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Reversible spastic paraparesis induced by high-dose intravenous methadone
P L Manfredi1, G R Gonzales, R Payne
1Department of Neurosurgery, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA. manfredp@mskcc.org
The Journal of Pain
|November 19, 2003
Summary
High doses of opioids can cause neurological side effects. This study details a patient experiencing reversible leg spasticity from intravenous methadone, highlighting potential motor system impacts.
Area of Science:
- Neurology
- Pharmacology
- Toxicology
Background:
- Parenteral opioids, particularly at high doses, are known to cause neurological adverse effects.
- Reported side effects include multifocal myoclonus and seizures.
- Spasticity has been previously observed in patients receiving intraspinal opioids.
Purpose of the Study:
- To describe a case of spastic paraparesis in a patient receiving intravenous methadone.
- To discuss the clinical presentation of this opioid-induced side effect.
- To explore potential pathophysiologic mechanisms underlying opioid effects on the somatic motor system.
Main Methods:
- Case report of a patient receiving intravenous methadone infusion.
- Clinical observation of neurological symptoms, specifically spastic paraparesis and extensor spasms.
- Review of literature on opioid-induced neurological and motor system side effects.
Main Results:
- A patient developed reversible spastic paraparesis with significant extensor spasms in the legs.
- The symptoms occurred during a continuous infusion of intravenous methadone at a high dose (100 mg/hr).
- The neurological deficits resolved, indicating a reversible nature of the side effect.
Conclusions:
- Intravenous methadone, even without intraspinal administration, can induce significant motor system dysfunction.
- Spastic paraparesis and extensor spasms are potential, reversible side effects of high-dose parenteral opioid therapy.
- Further investigation into the mechanisms of opioid neurotoxicity on motor pathways is warranted.