Underlying psychiatric disorders
—Conversion disorder is probably the most common psychiatric diagnosis among patients with a FMD. Coexisting personality disorders may predispose to FMD. Other psychiatric disorders and diagnoses among patients with FMD may include factitious disorder, anxiety disorders, and depression . Malingering, though not a psychiatric disorder, is probably an uncommon cause of FMD. An awareness of these conditions is important for the clinician caring for a patient with suspected FMD.
●Conversion disorder (functional neurologic symptom disorder) is characterized by neurologic symptoms (eg, weakness, abnormal movements, or nonepileptic seizures) that are inconsistent with a neurologic disease, but nevertheless cause distress and/or psychosocial impairment (table 1). While a psychological factor is often associated with conversion disorder, it is not necessary; a psychological factor is not always readily apparent in patients with nonphysiologic neurologic symptoms. There is no age restriction for onset.
●The commonly used terms “somatization,” “multiple somatizations,” or “somatoform disorders” are used to describe a syndrome of physical symptoms that cannot be explained by a known medical disease and are associated with substantial psychosocial impairment. However, the term “somatization” is not used in the Diagnostic and Statistical Manual, Fifth Edition (DSM-5) . For patients with prominent somatic symptoms that cause distress and impair psychosocial functioning, DSM-5 has replaced the category of somatoform disorders with a category called somatic symptom and related disorders. The different terms and diagnoses used to describe somatization can be confusing (table 2), a problem discussed in detail separately.
●While factitious disorder and malingering are both intentionally feigned or deliberately induced, they are distinguished by motivation.
•Factitious disorder (also known as Munchausen syndrome) refers to intentionally feigned or deliberately induced physical or psychological symptoms in order to assume the sick role in the absence of external rewards. That is, the motivation for factitious disorders is attention for illness.