key: cord-0897893-m9i7t9xl
authors: Ito, Hisashi; Kuroki, Takahiro; Horiuchi, Shigeto; Shinya, Yuichi
title: A case of restless legs syndrome after BNT162b2 mRNA COVID‐19 vaccination
date: 2022-03-26
journal: Neurol Clin Neurosci
DOI: 10.1111/ncn3.12594
sha: 55d8f68e53e53c759c63b394c01e4aaaa0c3aab6
doc_id: 897893
cord_uid: m9i7t9xl

Restless legs syndrome (RLS) can be secondary to several disorders. We present an 87‐year‐old woman who developed RLS 2 days after the first injection of BNT162b2 mRNA coronavirus disease 2019 vaccine. The symptoms of RLS tended to improve and eventually resolved with the administration of gabapentin.

Typical adverse events due to BNT162b2 mRNA COVID-19 vaccine are local injection-site reactions, fatigue, headache, myalgia, and chills. [1] [2] [3] We report a patient with restless legs syndrome (RLS) after BNT162b2 mRNA COVID-19 vaccination.

An 87-year-old Japanese woman was injected 30 μg of BNT162b2 mRNA COVID-19 vaccine intramuscularly for the first time in June 2021. The only adverse event immediately after the vaccination was focal pain at the injection site; however, she developed a tingling and burning sensation in her legs and an uncontrollable urge to move them 2 days after the vaccination. The sensory symptoms started when she was at rest, especially at bedtime, and were relieved by walking. She felt difficulty falling asleep. Her symptoms tended to improve spontaneously 10 days after the vaccination but did not disappear. She consulted our hospital 26 days after the vaccination.

She had a medical history of dyslipidemia, treated with 5 mg of atorvastatin, and pulmonary segmentectomy due to lung cancer 9 years ago. She had neither past nor family history of RLS.

On examination, she presented with mild hypopallesthesia in the legs; however, we observed neither cranial nerve abnormalities, pyramidal tract signs, ataxia, nor parkinsonism. The total score of the international RLS study group (IRLSSG) rating scale for the severity of RLS (Table 1) We administered 0.125 mg of pramipexole (PPX) at bedtime based on the diagnosis of RLS 5 ; however, it showed no efficacy. According to her wishes, we switched from PPX to gabapentin (GBP). The symptoms disappeared with 200 mg of GBP at bedtime (total score of IRLS: 0). Thereafter, we reduced and eventually discontinued GBP, which did not induce the recurrence of RLS (Figure 1 ).

Restless legs syndrome is categorized into primary (idiopathic) and secondary (symptomatic). The latter is associated with several conditions, such as iron-deficiency anemia, chronic renal failure, diabetes mellitus, pregnancy, polyneuropathy, and Parkinson's disease.

While the efficacy of the BNT162b2 mRNA COVID-19 vaccine is well-known, various neurological adverse events have been reported (Table 1 ). [1] [2] [3] The post-marketing surveillance of the BNT162b2 mRNA COVID-19 vaccine in Japan listed only one case of RLS. 6 To the best of our knowledge, this is the first detailed report of RLS occurring after vaccination of this novel vaccine. Since vaccineassociated RLS might have been overlooked in the past, we need to focus on it and investigate the frequency of its occurrence.

A limitation was that we could not clarify the pathogenesis of RLS in this patient. Nowadays, both dopaminergic system dysfunction and brain iron deficiency are recognized as main mechanisms in the development of RLS. In addition, the endogenous opioid system, glutamatergic system, and serotonergic system may also be involved in RLS pathophysiology. 7 Further investigations on the relationships between these conditions and this novel vaccine are necessary.

Moreover, there is one more possibility. RLS as the phenotype of somatic symptom disorder (SSD) was reported 8 

could induce SSD. 9 The possibility of RLS of SSD origin is not excluded since GBP is reported to ameliorate SSD. 10 However, it is important to exclude SSD in the diagnosis of RLS after vaccination.

The authors certify that appropriate patient consent for publication of this report was obtained. 

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