How to do it: investigate exertional rhabdomyolysis (or not)

Peripheral nervous system and neuromuscular disorders in the emergency department: A review

INTRODUCTION

Acute presentations and emergencies in neuromuscular disorders (NMDs) often challenge clinical acumen. The objective of this review is to refine the reader's approach to history taking, clinical localization and early diagnosis, as well as emergency management of neuromuscular emergencies.

METHODS

An extensive literature search was performed to identify relevant studies. We prioritized meta-analysis, systematic reviews, and position statements where possible to inform any recommendations.

SUMMARY

The spectrum of clinical presentations and etiologies ranges from neurotoxic envenomation or infection to autoimmune disease such as Guillain-Barré Syndrome (GBS) and myasthenia gravis (MG). Delayed diagnosis is not uncommon when presentations occur "de novo," respiratory failure is dominant or isolated, or in the case of atypical scenarios such as GBS variants, severe autonomic dysfunction, or rhabdomyolysis. Diseases of the central nervous system, systemic and musculoskeletal disorders can mimic presentations in neuromuscular disorders.

CONCLUSIONS

Fortunately, early diagnosis and management can improve prognosis. This article provides a comprehensive review of acute presentations in neuromuscular disorders relevant for the emergency physician.

A case report of near-missed heat stroke

RATIONALE

Heat-related illnesses have protean manifestations that can mimic other life-threatening conditions. The diagnosis of heat stroke requires a high index of suspicion if the patient has been exposed to a high-temperature environment. Central nervous system dysfunction is a cardinal feature. Strict adherence to temperature criteria can potentially lead to misdiagnosis.

PATIENT CONCERNS

A 37-year-old construction worker was brought in by his wife and coworker due to a sudden loss of consciousness while resting after completing his work.

DIAGNOSES

Due to challenges faced during the coronavirus disease 2019 pandemic, as well as language barriers, a detailed history from the coworker who witnessed the patient's altered sensorium was not available. He was initially suspected of having encephalitis and brainstem stroke. However, subsequent investigations revealed multiorgan dysfunction with a normal brain computed tomography and cerebral computed tomography angiogram. In view of the multiple risk factors for heat stroke, pupillary constriction, and urine color suggestive of rhabdomyolysis, a diagnosis of heat stroke was made.

INTERVENTIONS

Despite delayed diagnosis, the patient's multiorgan dysfunction recovered within days with basic supportive care.

OUTCOMES

There were no noticeable complications on follow-up 14 months later.

LESSONS

Heat stroke can be easily confused with other neurological pathologies, particularly if no history can be obtained from the patient or informant. When approaching a comatose patient, we propose that serum creatinine kinase should be considered as an initial biochemical screening test.

Clinical outcomes of hospitalised individuals with spin-induced exertional rhabdomyolysis

Introduction

Exertional rhabdomyolysis (ER) is caused by myocyte breakdown after strenuous physical activity. In recent years, the incidence of spin-induced ER (SER) has been increasing. We describe the clinical characteristics, management and outcomes of patients admitted for SER.

Method

A review was conducted for all patients admitted to Singapore General Hospital for SER from 1 March 2021 to 31 March 2022. All patients with the admission diagnosis of "rhabdomyolysis", "raised creatine kinase (CK) level", or "elevated CK level" with a preceding history of spin-related physical exertion were included. Patients without a history of exertion, with a history of non-spin related exertion, or with a peak serum CK <1000 U/L were excluded.

Results

There were 93 patients in our final analysis; mean age was 28.6±5.6 years and 66 (71.0%) were female patients. Mean body mass index was 25.0±5.7 kg/m2; 81 (87.1%) patients were first-time spin participants. All patients had muscle pain, 68 (73.1%) had dark urine, 16 (17.2%) muscle swelling and 14 (15.1%) muscle weakness. There were 80 (86.0%) patients with admission CK of >20,000 U/L. Mean admission creatinine was 59.6±15.6 μmol/L. Mean intravenous (IV) hydration received was 2201±496 mL/ day, oral hydration 1217±634 mL/day and total hydration 3417±854 mL/day. There was 1 (1.1%) patient with acute kidney injury, which resolved the next day with IV hydration.

