PSYCHOLOGICAL "THIN SKULL"
Somatoform Disorders are common and are not the result of intentional deception. The distressing or disabling symptoms suggest a physically-based disorder but cannot be fully explained by any such disorder, by the effects of substances or by other psychological disorders.
The varieties commonly seen in Personal Injury practice are Somatisation, Undifferentiated, Conversion, and Pain.
Somatisation Disorder, previously known as "hysteria", starts before age 30, lasts for years, and comprises pain, gastrointestinal, sexual, and pseudoneurological symptoms.
If physical symptoms are present for a minimum of 6 months and the criteria for Somatisation Disorder are incompletely satisfied, the diagnosis may be Undifferentiated Somatoform Disorder.
Conversion Disorder is limited to deficits or symptoms of voluntary muscle control or bodily sensation, associated with psychological factors.
In Pain Disorder, psychological factors are considered important in its onset, severity, exacerbation, or maintenance.
The outdated split into "body" and "mind" has led to scepticism for the legal principle of "psychological thin skull".
The question, "Absent the intervention of this injury..." may be more difficult to answer when the pre-existing condition is Undifferentiated Somatoform, Conversion or Somatisation Disorder. Nevertheless, psychiatrists or psychologists with extensive experience with these illnesses can give the court valuable information about their natural history.
It is no more appropriate to accept a diagnosis of "functional overlay" from a specialist in bone, joint or muscle disorders than to give credence to a psychiatrist's diagnosis of "rheumatism".
A recent paper, which also addresses the medicolegal concepts of malingering and illness behaviour in chronic pain, argues for the abandonment of the pseudo-diagnosis "functional overlay" as having no diagnostic or predictive validity.
A suggestion of "functional overlay" requires a valid psychiatric diagnosis.
Somatisation Disorder proved a more stable diagnosis at a 4-year follow-up comparison with Conversion Disorder. Out of 32 patients initially diagnosed as Conversion, 6 now fulfilled the criteria for Somatisation Disorder, and another 4 had developed physically-based disorders which better explained their original complaints.
The overall rate of misdiagnosis of physically-based complaints as Conversion Syndrome is generally accepted to be less than 10%.
Although only 5-6% of patients with anxiety disorders will also suffer from Somatoform Disorder, anxiety or depression may mask the Somatoform Disorder in the majority. Further complicating the Personal Injury picture, Post Traumatic Stress Disorder is nearly three times as common in clients with pre-existing Somatoform Disorder.
Clients with diagnoses of anxiety or depression may have undiagnosed Somatoform Disorder and also be more susceptible to Post Traumatic Stress Disorder.
Copyright © 2008 Electronic Handbook of Legal Medicine