Prolonged postoperative altered mental status after methylene blue infusion during parathyroidectomy: a case report and review of the literature

Use of hydroxocobalamin to treat intraoperative vasoplegic syndrome refractory to vasopressors and methylene blue during liver transplantation

INTRODUCTION

For patients with catecholamine-resistant vasoplegic syndrome (VS) during liver transplantation (LT), treatment with methylene blue (MB) and/or hydroxocobalamin (B12) has been an acceptable therapy. However, data on the effectiveness of B12 is limited to case reports and case series.

METHODS

We retrospectively reviewed records of patients undergoing LT from January 2016 through March 2022. We identified patients with VS treated with vasopressors and MB, and abstracted hemodynamic parameters, vasopressor requirements, and B12 administration from the records. The primary aim was to describe the treatment efficacy of B12 for VS refractory to vasopressors and MB, measured as no vasopressor requirement at the conclusion of the surgery.

RESULTS

One hundred one patients received intraoperative VS treatment. For the 35 (34.7%) patients with successful VS treatment, 14 received MB only and 21 received both MB and B12. Of the 21 patients with VS resolution after receiving both MB and B12, 17 (89.5%) showed immediate, but transient, hemodynamic improvements at the time of MB administration and later showed sustained response to B12.

CONCLUSION

Immediate but transient hemodynamic response to MB in VS patients during LT supports the diagnosis of VS and should prompt B12 administration for sustained treatment response.

Anticholinergic Toxidrome as a Possible Explanation for Methylene Blue Toxicity

BACKGROUND Methylene blue has multiple uses in medicine. It is generally used to treat refractory vasoplegia and methemoglobin toxicity, and can be used as a dye to localize the parathyroid glands intra-operatively. In refractory vasoplegia, methylene blue inhibits endothelial nitric oxide and guanylate cyclase, causing vasoconstriction and potentially stabilizing blood pressure. Multiple complications have been associated with the use of methylene blue. These are related to either the sole effect of methylene blue or the combined effect of methylene blue and certain antidepressants, such as selective serotonin reuptake inhibitors (SSRIs). To the best of our knowledge, in the setting of post-cardiac surgery vasoplegia, there have been no reports of the neurological toxicity of methylene blue in the absence of SSRI use. In this case report, we describe the anticholinergic manifestations associated with the use of methylene blue in post-cardiac surgery vasoplegia. CASE REPORT A male patient in his mid-sixties with severe mitral regurgitation underwent elective mitral valve replacement. Postoperatively, he was hypotensive and required a high dose of vasopressors. Methylene blue was administered to treat refractory vasoplegia. The patient became anuric and febrile, with bilateral mydriasis. Internal cooling and continuous renal replacement therapy were initiated, and symptoms rapidly resolved. The patient was discharged after prolonged hospitalization with a permanent catheter for hemodialysis. CONCLUSIONS Anticholinergic toxidrome may explain the neurological adverse effects associated with high doses of methylene blue. Physicians should be cautious when using methylene blue in combination with other anticholinergic drugs and in conditions of renal failure. The development of methylene blue toxicity warrants the urgent discontinuation of the agent and early drug elimination.

Intraoperative prevention of postoperative hypoparathyroidism

Objective

More than 30,000 thyroid surgeries are performed annually in the Russian Federation. The surgeries are relatively safe because of the prevention methods for postoperative complications. Currently, there is no single effective method of postoperative hypoparathyroidism prevention. This complication is frequently reported and may be health and life-threatening.

Aim

We aimed to estimate the effectiveness of the intraoperative ICG-angiography and intrathyroid injection of Brilliant Green for the prevention of postoperative hypoparathyroidism.

Material and methods

One hundred and forty-three thyroidectomies were performed. Patients were divided into three groups: intraoperative angiography was used in 24 cases; Brilliant Green was injected in 58 cases to identify parathyroid glands; the visual estimation of the parathyroid preservation was used in 61 cases. Calcium level was measured in all patients before and after surgery.

Results

Calcium level in the serum before and after surgery was 2.37±0.14 and 2.27±0.17 in Group 1, 2.38±0.16 and 2.21±0.16 in Group 2, and 2.39±0.17 and 2.18±0.19 in Group 3. Postoperative hypocalcemia was more prominent in the group with the visually estimated PTG than in the two other groups. The differences in postoperative calcium levels in Groups 1 and 3 were statistically different. Pre- and postoperative Parathormone levels were 6.2±0.4 in Group 1, 5.6±0.57 in Group 2, and 3.5±0.32 in Group 3. Postoperative levels significantly differed in Groups 1 and 3 (p<0.01) and in Groups 2 and 3 (p<0.05).

Conclusions

ICG-angiography and intrathyroid injection of the Brilliant Green are safe methods of identification and sparing of the parathyroid glands. The severity of hypocalcemia and hypoparathormonemia in Group 3 shows the necessity of finding new methods in endocrine surgery to improve patient outcomes.

