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Aswin Chari, Marek Czosnyka, Hugh K. Richards, John D. Pickard and Zofia H. Czosnyka

Object

The Cambridge Shunt Evaluation Laboratory was established 20 years ago. This paper summarizes the findings of that laboratory for the clinician.

Methods

Twenty-six models of valves have been tested long-term in the shunt laboratory according to the expanded International Organization for Standardization 7197 standard protocol.

Results

The majority of the valves had a nonphysiologically low hydrodynamic resistance (from 1.5 to 3 mm Hg/[ml/min]), which may result in overdrainage related to posture and during nocturnal cerebral vasogenic waves. A long distal catheter increases the resistance of these valves by 100%–200%. Drainage through valves without a siphon-preventing mechanism is very sensitive to body posture, which may result in grossly negative intracranial pressure. Siphon-preventing accessories offer a reasonable resistance to negative outlet pressure; however, accessories with membrane devices may be blocked by raised subcutaneous pressure. In adjustable valves, the settings may be changed by external magnetic fields of intensity above 40 mT (exceptions: ProGAV, Polaris, and Certas). Most of the magnetically adjustable valves produce large distortions on MRI studies.

Conclusions

The behavior of a valve revealed during testing is of relevance to the surgeon and may not be adequately described in the manufacturer's product information. The results of shunt testing are helpful in many circumstances, such as the initial choice of shunt and the evaluation of the shunt when its dysfunction is suspected.

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Aswin Chari, Martin M. Tisdall and Hani J. Marcus

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Aswin Chari, Angelos G. Kolias, Thomas Santarius, Simon Bond and Peter J. Hutchinson

Object

The incidence of chronic subdural hematoma (CSDH) is expected to increase substantially over the next 25 years. Continuing refinement of techniques for surgical evacuation is essential for optimizing patient outcomes. A novel technique involving a hollow screw, which is threaded through a twist-drill hole in the cranium and then connected to a closed drainage system, has been increasing in popularity. The aim of this systematic review is to collate and analyze the published experience with this novel technique and to evaluate its efficacy in comparison with the other surgical treatment methods.

Methods

This systematic review was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and has been registered with the PROSPERO International Prospective Register of Systematic Reviews (registration number CRD42013003544). MEDLINE, Web of Knowledge, EMBASE, and the Cochrane Database of Systematic Reviews were searched for published series involving more than 10 patients treated with these new techniques.

Results

Nine eligible studies were found (6 case series and 3 case-control studies) comprising 796 patients treated with these new techniques. Pooled analysis showed a “success rate” of 77.6% (95% CI 74.6%–80.4%), recurrence rate of 22.4%, and in-hospital mortality of 1.4%.

Conclusions

This systematic review adds further evidence to the pool of data assessing the safety and efficacy of the use of this novel, minimally invasive technique for the treatment for CSDH. Overall, twist-drill craniostomy with hollow screws appears to be safe and effective. Class I evidence is necessary to optimize the surgical management of patients with CSDH.