Future cortical visual prosthesis implants will likely be universally wireless in operation, permitting full implantation, dural closure and therefore a lower infection risk that we estimate to be 1–2%. Standard infection prophylaxis will nonetheless be required, including broad-spectrum

and staphylococcus-specific antibiotics. Where symptomatic postoperative bleeding is concerned, a prevalence of 0.8% has previously been reported for the general neurosurgical population (Kalfas and Little, 1988), which is consistent with the figure of 1.1% reported by Fenoy and Simpson (2014) for intracerebral hemorrhage resulting from Selleckchem ERK inhibitor DBS lead insertion. However, comparing the likely risk of clinically significant intracerebral hemorrhage resulting from the insertion of DBS electrodes vs. cortical electrode arrays is difficult. A DBS electrode penetrates both cortical and subcortical tissue, with tissue damage localized to the penetration trajectory. Crizotinib In the case of cortical electrode arrays, a greater cortical surface area is compromised, however using tiled electrodes will permit the avoidance of large vessels. Moreover, the electrodes in a cortical prosthesis will only penetrate to 1.5–3.0 mm. We therefore consider that the figure of 1.1% reported for DBS implantation is a reasonable estimate of the likely risk of clinically significant intracerebral hemorrhage

resulting from cortical visual prosthesis implantation. There is also a

risk of extracerebral (extradural or subdural) bleeding after neurosurgical procedures. For epileptic patients undergoing implantation of subdural recording electrodes, Arya et al. (2013) reported that 3.53% of patients in their systematic Sitaxentan review required postoperative evacuation of intracranial hemorrhage, the most common being subdural. Importantly, the size of the grids in this review varied greatly; Wong et al. (2009) reported grid size as an independent risk factor for postoperative complications in subdural grid surgery, reflecting the increased risk with greater surgical exposure. The craniotomy required for a cortical visual prosthesis will be smaller than that required for large subdural grid implantations. For example, one group report plans to implant up to 650 electrodes across the dorsolateral surface of the occipital pole, covering an area approximately 3 cm in radius or approximately 7 cm2 (Srivastava et al., 2007). Our group is planning for implantation of up to 500 electrodes over an area covering approximately 9–10 cm2 (Lowery, 2013). Taking into account the relatively small craniotomy required for a cortical visual prosthesis, we estimate that the risk of symptomatic postoperative extracerebral bleeding (e.g. subdural/extradural) will be consistent with that of the general neurosurgical population.