Conclusion

Inpatient management of SER includes laboratory investigations, analgesia and hydration. Risk of complications is low in SER patients. SER patients without risk factors for complications can be considered for hospital-at-home management with bed rest, aggressive hydration and early outpatient review.

Exertional Rhabdomyolysis in Athletes: Systematic Review and Current Perspectives

OBJECTIVE

Exertional rhabdomyolysis results from a breakdown of skeletal muscle cells after intense exercise in otherwise healthy patients, causing increased levels of creatine kinase (CK) or myoglobin, as well as urine dipstick positive for blood, and may result in kidney insufficiency. The aim of this study was to outline the current perspectives of exertional rhabdomyolysis in athletes and subsequent treatment based on the current literature.

DATA SOURCES

We searched the MEDLINE/PubMed and Google databases for ([exercise] OR [exertional]) AND rhabdomyolysis following the PRISMA guidelines. All abstracts were reviewed by 2 independent examiners. Inclusion criteria consisted of original articles presenting studies on exertional rhabdomyolysis or exercise-induced rhabdomyolysis with 7 or more cases. All case reports, case series, or editorials were excluded.

MAIN RESULTS

A total of 1541-abstracts were screened, leaving 25 studies for final inclusion and analysing 772patients. Especially, young male patients were affected at a mean age of 28.7 years (range 15.8-46.6 years). Most of the athletes performed running, including marathons in 54.3% of cases (n = 419/772), followed by weightlifting in 14.8% (n = 114/772). At the time of presentation, the mean creatine kinase was 31 481 IU/L (range 164-106,488 IU/L). Seventeen studies reported the highest level of CK, which was 38 552 IU/L (range 450-88,496 IU/L). For treatment, hydration was the most common method of choice reported by 8 studies.

CONCLUSIONS

Exertional rhabdomyolysis seems to be underestimated, and it is essential to screen patients who present with muscle soreness/cramps and/or dark urine after heavy endurance events to avoid any further complications.

LEVEL OF EVIDENCE

II; systematic review.

Feasibility and Safety of Whole-Body Electromyostimulation in Frail Older People—A Pilot Trial

Whole-body electromyostimulation (WB-EMS) induces high-intense stimuli to skeletal muscles with low strain on joints and the autonomic nervous system and may thus be suitable for frail, older people. However, if trained at very high intensities, WB-EMS may damage muscles and kidneys (rhabdomyolysis). This study aimed at investigating the feasibility, safety and preliminary efficacy of WB-EMS in frail, older people. Seven frail (81.3 ± 3.5 years), 11 robust (79.5 ± 3.6 years), 10 young (29.1 ± 6.4 years) participants completed an eight-week WB-EMS training (week 1–4: 1x/week; week 5–8: 1.5x/week) consisting of functional exercises addressing lower extremity strength and balance. Feasibility was assessed using recruitment, adherence, retention, and dropout rates. The satisfaction with WB-EMS was measured using the Physical Activity Enjoyment Scale for older adults (PACES-8). In week 1, 3, and 8 creatine kinase (CK) was assessed immediately before, 48 and 72 h after WB-EMS. Symptoms of rhabdomyolysis (muscle pain, muscle weakness, myoglobinuria) and adverse events were recorded. Functional capacity was assessed at baseline and after 8 weeks using the Short Physical Performance Battery (SPPB), Timed Up-and-Go Test (TUG), Choice Stepping Reaction Time Test (CSRT), 30-second Chair-Stand Test (30-STS), maximum isometric leg strength and handgrip strength. The recruitment rate of frail individuals was 46.2%, adherence 88.3% and the dropout rate 16.7%. All groups indicated a high satisfaction with WB-EMS. CK activity was more pronounced in young individuals with significant changes over time. Within older people CK increased borderline-significantly in the frail group from baseline to week 1 but not afterwards. In robust individuals CK increased significantly from baseline to week 1 and 3. No participant reached CK elevations close to the threshold of ≥5,000 U/l and no symptoms of rhabdomyolysis were observed. With the exception of the TUG (p = 0.173), frail individuals improved in all tests of functional capacity. Compared to the young and robust groups, frail individuals showed the greater improvements in the SPPB, handgrip strength, maximum isokinetic hip-/knee extension and flexion strength. WB-EMS is feasible for frail older people. There were no clinical signs of exertional rhabdomyolysis. WB-EMS proved to be sufficiently intense to induce meaningful changes in functional capacity with frail individuals showing greater improvements for several measures.

