Supraorbital microcraniotomy for acute aneurysmal subarachnoid haemorrhage: results of first 50 cases.

For the past 50 years the pterional craniotomy has been the standard approach for anterior circulation aneurysms. However, this is a major procedure. As the trend is towards minimally invasive surgery generally, we have been developing a minimally invasive approach for anterior circulation aneurysms - the supraorbital microcraniotomy. We present first 50 patients who underwent this operation after an aneurysmal subarchnoid haemorrhage. The data were collected prospectively between 2001 and 2004. A total of 60 aneurysms were clipped (10 patients had two aneurysms). Forty-one of fifty patients (82%) were good grade (WFNS I and II) and 9/50 (18%) were poor grade (WFNS III - V) at the time of surgery. Anterior communicating aneurysms were the commonest (37%), but aneurysms at all of the usual anterior circulation sites were included, apart from ophthalmic aneurysms, as none presented during this period, and pericallosal aneurysms, which were not appropriate for it. Five patients (10%) also had an intracerebral haematoma on presentation. The overall management mortality for this series was 3/50 (6%) with 82% achieving a favourable outcome on the Glasgow Outcome Scale (GOS). For those in good grade at surgery, the mortality was 1/41 (2.4%) with 87.7% achieving a favourable outcome on the GOS.

Intracranial metastasis from medullary carcinoma of the thyroid 25 years after primary surgery.

Medullary carcinoma of the thyroid is an uncommon tumour. In most patients, it is confined to the neck with or without involvement of the local cervical nodes. It rarely metastasizes to the mediastinum, lungs or liver. Intracranial metastasis is extremely rare with very few reported cases in the literature. We report an unusual case of an intracranial metastasis from a medullary carcinoma of the thyroid that occurred 25 years after primary surgery. We discuss the unusual features of our case together with a review of the literature.

Changes in plasma phenytoin level following craniotomy.

Phenytoin is often used to prevent postcraniotomy seizures, but is not always effective. We investigate changes in plasma phenytoin level ([phenytoin]) following craniotomy. The [phenytoin] in 28 patients who were receiving phenytoin (oral/ intravenous) and undergoing a craniotomy were prospectively measured 24 h preoperatively, immediately pre- and postcraniotomy, 24 and 48 h postoperatively. Factors examined included patients' age, sex, pathology, preoperative [phenytoin], operative duration and blood loss. Fifteen patients had [phenytoin] concentrations outside the therapeutic range. Twenty-five patients experienced a decrease in [phenytoin] immediately postcraniotomy: pre-, post- and 24 h postcraniotomy mean [phenytoin] were 13.4, 10.0 and 12.9 mg/l, respectively. Preoperative [phenytoin], operative duration and blood loss had significant correlation with the decrease in [phenytoin] (p < 0.05). In conclusion, < 50% of the patients had therapeutic preoperative [phenytoin]. In most patients, [phenytoin] decreases by 26% after craniotomy and returns to preoperative level within 24 h. These may contribute to early postoperative seizure development.

Brain abscesses associated with pulmonary arteriovenous malformations.

We present three patients with brain abscesses who also had pulmonary arteriovenous malformations (AVMs). All patients had hereditary haemorrhagic telangiectasia (Osler's Disease). It is probable that the lung AVMs contributed to the development of the brain abscesses by allowing bacteria easier access to the systemic circulation through a right to left pulmonary vascular shunt, bypassing the filtering action of the pulmonary capillaries. In addition, one patient required a period of postoperative ventilation using PEEP, which may have exacerbated the shunt through the lung AVM and led to difficulty in weaning her from the ventilator.

Protein adsorption to hydrocephalus shunt catheters: CSF protein adsorption.

OBJECTIVE: To assess the quantity and nature of the proteins that adsorb to hydrocephalus shunt catheters after implantation, and to determine whether sufficient could accumulate to obstruct the catheter. DESIGN: Elution of proteins from 102 explanted shunt catheters, with protein assay and electrophoresis of the eluate, and scanning electron microscopy (SEM) of the catheters. RESULTS: The amount of protein elutable was extremely low, and significant protein, apart from a thin film, was not found on SEM. Qualitative analysis disclosed that most of the adsorbed protein was albumin. CONCLUSIONS: Protein deposition on hydrocephalus catheters does not occur in sufficient quantities to cause catheter obstruction.

