Functional Neurological Symptom Disorder: A Continuing Conundrum for the Perioperative Physician

Abstract

Functional neurological symptom disorder (FNSD) or functional neurological disorder (FND) or conversion disorder, is a syndrome of neurological complications unexplained by neuropathology. The term FNSD or FND is now preferred, as conversion disorder is not an etiologically neutral term and is thus falling from use by researchers and clinicians in the field.We report a case of new-onset postoperative neurological deficit in a patient who had undergone uneventful general anesthesia for a urology procedure. Postoperatively, in the post-anesthesia care unit, the patient was found to be unable to move her upper and lower limbs. Organic pathology was excluded and a diagnosis of FNSD was made. Four weeks after the surgery, the patient was only able to ambulate with the help of a mechanical walker device.It is now suggested that procedures involving anesthesia are relatively common triggers for the development of FNSD. The occurrence of FNSD in the postoperative period is increasingly being attributed to the effects of anesthesia, the hypothesis being that it arises from the abreactive or dissociative effects of anesthetic agents. Another theory is the vulnerability of the anesthetized state which may evoke previous traumatic experiences. Psychiatric co-morbidities such as anxiety and depression may be seen in these patients. Preoperative psychological assessment may help identify patients at risk for FNSD. If postoperative neurological deficit occurs, detailed neurological, metabolic, and psychiatric assessments should be done with FNSD being a diagnosis of exclusion. We present this case to increase awareness regarding this uncommon condition which can cause significant distress to the patient and healthcare team. Management should comprise honest disclosure, reassurance of recovery, and reinforcement of alternative coping strategies. The development of preoperative screening tools may help identify patients at risk for this disorder.