Photodynamic Therapy, Probiotics, Acetic Acid, and Essential Oil in the Treatment of Chronic Wounds Infected with Pseudomonas aeruginosa

As a prevalent medical problem that burdens millions of patients across the world, chronic wounds pose a challenge to the healthcare system. These wounds, often existing as a comorbidity, are vulnerable to infections. Consequently, infections hinder the healing process and complicate clinical management and treatment. While antibiotic drugs remain a popular treatment for infected chronic wounds, the recent rise of antibiotic-resistant strains has hastened the need for alternative treatments. Future impacts of chronic wounds are likely to increase with aging populations and growing obesity rates. With the need for more effective novel treatments, promising research into various wound therapies has seen an increased demand. This review summarizes photodynamic therapy, probiotics, acetic acid, and essential oil studies as developing antibiotic-free treatments for chronic wounds infected with Pseudomonas aeruginosa. Clinicians may find this review informative by gaining a better understanding of the state of current research into various antibiotic-free treatments. Furthermore. this review provides clinical significance, as clinicians may seek to implement photodynamic therapy, probiotics, acetic acid, or essential oils into their own practice.

Safe thyroid surgery: comparison effectiveness of ICG angiography and intrathyroidal brilliant green injection for the prevention of postoperative hypoparathyroidism

BACKGROUND: More than 30,000 surgical interventions on the thyroid gland are performed annually in the Russian Federation. Surgeons are developing methods for the prevention of various postoperative complications, and therefore operations on this organ are considered relatively safe. Currently, there is no unequivocal effective method to prevent postoperative hypoparathyroidism. This complication is often recorded and can threaten the life and health of the patient, which is contrary to the concept of safe surgery.

AIM: To evaluate the effectiveness of intraoperative ICG angiography and intrathyroidal injection of brilliant green for the prevention of postoperative hypoparathyroidism.

MATERIALS AND METHODS: 143 thyroidectomies were performed. The patients were divided into 3 groups: intraoperative angiography was used in 24 cases, brilliant green was injected to identify the parathyroid glands in 58 cases, visual assessment of the preservation of the parathyroid glands was used in 61 case. Calcium levels were measured in all patients included in the study before and after surgery.

RESULTS: Serum calcium levels in the pre- and postoperative period: 2.37±0.14 and 2.27±0.17 in group 1, and 2.38±0.16 and 2.21±0.16 in group 2, 2.39±0.17 and 2.18±0.19 in group 3. Hypocalcemia in the postoperative period was significantly higher in the group with a visual assessment of the parathyroid glands relative to the first two groups. Differences between calcium levels in the postoperative period in groups 2 and 3 were significant with a probability of more than 99% (p<0.01). Significant differences (≥95%) in calcium levels in the postoperative period between groups 1 and 2 (p < 0.05) were obtained. Serum PTH levels in the postoperative period: 6,2±0,4 in group 1, 5,6±0,57 in group 2, 3,5±0,32 in group 3. Differences between PTH levels in the postoperative period in groups 1 and 3 were significant with a probability of more than 99% (p<0.01). Significant differences (≥95%) in PTH levels in the postoperative period between groups 2 and 3 (p < 0.05) were obtained.

CONCLUSION: ICG angiography and brilliant green intrathyroidal injection are safe methods for identifying and preserving the parathyroid glands. The high level of hypocalcemia in group 3 indicates the need to search for new techniques in endocrine surgery in order to improve the safety of patients undergoing surgical treatment of thyroid pathology.

Adverse effects of methylene blue in peripheral neurons: An in vitro electrophysiology and cell culture study

Methylene blue (MB) is an effective treatment for methemoglobinemia, ifosfamide-induced encephalopathy, cyanide poisoning, and refractory vasoplegia. However, clinical case reports and preclinical studies indicate potentially neurotoxic activity of MB at certain concentrations. The exact mechanisms of MB neurotoxicity are not known, and while the effects of MB on neuronal tissue from different brain regions and myenteric ganglia have been examined, its effects on primary afferent neurons from dorsal root ganglia (DRG) have not been studied. Mouse DRG were exposed to MB (0.3-10 μM) in vitro to assess neurite outgrowth. Increasing concentrations of MB (0.3-10 μM) were associated with neurotoxicity as shown by a substantial loss of cells with neurite formation, particularly at 10 μM. In parallel experiments, cultured rat DRG neurons were treated with MB (100 μM) to examine how MB affects electrical membrane properties of small-diameter sensory neurons. MB decreased peak inward and outward current densities, decreased action potential amplitude, overshoot, afterhyperpolarization, increased action potential rise time, and decreased action potential firing in response to current stimulation. MB induced dose-dependent toxicity in peripheral neurons, in vitro. These findings are consistent with studies in brain and myenteric ganglion neurons showing increased neuronal loss and altered membrane electrical properties after MB application. Further research is needed to parse out the toxicity profile for MB to minimize damage to neuronal structures and reduce side effects in clinical settings.

Methylene blue: a controversial diagnostic acid and medication?

