Pathophysiology of Contrast-Induced Neurotoxicity: A Narrative Review of Possible Mechanisms.

BACKGROUND: Contrast-induced neurotoxicity (CIN) is an increasingly observed event following the administration of iodinated contrast. It presents as a spectrum of neurological symptoms that closely mimic ischaemic stroke, however, CIN remains a poorly understood clinical phenomenon. An appreciation of the underlying pathophysiological mechanisms is essential to improve clinical understanding and enhance decision-making. METHODS: A broad literature search of Medline (1946 to December 2022) and Embase (1947 to December 2022) was conducted. Articles discussing the pathophysiology of CIN were reviewed. SUMMARY: The pathogenesis of CIN appears to be multifactorial. A key step is likely blood-brain barrier (BBB) breakdown due to factors including ischaemic stroke, uncontrolled hypertension, and possibly contrast agents themselves, among others. This is followed by passage of contrast agents across the BBB, leading to chemotoxic sequelae on neural tissue. KEY MESSAGES: This review provides a clinically oriented review on the pathophysiology of CIN to enhance knowledge and improve decision-making among clinicians.

Amyloid-ß (Aß)-Related Cerebral Amyloid Angiopathy Causing Lobar Hemorrhage Decades After Childhood Neurosurgery.

BACKGROUND: Recent reports raise the possibility of cerebral amyloid angiopathy (CAA) leading to intracerebral hemorrhage in young adults following childhood neurosurgery, suggesting transmission of amyloid-ß (Aß) through neurosurgical procedures including dura mater grafting. Parenchymal Aß deposition, and to a lesser extent tau aggregation, similar to that seen in Alzheimer disease, have also been described. METHODS: We conducted a database review of 634 consecutive intracerebral hemorrhage patients aged <65 years at a tertiary stroke center over 20 years to identify such patients. RESULTS: We identified 3 patients aged in their thirties who presented with spontaneous lobar intracerebral hemorrhage, with imaging or neuropathology consistent with CAA, and a history of childhood neurosurgery. Two of these patients had undergone a dural repair using cadaveric dura mater (Lyodura). In addition to CAA, both patients had neuropathologically confirmed parenchymal Aß and tau deposits, characteristic of Alzheimer disease. CONCLUSIONS: Our findings support the concept of neurosurgical Aß transmission but suggest that such cases are rare in standard clinical practice.

Rotation from methadone to buprenorphine using a micro-dosing regime in patients with opioid use disorder and serious mental illness: A case series.

INTRODUCTION: Inducting buprenorphine from methadone has traditionally involved initial opioid withdrawal, with risk of mental state deterioration in patients with serious mental illness (SMI). Micro-dosing of buprenorphine, with small incremental doses, is a novel off-label approach to transitioning from methadone and does not require a period of methadone abstinence. Given the limited literature about buprenorphine microdosing, we aimed to evaluate the feasibility and safety of inducting buprenorphine in a series of patients on methadone with SMI. METHODS: For this retrospective case series, we reviewed the records of 16 patients with SMI at a Melbourne addiction treatment centre, from January 2021 to July 2022, who transitioned via micro-dosing, from high-dose methadone (>30 mg) to buprenorphine and depot-buprenorphine. Psychiatric diagnoses, mental state, other substance withdrawal, transfer success, transition time, opioid withdrawal symptoms and overall patient experience were collected via objective and subjective reporting. RESULTS: Methadone to buprenorphine transfer was completed by 88% of patients. Mental health measures remained stable with the exception of mildly increased anxiety. Median transfer time was 6.5 days for inpatients, 9 days for mixed setting and 10 days for outpatients. Most patients (93%) rated their experience 'manageable' reporting mild withdrawal symptoms. One patient met study criteria for precipitated withdrawal. DISCUSSION AND CONCLUSIONS: This retrospective case series provides evidence that the use of a micro-dosing buprenorphine induction for methadone to buprenorphine transitions, including to depot-buprenorphine, has negligible risk, is tolerated by patients with SMI and is unlikely to precipitate an exacerbation of their mental illness.

Intraoperatively predicting postoperative sagittal balance using intraoperative X-rays.

This study aimed to assess the correlation of sagittal balance parameters measured intraoperatively, against the gold standard post-operative standing full spine X-ray. A secondary aim was to create a predictive algorithm, that could be used intraoperatively to predict the post-operative balance. 49 patients, who underwent thoracolumbar spinal fusion over a 12-month period were included in this study. Standing full-spine X-rays were obtained both pre and post-surgical fixation. Parallel intraoperative X-rays were taken with the c-arm centred on femoral heads, operative level, S1 and L1. The sagittal parameters pelvic incidence (PI), lumbar lordosis (LL), spino-pelvic mismatch (PI-LL), and sagittal vertical axis were then measured and the correlations statistically analysed. For prone positioned patients the mean LL was 59.9°â€¯±â€¯10.6° intraoperatively (post-fixation) and post-operatively 55.4°â€¯±â€¯10.9° with a mean difference of -4.5°â€¯±â€¯6.1° (p-value < 0.001). For laterally positioned patients the mean LL was 50.9°â€¯±â€¯8.6° intraoperatively and 53.1°â€¯±â€¯10.1° postoperatively for a mean difference of -2.3°â€¯±â€¯6.5° (p-value = 0.117). The linear regression analysis resulted in a predictive algorithm that can be utilised intraoperatively to predict the post-operative standing pelvic mismatch for prone positioned patients. In conclusion, measuring spino-pelvic parameters of sagittal balance intraoperatively can be used to estimate postoperative standing full spine x-ray result. Specifically, in the prone position, the surgeon should aim for intraoperative lordosis that is 4.5° more than the desired post-operative lordosis. The predictive formula provides a direct method to quickly calculate the post-operative pelvic mismatch intraoperatively.

Deep vein thrombosis and pulmonary embolus in patients with traumatic brain injury: a prospective observational study.

BACKGROUND: Intensive care patients with traumatic brain injury (TBI) are at high risk of developing deep vein thrombosis (DVT). A high rate of DVT was reported before routine thromboprophylaxis, but the current DVT rate in TBI patients receiving best-practice mechanical and pharmacological prophylaxis is unknown. OBJECTIVES: To determine the prevalence of DVT among TBI patients. DESIGN, PARTICIPANTS AND SETTING: A prospective observational pilot study of adult patients admitted to the intensive care unit of a level 1 trauma centre within 72 hours of sustaining a TBI (Glasgow Coma Scale score _14). MAIN OUTCOME MEASURES: Rate of DVT determined using twice-weekly compression ultrasound; rate of pulmonary embolism (PE) and length of stay. RESULTS: 36 patients (28 men; mean age, 40.3 years) were included. Six had moderate and 21 had severe TBI. Two patients (6%) developed a DVT and two patients (6%) developed a PE. The proximal leg DVT rate was 3%, but the overall venous thromboembolism rate was 11% (4 patients). CONCLUSIONS: Mechanical and pharmacological prophylaxis appeared to be effective. The incidence of clinically identified PE is of concern and suggests that thromboembolic sources other than large leg veins may not be being adequately controlled by modern thromboprophylaxis regimens.