Clinical characteristics and outcomes of exertional rhabdomyolysis after indoor spinning: a systematic review

OBJECTIVES

An increasing number of patients are diagnosed with exertional rhabdomyolysis secondary to indoor spinning. We performed a systematic review to characterize the clinical features of this new clinical entity.

METHODS

We conducted a thorough literature search on PubMed, Embase, Web of Science, Scopus, and The Cumulative Index to Nursing and Allied Health Literature (CINAHL). Articles published from inception to 23 June 2021 were considered. A two-stage article selection process was performed. Articles that reported clinical characteristics and outcomes in patients with spin-induced exertional rhabdomyolysis (SIER) were included. Quality assessment was performed using the Joanna Briggs Institute checklists.

RESULTS

There were a total of 22 articles and 97 patients with SIER. Most patients were healthy females who had attended their first spinning session. The mean time to clinical presentation was 3.1 ± 1.5 days. The most common presenting symptoms were myalgia, dark urine, and muscle weakness in the thighs. Seven patients (7.2%) developed acute kidney injury, and two patients (2.1%) required temporary inpatient hemodialysis. Four patients (4.1%) developed thigh compartment syndrome and required fasciotomies. No long-term sequelae or mortality were observed. The mean length of stay was 5.6 ± 2.9 days.

CONCLUSIONS

Healthcare professionals must have a high index of suspicion for SIER when a patient presents with myalgia, dark urine, or weakness after a recent episode of indoor spinning. Fitness center owners, spinning instructors, and participants should also be better educated about the clinical features and manifestations of SIER.

RYR1-related rhabdomyolysis: a spectrum of hypermetabolic states due to ryanodine receptor dysfunction

Variants in the ryanodine receptor-1 gene (RYR1) have been associated with a wide range of neuromuscular conditions, including various congenital myopathies and malignant hyperthermia (MH). More recently, a number of RYR1 variants, mostly MH-associated, have been demonstrated to contribute to rhabdomyolysis events not directly related to anesthesia in otherwise healthy individuals. This review focuses on RYR1-related rhabdomyolysis, in the context of several clinical presentations (i.e., exertional rhabdomyolysis, exertional heat illnesses and MH), and conditions involving a similar hypermetabolic state, in which RYR1 variants may be present (i.e., neuroleptic malignant syndrome and serotonin syndrome). The variety of triggers that can evoke rhabdomyolysis, on their own or in combination, as well as the number of potentially associated complications, illustrates that this is a condition relevant to several medical disciplines. External triggers include but are not limited to strenuous physical exercise, especially if unaccustomed or performed under challenging environmental conditions (e.g., high ambient temperature or humidity), alcohol/illicit drugs, prescription medication (in particular statins, other anti-lipid agents, antipsychotics and antidepressants) infection, or heat. Amongst all patients presenting with rhabdomyolysis, a genetic susceptibility is present in a proportion, with RYR1 being one of the most common genetic causes. Clinical clues for a genetic susceptibility include recurrent rhabdomyolysis, creatine kinase (CK) levels above 50 times the upper limit of normal, hyperCKemia lasting for 8 weeks or longer, drug/medication doses insufficient to explain the rhabdomyolysis event, and a positive family history. For the treatment or prevention of RYR1-related rhabdomyolysis, the RYR1 antagonist dantrolene can be administered, both in the acute phase, or prophylactically in patients with a history of muscle cramps and/or recurrent rhabdomyolysis events. Aside from dantrolene, several other drugs are being investigated for their potential therapeutic use in RYR1-related disorders. These findings offer further therapeutic perspectives for humans, suggesting an important area for future research.