A narrative review of the literature was conducted to determine if the administration of methylene blue (MB) in humans has potential risks. Studies were identified from MEDLINE, Web of Science, Scopus, and Cochrane. MB is a diagnostic substance used during some diagnostic procedures and also a part of the treatment of several diseases including methemoglobinemia, vasoplegic syndrome, fosfamide-induced encephalopathy, and cyanide intoxication, and the detection of leaks or position of parathyroid corpuscles during surgery. Although the use of MB is historically justified, and it ought to be safe, because it originated as a diagnostic material, the basic toxicological characteristics of this substance are unknown. Despite reports of severe adverse effects of MB, which could significantly exceed any possible benefits evaluated for the given indication. Therefore, the clinical use of MB currently represents a controversial problem given the heterogeneity of available data and the lack of preclinical data. This is in conflict with standards of safe use of such substances in human medicinal practice. The toxic effects of the application of MB are dose-dependent and include serious symptoms such as hemolysis, methemoglobinemia, nausea and vomitus, chest pain, dyspnoea, and hypertension. Some countries regard MB as harmful because of the resulting skin irritation and triggering of an adverse inflammatory response. MB induced serotoninergic toxicity clinically manifests as neuromuscular hyperactivity. This review aims to summarize the current understanding concerning the indications for MB administration and define the potential adverse effects of MB.

Rapid intraoperative perfusion assessment of parathyroid adenomas with ICG using a wide-field portable hand-held fluorescence imaging system

BACKGROUND

Fluorescence angiography (FA) using indocyanine green dye (ICG) has recently been introduced for real-time identification of parathyroid adenomas. However, time to peak fluorescence has not yet been critically evaluated.

METHODS

This was a retrospective review of parathyroidectomies with ICG FA over a one-year period.

RESULTS

There were 66 patients with average age of 64 years. The average time to initial fluorescence was 26.7 s and to peak fluorescence was 38.0 s. The time to saline flush administration significantly correlated with times to initial and peak fluorescence (p < .0001). The rate of in-situ fluorescence was 97%. The rates of suspected adenoma detection were 69% for sestamibi scan, 71% for ultrasound, and 96% for CT scan. Imaging was discordant in 13 cases (20%), with the adenoma located on the opposite side of the neck in 4 cases.

CONCLUSIONS

ICG FA is a rapid and effective adjunct for the intraoperative identification of parathyroid adenomas.

Methylene Blue Application to Lessen Pain: Its Analgesic Effect and Mechanism

Methylene blue (MB) is a cationic thiazine dye, widely used as a biological stain and chemical indicator. Growing evidence have revealed that MB functions to restore abnormal vasodilation and notably it is implicated even in pain relief. Physicians began to inject MB into degenerated disks to relieve pain in patients with chronic discogenic low back pain (CDLBP), and some of them achieved remarkable outcomes. For osteoarthritis and colitis, MB abates inflammation by suppressing nitric oxide production, and ultimately relieves pain. However, despite this clinical efficacy, MB has not attracted much public attention in terms of pain relief. Accordingly, this review focuses on how MB lessens pain, noting three major actions of this dye: anti-inflammation, sodium current reduction, and denervation. Moreover, we showed controversies over the efficacy of MB on CDLBP and raised also toxicity issues to look into the limitation of MB application. This analysis is the first attempt to illustrate its analgesic effects, which may offer a novel insight into MB as a pain-relief dye.

Methylene Blue-Current Knowledge, Fluorescent Properties, and Its Future Use

Methylene blue is a fluorescent dye discovered in 1876 and has since been used in different scientific fields. Only recently has methylene blue been used for intraoperative fluorescent imaging. Here, the authors review the emerging role of methylene blue, not only as a dye used in clinical practice, but also as a fluorophore in a surgical setting. We discuss the promising potential of methylene blue together with the challenges and limitations among specific surgical techniques. A literature review of PubMed and Medline was conducted based on the historical, current and future usage of methylene blue within the field of medicine. We reviewed not only the current usage of methylene blue, but we also tried to grasp its' function as a fluorophore in five main domains. These domains include the near-infrared imaging visualization of ureters, parathyroid gland identification, pancreatic tumors imaging, detection of breast cancer tumor margins, as well as breast cancer sentinel node biopsy. Methylene blue is used in countless clinical procedures with a relatively low risk for patients. Usage of its fluorescent properties is still at an early stage and more pre-clinical, as well as clinical research, must be performed to fully understand its potentials and limitations.

Novel techniques for intraoperative parathyroid gland identification: a comprehensive review

INTRODUCTION

The parathyroid glands (PGs) are critical for calcium regulation and homeostasis. The preservation of PGs during neck surgery is crucial to avoid postoperative hypoparathyroidism. There are no existing guidelines for intraoperative PG identification, and the current approach relies heavily on the experience of the operating surgeon. A technique that accurately and rapidly identifies PGs would represent a useful intraoperative adjunct.

AREAS COVERED

This review aims to assess common dye and fluorescence-based PG imaging techniques and examine their utility for intraoperative PG identification. A literature search of published data on methylene blue (MB), indocyanine green (ICG) angiography, near-infrared autofluorescence (NIRAF), and the PGs between 1971 and 2020 was conducted on PubMed.

