Martin Chapman

MR-guided focused ultrasound thalamotomy for essential tremor: a proof-of-concept study

BACKGROUNDnEssential tremor is the most common movement disorder and is often refractory to medical treatment. Surgical therapies, using lesioning and deep brain stimulation in the thalamus, have been used to treat essential tremor that is disabling and resistant to medication. Although often effective, these treatments have risks associated with an open neurosurgical procedure. MR-guided focused ultrasound has been developed as a non-invasive means of generating precisely placed focal lesions. We examined its application to the management of essential tremor.nnnMETHODSnOur study was done in Toronto, Canada, between May, 2012, and January, 2013. Four patients with chronic and medication-resistant essential tremor were treated with MR-guided focused ultrasound to ablate tremor-mediating areas of the thalamus. Patients underwent tremor evaluation and neuroimaging at baseline and 1 month and 3 months after surgery. Outcome measures included tremor severity in the treated arm, as measured by the clinical rating scale for tremor, and treatment-related adverse events.nnnFINDINGSnPatients showed immediate and sustained improvements in tremor in the dominant hand. Mean reduction in tremor score of the treated hand was 89·4% at 1 month and 81·3% at 3 months. This reduction was accompanied by functional benefits and improvements in writing and motor tasks. One patient had postoperative paraesthesias which persisted at 3 months. Another patient developed a deep vein thrombosis, potentially related to the length of the procedure.nnnINTERPRETATIONnMR-guided focused ultrasound might be a safe and effective approach to generation of focal intracranial lesions for the management of disabling, medication-resistant essential tremor. If larger trials validate the safety and ascertain the efficacy and durability of this new approach, it might change the way that patients with essential tremor and potentially other disorders are treated.nnnFUNDINGnFocused Ultrasound Foundation.

Expanding the scope of Critical Care Rapid Response Teams: a feasible approach to identify adverse events. A prospective observational cohort

Introduction Adverse events (AEs) affect 3–12% of hospitalised patients. These are estimates from a labour-intensive chart review process,which is not feasible outside research. Clinical deterioration on the wards triggers a rapid response teams (RRTs) consult and can be used to identify an AE prospectively. Objectives To demonstrate the feasibility of using RRT to detect AEs and compare this methodology to the rates reported using an electronic safety reporting system. Methods Prospective observational cohort of RRT consults. Three independent physicians reviewed all cases for the occurrence of an AE and its preventability. We summarise AEs as rates per 1000 patient-days, and compared the rates between RRT and the safety reporting system using a Poisson model. Results There were 8713 hospital admissions, with 531 RRT consults and 247 (2.8%) cases included. Forty-four (17.8%) and 35 cases (14.2%) were judged as AEs and preventable AEs, respectively. RRT identified 0.52 AE/1000 patient-days, compared with 0.21 AE/1000 patient-days detected through the electronic safety reporting system (rate ratio 2.4, 95% CI 1.4 to 4.2, p=0.0014). Patients in surgical wards had more AEs (0.83/1000 vs 0.36/1000, p<0.01) and preventable AEs (0.70 vs 0.21, p<0.01) than patients in medical wards. Agreement for AE (κ 0.46, 95% CI 0.39 to 0.53) and preventable AE (κ 0.47, 95% CI 0.40 to 0.53) was moderate among reviewers. Conclusions Reviewing RRT consults identified a high proportion of AEs and preventable AEs. This methodology detected twice as many AEs as the hospitals safety reporting system. RRT clinicians provide a complementary and more sensitive mechanism than traditional safety reporting systems to identify possible AEs in hospitals.

Greening critical care

Climate change and environmental stewardship are phrases that have been defining the past few decades and promoting change in our societies. The sensitivities of intensive care as a specialty make the process of greening an intensive care unit a challenge, but not one that is insurmountable. This paper discusses opportunities for critical care to reduce its environmental impact and provide a framework change. The article includes suggestions of what can be done as an individual, as a unit and as a hospital. Generally, practices in critical care are accepted without questioning the environmental consequences. We believe it is time for change, and critical care should give environmental stewardship a higher priority.

