Risk factors and future directions for preventing and diagnosing exertional rhabdomyolysis

276th ENMC workshop: recommendations on optimal diagnostic pathway and management strategy for patients with acute rhabdomyolysis worldwide. 15th-17th March 2024, Hoofddorp, The Netherlands

The 276th ENMC Workshop on rhabdomyolysis brought together 21 experts to address the compelling need for standardized guidelines on the clinical approach of rhabdomyolysis. There was a general agreement that a diagnosis of rhabdomyolysis require that 1) clinical symptoms include severe muscle swelling, weakness and/or myalgia; 2) serum CK-levels exceed 10,000 IU/L in case of exertional, and >5000 IU/L in non-exertional rhabdomyolysis; 3) CK-levels reaching a maximum 1-4 days after the event and normalizing to baseline within 1-2 weeks of rest. In case of an underlying neuromuscular condition, CK-levels should exceed 5-10 times the patient's baseline level. Treatment should be initiated only in case of high risk on acute kidney injury, which can be predicted by the McMahon score. Furthermore, recommendations on performing genetic testing were formulated and the use of the 'RHABDO'- acronym was generally agreed upon as a tool to aid clinicians in deciding which patients require genetic testing. Moreover, recommendations on follow-up were made, with a particular emphasis on evaluation of physical and psychological sequelae. Patient representatives present during the workshop emphasized the importance of the current recommendations for future clinical guidelines on rhabdomyolysis.

The Association Between Statin Drugs and Rhabdomyolysis: An Analysis of FDA Adverse Event Reporting System (FAERS) Data and Transcriptomic Profiles

BACKGROUND/OBJECTIVES

Rhabdomyolysis, a dangerous breakdown of skeletal muscle, has been reported as an adverse event in those prescribed a statin therapy for the treatment of hypercholesterolemia. Statin drugs are some of the most prescribed treatments for elevated cholesterol levels. The purpose of this comparative study was to determine the association between the statin drugs used and the risk of rhabdomyolysis using the FDA Adverse Event Reporting System (FAERS) and transcriptomic data.

METHODS

A disproportionality analysis was performed to compare the risk of rhabdomyolysis between the reference statin drug (simvastatin) and the treatment group, with patient age assessed as a possible confounder. In addition, association rule mining was utilized to both identify other adverse events that frequently presented with rhabdomyolysis and identify possible drug-drug interactions (DDIs). Finally, public transcriptomic data were explored to identify the possible genetic underpinnings highlighting these differences in rhabdomyolysis risk across statins.

RESULTS

Rhabdomyolysis is a commonly reported adverse event for patients treated with statins, particularly those prescribed simvastatin. Simvastatin was associated with a more than 2-fold increased likelihood of rhabdomyolysis compared to other statins. Men were twice as likely to report rhabdomyolysis than women regardless of statin treatment, with the highest risk observed for pravastatin (ROR = 2.30, p < 0.001) and atorvastatin (ROR = 2.03, p < 0.0001). Several possible DDIs were identified, including furosemide/Lasix, allopurinol clopidogrel/Plavix, and pantoprazole, which may elevate rhabdomyolysis risk through impaired muscle function and delayed statin metabolism. Finally, nine myopathic genes were identified as possible regulators of statin-induced rhabdomyolysis, including DYSF, DES, PLEC, CAPN3, SCN4A, TNNT1, SDHA, MYH7, and PYGM in primary human muscle cells.

CONCLUSIONS

Simvastatin was associated with the highest risk of rhabdomyolysis. The risk of rhabdomyolysis was more pronounced in men than women. Several possible DDIs were identified including furosemide/Lasix, allopurinol clopidogrel/Plavix, and pantoprazole.

Effects of a single bout of exercise on human hemocytes and serum interleukin 3, erythropoietin, and soluble transferrin receptor in a hot and humid environment

Background

Exercise in humid and hot environments (HHEs) may result in decreased perception, motor performance, and memory owing to endogenous heat production and exogenous load. However, whether a single bout of exercise (SBOE) intensity affects the magnitude of changes in the levels of hemocytes remains controversial. In this article, we aimed to investigate the effects of a SBOE of varying intensities on blood cells in HHE.