EXPERT OPINION

NIRAF and near-infrared (NIR) parathyroid angiography have emerged as promising and reliable techniques for intraoperative PG identification. NIRAF may aid with real-time identification of both normal and diseased PGs and reduce the risk of postoperative complications such as hypocalcemia. Further large prospective multicenter studies should be conducted in thyroid and parathyroid surgical patient populations to confirm the clinical efficacy of these intraoperative NIR-based PG detection techniques.

Rescue of Nimodipine-Induced Refractory Vasoplegia With Hydroxocobalamin in Subarachnoid Hemorrhage: A Case Report

Background:

We report a case of refractory vasoplegia after nimodipine administration that was unresponsive to triple vasopressor therapy and was rescued by IV hydroxocobalamin.

Case Summary:

An 84-year-old male presented comatose from a subarachnoid hemorrhage and developed severe hypotension unresponsive to three vasopressors following a single dose of enteral nimodipine. Multisystem point-of-care ultrasonography ruled out alternate etiologies of shock, indicating that this was likely a vasoplegic state caused by nimodipine. We administered 5 grams of IV hydroxocobalamin over 15 minutes due to the possibility of impaired nitric oxide metabolism as the driver of vasoplegia. This led to immediate improvement in hemodynamics and rapid discontinuation of vasopressors. The patient experienced chromaturia but no other adverse effects due to hydroxocobalamin.

Conclusions:

Nimodipine administration is a standard practice for patients with aneurysmal subarachnoid hemorrhage to reduce unfavorable outcomes from cerebral vasospasm. Although mild hypotension is a common side effect of nimodipine, in rare cases, it may become profound, leading to refractory vasoplegia. There is no evidence-base for reversal agents for nimodipine-induced vasoplegia, and this case is the first to demonstrate successful use of hydroxocobalamin as a potential rescue therapy. We also propose an algorithm for treatment of vasoplegia with consideration of medications that act on nitric oxide–mediated vasodilation and their side-effect profiles.

Impact of fluorescence and autofluorescence on surgical strategy in benign and malignant neck endocrine diseases

Fluorescence and autofluorescence have been shown by several recent studies to be valuable adjuncts in identifying parathyroid glands during thyroidectomy and parathyroidectomy. The aim of this chapter is to review the impact of this new technology on surgical strategy concerning identification and preservation of parathyroid glands during thyroidectomy, identification of parathyroid glands in hyperparathyroidism, and the potential role in thyroid cancer surgery.

Efficacy and safety of methylene blue in the treatment of malaria: a systematic review

BACKGROUND

Methylene blue (MB) was the first synthetic antimalarial to be discovered and was used during the late 19th and early 20th centuries against all types of malaria. MB has been shown to be effective in inhibiting Plasmodium falciparum in culture, in the mouse model and in rhesus monkeys. MB was also shown to have a potent ex vivo activity against drug-resistant isolates of P. falciparum and P. vivax. In preclinical studies, MB acted synergistically with artemisinin derivates and demonstrated a strong effect on gametocyte reduction in P. falciparum. MB has, thus, been considered a potentially useful partner drug for artemisinin-based combination therapy (ACT), particularly when elimination is the final goal. The aim of this study was to review the scientific literature published until early 2017 to summarise existing knowledge on the efficacy and safety of MB in the treatment of malaria.

METHODS

This systematic review followed PRISMA guidelines. Studies reporting on the efficacy and safety of MB were systematically searched for in relevant electronic databases according to a pre-designed search strategy. The search (without language restrictions) was limited to studies of humans published until February 2017.

RESULTS

Out of 474 studies retrieved, a total of 22 articles reporting on 21 studies were eligible for analysis. The 21 included studies that reported data on 1504 malaria patients (2/3 were children). Older studies were case series and reports on MB monotherapy while recent studies were mainly controlled trials of combination regimens. MB was consistently shown to be highly effective in all endemic areas and demonstrated a strong effect on P. falciparum gametocyte reduction and synergy with ACT. MB treatment was associated with mild urogenital and gastrointestinal symptoms as well as blue coloration of urine. In G6PD-deficient African individuals, MB caused a slight but clinically non-significant haemoglobin reduction.

CONCLUSIONS

More studies are needed to define the effects of MB in P. falciparum malaria in areas outside Africa and against P. vivax malaria. Adding MB to ACT could be a valuable approach for the prevention of resistance development and for transmission reduction in control and elimination programs.

SYSTEMATIC REVIEW REGISTRATION

This study is registered at PROSPERO (registration number CRD42017062349 ).

Synthesis of biosurfactant‐coated magnesium oxide nanoparticles for methylene blue removal and selective Pb2+ sensing

Dyes and lead (Pb2+) are toxic compounds that can contaminant water. In this study, magnesium oxide (MgO) nanoparticles (NPs) prepared using clove, i.e. Syzygium aromaticum extract [clove extract (CE)] were used for methylene blue (MB) removal and Pb2+ ion sensing in aqueous solution. Maximum 90% MB removal was achieved using MgO NPs. The MB adsorption on MgO NPs surface followed second‐order kinetics and Langmuir isotherm. MB dye was adsorbed as a monolayer on the surface of MgO NPs with maximum adsorption capacity, 5555 mg g−1. MgO NPs were also able to selectively detect lead (Pb2+) in 1 nM–200 µM range with 24 µM (3σ) limit of detection. So, CE prepared MgO NPs are useful for MB dye adsorption and metal ion sensing applications.

