Editing Conversion disorder (section)

===Exclusion of neurological disease===

Conversion disorder presents with symptoms that typically resemble a [[neurological disorder]] such as [[stroke]], [[multiple sclerosis]], [[epilepsy]], [[hypokalemic periodic paralysis]], or [[narcolepsy]]. The neurologist must carefully exclude neurological disease, through examination and appropriate investigations.<ref name="Stone_2005">{{cite journal |vauthors=Stone J, Carson A, Sharpe M | title = Functional symptoms and signs in neurology: assessment and diagnosis | journal = J. Neurol. Neurosurg. Psychiatry | volume = 76 | pages = i2–12 | year = 2005 | issue = Suppl 1 | pmid = 15718217 | pmc = 1765681 | doi = 10.1136/jnnp.2004.061655 }}</ref> However, it is not uncommon for patients with neurological disease to also have conversion disorder.<ref name="pmid1469401">{{cite journal | author = Eames P | title = Hysteria following brain injury | journal = J. Neurol. Neurosurg. Psychiatry | volume = 55 | issue = 11 | pages = 1046–53 | year = 1992 | pmid = 1469401 | pmc = 1015291 | doi = 10.1136/jnnp.55.11.1046}}</ref>

In excluding neurological disease, the neurologist has traditionally relied partly on the presence of positive signs of conversion disorder (i.e., certain aspects of the presentation that were thought to be rare in neurological disease but common in conversion disorder). The validity of many of these signs has been questioned by a study showing that they also occur in neurological disease.<ref name="pmid3760849">{{cite journal |vauthors=Gould R, Miller BL, Goldberg MA, Benson DF | title = The validity of hysterical signs and symptoms | journal = J. Nerv. Ment. Dis. | volume = 174 | issue = 10 | pages = 593–7 | year = 1986 | pmid = 3760849 | doi = 10.1097/00005053-198610000-00003| s2cid = 38888726 }}</ref> One such symptom, for example, is ''la belle indifférence'', described in DSM-IV as "a relative lack of concern about the nature or implications of the symptoms". In a 2006 study, no evidence was found that patients with [[functional symptom]]s are any more likely to exhibit this than patients with a confirmed organic disease.<ref name="pmid16507959">{{cite journal |vauthors=Stone J, Smyth R, Carson A, Warlow C, Sharpe M | title = La belle indifférence in conversion symptoms and hysteria: systematic review | journal = Br J Psychiatry | volume = 188 | pages = 204–9 | year = 2006 | pmid = 16507959 | doi = 10.1192/bjp.188.3.204 | doi-access = free }}</ref> In the DSM-5, ''la belle indifférence'' was removed as a diagnostic criterion.

Another feature thought to be important was that symptoms tended to be more severe on the non-dominant, usually left side of the body. There have been a number of theories about this, such as the relative involvement of cerebral hemispheres in emotional processing, or more simply, that it was "easier" to live with a functional deficit on the non-dominant side. However, a literature review of 121 studies established that this was not true, with [[publication bias]] the most likely explanation for this commonly held view.<ref name="pmid12397155">{{cite journal |vauthors=Stone J, Sharpe M, Carson A, Lewis SC, Thomas B, Goldbeck R, Warlow CP | title = Are functional motor and sensory symptoms really more frequent on the left? A systematic review | journal = J. Neurol. Neurosurg. Psychiatry | volume = 73 | issue = 5 | pages = 578–81 | year = 2002 | pmid = 12397155 | pmc = 1738113 | doi = 10.1136/jnnp.73.5.578}}</ref> Although agitation is often assumed to be a positive sign of conversion disorder, release of [[epinephrine]] is a well-demonstrated cause of paralysis from [[hypokalemic periodic paralysis]].<ref>{{cite web|url=https://www.uni-ulm.de/fileadmin/website_uni_ulm/med.inst.040/Dokumente/owner.html |title=Segal MM, Jurkat-Rott K, Levitt J, Lehmann-Horn F, Hypokalemic periodic paralysis—an owner's manual |publisher=Uni-ulm.de |date=2009-06-05 |access-date=2013-11-30}}</ref>

Misdiagnosis does sometimes occur. In a highly influential<ref name="pmid14286998">{{cite journal | author = Slater E | title = Diagnosis of Hysteria | journal = Br Med J | volume = 1 | issue = 5447 | pages = 1395–9 | year = 1965 | pmid = 14286998 | pmc = 2166300 | doi = 10.1136/bmj.1.5447.1395}}</ref> study from the 1960s, [[Eliot Slater]] demonstrated that misdiagnoses had occurred in one third of his 112 patients with conversion disorder.<ref name="pmid5857619">{{cite journal |vauthors=Slater ET, Glithero E | title = A follow-up of patients diagnosed as suffering from "hysteria" | journal = J Psychosom Res | volume = 9 | issue = 1 | pages = 9–13 | year = 1965 | pmid = 5857619 | doi = 10.1016/0022-3999(65)90004-8}}</ref> Later authors have argued that the paper was flawed.<ref name="ReferenceB">{{cite journal|year=2005|title=Eliot Slater's myth of the non-existence of hysteria|journal=J R Soc Med|volume=98|issue=12|pages=547–8|doi=10.1177/014107680509801214|pmc=1299341|pmid=16319432|vauthors=Stone J, Warlow C, Carson A, Sharpe M}}</ref><ref>Ron M, "The Prognosis of Hysteria" In P. Halligan, C. Bass, J. Marshall (Eds.) Hysterical Conversion: clinical and theoretical perspectives (pp. 73–87). Oxford: Oxford University Press.</ref> A 2005 meta-analysis has shown that misdiagnosis rates since that paper was published are around four percent, the same as for other neurological diseases.<ref name="Stone_2005"/>