Skull bone marrow injury caused by MR-guided focused ultrasound for cerebral functional procedures

OBJECTIVEOne patient for whom an MR-guided focused ultrasound (MRgFUS) pallidotomy was attempted was discovered to have multiple new skull lesions with the appearance of infarcts on the MRI scan 3 months after his attempted treatment. The authors conducted a retrospective review of the first 30 patients treated with MRgFUS to determine the incidence of skull lesions in patients undergoing these procedures and to consider possible causes.METHODSA retrospective review of the MRI scans of the first 30 patients, 1 attempted pallidotomy and 29 ventral intermediate nucleus thalamotomies, was conducted. The correlation of the mean skull density ratio (SDR) and the maximum energy applied in the production or attempted production of a brain lesion was examined.RESULTSOf 30 patients treated with MRgFUS for movement disorders, 7 were found to have new skull lesions that were not present prior to treatment and not visible on the posttreatment day 1 MRI scan. Discomfort was reported at the time of treatment by some patients with and without skull lesions. All patients with skull lesions were completely asymptomatic. There was no correlation between the mean SDR and the presence or absence of skull lesions, but the maximum energy applied with the Exablate system was significantly greater in patients with skull lesions than in those without.CONCLUSIONSIt is known that local skull density, thickness, and SDR vary from location to location. Sufficient energy transfer resulting in local heating sufficient to produce a bone lesion may occur in regions of low SDR. A correlation of lesion location and local skull properties should be made in future studies.

EEG utilization in Canadian intensive care units: A multicentre prospective observational study

PURPOSEnWe have previously shown that electroencephalography (EEG) may be an underutilized monitoring modality in a single general medical-surgical ICU, that does not have a specific neurocritical care consultation service or neurocritical care unit. The present study was designed to describe the pattern of EEG utilization across 3 academic ICUs in Ontario, Canada that use different models of neurocritical care.nnnMETHODnIn this prospective multicentre observational study, ICU patients were screened weekly for 6 non-consecutive weeks to determine if they met the ESICMs recommendations or suggestions for EEG monitoring. If EEGs were performed, the results were recorded. Three models of neurocritical care provision were examined in 3 academic tertiary ICUs. Site 1 is an intensivist-led, medical-surgical ICU with no specific neurocritical care consultation service. The second site is also an intensivist led medical-surgical ICU, but with a formal neurocritical care consultation service. The third site is a virtual neurological and neurotrauma ICU within a medical-surgical ICU, staffed by rotating neurointensivists and general intensivists.nnnRESULTSnOf the 375 patients who were screened, 127 patients (34%) met at least one ESICM indication for EEG monitoring. Among the 127 patients, 46 patients (37%) had an EEG performed. Site 1 had the highest proportion of EEGs performed. The most common indication for EEG monitoring was for patients with unexplained altered level of consciousness, in the absence of primary brain injury. For the EEGs performed per ESICM indication, the majority of epileptiform abnormalities were found in patients admitted with status epilepticus.nnnCONCLUSIONSnEEG may be underutilized in Canadian ICUs. The impact on patient management and outcomes are unknown.

Patterns of use of somatosensory-evoked potentials for comatose patients in Canada.

