Lateral Pterygoid Muscle Rhabdomyolysis

Abstract

SUMMARY:We report a case of rhabdomyolysis due to acetaminophen overdose involving the lateral pterygoid muscles bilaterally, in addition to the other muscles of the abdomen and pelvis. To the best of our knowledge, involvement of the head and neck muscles by rhabdomyolysis has not been reported previously. The isolated involvement of the lateral pterygoid muscles may be due to the presence of the surrounding pterygoid venous plexus. It is important to be aware of the imaging characteristics of rhabdomyolysis and to consider the possibility of involvement of head and neck muscles to aid in early diagnosis and avoid misinterpretation of the imaging findings. Rhabdomyolysis is defined as disintegration of skeletal muscles that causes myoglobinuria, raised creatine kinase (CK), and renal failure in severe cases.1 CT scans initially show rhabdomyolysis as areas of low attenuation within affected muscles, which may become hyperattenuated in later stages and ultimately normalize, with or without subsequent atrophy.2,3 MR imaging shows hyperintensity on T2-weighted images with avid contrast enhancement on postgadolinium T1-weighted images and may demonstrate T1 hyperintensity later in the course of the disease in some patients. 4 An extensive search of the literature revealed the findings of rhabdomyolysis described in relation to the pelvic and lower extremity muscles but, to the best of our knowledge, this is the first reported case of rhabdomyolysis affecting the head and neck muscles. The lateral pterygoid muscles were selectively involved among the muscles of mastication. We propose that the intimate association of the lateral pterygoid muscles to the pterygoid venous plexus may be the cause of isolated involvement of these muscles. Case ReportA 28-year-old man with long-standing psychiatric problems and suicidal ideation presented to the emergency department after a suicide attempt by ingestion of a large dose of acetaminophen. Initial clinical and laboratory examination were significant for fulminant hepatic failure, acute renal failure, hypotension, respiratory distress, raised CK, metabolic acidosis, hyperkalemia, hypocalcemia, and coagulopathy. His acetaminophen level on admission was 303 g/mL (critical value, Ͼ40 g/mL). The CK increased from 20 -306 U/L (reference, 40 -200 U/L) on hospital day 1 to 245-595 U/L on day 2. The renal failure was managed by hemodialysis, and liver transplant was performed on hospital day 3.A noncontrast CT scan of the brain was performed on hospital day 2 to rule out cerebral edema. The brain was normal but, in retrospect, the study showed lateral pterygoid muscle hypoattenuation bilaterally (Fig 1A). An MR examination of brain was performed on hospital day 16 for suspected stroke. The study was negative for stroke but showed T2 prolongation and homogenous contrast enhancement in the lateral pterygoid muscles bilaterally (Fig 1B-D). Another MR to rule out stroke on day 26 revealed similar findings, though the lateral pterygoid muscles, which were previously isointense, now demons...

Rhabdomyolysis of the head and neck: computed tomography and magnetic resonance imaging findings

“…3 More recently, Jain et al reported low density of the lateral pterygoid muscles on CT with subsequent hyperintensity and contrast enhancement on MRI done several days later in a 28-year-old with psychiatric problems who was admitted to the hospital for an acetaminophen overdose. 4 CT and MRI findings of rhabdomyolysis in the extremities have also been reported, 9,10 and two types of rhabdomyolysis have been described. 9 Type I rhabdomyolysis presents with oedema and the affected muscles reveal homogeneous isointensity to hypointensity on T 1 -weighted images, homogeneous hyperintensity on T 2 -weighted and STIR images and homogeneous enhancement.…”

“…8 To our knowledge, three cases of rhabdomyolysis in the head and neck have been reported. [2][3][4] Riggs et al reported swelling and a low density area in the left neck muscles on CT and hyperintensity of the muscles and adjacent soft tissues on MRI in a 22-year-old man with heroin and chronic ethanol use. 2 Shah et al reported sonographic findings of rhabdomyolysis of the masseter muscle in a 33-year-old man with ingestion of an unknown quantity of alcohol and drugs.…”

“…There has been description of rhabdomyolysis in the head and neck owing to drug toxicity described in the literature. [2][3][4] We describe a case of rhabdomyolysis of the head and neck, including clinical presentation, and CT and MRI characteristics.…”

Case 251: Nontraumatic Drug-associated Rhabdomyolysis of Head and Neck Muscles

“…In the craniofacial region, isolated rhabdomyolysis of the lateral pterygoid (8), masseter (9), and sternomastoid (10) muscles associated with acute cocaine intoxication have been described, with initial muscle hypoattenuation on unenhanced CT images, normal or decreased signal intensity on T1-weighted images, and increased signal intensity on T2-weighted images (8)(9)(10). Secondary hyperintensity on T1-weighted images has been reported and attributed to delayed calcium deposition in the affected muscles (8). Here, the right and left longus colli and longus capitis muscles had normal signal intensity on T1-weighted images, while the other neck muscles showed decreased signal intensity.…”

Computed tomography and magnetic resonance imaging of lesions at masticator space

“…CT scans initially show areas of low attenuation within affected muscles, which may become hyperattenuated in later stages, with or without subsequent atrophy. MR imaging shows hyperintensity on T2-weighted images with avid contrast enhancement and may demonstrate T1 hyperintensity later in the course of the disease in some patients [38].…”