Diagnostic challenges of functional neurological disorders after covid-19 disease or vaccination: case series and review of the literature

BACKGROUND: Functional neurological disorders have rarely been described in patients recovering from Covid-19 or after vaccination but they are probably under diagnosed. MATERIAL AND METHODS: Six patients referred for rehabilitation of persistent symptoms and/or sequelae of Coronavirus disease 2019 (COVID-19) were diagnosed with functional neurological disorders. A literature review was conducted to identify reported cases of functional neurological disorders after Covid-19 infection or vaccination. RESULTS: In the current case series, patients diagnosed with functional neurological disorders presented high variability of clinical symptoms including hemiplegia, lower limb unilateral or bilateral paralysis, myoclonus, dystonia, tremor and sensory impairment. Four patients were young females with mild Covid-19 infection without hospital admission. Their neurological symptoms developed over the course of 4 weeks after the beginning of Covid-19 symptoms or vaccine administration with normal ancillary exams. One patient presented overlapping functional neurological symptoms and mild impairment of the left common peroneal nerve after prolonged ICU stay. In addition, all patients in our case series reported other non-motor symptoms such as fatigue, cognitive impairment and diffuse pain or dysesthesia, which are compatible with post Covid-19 condition. CONCLUSIONS: It is important that clinicians recognize functional neurological symptoms and consider it as a differential diagnosis in patients with neurological complications of Covid-19 infection and vaccination. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13760-022-02140-7.