PURPOSEnTo measure how frequently somatosensory-evoked potentials (SEPs) are used in comatose patients after traumatic brain injury (TBI) and hypoxic ischemic encephalopathy (HIE), how SEPs contribute to outcome prediction and clinical decision making, and how available they are to clinicians.nnnMETHODSnA novel factual and scenario-based survey instrument to measure patterns of SEPs use in comatose patients due to HIE or TBI was distributed to critical care, neurology, and neurosurgical physicians across Canada. The analysis was based on 86 completed surveys from specialists in neurology (36), neurosurgery (24), and critical care (22).nnnRESULTSnMost (73%) of respondents reported that SEPs were available. When provided clinical vignettes, only 36% indicated that they would use them in TBI and 49% would use them in HIE. When respondents ranked the various methods available for establishing prognosis for awakening, SEP was ranked after cerebral blood flow and magnetic resonance imaging. The majority did not accurately estimate chances of awakening when SEP responses were bilaterally absent.nnnCONCLUSIONSnThere are significant opportunities to optimize the use of SEPs in comatose patients including standardizing SEP testing and reporting, better communicating results to critical care physicians, and improving the understanding regarding the recommended use and interpretation of these tests.

Diffuse Ischemia in Noncontrast Computed Tomography Predicts Outcome in Patients in Intensive Care Unit

Purpose In the intensive care unit (ICU), prognosticating patients who are comatose or defining brain death can be challenging. Currently, the criteria for brain death are clinical supported by paraclinical tests. Noncontrast computed tomography (CT) shows diffuse loss of grey-white differentiation consistent with infarction. We hypothesize that the extent of hypodensity is predictive of poor neurologic outcome or brain death. Materials and Methods A total of 235 consecutive adult patients with cardiac arrest or with serious trauma admitted to ICU in 1 year were studied. Seventy met inclusion criteria. CT images were reviewed by multiple observers blinded to final outcome who assessed for loss of grey-white conspicuity. A modification of the validated Alberta Stroke Program Early CT Score (ASPECTS) was used to include non–middle cerebral artery territories. Primary outcome was death or functional disability at 3 months. Dichotomized CT scores were correlated with poor clinical status (Glasgow Coma Score < 5 and APACHE [Acute Physiology and Chronic Health Evaluation] score >19) and poor outcome (modified Rankin Scale >2). Results The CT score was ≤10 in 7 patients and >10 in 63 patients. The CT score value correlated with the severity of baseline clinical status on the Glasgow Coma Score (r = 0.53, P < .01) and negatively with the APACHE-II score (r = −0.27, P < .05). The CT score value negatively correlated with functional outcome (r = −0.40, P < .01). All the patients with a CT score ≤10 died. The sensitivity of the CT score for functional outcome was 24%, and specificity was 100%. Agreement among observers for the CT score was good (Intraclass correlation coefficient = 0.77). Conclusion Diffuse loss of grey-white matter differentiation is subtle but specific for poor neurologic outcome, which may allow earlier prognostication of patients in whom clinical parameters are difficult to assess.

Using Barriers Analysis to Refine a Novel Model of Neurocritical Care

BackgroundIn order to deliver specialized neurocritical care (NCC) without a dedicated neurological intensive care unit (ICU), we established a virtual NCC unit within an existing mixed level III ICU. This initiative required changes to patient allocation, physician staffing, and care protocols. In advance of its implementation, we gaged readiness, assessed barriers, and solicited feedback from staff.MethodsClinicians at our academic hospital and trauma centre in Toronto, Ontario were the subjects of this concurrent mixed methods study. Eighteen stakeholders were individually interviewed. 116 of 217 eligible ICU staff participated in the survey and 36 staff attended the focus group sessions.ResultsFrom the survey, the most significant barriers to this reorganization were staff anxiety about coping (28xa0%) and a concern that patients would not receive better care (24xa0%). Noteworthy obstacles about the use of protocols were their lack of flexibility (19xa0%) and that implementation was seen as impractical (16xa0%). Seventeen barriers were proposed through an open-ended survey question. Content analysis revealed general resistance, educational challenges, workflow adjustment to a diagnosis-based rounding pattern and coordination conflicts to be the central barriers. These findings were confirmed in focus group discussions, with a lack of resources as an additional important challenge.ConclusionsA new workable model for NCC has been developed, facilitated by this analysis. Steps to overcome barriers demonstrated in this study include additional educational measures, changes to the rounding protocols, and patient allocation algorithms.