteria. Conclusion: Our study demonstrates that there was no statistically significant difference in the infection rates for the Standard and antibiotic-impregnated external ventriculostomy catheters. The duration of catheterization was significantly higher for the Antibiotic-impregnated catheter group. The antibiotic-impregnated catheter infections tended to occur later as compared with the Standard catheter group.

Flow dynamics in lumboperitoneal shunts and their implications in vivo

OBJECT Lumboperitoneal shunting is the standard treatment for pseudotumour cerebri or idiopathic intracranial hypertension. Complications are common, particularly the problem of overdrainage leading to low pressure symptoms. The authors designed a simple experiment using catheters of different lengths that drained at different pressure heads and with different vertical drops to study the flow characteristics in these shunts and determine the optimal catheter placement and length that would reduce the occurrence of low pressure headaches. METHODS The flow rates through catheters of 3 different lengths (60, 83, and 100 cm) with the same internal radius, at 3 different pressure heads (15, 25, and 35 cm H2O to simulate 3 different placements in the lumbar theca), and 3 different vertical drops (10, 20, and 30 cm to simulate the possible effect of siphoning) were measured and the results analyzed. RESULTS Application of Poiseuilles law and Bernoullis principle to the experimental design shows that the volume of flow is directly proportional to the sum of the pressure head and the vertical drop and inversely proportional to the length of the catheter. The flow rate through the standard catheter lengths over the course of 24 hours can be abnormally high. An attempt to predict the optimal catheter length was made. CONCLUSIONS Although the catheter position in the theca and abdomen cannot be altered significantly and the internal radius of the tube cannot be reduced further without increasing the risk of blockage, the length of the tube can be increased to combat overdrainage. The authors suggest that currently available catheters are too short.

Counting the cost of negligence in neurosurgery: Lessons to be learned from 10 years of claims in the NHS *

Abstract Introduction. Despite substantial progress in modernising neurosurgery, the specialty still tops the list of medico-legal claims. Understanding the factors associated with negligence claims is vital if we are to identify areas of underperformance and subsequently improve patient safety. Here we provide data on trends in neurosurgical negligence claims over a 10-year period in England. Methods. We used data provided by the National Health Service Litigation Authority to analyse negligence claims related to neurosurgery from the financial years 2002/2003 to 2011/2012. Using the abstracts provided, we extracted information pertaining to the underlying pathology, injury severity, nature of misadventure and claim value. Results. Over the 10-year period, the annual number of claims increased significantly. In total, there were 794 negligence claims (range 50–117/year); of the 613 closed cases, 405 (66.1%) were successful. The total cost related to claims during the 10 years was £65.7 million, with a mean claim per successful case of £0.16 million (total damages, defence and claimant costs of £45.1, £6.36 and £14.3 million, respectively). Claims related to emergency cases were more costly compared to those of elective cases (£209,327 vs. £112,627; P = 0.002). Spinal cases represented the most frequently litigated procedures (350; 44.1% of total), inadequate surgical performance the most common misadventure (231; 29.1%) and fatality the commonest injury implicated in claims (102; 12.8%). Negligence claims related to wrong-site surgery and cauda equina syndrome were frequently successful (26/26; 100% and 14/16; 87.5% of closed cases, respectively). Conclusion. In England, the number of neurosurgical negligence claims is increasing, the financial cost substantial, and the burden significant. Lessons to be learned from the study are of paramount importance to reduce future cases of negligence and improve patient care.

Hydrocephalus as presenting feature of spinal astrocytoma in a adolescent patient.

We report the case of an adolescent with a thoracic spine astrocytoma whose initial presentation was communicating hydrocephalus. We speculate that the mechanism may be reduced meningeal compliance due to meningeal spread of the tumour. Craniospinal MR imaging should be considered as part of the routine work up for patients presenting with unexplained hydrocephalus, elevated CSF protein and/or long tract symptoms/signs.

Recurrence of fourth ventricular choroid plexus papilloma with late occurrence of a spinal drop metastasis

Choroid plexus papillomas are rare tumours, which occasionally spread both intracranially and down the spinal canal. Spinal metastasis has been reported infrequently and only once many years since the initial diagnosis. This is the first reported case of late recurrence, metastasis and transformation of a benign to an atypical lesion.

CSF hydrothorax: An unusual cause of pleural effusion.

Abstract A 20-year-old male with hydrocephalus managed with a ventriculoperitoneal shunt (VP) was diagnosed with a cerebrospinal fluid (CSF) pleural effusion. Imaging studies revealed an intrathoracic course of a disconnected VP shunt. Physicians should consider CSF effusion in their differential diagnosis in patients with a VP shunt and an unexplained pleural effusion.

Intracranial metastasis masquerading as acute subdural haematoma

We discuss a case of subdural metastasis in which the clinical features and associated images mimic acute subdural haematoma.

Reducing the radiation exposure from CT scanning in children with shunts: a nationwide survey and a departmental CT protocol

Abstract Introduction: Low dose ionising radiation such as from CT scans carries a low but cumulative risk of cancer and children are particularly sensitive. Children with VP Shunts often undergo multiple CT scans. We developed a CT protocol with reduced radiation for paediatric patients with shunts and compared it with the current practice in the other neurosurgical units in the UK and ROI by conducting a nationwide survey. Methods: An email questionnaire was send to the superintendent radiographer in every Neurosurgical unit in the UK and the ROI. Results: The response rate was 70%. Only 5 (19%) of the responding units used a dedicated CT shunt protocol with reduced radiation. Radiation was reduced by lowering the tube current. In comparison, our protocol uses a combination of less tube current and fewer slices. This reduced the radiation exposure of a CT head significantly with sufficient image quality to make a diagnosis. Conclusion: Radiation from CT for paediatric shunt patients scans can and should be reduced. This can be achieved by using reduced radiation protocols. A national paediatric CT shunt protocol could lead to significant reduction in effective radiation dose.

Gravity-assisted valve (GAV) systems to prevent low-pressure headaches in patients with lumboperitoneal shunts

Abstract Objectives: Low-pressure symptoms after lumboperitoneal (LP) shunting for idiopathic intracranial hypertension (IIH) remain a significant problem. Gravity-assisted valves (GAV) operate at a higher pressure in a vertical position and therefore aim to reduce postural over-drainage. We audited patients with GAV valves inserted in their shunt system to assess their efficacy in reducing low-pressure symptoms and ascertain whether the additional cost of such device can be justified. Method: Using a standard proforma, we reviewed patient medical notes and recorded indications and post-operative outcomes in symptom control. Results: In total, 24 patients had the GAV system inserted, 12 had low-pressure symptoms after LP and had LP shunts inserted with GAV valves and 11 in developed low-pressure symptoms after insertion of plane LP shunts and had GAV valves added as secondary procedures. One patient was excluded from the study because the indication for the GAV system was secondary to the presence of low lying cerebellar tonsils (secondary Chiari) rather than headache in a patient with IIH who had undergone previous LP shunt insertion. The GAV system was introduced to prevent further tonsillar decent.Out of 23 patients, 17 patients who had the system inserted to prevent or improve low-pressure symptoms reported improvement in their symptoms. Conclusions: GAV inserted into LP shunts were effective in reducing low-pressure headaches induced by changes in posture whilst still sufficiently lowering ICP to ameliorate high-pressure symptoms.