Methods

Thirty-two volunteers were randomly divided into a quiet control group (QC), 55% VO2max intensity exercise group (HHE55%), 70% VO2max intensity exercise group (HHE70%), and 85% VO2max intensity exercise group (HHE85%). The participants in the exercise groups were assigned to perform an SBOE on the treadmill under HHE conditions for 30 min, whereas participants in the QC remained still under HHE conditions for 30 min (temperature: 28-32 °C, relative humidity: 85-95%).

Results

The net body mass (NBM), perfusion index (PI), mean corpuscular volume (MCV), platelet (PLT), and plateletcrit (PCT) values were affected significantly by the exercise intensity (P < 0.01) the hemoglobin (HGB) and neutrophil count (NE) were affected significantly by exercise intensity (P < 0.05). After an SBOE, compared with that before exercise, the sublingual temperature (ST) of all groups, the NBM and MCV of all exercise groups, the PI of the HHE55% and HHE70% groups, the HGB, hematocrit (HCT), and NE of the HHE70% group, the red blood cell count (RBC), PLT, and PCT of the HHE70% and HHE85% groups, and the white blood cell count (WBC) of HHE85% changed very significantly (P < 0.01). The PCT of QC, blood oxygen saturation (SaO2), and soluble transferrin receptor (sTfR) levels in the HHE55% group, the lymphocyte count (LY) in the HHE70% group, and the HGB and HCT in the HHE85% group changed significantly (P < 0.05).

Conclusion

Low- and moderate-intensity SBOE in HHE could increase the serum EPO and serum sTfR levels and decrease the serum IL-3 levels. Conversely, a high-intensity load could increase the risk of inflammation. Therefore, low-intensity exercise may be more appropriate for an SBOE in HHE.

Genome-Wide Analysis of Exertional Rhabdomyolysis in Sickle Cell Trait Positive African Americans

Sickle cell trait (SCT), although generally a benign carrier state of hemoglobin S (HbAS), is a risk factor for exertional rhabdomyolysis (ERM), a rare but potentially fatal consequence of highly intense physical exercise, particularly among active-duty military personnel and high-performance athletes. The association between SCT and ERM is poorly understood. The objective of this study was to elucidate the genetic basis of ERM in an SCT-positive African American cohort. SCT-positive African Americans with a personal history of ERM (cases, n = 30) and without history of ERM (controls, n = 53) were enrolled in this study. Whole-genome sequencing was performed on DNA samples isolated from peripheral white blood cells. Participants' demographic, behavioral, and medical history information was obtained. An additional 131 controls were extracted from SCT-positive subjects of African descent from the 1000 Genomes Project. SCT carriers with ERM were characterized by myotoxicity features, significant muscle involvement dominated by muscle weakness, and severe pain and substantial increase in serum creatine kinase, with a mean value of 50,480 U/L. A distinctive feature of the SCT individuals with ERM was exertional collapse, which was reported in 53.3% of the cases in the study cohort. An important factor for the development of ERM was the duration and frequency of strenuous physical activity in the cases compared to the controls. Whole-genome sequencing identified 79,696 protein-coding variants. Genome-wide association analysis revealed that the p.C477R, rs115958260 variant in the SLC44A3 gene was significantly associated with ERM event in SCT-positive African Americans. The study results suggest that a combination of vigorous exercise and a genetic predisposing factor is involved in ERM.

First Case of Surgically Treated Chronic Exertional Compartment Syndrome of the Arm

This paper reports the first case of chronic exertional compartment syndrome in the arm treated surgically. The diagnosis was made in a patient who is under 30 years old, military, and very athletic, with recurrent exertional pain in the anterior compartment of the arms associated with rhabdomyolysis. The high-pressure measurements in the arms' anterior compartment after exertional exercise confirmed the diagnosis. Given the patient's functional demands, a surgical treatment of fasciotomy of the anterior compartment by miniapproach was performed and allowed the resolution of symptomatology with a return to sport at the same level after 3 months.

