A mysterious condition known as "restless anal syndrome" has been linked to COVID-19, according to new medical research published by Japanese experts.

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The term is similar to restless legs syndrome (RLS), and it accurately fits the symptoms of one 77-year-old male patient. According to the report published in BMC Infectious Diseases, RLS is a common neurological, sensorimotor disorder, but highly under-diagnosed disorder.

The symptom of RLS is an overwhelming urge to move your legs. It can also cause an unpleasant crawling or creeping sensation in the feet, calves and thighs. The sensation is often worse in the evening or at night. The report said that although a patient with COVID-19 improved to normal respiratory function 21 days after admission and treatment for days, insomnia and anxiety symptoms remained.

Several weeks after discharge, the patient gradually began to experience restless, deep anal discomfort, approximately 10 cm from the perineal region. Colonoscopy revealed internal haemorrhoids without other rectal lesions. Neurological findings including deep tendon reflex, perineum loss of sensory and spinal cord injury, revealed no abnormalities.

The authors, including Itaru Nakamura from Tokyo Medical University Hospital, mentioned that this case fulfilled 4 essential symptoms of RLS. To date, no case of a restless anal syndrome associated with COVID-19 has been previously published, the team said This case report may reflect the associative impacts of COVID-19 on the neuropsychiatric state. The long-term outcomes of neuropsychiatric conditions should continue to be monitored, they added.