We reported a case presenting with restless anal syndrome following affection of COVID-19 as restless legs syndrome variant. This case fulfilled 4 essential features of RLS, urge to move, worsening with rest, improvement with exercise, and worsening at evening. Because he had never experienced anal restless and discomfort before affecting COVID-19 and the anal restless symptom developed after COVID-19, we considered that these anal restless symptoms were suggested the COVID-19 related syndrome.
This virus may spread to the central nervous system through several potential routes, including hematogenous dissemination and the destruction of the olfactory bulb . Reported neuropsychiatric manifestations of COVID-19 have included delirium, confessional states, dysfunctional olfaction and taste sensation, acute psychosis, encephalitis, and acute cerebrovascular events during COVID-19 . Compared with these manifestations, peripheral neuropathies and Guillain-Barre Syndrome associated with COVID-19 have been rarely reported . However, the understanding of the neuropsychiatric sequelae associated with COVID-19 remains in the initial stages, and the potential mechanisms underlying these varied symptoms are not yet fully understood. Insomnia, depressed mood, post-traumatic stress disorder, and cognitive impairment have been reported in patients after discharge from the hospital . Previous reports have suggested that depressive symptoms are associated with systemic immune suppression, based on increased white blood cells and inflammatory factors . The onset of neuropsychiatric symptom are reported to occur in most hospitalization patients during the disease, while time lines of some disorders and cases including Guillain-Barre Syndrome has been broad with para-infections and post-infection after a few weeks from COVID onset [12, 14].
RLS arises from dysfunction of the central nervous system leading to both sensory and motor symptoms . According to the ethology study of RLS at pre COVID era, the prevalence ranges from1.0 to 4.0% in Japanese population [7, 8, 15, 16]. To the data, limited cases of COVID-19 related RLS were sporadically reported. Previous study [17, 18] reported a 36-year-old female case and a 48-year old female case of RLS during COVID-19. Although COVID related RLS itself remains rare, no case of restless anal syndrome associated with COVID-19 has been previously published.
This case fulfilled with the essential features of urge to move is essential, with worsening with rest, improvement with exercise, and worsening at evening among the specific criteria of RLS. These 4 features were essential diagnostic criteria for RLS  Additionally, another medical condition possibly caused by such as diabetes mellitus, iron deficiency anemia, renal dysfunction, spinal cord dysfunction, was not observed. Anorectal disorders such as anorectal tumor, fistula, or inflammation are conditions that require treatment and care, resulting in anxiety, depression or sleep problems . In this case, these structural and mechanical anorectal disorder was not also observed. Although functional anorectal pain is basically observed in the cases of levator ani syndrome or proctalgia fugax, the following 4 features was able to exclude functional anorectal pain.
Because the symptom localized in legs was not observed, this case was diagnosed as a variant of RLS. Reports of RLS variant has been increased and expand the clinical spectrum. Various other parts of the body than legs can be involved from arms, abdomens, face, head, oral cavity, bladder and genital area [9, 11, 20,21,22]. Supportively, this case did not report daytime sleepiness, which was also supporting feature of RLS . This case also had the tendency of the anxiety and impatient, but no history of panic attack. As SARS-Cov-2 can also cause digestive system disease such as diarrhea, nausea, or vomiting, medical imaging might manifest as thickening of the intestinal wall . In this case, the symptom was not localized in intestine, in addition to urge to move and relief by move, which characteristic was not compatible to intestinal symptoms. Also, medical imaging showed no abnormal finding in intestine.
Clonazepam treatment at 1.5 mg per day was selected in this case, which is a treatment option of restless legs syndrome recommended in guideline of Japanese society of neurological therapeutics. International restless legs syndrome study group mention that dopaminergic treatment generally shows clinical benefit for most RLS, and failure to respond to dopaminergic treatment raise some concern about diagnostic accuracy. However, they also states that the lack of dopaminergic treatment response does not preclude as the diagnosis .
This case report may reflect the associative impacts of COVID-19 on the neuropsychiatric state. On the other hand, the causative relation remains unclear because of a case report. Other study cautioned mimic RLS cases even if the symptoms fulfilled the diagnostic criteria [24, 25]. Because neuropsychiatric sequelae require longitudinal observation, the long-term outcomes of neuropsychiatric conditions should continue to be monitored. COVID-19 related RLS or RLS variant may be underdiagnosed and we should pay attention to similar cases in order to clarify of relation between COVID-19 and RLS.