The use of near-infrared fluorescence imaging in endocrine surgical procedures

Near-infrared fluorescence imaging in endocrine surgery is a new, yet highly investigated area. It involves indocyanine green use as well as parathyroid autofluorescence. Several groups have described their technique and reported on the observed utility. However, there is no consensus on technical details. Furthermore, the correlation between intraoperative findings and postoperative outcomes is unclear. With this study, we aim to review the current literature on fluorescence imaging and share our insights on technical details.

The utility of indocyanine green near infrared fluorescent imaging in the identification of parathyroid glands during surgery for primary hyperparathyroidism

BACKGROUND AND OBJECTIVES

Intraoperative adjuncts for the localization of parathyroid glands in parathyroid surgery are limited. The aim of this study is to assess the usefulness of indocyanine green (ICG) near-infrared (NIR) fluorescent imaging in patients undergoing surgery for primary hyperparathyroidism (PHPT).

METHODS

ICG imaging was performed in 33 patients undergoing parathyroidectomy (PTX). Thyroid and parathyroid ICG uptake were assessed and independently verified on a grading scale. Clinical variables were recorded and analyzed for factors associated with ICG uptake.

RESULTS

Of 112 glands identified by naked eye, 104 (92.9%) demonstrated ICG uptake. Concomitant ICG fluorescence was identified in the thyroid in all patients. There was a trend toward increased ICG fluorescence in patients <60 years of age (P = 0.05). A higher degree of fluorescence was seen in patients presenting with pre-operative calcium values >11 mg/dl (P = 0.04) and in those parathyroids larger than 10 mm (P < 0.01). All patients had biochemically proven cure. No patients who underwent subtotal PTX (n = 6) developed postoperative hypoparathyroidism.

CONCLUSION

ICG can reliably localize parathyroid glands during PTX and additionally allow for assessment of parathyroid perfusion in patients undergoing subtotal resection. Concomitant fluorescence of the thyroid gland limits ICG's usefulness in directing the course of PTX. J. Surg. Oncol. 2016;113:771-774. © 2016 Wiley Periodicals, Inc.

The feasibility of indocyanine green fluorescence imaging for identifying and assessing the perfusion of parathyroid glands during total thyroidectomy

BACKGROUND

There are limited adjuncts available for identifying and assessing the viability of parathyroid glands (PGs) during total thyroidectomy (TT). The aim of this study is to determine the feasibility of indocyanine green (ICG) imaging in identifying and assessing perfusion of PGs during TT.

METHODS

ICG was administered in patients undergoing TT and fluorescence of PGs was assessed. A grading scale was developed for assessing degree of ICG uptake. Patients were evaluated for hypocalcemia and hypoparathyroidism on post-operative day (POD) #1.

RESULTS

Twenty-seven patients underwent TT with ICG imaging for multinodular goiter (n = 13), thyroid cancer (n = 10), and Graves' disease (n = 4). Eight-five PGs were identified visually, 71 (84%) of which showed ICG fluorescence. False negative rate was 6%. Post-operatively, three patients (11%) had a serum calcium value <8 mg/dl. ICG uptake after TT correlated with post-operative PTH levels: mean POD#1 PTH of those patients with at least two PGs exhibiting <30% fluorescence was 9 pg/ml; whereas those with fewer than two demonstrating <30% fluorescence had a POD#1 PTH of 19.5 pg/ml (P = 0.05).

CONCLUSION

ICG imaging of PGs during TT is feasible. ICG might be a useful adjunct in identifying those patients at risk for post-thyroidectomy hypoparathyroidism. J. Surg. Oncol. 2016;113:775-778. © 2016 Wiley Periodicals, Inc.

Video assisted thoracoscopic excision of mediastinal ectopic parathyroid adenomas: a UK regional experience

BACKGROUND

To report the first series of video-assisted thoracoscopic surgery (VATS) resection of mediastinal ectopic parathyroid adenomas (MEPAs) in the UK.

METHODS

A case series of seven cases undergoing VATS between 2004 and 2009 to treat single gland hyperparathyroidism. Methylene blue (MB) was used in 5/7 cases immediately before exploration to identify the adenomas. Carbon dioxide (CO2) up to pressures of 10 mmHg was used safely to deflate the lung in two cases.

RESULTS

There were five women and two men with a mean age of 53 years (range, 27-72 years). Histopathology confirmed successful resection of the parathyroid adenoma in 6/7 cases. There was one conversion to open thoracotomy due to bleeding from the azygos vein resulting from excessive traction. Despite marked MB uptake, this patient proved to have tuberculoid adenopathy and no parathyroid tissue was identified. Postoperative plasma calcium returned to normal in 6/7 patients and parathyroid hormone (PTH) level in 6/7 patients. The median hospital stay was 2 days and there was no mortality in this series.

