Abstract
Background
A study of the risk factors associated with complications during intracranial EEG monitoring led to a change in protocol for monitoring and implantation at our centres. We conducted a study to identify any reduction in complications following the changed protocols involving the use of smaller subdural electrode arrays, continuous ICP monitoring, use of a central line, and intake of prophylactic antibiotics and dexamethasone.
Methods
We prospectively collected data on patient outcomes between 2005 and 2012 (group B) compared with patients between 1988 and 2004 (group A) before the protocol changes.
Results
Seventy-one patients in group A and 58 patients in group B underwent intracranial electrode implantation. Complications directly related to grids occurred in 25 % of group A vs. 8.6 % in group B (p < 0.05) and those indirectly related to grids were 11.2 % in group A vs. none in group B. The rate of transient complications requiring no treatment was 12.5 % in group A versus 1.7 % in group B. The rate of transient complications requiring treatment was 10 % in group A and 6.9 % in group B. There were two deaths in group A. The infection rate was higher in group B than group A (5.2 % vs. 2.8 %; p = 0.90). Since 2008 there have been no infective complications. Complications directly related to intracranial EEG monitoring were significantly reduced using the revised protocol (p < 0.05). Regression analysis identifying only the size of the grids (≤4 × 8 grid arrays) implanted was an independent predictor of more complications in group A (P < 0.05).
Conclusions
Complication rates following intracranial implantation decreased following the use of a small grid size and adherence to a stringent protocol.
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Comment
This is an interesting and important paper by Rahman et al. in which they describe their method to decrease complication rates during invasive recordings with subdural grids. This is an important paper in relation to the safety of patients undergoing these procedures. Their starting point was the group of patients published by Wong et al. in 2009. The study group described in that paper included 71 patients, 2 of whom died from herniation due to the lack of adequate surveillance. They also reported the importance of the grid size. In this study they compared the first group investigated in 1988–2004 with patients followed prospectively in 2005–2012. They concluded that the reduced size of the grids used was an independent predictor of reduced complication rates in the latter group. They now do not use grids larger than a maximum of 4 × 8. However, they also made significant changes in the surveillance protocol, introducing a one-to-one nursing ratio for the first 72 h, then decreasing to 7 p.m. to 7 a.m., leaving surveillance to relatives during the day. They also included intracranial pressure monitoring in the latter group. In spite of the important message of this paper, I have some concerns mainly based on my own experience. The first is that I find it more dangerous to implant bilateral grid arrays (in 33.8 % and 19.3 % in the two groups, respectively) and it is also a little contradictory to the concept of invasive evaluation in epilepsy surgery where the seizure generator should be at least lateralised before invasive evaluation is started. In difficult to lateralise cases I might have used some extra strips on the other side only for confirmation, not grids. However, I am perfectly aware of that several groups do this with obviously good results and low risks. Then I have concerns about the intracranial pressure monitoring. The same concern is valid for neurointensive care patients. If you have a patient who is fully awake, then intracranial pressure monitoring does not give any extra information. If the patient with a grid is not awake or cannot be waked up there is certainly an emergency that is not cured by pressure monitoring. However, I would finally like to stress that the absolute strength of this report is the authors' open discussion of previous severe problems in surveillance and the implementation of a strict surveillance protocol, which I do think is the main reason for the positive results and the main important message. The use of smaller grids is also an important factor, as shown by the authors. I strongly recommend reading this paper and also the first paper by Wong et al. (2009).
Bertil Rydenhag
Professor of Neurosurgery
Göteborg, Sweden
Zebunnessa Rahman, Chong Ho Wong, Melissa Bartley, Mark Dexter, Deepak Gill, Tony Galea, Samantha Soe and Andrew Fabian Bleasel were responsible for the collection and review of the data and preparation of the manuscript.
Karen Byth was responsible for the statistical analysis of the data.
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Rahman, Z., Bleasel, A.F., Bartley, M. et al. Reduced complications from intracranial grid insertion by using a small grid size and a precise protocol during monitoring. Acta Neurochir 158, 395–403 (2016). https://doi.org/10.1007/s00701-015-2647-6
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DOI: https://doi.org/10.1007/s00701-015-2647-6