Muscular fibrosis due to chronic intramuscular administration of narcotic analgesics

Radiographic Musculoskeletal Findings Indicating Opioid Misuse: An Overview for Orthopedic Surgeons

BACKGROUND

Given the high prevalence of musculoskeletal conditions in the USA, it is important for orthopedic surgeons to promptly identify patients who may be at risk for opioid misuse.

QUESTIONS/PURPOSES

The aim of this literature review was to elucidate various musculoskeletal pathologies and complications, as seen on imaging, that may indicate opioid misuse or opioid use disorder.

METHODS

A literature search was conducted using the PubMed, Scopus, and Cochrane Library databases for articles related to imaging findings associated with chronic opioid use or misuse in orthopedic patients. Two independent reviewers conducted the search utilizing pertinent Boolean operations.

RESULTS

We reviewed 36 full-text articles and categorized the radiographic evidence of opioid misuse as follows: soft-tissue radiologic findings, cellulitis, necrotizing fasciitis, abscess formation, retained needles, discitis, myopathy and rhabdomyolysis, osteomyelitis, septic arthritis, and septic thrombophlebitis.

CONCLUSION

Knowledge of the radiologic findings of opioid misuse will assist orthopedic surgeons in making timely diagnoses that may alter therapeutic regimens for their patients.

Fibrous myopathy as a complication of repeated intramuscular injections for chronic headache

Two cases of fibrous myopathy associated with repeated, long-term intramuscular injections for treatment of chronic temporomandibular joint pain and chronic headache, respectively, are described. Both patients developed severe, function-limiting contractures in upper and lower extremity muscles used as injection sites. In one of the cases, the contractures were painful. Electrophysiological testing, magnetic resonance imaging and muscle biopsy results were all consistent with myopathy and replacement of skeletal muscle with noncontractile fibrous tissue. These cases are presented to increase awareness of fibrous myopathy and to promote surveillance for this serious potential complication of long-term intramuscular injections in chronic headache and other pain patients.

Radial entrapment neuropathy due to chronic injection-induced triceps fibrosis

We report two patients who developed progressive, severe, painless radial neuropathies (bilateral in one, unilateral in the other) as a delayed complication of chronic intramuscular analgesic injection. In each instance, exploration of the radial nerve revealed multifocal entrapment within a densely fibrotic triceps muscle at sites between the spiral groove and distal course of the radial nerve near the elbow. Release of the nerve from constriction within the fibrotic triceps muscle produced improvement in all three affected nerves.

Focal myopathy induced by chronic heroin injection is reversible

We report a patient who developed a focal myopathy with prominent contractures of his thigh muscles induced by chronic heroin injection. Muscle biopsy and magnetic resonance imaging (MRI) were indicative of a fibrotic and inflammatory process. Treatment with steroids, D-penicillamine, and physical therapy led to full functional recovery within 6 months. Sequential electromyographic (EMG) studies and muscle biopsies showed evidence of regenerating muscle fibers and absence of inflammatory cells. We conclude that heroin-induced focal myopathy is reversible and that combination therapy with D-penicillamine and steroids may be useful.

Focal myopathy associated with chronic intramuscular injection of piritramide

We report a patient in whom chronic intramuscular piritramide led to a focal fibrotic myopathy. Since piritramide myotoxicity has never been reported, we have studied its effect on rat skeletal muscle. Chronic intramuscular piritramide led to fibrous connective tissue replacement of rat skeletal muscle, similar to that found in the patient's muscle. Although the pathogenetic mechanism of piritramide myopathy is unclear, we caution against prolonged intramuscular use of piritramide to prevent this potentially debilitating adverse effect.

Focal myopathy induced by chronic intramuscular heroin injection

A patient developed focal fibrotic myopathy after many years of intramuscular heroin use. While such changes have been associated with chronic intramuscular injections of pentazocine and meperidine, a similar myopathy resulting from chronic intramuscular heroin has not been convincingly described.

Drug-induced myopathies

Myopathies are not an unusual complication of drug therapy. The major symptoms in drug-induced myopathies are proximal muscle weakness, increased muscle enzyme levels, electromyographic changes and histological lesions. Some drug-induced myopathies are associated with neuropathy. Drug-induced myopathies can be classified according to the presence or absence of muscular pain and associated neuropathy. Among painless myopathies, we can distinguish myopathies without neuropathy (corticosteroids), myopathies with neuropathy (colchicine, chloroquine and hydroxychloroquine) and myasthenic syndromes (D-penicillamine, antibiotics, beta-blockers). Among painful myopathies, the classification is similar: painful myopathies may or may not be associated with neuropathies. Painful myopathies include polymyositis (D-penicillamine, cimetidine, zidovudine) and other myopathies without polymyositis (clofibrate, statines, cyclosporin). Among the painful neuromyopathies, eosinophilia-myalgia syndrome is a recently described disorder associated with the use of L-tryptophan. Combinations of drugs (for example, a fibrate and a statine or cyclosporin and colchicine) can induce severe myopathies. If such drugs are used together a vigorous surveillance to detect any sign of myopathy is warranted. Instead of classifying drug-induced myopathies according to clinical features, a histological classification can be proposed. Many drugs can induce vacuolar myopathy (colchicine, chloroquine, amiodarone, cyclosporin, drugs causing hypokalaemia and lipid-lowering agents), some others cause a mitochondrial myopathy (zidovudine) or a necrotizing myopathy as seen with vincristine. Overall, several criteria for reporting drug-induced myopathy can be recommended: lack of pre-existent muscular symptoms, a free period between the beginning of the treatment and the appearance of symptoms, lack of another cause accounting for the myopathy, and complete or incomplete resolution after withdrawal of the treatment. Rechallenge of the treatment is not advisable because of the risk of a serious relapse. The exact mechanisms by which drugs cause myopathies are unknown. Some cases may be due to metabolic changes, whereas others may be immune mediated. Nevertheless, the aspect these conditions have in common is the regression of the myopathy with the discontinuation of the drug.