ACUTE DYSTONIA AFTER INITIATION OF DULOXETINE FOR CHRONIC PAIN: A CASE REPORT

Mahmoud Morsi, MD. (Taruna Penmetcha, MD). Willaim Sierraalta, MD. Maria Torres, MD. Syed Rahman, MD.

John H Stroger Hospital of Cook County. Chicago, IL.

 Introduction: Duloxetine is a serotonin-norepinephrine reuptake inhibitor (SNRI) that is used to manage anxiety and depression. It is also approved for management of chronic musculoskeletal pain, fibromyalgia, and neuropathic pain. In general, it is considered safe and is well-tolerated. Common adverse side effects are minor and affect mainly gastrointestinal and the nervous systems, consistent with pharmacology of the molecule. However, extrapyramidal symptoms like acute dystonia are an uncommon but serious side effect. This may raise questions regarding the safe use of this drug in an outpatient setting. The following is a case of acute dystonia after only two doses of 30 mg duloxetine.

 

Case Presentation: 55-year-old, male patient with back pain due to facet arthropathy and history of anxiety presents with a new complaint of jaw-clenching  during a follow-up appointment. The patient stated that the complaint started on the second day after taking duloxetine 30 mg, which he had been prescribed two weeks prior. The clenching appeared immediately after taking it and had been constant. He mentioned that although it was very uncomfortable it was not severe enough to cause dysphagia, shortness of breath, distress, or severe difficulties with his regular activities. It was accompanied by somnolence and drowsiness. He was not taking any other antipsychotics or antidepressants during that time. He was instructed to stop the medication immediately. The symptoms progressively subsided within the following two weeks after discontinuation of duloxetine. During follow-up appointment two months after the episode the patient referred no recurrence of symptoms. 

 Materials and Methods: As the case reports are devoid of patient-identifiable information, it is exempt from IRB review requirements as per Cook County Health Services policy.

Discussion: Acute dystonias such as bruxism after initiation of serotonin-norepinephrine reuptake inhibitors are uncommon but can occur even with a few doses. Duloxetine is often used in a chronic pain setting for management of chronic musculoskeletal and neuropathic pain. Our patient’s complaints, history of exposure to duloxetine and recovery after discontinuation are highly suggestive of medication-induced dystonic reaction. Failure to improve, however, should prompt the consideration of alternative diagnosis. The pathophysiology of this condition is unclear, and it has been hypothesized that dopaminergic and serotonergic systems disturbances are related to its development. Anticholinergic drugs have been used to manage acute dystonia secondary to antidepressant medications. It is unclear if a lower dose of duloxetine may impact incidence of dystonia, and this could be researched in future studies. Pain physicians should be aware of this adverse effect and its management given the increasing use of duloxetine to manage chronic pain conditions.

 

References: 

1. Kantor, E.et al. (2015) JAMA 314:1818–31. 

2. Görkem, K.et al. (2013) Psychiatry Investig. 10(1): 95–97.