Isolated rhabdomyolysis of long head of triceps mimicking upper extremity deep vein thrombosis
- 1 Medicine, Northern Hospital Epping, Epping, Victoria, Australia
- 2 Surgery, Austin Health, Heidelberg, Victoria, Australia
- 3 Vascular Surgery, Epworth HealthCare, Richmond, Victoria, Australia
- Correspondence to Dr Benjamin Filipopoulos; bfilipopoulos@gmail.com
Abstract
Rhabdomyolysis is characterised by skeletal muscle breakdown, with release of toxic intracellular contents into the circulation. A man in his 20s presented to the emergency department with acute-onset right arm swelling, with pitting oedema extending into his forearm without clear precipitant. Initial differential diagnosis was upper extremity deep vein thrombosis, however none was identified on CT venogram. Instead, rhabdomyolysis of long head of triceps was diagnosed after multidisciplinary review of the venogram by the treating vascular surgeon and radiologist. Retrospectively, added serum creatine kinase was found to be 11 587 U/L, and together with MRI of the right arm, the diagnosis was established. Given the patient’s lack of comorbidities, normal renal function and reliability, he was managed conservatively as an outpatient without hospital admission for intravenous hydration. This is the only case to our knowledge of isolated long head of triceps’ rhabdomyolysis reported in Australia and the second case worldwide.
Background
The main differential diagnoses for atraumatic, isolated unilateral upper limb swelling include deep vein thrombosis, cellulitis and lymphoedema.1 Upper extremity deep vein thrombosis (UEDVT) is less common than lower extremity deep vein thrombosis; however, its incidence is on the rise.1 2 Idiopathic or primary UEDVT can be due to anatomical variants, whereas secondary UEDVT is associated with malignancy, intravenous catheters and pacemaker cables.2 3 Furthermore, they can also be effort-induced (Paget-Schroetter syndrome). After foreign bodies in the vascular system, the second independent risk factor for UEDVT is underlying malignant disease, with up to 49% of patients with UEDVT having an underlying tumour.2–5 In view of the possibility of UEDVT progressing to life-threatening pulmonary embolism (PE), it is a serious diagnosis to consider. If present, it is also essential to identify possible underlying malignancy or thrombophilia. While we expected our patient to have an UEDVT, we were surprised to find he had isolated rhabdomyolysis of the long head of triceps. Rhabdomyolysis is a clinical syndrome characterised by the breakdown of skeletal muscle, with subsequent release of intracellular contents such as myoglobin and creatine kinase (CK) into the circulation.6 Undiagnosed and unmanaged, it can result in acute compartment syndrome requiring fasciotomies, acute renal failure, cardiac arrhythmia and death.7–11 The most common causes of single episode of rhabdomyolysis are drugs, unaccustomed exercise and immobility.9 In various centres around the globe, presentations of exercise-induced rhabdomyolysis have been increasingly reported.7 10 12–15 Interestingly, while our patient’s only identifiable risk factor was exercise, he had no interval symptoms between last exercise session and symptom onset. We present the interesting case of a patient who presented with acute upper limb swelling presumed to be an unprovoked UEDVT, but interestingly, through careful review of imaging and additional biochemistry, was found to be isolated long head of triceps rhabdomyolysis.
Case presentation
Our patient is an otherwise well man in his late 20s who presented to the emergency department with an acutely swollen right upper extremity. This was atraumatic and noted by the patient to have started developing within the 1.5-hour period of driving one evening from his workplace to his home. There was no history of trauma, fevers, prolonged immobilisation, drug use, thrombophilias, rheumatological, autoimmune or other systemic illness or malignancy. Similarly, he denied any history of scratches, insect bites or new or pre-existing regular medications. He denied smoking and significant alcohol intake. His social and work routine had not changed in the immediate preceding days. He would regularly attend the gym but denied overexertion there. He reported having engaged in a callisthenics body weight class 7 days prior to presentation during which time he stated undertaking a single triceps exercise however with equal weight distributed bilaterally and no interval symptoms between this and his presentation. Given the rapidity of symptom onset and development, he self-presented to the emergency department and was assessed for a provisional clinical diagnosis of UEDVT.
On examination, he had a swollen right upper limb, with swelling throughout the whole arm, extending into the forearm progressively on serial examination, with pitting oedema (figure 1A and B). There was no appreciable cellulitis, crepitus or focal tenderness in the limb. There was no obvious neurovascular compromise, with intact pulses throughout the limb.
Dorsal (A) and ventral (B) aspects of patient’s distal arms and forearms. Pitting oedema throughout the right upper limb indicated by red arrows and compared with normal tissue (by blue arrows) in the contralateral upper limb.