Use of a commercial computer program for continuous audit of surgical complications.

Audit is essential for good medical practice, but is time-consuming, and each unit has been left to devise their own techniques. One method is described using a widely available computer package that allows the results to be charted and updated automatically. Any deterioration in performance is thus readily apparent. This method has been particularly useful for auditing shunt infections, but could easily be adapted for other uses.

Removed shunt valves: reasons for failure and implications for valve design.

Most removed shunt valves are discarded with no investigation into why they had to be replaced or whether they still performed to specification. However, improvements in valve design will only occur if valves that have needed removal are examined and the reasons that they failed are determined. An in-depth study of 43 valves that were removed in this unit over a 15-month period was performed. They were submitted to a four-part study, comprising flow-pressure testing, opening and closing pressure measurement, assessment of the susceptibility to syphoning, and dismantling with internal inspection of the valve components. Overall, 81% of valves failed to meet the manufacturers' specified performance data, even though the peroperative cause of shunt failure was thought to lie outside the valve. Over 80% of valves with metallic parts were found to have accumulated debris internally, and this was thought to have impaired their performance. In contrast, only 25% of non-metallic valves contained debris, a significant difference (0.01 > p > 0.001). All of the valves had a high tendency to overdrainage. Attention is drawn to the high number of malfunctioning valves. It is recommended that a change of valve should be considered in all shunt revisions, and that future valve designs should avoid metal components.

Does the cerebrospinal fluid protein concentration increase the risk of shunt complications?

A prospective study was performed to determine whether the popular opinion that a high CSF protein concentration increases the risk of shunt complications is true. Ninety-five patients were enrolled into the study and they had 116 shunt operations over 15 months. It was considered that the CSF protein content might influence the development of complications that occurred within 2 months of surgery. Shunt complications occurred following 24.6% of operations within this period. This included 12 infections, 13 obstructions and three cases of overdrainage. The distribution of complications, compared to CSF protein content, was non-significant on a chi 2-test (p > 0.5). The total protein content of each of the complication groups was also analysed using the Mann-Whitney U-test and the differences were non-significant for the infection (0.1 > p > 0.05) and obstruction groups (0.5 > p > 0.1). It is concluded that an elevated CSF protein content does not increase the risk of shunt complications, and that there is no reason why shunting should be delayed in patients with a high CSF protein content.

Reduced bacterial adhesion to hydrocephalus shunt catheters mediated by cerebrospinal fluid proteins.

BACKGROUND: Prosthetic infections are a major problem, requiring complex and lengthy management. The role of blood proteins in the pathogenesis of implant infection has been investigated, but research into the role of CSF protein in shunt infections has not been undertaken, even though a high CSF protein has been assumed to increase the risk of such infections. METHODS: New shunt catheters were exposed to either CSF or individual protein solutions, and the numbers of radiolabelled staphylococci that adhered to them were compared with controls that had been exposed to saline only. RESULTS: A significant reduction in bacteria adhering to the test catheter was found in each instance. Furthermore, the CSF with the highest protein content, from a patient with intraventricular haemorrhage, had the greatest inhibitory effect on bacterial adhesion. The effect of the solutions on the hydrophobicity of the silicone rubber was also investigated. The silicone rubber was more hydrophilic, and bacterial adhesion was less, with solutions containing a higher protein content, and these findings were in keeping with the current theories on the mechanism of bacterial adhesion to polymers. CONCLUSIONS: A high CSF protein content does not predispose to the development of shunt infections.

The effect of protein and blood cells on the flow-pressure characteristics of shunts.

