The field of neurobionics offers hope to patients with sensory and motor impairment. Blindness is a common cause of major sensory loss, with an estimated 39 million people worldwide suffering from total blindness in 2010. Potential treatment options include bionic devices employing electrical stimulation of the visual pathways. Retinal stimulation can restore limited visual perception to patients with retinitis pigmentosa, however loss of retinal ganglion cells precludes this approach. The optic nerve, lateral geniculate nucleus and visual cortex provide alternative stimulation targets, with several research groups actively pursuing a cortically-based device capable of driving several hundred stimulating electrodes. While great progress has been made since the earliest works of Brindley and Dobelle in the 1960s and 1970s, significant clinical, surgical, psychophysical, neurophysiological, and engineering challenges remain to be overcome before a commercially-available cortical implant will be realized. Selection of candidate implant recipients will require assessment of their general, psychological and mental health, and likely responses to visual cortex stimulation. Implant functionality, longevity and safety may be enhanced by careful electrode insertion, optimization of electrical stimulation parameters and modification of immune responses to minimize or prevent the host response to the implanted electrodes. Psychophysical assessment will include mapping the positions of potentially several hundred phosphenes, which may require repetition if electrode performance deteriorates over time. Therefore, techniques for rapid psychophysical assessment are required, as are methods for objectively assessing the quality of life improvements obtained from the implant. These measures must take into account individual differences in image processing, phosphene distribution and rehabilitation programs that may be required to optimize implant functionality. In this review, we detail these and other challenges facing developers of cortical visual prostheses in addition to briefly outlining the epidemiology of blindness, and the history of cortical electrical stimulation in the context of visual prosthetics.
The nonoperative management of Type II odontoid fractures in elderly patients results in fracture stability, by either osseous union or fibrous union in almost all patients. Long-term clinical and functional outcomes seem to be more favorable when fractures have been treated with halothoracic bracing in preference to cervical collars. Stable fibrous union may be an adequate aim of management in elderly patients.
The purpose of the study was to investigate the incidence, management, and outcomes of occipital condyle fractures at a level 1 trauma center. Blunt trauma patients with occipital condyle fracture admitted to a level 1 trauma center over a 3-year period were identified. Prospective clinical and functional follow-up was undertaken, including further radiographic imaging. The incidence of occipital condyle fracture in patients presenting to our level 1 trauma center was 1.7/1,000 per year. Twenty-four patients were followed up at a mean of 27 months post-injury. There was one case of isolated occipital condyle fracture; all other patients had sustained additional orthopedic, cervical spine, and/or head injury. Seven (29%) patients sustained unilateral Type III avulsion fractures, none of which were isolated injuries. Traumatic brain injury was detected in 46% of study patients, and 42% had cervical spine injury. External halothoracic immobilization was used in 33% of cases. Fracture union with anatomical alignment occurred in 21 patients (88%). No patient had cranial nerve deficit at admission or follow-up. Three patients (12.5%) had moderate to severe neck pain/disability at follow-up, all of whom had sustained multiple injuries. Occipital condyle fractures most frequently occur in conjunction with additional injuries, particularly head and cervical spine injuries. Most cases can be managed successfully nonoperatively. Functional outcome is generally determined by pain and disability related to other injuries, rather than occipital fracture configuration.
In major trauma patients at a level 1 trauma center, the risk of CRU development increased significantly for every day of Philadelphia cervical collar time. Associated increased morbidity may be reduced by measures aimed at earlier cervical spine clearance.
Dynamic flexion-extension X-ray studies with fluoroscopy delayed cervical spine clearance and were almost always reported as normal. In a cervical spine clearance protocol for unconscious traumatic brain injury patients, dynamic flexion-extension X-ray studies with fluoroscopy did not identify any patients with cervical fracture or instability not already identified by plain radiographs and fine-cut CT (C0 to T2) with 3D reconstructions.
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