CONCLUSIONS

MEPAs can be safely resected using VATS with minimal surgical morbidity, short drainage time and short hospital stay. CO2 insufflation and the intraoperative use of MB are safe and help to accurately localise the ectopic adenoma. VATS should be considered as the first-line approach for resection of MEPAs.

Delayed Recovery from General Anaesthesia: A Post-operative Diagnostic Dilemma and Implications of ICU Management of Serotonin Toxicity. Case report

We report a case of delayed recovery from general anesthesia following a routine parathyroidectomy. Our objectives are to describe the process of establishing a differential diagnosis and subsequent management of a patient presenting with atypical neurological signs from an unknown etiology and to increase awareness about the potential for serotonin syndrome and neurotoxicity due to known interactions between methylene blue and selective serotoninnoradrenaline re-uptake inhibitors. ICU management of Serotonin Toxicity is briefly described.

[Not Available]

BACKGROUND

Methylene blue is used in medical practice for various reasons. Recent findings point to a potential interaction with serotonin reuptake inhibitors (SRIs) that could lead to serotonergic toxicity.

OBJECTIVE

To describe the risk of serotonergic toxicity associated with the interaction between methylene blue and SRIs.

DATA SOURCES

Relevant publications were searched systematically via MEDLINE (1946 to March 21, 2013) and Embase (1974 to 2013, week 11) with the following search terms: "methylene blue", "methylthioninium", "monoamine oxidase inhibitors", "serotonin reup-take inhibitors", and "serotonin syndrome". No restrictions were applied in relation to the indication for methylene blue or the language of publication. The reference lists of identified articles were also searched.

STUDY SELECTION AND DATA EXTRACTION

Eighteen case reports and 2 case series were identified for inclusion. To date, no randomized controlled trials have been published.

DATA SYNTHESIS

The first case report indicating suspicion of an interaction between methylene blue and SRIs was published in 2003. Seventeen other case reports describing the same type of interaction have been published since then. The 2 case series provided data from about 325 parathyroidectomies in which methylene blue was used for staining. The 17 patients who experienced central nervous system toxicity were all taking SRIs in the preoperative period.

CONCLUSION

When administered in combination with SRIs, methylene blue may lead to serotonergic toxicity at doses as low as 0.7 mg/kg. Methylene blue would seem to have monoamine oxidase A inhibitory properties. Precautions should be taken to avoid this interaction. [Publisher's translation].

Myoclonus in patient on fluoxetine after receiving fentanyl and low-dose methylene blue during sentinel lymph node biopsy

Serotonin released in the nerve synapses is cleared through reuptake into presynaptic neurons and metabolism with monoamine oxidase (MAO). Therapy with selective serotonin reuptake inhibitors (SSRIs) or MAO inhibitors increases serotonin concentration in the synaptic cleft and may result in serotonin syndrome (SS). Our patient undergoing sentinel lymph node biopsy was on fluoxetine (SSRI) and intraoperatively developed SS after receiving fentanyl (200 μg) and methylene blue (MAO inhibitor), 7 mg subcutaneously into the scalp. Initial presentation was several episodes of generalized muscle activity, which was later diagnosed as lower extremity myoclonus consistent with SS. Upon awakening, the patient showed no evidence of encephalopathy, and the clonus was less intense. The patient was discharge home the next day. Our case suggests the possibility that even a small dose of methylene blue, when administered simultaneously with other serotoninergic medications, may be associated with serotonin toxicity.

Systematic review of intravenous methylene blue in parathyroid surgery

Background

Methylene blue is an intraoperative adjunct for localization of enlarged parathyroid glands. The availability of preoperative and other intraoperative localization methods, and the reported adverse effects of methylene blue make its routine use debatable. The aim of this study was to perform a systematic review of the use of methylene blue in parathyroidectomy.

Methods

A systematic review of English-language literature in MEDLINE and Scopus databases on the use of intravenous methylene blue in parathyroid surgery was carried out.

Results

There were no randomized clinical trials. Thirty-nine observational studies were identified, of which 33 did not have a control arm. The overall median staining rate for abnormal parathyroid glands was 100 per cent. The median cure rates in the methylene blue and no-methylene blue arms were 100 and 98 per cent respectively. Neurotoxicity was reported in 25 patients, all of whom were taking serotonergic medication.

Conclusion

Observational evidence suggests that methylene blue is efficacious in identifying enlarged parathyroid glands. Toxicity appears to be mild in the absence of concomitant use of serotonin reuptake inhibitors. The effectiveness of methylene blue in the context of currently used preoperative and intraoperative localization techniques has yet to be shown.