Intrinsic and extrinsic regulation of rhabdomyolysis susceptibility by Tango2

Rhabdomyolysis is a clinical emergency characterized by severe muscle damage, resulting in the release of intracellular muscle components, which leads to myoglobinuria and, in severe cases, acute kidney failure. Rhabdomyolysis is caused by genetic factors linked to increased disease susceptibility in response to extrinsic triggers. Recessive mutations in TANGO2 result in episodic rhabdomyolysis, metabolic crises, encephalopathy and cardiac arrhythmia. The underlying mechanism contributing to disease onset in response to specific triggers remains unclear. To address these challenges, we created a zebrafish model of Tango2 deficiency. Here, we demonstrate that the loss of Tango2 in zebrafish results in growth defects, early lethality and increased susceptibility of skeletal muscle defects in response to extrinsic triggers, similar to TANGO2-deficient patients. Using lipidomics, we identified alterations in the glycerolipid pathway in tango2 mutants, which is critical for membrane stability and energy balance. Therefore, these studies provide insight into key disease processes in Tango2 deficiency and have increased our understanding of the impacts of specific defects on predisposition to environmental triggers in TANGO2-related disorders.

Clinical Diagnosis of Rhabdomyolysis without Myoglobinuria or Electromyographic Abnormalities in a Dog

A 2-year-old female neutered Old German Shepherd was presented for acute non-ambulatory tetraparesis. Upon presentation to the emergency department, hematology and biochemical blood tests revealed no abnormalities aside from mildly elevated C-reactive protein levels (22.5 mg/L, reference range 0.0-10.0) and immeasurable creatine kinase (CK) activity. Neurological evaluation the next day revealed ambulatory tetraparesis, general proprioceptive deficits, mild ataxia and dubious diffuse myalgia. Withdrawal reflexes were weak on both thoracic and pelvic limbs. The CK was determined to be significantly elevated at that point (32.856 U/L, ref. range 10.0-200.0). Urinalysis revealed no abnormalities. An electromyographic (EMG) study of thoracic limb, paraspinal and pelvic limb muscles revealed no abnormalities. A magnetic resonance imaging (MRI) study of the cervicothoracic spinal cord was performed and revealed no abnormalities. A presumptive clinical diagnosis of rhabdomyolysis without myoglobinuria or EMG abnormalities was formed. Muscular biopsies were declined due to the rapid clinical improvement of the dog. A follow-up showed the progressive decline of CK activity to normal values and clinical remission of signs. A diagnosis of rhabdomyolysis was concluded based on clinical signs, consistent CK activity elevations and the response to supportive treatment for rhabdomyolysis, despite the absence of myoglobinuria and EMG abnormalities. Rhabdomyolysis should not be excluded based on the lack of EMG abnormalities or myoglobinuria in dogs.

Recent advances in our understanding of genetic rhabdomyolysis

PURPOSE OF REVIEW

This review summarizes recent advances in our understanding of the genetics of rhabdomyolysis.

RECENT FINDINGS

Rhabdomyolysis is the acute breakdown of myofibres resulting in systemic changes that can be life-threatening. Environmental triggers, including trauma, exercise, toxins and infections, and/or gene defects can precipitate rhabdomyolysis. A schema (aptly titled RHABDO) has been suggested for evaluating whether a patient with rhabdomyolysis is likely to harbour an underlying genetic defect. It is becoming increasingly recognized that defects in muscular dystrophy and myopathy genes can trigger rhabdomyolysis, even as the sole or presenting feature. Variants in genes not previously associated with human disease have been identified recently as causative of rhabdomyolysis, MLIP , MYH1 and OBSCN . Our understanding of the pathomechanisms contributing to rhabdomyolysis have also improved with an increased awareness of the role of mitochondrial dysfunction in LPIN1 , FDX2 , ISCU and TANGO2 -mediated disease.

SUMMARY

An accurate genetic diagnosis is important for optimal clinical management of the patient, avoiding associated triggers and genetic counselling and cascade screening. Despite recent advances in our understanding of the genetics contributing to rhabdomyolysis, many patients remain without an accurate genetic diagnosis, suggesting there are many more causative genes, variants and disease mechanisms to uncover.