It has long been assumed that a high cerebrospinal fluid protein concentration adversely affects the performance of shunts. There is little experimental evidence to support this viewpoint, however, and the few reports that have been published can be criticized for poor experimental design or presentation of results. A flow-dependent shunt perfusion model was constructed. PS Medical Flow Control valves (PS Medical Corporation, Goleta, CA) and Cordis-Hakim valves (Cordis Corporates, Miami, FL) were perfused with saline-plasma solutions in concentrations from 0 to 9 g/L of protein. Blood suspensions in dilutions from 0.25 to 1% were also studied. The opening and closing pressures of the valves were measured with a simple manometer, and the physical properties of the solutions were studied. The results indicated that the valves performed within the ranges specified by their manufacturers, even with markedly increased protein concentrations in the perfusate. Furthermore, the valve opening and closing pressures were lower with the protein-containing solutions than with the control solutions. Thus, the protein did not impair shunt function and we conclude that shunts can be inserted into patients who have elevated cerebrospinal fluid protein contents. However, blood cells did adversely affect performance and, therefore, patients with hemorrhagic cerebrospinal fluid should not receive shunts.

Physical properties of cerebrospinal fluid of relevance to shunt function. 2: The effect of protein upon CSF surface tension and contact angle.

CSF surface tension has received little study, and yet it will effect the pressure at which shunt valves operate, and by influencing the degree of hydrophobicity (contact angle) will alter the attraction between bacteria and neurosurgical prostheses. A study is therefore presented of the effect of protein content upon the surface tension of CSF and its contact angle to silicone rubber. Both of these quantities fell throughout the normal range of CSF protein, but above 1 g/l, additional protein had little effect, and the results obtained were similar to that reported for plasma. The effect of surface tension on the opening and closing pressures of hydrocephalus shunt valves and of contact angle in the adhesion of bacteria to neurosurgical implants is discussed.

Physical properties of cerebrospinal fluid of relevance to shunt function. 1: The effect of protein upon CSF viscosity.

Viscosity is the resistance to flow of a fluid and it is the only property of a fluid that will affect its flow through a system of valveless tubing (surface tension will affect the opening and closing of valves that are included in the system). The effect that an elevated protein concentration has upon CSF viscosity has received little study, yet many neurosurgeons believe that CSF with an elevated protein content is too viscous to flow satisfactorily through shunts. The total protein content and viscosity of 126 specimens of CSF from hydrocephalic patients were measured and analysed with reference to the aetiology of the hydrocephalus. The results indicate that high protein concentrations do not greatly affect the viscosity of CSF, and that the aetiology is also of little consequence. These findings were highly significant on linear regression analysis (p < 0.001). The flow of the most viscous CSF that is likely to be encountered would be reduced by only 7% through a given catheter, compared with that of the least viscous CSF.

The management of cerebellar abscess since the introduction of CT scanning.

Sixteen patients with surgical infection of the posterior fossa are presented. There were 14 patients with cerebellar abscess, one patient with a solitary posterior fossa subdural empyema, and another with a combined cerebellar abscess and subdural empyema. Two of the cerebellar abscess patients also had supratentorial infections. The presenting features, aetiology, radiology and bacteriology are discussed with particular reference to differences in abscess re-accumulation, and outcome between those managed by aspiration and excision. We have been unable to show that either method of treatment is superior to the other. An overall mortality rate of 19% was achieved; however, for those with parenchymal cerebellar abscesses this was reduced to 13%. We conclude that burr hole aspiration with regular CT is a satisfactory method of treatment for cerebellar abscess.

Intracranial dermoid cysts with nasal dermal sinuses.

Dermal sinuses penetrating the dura are important in that they may be complicated by C.N.S. infection, and this complication can be prevented by early surgery. Although well recognised over the occiput and lumbar spine, nasal dermal sinuses extending intracranially are much rarer and have received little attention in the neurosurgical literature. Two unique cases are presented, together with a literature review, discussing the anatomy, radiology, and management of the condition.

Medulloblastoma metastasizing to a breast fibroadenoma: a case report.

The extracranial spread of primary intercranial tumours is infrequent, occurring most commonly with medulloblastoma. The spread of one malignant tumour to a second tumour, benign or malignant, is also very rare. This case appears to be unique, in that a primary malignant cerebral tumour metastasized to a benign extracranial tumour.