Suspected serotonin syndrome in a patient being treated with methylene blue for ifosfamide encephalopathy

Methylene blue has been used not only as a diagnostic agent, but also as an agent in the treatment of ifosfamide-induced encephalopathy (IIE) for several years. Recently, several cases of suspected serotonin syndrome have been reported in patients who received methylene blue in combination with serotonin active agents. Rodent models have revealed that methylene blue is a potent, reversible inhibitor of monoamine oxidase A. It is well known that serotonin active drugs, in combination with monoamine oxidase inhibitors can produce profound serotonin syndrome. To date, cases of serotonin syndrome, which resulted from concurrent methylene blue and serotonin active agents, have been published in the anesthesia literature. We report the first known case of serotonin syndrome in a patient receiving methylene blue for IIE.

Cellular and molecular actions of Methylene Blue in the nervous system

Methylene Blue (MB), following its introduction to biology in the 19th century by Ehrlich, has found uses in various areas of medicine and biology. At present, MB is the first line of treatment in methemoglobinemias, is used frequently in the treatment of ifosfamide-induced encephalopathy, and is routinely employed as a diagnostic tool in surgical procedures. Furthermore, recent studies suggest that MB has beneficial effects in Alzheimer's disease and memory improvement. Although the modulation of the cGMP pathway is considered the most significant effect of MB, mediating its pharmacological actions, recent studies indicate that it has multiple cellular and molecular targets. In the majority of cases, biological effects and clinical applications of MB are dictated by its unique physicochemical properties including its planar structure, redox chemistry, ionic charges, and light spectrum characteristics. In this review article, these physicochemical features and the actions of MB on multiple cellular and molecular targets are discussed with regard to their relevance to the nervous system.

CNS toxicity involving methylene blue: the exemplar for understanding and predicting drug interactions that precipitate serotonin toxicity

Methylene blue has only recently been noted to cause severe central nervous system toxicity. Methylene blue is used for various conditions, including, intravenously, in methemoglobinemia, vasoplegia and as an aid to parathyroidectomy (at doses of 1-7.5 mg kg(-1)). This review of the current evidence concludes that 13 of 14 of the reported cases of CNS toxicity were serotonin toxicity that met the Hunter Serotonin Toxicity Criteria. That has important preventative and treatment implications. Serotonin toxicity is precipitated by the monoamine oxidase inhibitor (MAOI) property of methylene blue interacting with serotonin reuptake inhibitors. Serotonin toxicity is reviewed, using the lessons inherent in the methylene blue story and experience, to illustrate how the mechanisms and potency of serotonergic drugs interact to determine severity. Recent human data showed that an intravenous dose of only 0.75 mg kg(-1) of methylene blue produced a peak plasma concentration of 500 ng ml(-1) (1.6 µM), indicating that the concentration in the central nervous system reaches a level that inhibits monoamine oxidase A. That is consonant with the actual occurrence of severe serotonin toxicity in humans at the dose of only 1 mg kg(-1). It seems that all proposed uses of methylene blue entail levels that block monoamine oxidase, so cessation of serotonin reuptake inhibitors should be very carefully considered before using methylene blue.

Palmar staining following methylene blue leak test during laparoscopic Roux-en-Y gastric bypass

A morbidly obese female with a body mass index of 39 and without a past medical history of skin or connective tissue disorders was taken to the operating room for a laparoscopic Roux-en-Y gastric bypass, utilizing the methylene blue leak test. On the following day, she developed significant blancheable bluish skin discoloration on her bilateral fingers and palms without sensory changes. The rest of her postoperative course was otherwise uneventful. In this article, we describe an unusual dermatologic change related to the use of methylene blue during bariatric surgery.

Real-time, near-infrared, fluorescence-guided identification of the ureters using methylene blue

BACKGROUND

The aim of this study was to determine whether the invisible near-infrared (NIR) fluorescence properties of methylene blue (MB), a dye already approved by the U.S. Food and Drug Administration for other indications, could be exploited for real-time, intra-operative identification of the ureters.

METHODS

The optical properties of MB were quantified in vitro. Open surgery and laparoscopic NIR fluorescence imaging systems were employed. Yorkshire pigs were injected intravenously with 0.1-mg/kg MB (n = 8), 10-mg furosemide followed by 0.1-mg/kg MB (n = 6), or 0.5-mg/kg MB (n = 6). The contrast-to-background ratio (CBR) of the kidney and ureters, and the MB concentration in the urine, were quantified.

RESULTS

Peak MB absorbance, emission, and intensity in urine occurred at 668 nm, 688 nm, and 20 mumol/L, respectively. After intravenous injection, doses as low as 0.1-mg/kg MB provided prolonged imaging of the ureters, and a dose of 0.5 mg/kg provided statistically significant improvement of CBR. The preinjection of furosemide increased urine volume but did not improve CBR. Laparoscopic identification of the ureter using MB NIR fluorescence was demonstrated.

CONCLUSION

Ureteral imaging using MB NIR fluorescence provides sensitive, real-time, intra-operative identification of the ureters during open and laparoscopic surgeries.

