Changes are made in an effort to  simplify the criteria for conversion disorder. First, we suggest removing the requirement that the clinician actively establish that the patient is not feigning. This is because (a) it is probably clinically impossible to prove that a patient is not feigning  (Sharpe, 2003)  and (b) there is no evidence that feigning of conversion symptoms is more common than feigning of other mental disorders. However as with other disorders positive evidence of feigning remains an exclusion, thereby differentiating conversion from factitious disorder and malingering.

Second, we suggest removing the requirement that the clinician has to establish that there are associated psychological factors . This is because (a) as with feigning, it is very difficult to reliably establish that relevant psychological factors are present in all cases and (b) the research evidence suggests that psychological factors can often be found but are not specific and have only a weak association with the diagnosis (Roelofs, 2005). The association with psychological factors has therefore been relegated to accompanying text rather than remaining a clinical requirement for diagnosis.

Third, we emphasize the importance of obtaining positive evidence of the diagnosis from appropriate neurological assessment and testing. Current diagnostic criteria require that the symptom, after appropriate medical assessment, is found not to be due to a general medical condition. In contrast to most other somatic symptoms, it can be usually be reliably determined whether neurological symptoms are due to an organic disease (Stone et al 2009). Additionally there are also findings on neurological assessment and investigation that positively suggest the symptoms are those of conversion (such as Hoovers sign for motor weakness or absence of seizure activity on an EEG during apparent seizures for seizures)  (Hallett 2005; Reuber 2004; Stone 2005).

We suggest retaining Conversion Disorder in the Somatic Symptom Disorders section of the DSM. Conversion remains a condition defined by a somatic symptom that causes disability or distress and therefore sits comfortably in the new Somatic Symptom Disorders category that replaces somatoform disorders on grounds of utility. The alternative placement of this diagnosis is with dissociative disorders. The argument for moving conversion there is that the mental mechanisms involved are similar. However dissociation is a hypothetical process and moving conversion would (a) risk making an unjustified assumption about cause (b) lose the utility of grouping with other conditions that present with a somatic symptom. 

Please see the full rationale document here.