Electronic phenotyping of health outcomes of interest using a linked claims-electronic health record database: Findings from a machine learning pilot project

OBJECTIVE

Claims-based algorithms are used in the Food and Drug Administration Sentinel Active Risk Identification and Analysis System to identify occurrences of health outcomes of interest (HOIs) for medical product safety assessment. This project aimed to apply machine learning classification techniques to demonstrate the feasibility of developing a claims-based algorithm to predict an HOI in structured electronic health record (EHR) data.

MATERIALS AND METHODS

We used the 2015-2019 IBM MarketScan Explorys Claims-EMR Data Set, linking administrative claims and EHR data at the patient level. We focused on a single HOI, rhabdomyolysis, defined by EHR laboratory test results. Using claims-based predictors, we applied machine learning techniques to predict the HOI: logistic regression, LASSO (least absolute shrinkage and selection operator), random forests, support vector machines, artificial neural nets, and an ensemble method (Super Learner).

RESULTS

The study cohort included 32 956 patients and 39 499 encounters. Model performance (positive predictive value [PPV], sensitivity, specificity, area under the receiver-operating characteristic curve) varied considerably across techniques. The area under the receiver-operating characteristic curve exceeded 0.80 in most model variations.

DISCUSSION

For the main Food and Drug Administration use case of assessing risk of rhabdomyolysis after drug use, a model with a high PPV is typically preferred. The Super Learner ensemble model without adjustment for class imbalance achieved a PPV of 75.6%, substantially better than a previously used human expert-developed model (PPV = 44.0%).

CONCLUSIONS

It is feasible to use machine learning methods to predict an EHR-derived HOI with claims-based predictors. Modeling strategies can be adapted for intended uses, including surveillance, identification of cases for chart review, and outcomes research.

Pediatric Paroxysmal Exercise-Induced Neurological Symptoms: Clinical Spectrum and Diagnostic Algorithm

Paroxysmal exercise-induced neurological symptoms (PENS) encompass a wide spectrum of clinical phenomena commonly presenting during childhood and characteristically elicited by physical exercise. Interestingly, few shared pathogenetic mechanisms have been identified beyond the well-known entity of paroxysmal exercise-induced dyskinesia, PENS could be part of more complex phenotypes including neuromuscular, neurodegenerative, and neurometabolic disease, epilepsies, and psychogenetic disorders. The wide and partially overlapping phenotypes and the genetic heterogeneity make the differential diagnosis frequently difficult and delayed; however, since some of these disorders may be treatable, a prompt diagnosis is mandatory. Therefore, an accurate characterization of these symptoms is pivotal for orienting more targeted biochemical, radiological, neurophysiological, and genetic investigations and finally treatment. In this article, we review the clinical, genetic, pathophysiologic, and therapeutic landscape of paroxysmal exercise induced neurological symptoms, focusing on phenomenology and differential diagnosis.

Clinical Practice Guidelines for Exertional Rhabdomyolysis: A Military Medicine Perspective

ABSTRACT

Exertional rhabdomyolysis (ER) is an uncommon condition with a paucity of evidence-based guidance for diagnosis, management, and return to duty or play. Recently, a clinical practice guideline for diagnosis and management of ER in warfighters was updated by a team of military and civilian physicians and researchers using current scientific literature and decades of experience within the military population. The revision concentrated on challenging and controversial clinical questions with applicability to providers in the military and those in the greater sports medicine community. Specific topics addressed: 1) diagnostic criteria for ER; 2) clinical decision making for outpatient versus inpatient treatment; 3) optimal strategies for inpatient management; 4) discharge criteria; 5) identification and assessment of warfighters/athletes at risk for recurrent ER; 6) an appropriate rehabilitative plan; and finally, 7) key clinical questions warranting future research.

