Application of emerging technologies to improve access to ischemic stroke care.

During the past 20 years, the traditional supportive treatment for stroke has been radically transformed by advances in catheter technologies and a cohort of prominent randomized controlled trials that unequivocally demonstrated significant improvement in stroke outcomes with timely endovascular intervention. However, substantial limitations to treatment remain, among the most important being timely access to care. Nonetheless, stroke care has continued its evolution by incorporating technological advances from various fields that can further reduce patients' morbidity and mortality. In this paper the authors discuss the importance of emerging technologies-mobile stroke treatment units, telemedicine, and robotically assisted angiography-as future tools for expanding access to the diagnosis and treatment of acute ischemic stroke.

Feasibility of Telementoring for Microneurosurgical Procedures Using a Microscope: A Proof-of-Concept Study.

BACKGROUND: Our pilot study evaluated the effectiveness of our telementoring-telescripting model to facilitate seamless communication between surgeons while the operating surgeon is using a microscope. METHODS: As a first proof of concept, 4 students identified 20 anatomic landmarks on a dry human skull with or without telementoring guidance. To assess the ability to communicate operative information, a senior neurosurgery resident evaluated the student's ability and timing to complete a stepwise craniotomy on a cadaveric head, with and without telementoring guidance; a second portion included exposure of the anterior circulation. The mentor was able to annotate directly onto the operator's visual field, which was visible to the operator without looking away from the binocular view. RESULTS: The students showed that they were familiar with half (50% ± 10%) of the structures for identification and none was familiar with the steps to complete a craniotomy before using our system. With the guidance of a remote surgeon projected into the visual field of the microscope, the students were able to correctly identify 100% of the structures and complete a craniotomy. Our system also proved effective in guiding a more experienced neurosurgery resident through complex operative steps associated with exposure of the anterior circulation. CONCLUSIONS: Our pilot study showed a platform feasible in providing effective operative direction to inexperienced operators while operating using a microscope. A remote mentor was able to view the visual field of the microscope, annotate on the visual stream, and have the annotated stream appear in the binocular view for the operating mentee.

Aneurysm growth and de novo aneurysms during aneurysm surveillance.

OBJECTIVE Many low-risk unruptured intracranial aneurysms (UIAs) are followed for growth with surveillance imaging. Growth of UIAs likely increases the risk of rupture. The incidence and risk factors of UIA growth or de novo aneurysm formation require further research. The authors retrospectively identify risk factors and annual risk for UIA growth or de novo aneurysm formation in an aneurysm surveillance protocol. METHODS Over an 11.5-year period, the authors recommended surveillance imaging to 192 patients with 234 UIAs. The incidence of UIA growth and de novo aneurysm formation was assessed. With logistic regression, risk factors for UIA growth or de novo aneurysm formation and patient compliance with the surveillance protocol was assessed. RESULTS During 621 patient-years of follow-up, the incidence of aneurysm growth or de novo aneurysm formation was 5.0%/patient-year. At the 6-month examination, 5.2% of patients had aneurysm growth and 4.3% of aneurysms had grown. Four de novo aneurysms formed (0.64%/patient-year). Over 793 aneurysm-years of follow-up, the annual risk of aneurysm growth was 3.7%. Only initial aneurysm size predicted aneurysm growth (UIA < 5 mm = 1.6% vs UIA ≥ 5 mm = 8.7%, p = 0.002). Patients with growing UIAs were more likely to also have de novo aneurysms (p = 0.01). Patient compliance with this protocol was 65%, with younger age predictive of better compliance (p = 0.01). CONCLUSIONS Observation of low-risk UIAs with surveillance imaging can be implemented safely with good adherence. Aneurysm size is the only predictor of future growth. More frequent (semiannual) surveillance imaging for newly diagnosed UIAs and UIAs ≥ 5 mm is warranted.

Real-time monitoring of extracellular adenosine using enzyme-linked microelectrode arrays.

Throughout the central nervous system extracellular adenosine serves important neuroprotective and neuromodulatory functions. However, current understanding of the in vivo regulation and effects of adenosine is limited by the spatial and temporal resolution of available measurement techniques. Here, we describe an enzyme-linked microelectrode array (MEA) with high spatial (7500 µm(2)) and temporal (4 Hz) resolution that can selectively measure extracellular adenosine through the use of self-referenced coating scheme that accounts for interfering substances and the enzymatic breakdown products of adenosine. In vitro, the MEAs selectively measured adenosine in a linear fashion (r(2)=0.98±0.01, concentration range=0-15 µM, limit of detection =0.96±0.5 µM). In vivo the limit of detection was 0.04±0.02 µM, which permitted real-time monitoring of the basal extracellular concentration in rat cerebral cortex (4.3±1.5 µM). Local cortical injection of adenosine through a micropipette produced dose-dependent transient increases in the measured extracellular concentration (200 nL: 6.8±1.8 µM; 400 nL: 19.4±5.3 µM) [P<0.001]. Lastly, local injection of dipyridamole, which inhibits transport of adenosine through equilibrative nucleoside transporter, raised the measured extracellular concentration of adenosine by 120% (5.6→12.3 µM) [P<0.001]. These studies demonstrate that MEAs can selectively measure adenosine on temporal and spatial scales relevant to adenosine signaling and regulation in normal and pathologic states.

Conus medullaris syndrome after epidural steroid injection: Case report.

BACKGROUND: Given the risk of paralysis associated with cervical transforaminal injection, is it time to reconsider transforaminal injections of the lumbar spine? Arguments for discontinuing lumbar injections have been discussed in the anesthesia literature, raising concern about the risks of epidural steroid injections (ESIs). METHODS: In a 47-year-old man, paraplegia of the lower extremities developed, specifically conus medullaris syndrome, after he underwent an ESI for recurrent pain. Correct needle placement was verified with epidurography. Immediately after the injection, the patient felt his legs "going dead"; paraplegia of the lower extremities was noted. RESULTS: An initial magnetic resonance imaging study performed after the patient was transferred to the emergency department was unremarkable. However, a later neurosurgical evaluation showed conus medullaris syndrome, and a second magnetic resonance imaging study showed the conus infarct. We conducted a search of the PubMed database of articles from 2002 to 2011 containing the following keywords: complications, lumbar epidural steroid injection(s), cauda equina syndrome, conus medullaris infarction, spinal cord infarction, spinal cord injury, paralysis, paresis, plegia, paresthesia, and anesthesia. CONCLUSIONS: Summarizing this case and 5 similar cases, we weigh the potential benefits and risks of ESI. Although one can safely assume that this severe, devastating complication is rare, we speculate that its true incidence remains unknown, possibly because of medicolegal implications. We believe that the rarity of this complication should not preclude the continued use of transforaminal ESI; rather, it should be emphasized for discussion with patients during the consent process.