Investigations
Full blood count, urea and electrolytes and C reactive protein were all within normal limits (tables 1 and 2). Our patient presented to the emergency department outside of business hours and as such, ultrasound services were not initially available. Given the concern for UEDVT and extension into the subclavian vein, a CT venogram of the affected limb was obtained (figure 2). No evidence of right UEDVT was reported or focal vascular abnormality, however a moderate amount of subcutaneous oedema, particularly along the dorsal surface of the elbow and right forearm was noted, but without subcutaneous gas. A venous doppler the next day also affirmed extensive subcutaneous oedema throughout the arm, without venous occlusion or abnormality. On subsequent review of the CT venogram by the treating vascular surgeon together with consultant radiologist, uniform hyperdensity of the long head of triceps was noted, with no apparent rupture. Subsequent MRI of the right arm and shoulder further demonstrated extensive intramuscular oedema involving the entire long head of the right triceps, with no intramuscular abscesses, collections or focal muscle tear, confirming the diagnosis of rhabdomyolysis (figure 3A,B). CK added onto the initial bloods was measured at 11 587 U/L.
Full blood count and C reactive protein (CRP) results on initial presentation and 48 hours postdischarge
| Parameter | Value | |
| Initial presentation | 48 hours postdischarge | |
| Haemoglobin | 151 g/L | 141 g/L |
| White cell count | 7.7×109/L | 4.6×109/L |
| Platelets | 289×109/L | 254×109/L |
| CRP | 1 | <1 |
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CRP, C reactive protein.
Urea and electrolytes results on initial presentation and 48 hours post-discharge
| Parameter | Value (mmol/L) | |
| Initial presentation | 48 hours post-discharge | |
| Sodium | 140 | 141 |
| Potassium | 3.8 | 4.3 |
| Chloride | 98 | 103 |
| Bicarbonate | 28 | 25 |
| Urea | 3.3 | 3.6 |
| Creatinine | 76 | 70 |
| eGFR | >90 | >90 |
CT venogram of distal right arm (axial view) demonstrating extensive subcutaneous oedema and long-head of triceps hyperdensity but patent veins.
MRI of the right arm—coronal (A) and axial (B) views. Hyperintense signal on T1 weighted images throughout all of long-head of triceps indicating muscle inflammation, with overlying subcutaneous oedema.
Differential diagnosis
Our main differential diagnosis in this patient was UEDVT or early infective process, despite the absence of overt cellulitis and erythema or history suggestive of this. Our reasoning for this was the absence of trauma or history suggestive of rheumatological conditions. Once the investigations were negative for the aforementioneddiagnosis, serial multidisciplinary review of the CT venogram by a consultant vascular surgeon and radiologist, resulted in the difference in intensity of the long head of triceps being noted. Given this finding, the decision to retrospectively add CK to the presentation bloods was made, furthermore supporting the diagnosis. Subsequent MRI confirmed the diagnosis of rhabdomyolysis and also reassured us of no focal muscular tear or rupture.
Treatment
As our patient was otherwise healthy with no comorbidities or concomitant risk factors for renal failure, we decided to treat our patient as an outpatient. We took a ‘RICE’ approach (rest, ice, compression, elevation), and applied compression to the whole length of the affected limb with double-layer tubigrip, and educated the patient on keeping it elevated and abstaining from any heavy lifting. Given the risk of acute kidney injury (AKI), we educated our patient on judicious oral hydration, supplemented with baking soda at home for urinary alkalinisation. For the first 32 hours after discharge, he consumed 1600 mL bottle of water every 2 hours while awake (from 08:00 to 22:00) and a further three glasses of 500 mL water with one tablespoon of baking soda dissolved in each, to alkalinise his urine.
Outcome and follow-up
Our patient abstained from work for 4 days, intermittently icing the limb during this time. He underwent repeat blood tests 48 hours postdischarge (tables 1 and 2). His CK decreased from 11 587 U/L to 2353 U/L, with unchanged renal function. At 8 weeks postpresentation, all swelling had resolved within the limb. He lost no function within the triceps muscle and began applying weight associated with activities of daily living through it from approximately 3–4 weeks after presentation. Furthermore, his renal function remained normal 6 weeks postpresentation. Following his initial presentation, the patient remained well and was able to re-engage with exercise and normal activities of daily living without recurrence or limitation. At approximately 23 months following his initial presentation and rhabdomyolysis, the patient again reported having remained well. He had not acquired new comorbidities. Importantly, he did not describe persistent symptoms of recurrent muscle fatigue or swelling suggestive of an undiagnosed familial metabolic defect or myopathy. Repeat MRI of the right arm and shoulder at 23 months demonstrated normal (long head of) triceps, with no residual inflammation, or development of fibrosis or necrosis (figure 4).
MRI of the right arm 23 months following initial presentation—coronal (A) and axial (B) views. No residual inflammation was present throughout long-head of triceps, or development of muscle fibrosis or necrosis.