Rhabdomyolysis and Muscle Necrosis Induced By Lead Poisoning

A case is presented on a 40-year-old male with chronic lead poisoning with loss of consciousness, rhabdomyolysis, and acute renal failure after occupational exposure. Physical examination revealed generalized atrophy, tenderness, and swelling in the right limb and a decreased proximal muscle strength in the lower limb. A severe acute polyradiculoneuropathy in lower limbs documented by electromyography. All paraclinical tests were normal except increased blood lead level (75 μg/dl) and blue line in gum of the teeth. The patient was treated with penicillamine (500 mg q8 h) and pyridoxine (50 mg daily) for 8 months, only accessible drug in Iran. Force of patient's muscles in the proximal part of the lower limb was improved, and also the blood lead level reached to normal range. This is the first patient with rhabdomyolysis and muscle necrosis induced by lead poisoning.

[CME: Elevated Creatine Kinase as a Diagnostic Parameter of Rhabdomyolysis]

CME: Elevated Creatine Kinase as a Diagnostic Parameter of Rhabdomyolysis Abstract. Elevated CK values with or without symptoms require clarification in order to rule out possible secondary complications. Adequate hydrogenation, discontinuation of possibly triggering drugs and noxious agents, and close laboratory controls are decisive for the outcome. Acute rhabdomyolysis can have various causes, which can generally be classified as traumatic or atraumatic. In case of recurrent occurrence, genetic or autoimmunological diseases must also be excluded. In addition to a detailed anamnesis, physical examination, laboratory and urine tests, a variety of diagnostic methods are available, which should be used selectively. The aim of this work is to address possible clarification strategies, causes and differential diagnoses of an increase in creatine kinase and rhabdomyolysis. We illustrate these with a case.

The etiology of rhabdomyolysis: an interaction between genetic susceptibility and external triggers

Background and purpose

Rhabdomyolysis is a medical emergency characterized by acute skeletal muscle breakdown with a sudden rise and subsequent fall of serum creatine kinase (CK) levels. Rhabdomyolysis events are provoked by exposure to external triggers, possibly in combination with an increased genetic susceptibility. We aimed to describe comprehensively the external triggers and potentially pathogenic genetic variants possibly implicated in increased rhabdomyolysis susceptibility.

Methods

We performed a retrospective single‐center study, including a total of 1302 patients with an acute CK level exceeding 2000 IU/l.

Results

Anoxia was the most frequently reported trigger (40%). A subset of 193 patients were clinically suspected of an underlying genetic disorder (recurrent episodes, a positive family history, very high or persistently increased CK levels). In 72 of these patients, an unequivocal genetic defect was identified. A total of 22 genes with pathogenic variants were identified, including 52 different variants. Of those, 11 genes have been previously associated with rhabdomyolysis (ACADVL, ANO5, CPT2, DMD, DYSF, FKRP, HADHA, PGM1, LPIN1, PYGM, RYR1). Eleven genes are probably implicated in increased susceptibility (including AGL, CAPN3, CNBP, DMPK, MAGT1, ACADM, SCN4A, SGCA, SGCG, SMPD1, TANGO2).

Conclusion

These findings suggest that the spectrum of genetic susceptibility for rhabdomyolysis has not yet been completely clarified. With the increasing availability of next‐generation sequencing in a diagnostic setting, we expect that in more cases a genetic defect will be identified.

Muscle biopsy: what and why and when?

Skeletal muscle biopsy remains an important investigative tool in the diagnosis of a variety of muscle disorders. Traditionally, someone with a limb-girdle muscle weakness, myopathic changes on electrophysiology and raised serum creatine kinase (CK) would have a muscle biopsy. However, we are living through a genetics revolution, and so do all such patients still need a biopsy? When should we undertake a muscle biopsy in patients with a distal, scapuloperoneal or other patterns of muscle weakness? When should patients with myositis, rhabdomyolysis, myalgia, hyperCKaemia or a drug-related myopathy have a muscle biopsy? What does normal muscle histology look like and what changes occur in neurogenic and myopathic disorders? As with Kipling's six honest serving men, we hope that by addressing these issues we can all become more confident about when to request a muscle biopsy and develop clearer insights into muscle pathology.