Restless legs syndrome (RLS) causes an uncomfortable urge, which is associated with unpleasant sensations and the urge to move the legs. The cause of RLS is not fully understood, but evidence suggests that it involves dopaminergic and alterations of brain iron metabolism.1 Previous reports have revealed that anesthesia induces or worsens RLS.2,3 To the best of our knowledge, postoperative akinesia after anesthesia in RLS is rare. Herein, we report a case of RLS with four-limb weakness after monitored anesthesia.
A 36-year-old woman with a body mass index of 20 was previously diagnosed with RLS in her late twenties. She had the urge to move her legs while sitting or resting for an extended time. Symptoms, such as throbbing and pulling, were noted by her family when she remained still, and they worsened in the evening but appeared less common when she was walking. After reasonable dopamine D2/D3 receptor agonist therapy at a daily and basic dose of 0.375 mg pramipexole, the symptoms were hardly noted before anesthesia. She had no previous history of anesthesia and was scheduled for hysteroscopic polypectomy.
She was administered fentanyl 50 µg and propofol 50 mg, followed by continuous infusion with 560 mg total propofol for 60 minutes. However, it took one hour for the patient to regain consciousness, and limb weakness (muscle power: 0) without respiratory distress was noted. She was clear and able to talk, and the train of four revealed 4/4. Owing to the low availability of electromyography (EMG) tests in the postoperative care unit, we did not arrange the EMG test.
Although propofol caused less muscle hypotonicity than inhaled anesthetics, the possibility of residual propofol’s effect on fatigue could not be ruled out. Since prolonged postoperative akinesia was noted, and RLS has been mentioned to be related to other neurological diseases, the neostigmine test was administered to observe whether it would help in solving muscle weakness.
Therefore, 2 hours after surgery, neostigmine 1.0 mg was prescribed because of persistent symptoms. Fifteen minutes after neostigmine treatment, the patient was able to move horizontally (muscle power: 2). One milligram of neostigmine was administered again, and the patient completely recovered 15 minutes later. The duration of stay in the post-anesthetic care unit amounted to 3.5 hours, and she was discharged without any sequelae.
There are many exacerbating factors, such as temporary cessation of symptomatic treatment, the use of certain medications (dopamine receptor antagonists, neuroleptics, selective serotonin reuptake inhibitors, tricyclic antidepressants and antihistamines, caffeine, alcohol, or nicotine), prolonged immobilization, and the possibility of anesthetic effect.2,3 Moreover, the symptoms for diagnosis of RLS may also result from other medical or behavioral conditions. Transient postoperative akinesia after anesthesia is rare, and the patient’s sister was diagnosed with multiple sclerosis. Therefore, undiagnosed medical diseases, such as multiple sclerosis or mitochondrial myopathy, must be considered in our patients.
While volatile anesthetics may prolong muscle hypotonicity, propofol can prevent postoperative hypotonia and provide a safe anesthetic condition for patients with stiff-person syndrome (muscle rigidity and painful spasms in the axial and limb muscles).4 In addition, this patient did not receive muscle relaxants, so muscle relaxant-related muscle hypotonia was excluded.
Neostigmine is used to improve muscle tone in patients with myasthenia gravis and to reverse the effects of non-depolarizing muscle relaxants. Consequently, we prescribed a neostigmine test, and the result was positive. However, the limitation of the absence of EMG data determined before neostigmine administration results in the dilemma to rule out neuromuscular diseases in this patient.
This report highlights that transient postoperative akinesia might occur in RLS patients under propofol sedation, and a positive neostigmine test result was observed.
Drs. YTC and TSW wrote the article. Drs. WJC and ZFW prepared the manuscript.
Conflict of Interest
Restless legs syndrome.
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Transient restless legs syndrome after spinal anesthesia: a prospective study.
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