Discussion
Rhabdomyolysis is a clinical syndrome characterised by the breakdown of skeletal muscle, with subsequent release of intracellular contents such as myoglobin and creatine kinase into the circulation.6 Undiagnosed, the complications range from AKI to compartment syndrome and death.8–11 The most common causes of single episodes of rhabdomyolysis are drugs, unaccustomed exercise and immobility.9 Other aetiologies include muscle enzyme deficiencies, electrolyte abnormalities, infections, alcohol consumption, toxins and endocrinopathies.8 Regardless of the aetiology, muscle damage disturbs sarcolemma integrity, resulting in increased intracellular calcium, protease activation and muscle necrosis, with resultant release of toxic intracellular components.10 11 In various centres around the globe presentations of exercise-induced rhabdomyolysis have been increasingly reported.7 10 12–16 When exercise-induced, typically patients will present with myalgia, weakness in affected muscles and myoglobulinuria.13 Interestingly, despite this, a Norwegian study noted no significant correlation between the degree of self-reported muscle pain and CK increase.16 Certainly, our patient’s primary complaint was not pain but acute limb oedema, hence no initial consideration of rhabdomyolysis as a differential diagnosis.
It is typically diagnosed on clinical basis, together with a CK level of five times the upper reference limit.6 7 Due to the risk of renal failure, it often requires a period of intravenous hydration and monitoring for complications. Aggressive intravenous fluid resuscitation aims to maintain or enhance renal perfusion, increase urine flow rate and minimise intratubular cast formation.17 While there is no clear direct cut-off, a CK level of greater than 5000 U/L is generally indicative of serious muscle injury, with levels>15 000 U/L often predictive of renal impairment.18–21 The mainstay of prevention of AKI secondary to rhabdomyolysis involves treating the precipitating aetiology and maintaining high urine output, with concurrent alkalinisation of urine to prevent precipitation of casts in the renal tubules.18 Various protocols exist for initial fluid resuscitation and urine output, with some sources suggesting an initial fluid resuscitation with isotonic saline at a rate of 1–2 L/hour until plasma CK is stable or decreasing.17 18 Furthermore, patients with a serum CK above 5000 U/L or evidence of severe muscle injury are reported to benefit from bicarbonate infusions.17 18
While our patient certainly met biochemical criteria for consideration of admission for intravenous hydration, given his lack of comorbidities and willingness to maintain oral hydration himself, we chose to manage him as an outpatient. A recent Brisbane-based study of emergency department presentations of exertional rhabdomyolysis showed that approximately 47.2% of patients were admitted either to an inpatient unit or short stay unit for intravenous hydration and monitoring of renal function, with an average length of stay of 2.51 days.13 They did not determine or suggest features at presentation that were predictive for development of renal impairment. Previous retrospective studies and reviews have indicated that between 16.5% and 33% of patients with rhabdomyolysis progress to develop renal impairment.22 23 Another notable contrast between our patient and the results described elsewhere is that the majority of patients with exertional rhabdomyolysis tend to present on the same day as the precipitating event. Only 9.6% of patients present 7 days later, as did our patient, if indeed our patient’s rhabdomyolysis was due to overexertion, as we propose it to be.
As previously mentioned, multiple centres have reported increases in presentations of patients with diffuse exertional rhabdomyolysis, with the majority of the precipitating activities involving cross-fit, spinning and excessive weight-lifting.13 16 Swimming has also been reported to have resulted in extensive exertional rhabdomyolysis in a young Asian man.8 24 Interestingly, rhabdomyolysis localised to one muscle is rare, with only one other case of isolated unilateral long head of triceps rhabdomyolysis reported previously in Baltimore, USA in 1994 and a bilateral case in France in 2001.25 26 To our knowledge, no other cases of isolated unilateral long head of triceps rhabdomyolysis have been reported previously in Australia.
We present this case as to our knowledge, a similar case has not previously been reported in Australia. It is an important lesson for treating clinicians to always review imaging themselves and also consider rhabdomyolysis as a differential whenever seeing an acutely swollen limb even in the absence of an obvious precipitating event.
Learning points
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Rhabdomyolysis should always be considered as a differential diagnosis in a patient presenting with acute limb oedema.
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In an appropriately selected and compliant patient, rhabdomyolysis can be successfully managed in an outpatient setting with appropriate close follow-up for complications - we have demonstrated one home-based oral hydration regimen.
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This case report highlights the importance for treating clinicians to take a multidisciplinary approach when a diagnosis is not immediately clear and to frequently include radiologist consultation in this process.
Ethics statements
Patient consent for publication
Acknowledgments
The authors would like to acknowledge Associate Professor Marinis Pirpiris for his guidance and clinical acumen.
Footnotes
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Contributors BF drafted the work and figures, as well as collated investigations and SB reviewed and drafted the work, oversaw clinical management and gave approval for the final piece.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.
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Competing interests None declared.
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Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.
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