Radio-guided thoracoscopic surgery with (99m)Tc-methoxy-isobutylisonitrile for treating an ectopic mediastinal parathyroid adenoma in an adolescent girl

Here we report the case of a 17-year-old girl treated for an ectopic mediastinal parathyroid adenoma using (99m)Tc-methoxy-isobutyl-isonitrile (MIBI) and radio-guided thoracoscopic surgery. Her serum calcium and intact parathyroid hormone levels were elevated, and an anterior mediastinal tumor was noted on her chest computed tomography scan. At 2 h before surgery, the patient was given an injection of 370 MBq of (99m)Tc-MIBI. Because it was not possible visually to distinguish the tumor from the mature thymic tissue in which it was embedded, a search for the tumor was carried out using a gamma probe under thoracoscopy. Thereafter, the left thymus, including the radioactivity-positive tumor, was resected. We suggest that radio-guided thoracoscopic surgery with (99m)Tc-MIBI is an excellent procedure for treating ectopic mediastinal parathyroid adenomas embedded in the mature thymus of adolescents and young adults. This approach could be especially useful for young female patients, given its cosmetic advantage.

Intraoperative adjuncts in surgery for primary hyperparathyroidism

PURPOSE

This paper is a review of the evidence base to produce recommendations for the use of intraoperative parathyroid hormone (PTH), radioguided parathyroidectomy (RGP), methylene blue (MB), frozen section, and intraoperative neuromonitoring during surgery for primary hyperparathyroidism (PHPT).

MATERIALS AND METHODS

A Medline keyword search of English-language articles led to the production of a draft document, subsequently revised by committee, containing levels of evidence and the grading of recommendations as proposed by the Agency for Healthcare Research and Quality.

RESULTS

Literature review provides the basis for clear recommendations on the use of intraoperative PTH at surgery for PHPT. There is little evidence to support the use of RGP, MB, routine frozen section, and intraoperative neuromonitoring.

Methylene blue-associated serotonin syndrome: a 'green' encephalopathy after parathyroidectomy

INTRODUCTION

Methylene blue (MB) infusion is frequently used to localize the parathyroid glands during parathyroidectomy and generally considered safe. Several recent reports suggest neurological toxicity and post-operative altered mental state typically after large dose infusions. The mechanism by which MB has neurotoxic effects in some patients remains uncertain.

METHODS/RESULTS

CASE REPORT

A 67-year-old male underwent lumbar laminectomy followed by parathyroidectomy. Postoperatively, he was comatose (Glasgow Coma Scale of 7) and underwent extensive neurological evaluation. Brain computed tomography (CT) imaging and CT angiography revealed no ischemia, vessel occlusion, or hemorrhage. Electroencephalogram (EEG) showed only slowing of cerebral hemispheric activity bilaterally. Over the next 48 h, his mental status slowly improved and the patient made a full neurological recovery (Glasgow Coma Scale 15).

CONCLUSION

Methylene blue, when used in patients on antidepressant drugs, may be associated with a transient encephalopathic state and serotonin syndrome. Patients on antidepressants undergoing parathyroidectomy who may receive MB infusion should be considered for alternative parathyroid gland identification or discontinuation of the antidepressants before surgery. MB-associated serotonin syndrome is an increasing and under recognized ('green') post-operative encephalopathy that warrants education to critical care neurologists and other physicians.

Effects of methylene blue on propofol requirement during anaesthesia induction and surgery

Delayed emergence from anaesthesia and neurological disturbances have been reported in patients undergoing parathyroidectomy who received methylene blue (MB) pre-operatively. We hypothesised that MB would decrease propofol requirements. The Bispectral index (BIS) and a target-controlled infusion of propofol were used in two groups of 11 matched patients. Patients in one group were pretreated with MB. During induction, clinical sedation scores and BIS values were significantly lower at the predicted effect-site propofol concentration of 2 microg x ml(-1) in the MB compared with the control group. Intra-operatively, although similar BIS values were achieved in the two groups, patients pretreated with MB required a mean 50% lower dose of propofol compared with controls. In view of these findings, care should be taken to ensure an adequate depth of anaesthesia by titrating the administration of anaesthetic agents whenever MB is infused peri-operatively.

[Serotonin syndrome following methylene blue infusion during parathyroidectomy: a case report and literature review]

PURPOSE

To report a case of autonomic, neurological and neuromuscular instability following methylene blue infusion for parathyroidectomy; to advance the argument for a diagnosis of serotonin syndrome; and to consider this diagnosis in previous, unexplained reports of adverse reactions amongst patients undergoing parathyroidectomy using methylene blue.

CLINICAL FEATURES

Methylene blue was administered to a 58-yr-old woman undergoing a parathyroidectomy under general anesthesia. The patient had a background of obsessive compulsive disorder treated with paroxetine. Postoperatively, she demonstrated symptoms and signs of serotonin syndrome; specifically tachycardia, agitation, dystonia and abnormal eye movements. These clinical findings spontaneously resolved themselves over the subsequent 48 hr.

CONCLUSION

An interaction between methylene blue and serotonergic agents may give rise to the serotonin syndrome. Consideration should be given to avoiding methylene blue in patients taking serotonergic agents. The diagnosis should be considered in patients with autonomic, neuromuscular or neurological changes and should be managed accordingly.