Musculoskeletal systemCase Type
Fernando González Tello, Almudena Gil Boronat, Noelia Arévalo Galeano, Carmen Soteras Roura, Jose Acosta Batlle, Javier Blázquez SánchezPatient
23 years, male
A 23-year-old man was taken to the emergency department for attempted suicide (intake of several tablets of quetiapine). At the emergency room, CPK and creatinine levels were 6152 U/L and 1.5 mg/dl respectively. One day later, the patient began with local pain and swelling, weakness and sensory changes in his right forearm.
Due to clinical worsening, four days later an ultrasound was requested, showing an increase in volume and diffuse alteration of the echogenicity of the right forearm, with loss of its normal fibrillar echostructure (fig.1). Soft tissue collections were not defined. The main venous and arterial flows were preserved (fig.2).
The study was completed the same day with an MRI, which confirmed a diffuse involvement of the forearm muscles. This involvement was globally isointense on T1 with a mild and heterogeneous signal hyperintensity in the posterior compartment muscle groups and hyperintense on fluid-sensitive sequences.
It showed a well-defined proximal margin and two patterns of alteration:
• At the proximal level, there was greater signal heterogeneity in long TR sequences and a peripheral enhancement in the post-contrast study, with a central hypocaptant region (fig.4).
• Distally, the signal was more homogeneous and the enhancement diffuse (fig.3).
The set of findings suggested a pattern of rhabdomyolysis, with the more proximal portion showing a more established myonecrosis (fig.5).
Rhabdomyolysis is the clinical situation in which rapid breakdown of skeletal muscle fibres is produced. As a result, there is a leakage of intracellular contents like electrolytes, myoglobin and other sarcoplasmic proteins into the systemic circulation . It is caused by various factors including traumatic, infectious, immunological, electrolyte abnormalities, metabolic diseases, ischemia and immobilization. Multiple cases of rhabdomyolysis due to psychiatric drugs have also been reported, among them the overdose of quetiapine [2, 3, 4]. The CPK concentration is the best indicator of rhabdomyolysis due to serum levels increase proportionally to muscle damage extension. A concentration higher than 5 times the upper limit is diagnostic .
Despite the presence of rhabdomyolysis is clinically evident in most cases, it is not clinically diagnosed in 27% of patients. In these cases, MRI can be useful to evaluate the distribution and extension of the affected muscles, the differentiation from other musculoskeletal diseases and prevent serious complications such as peripheral neuropathy .
Two types of MRI findings have been described [7, 8]:
Type 1: It is the representation of oedema of the affected muscles in the initial stage of rhabdomyolysis and is non-specific (myositis).
Type 2: It represents myonecrosis, and is the most specific of rhabdomyolysis.
In both types, the high signal intensities on T1-weighted images may represent the presence of methemoglobin after intramuscular haemorrhage.
Paramagnetic contrast can be used to assess possible collections, in addition to assessing the viability of the muscle tissue and predicting the degree of muscle destruction. Recently, several studies reported that diffusion-weighted imaging and diffusion tensor imaging can help in the detection of muscle ischemia and differentiation between healthy and injured nerves [9, 10]
The treatments are focused on the aetiology of the rhabdomyolysis and on controlling the possible complications such as myoglobinuric acute renal failure and peripheral neuropathy. Our patient received conservative treatment with intense replacement of volume and control of electrolytes imbalance. On the 10th day of admission, an electromyogram was performed that showed signs of sensory-motor axonal neuropathy of the right median, ulnar and radial nerves. Two weeks after admission, the patient was discharged with minimal residual sensory-motor impairment of the right forearm.
Finally, it is interesting to know that MRI does not play a clear role in patient follow-up (no follow-up imaging test was performed on our patient), except for assessing the degree of muscle atrophy and fat infiltration.
 Cheng YC, Lan HHC, Shih CH, et al (2013). Magnetic resonance imaging of rhabdomyolysis: muscle necrosis versus ischemia. Journal of Radiological Science, 38(4), 143-148.
 Smith, RP, Puckett BN, Crawford J, et al (2004). Quetiapine overdose and severe rhabdomyolysis. Journal of clinical psychopharmacology, 24(3), 343. (PMID: 15118490)
 Quetiapine Technical Data Sheet. Available in: https://cima.aemps.es/cima/pdfs/es/ft/75501/FT_75501.pdf (consulted September 2020).
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 Jun HK, Yeo JK, Sung HK, et al (2018). Rhabdomyolysis revisited: Detailed analysis of magnetic resonance imaging findings and their correlation with peripheral neuropathy. Medicine; 97(33): e11848 (PMID: 30113478)
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 Zhang H, Wang X, Guan M, et al (2013). Skeletal muscle evaluation by MRI in a rabbit model of acute ischaemia. Br J Radiol;86(1026):20120042 (PMID: 23658466).
 Razek AAKA, Shabana AAE, El Saied TO, et al (2017). Diffusion tensor imaging of mild-moderate carpal tunnel syndrome: correlation with nerve conduction study and clinical tests. Clin Rheumatol; 36(10):2319–24 (PMID: 27812818).
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