Somatoform Disorder not Otherwise Specified

Somatoform Disorder not Otherwise Specified

Definition

Somatoform disorder NOS is the true residual category (see Table 54.1). Disorders considered under this category are charac-terized by somatic symptoms, but criteria for any of the specific somatoform disorders are not met. Several examples are given, but syndromes potentially included under this category are not limited to these. Unlike for undifferentiated somatoform disor-der, no minimal duration is required. DSM-IV lists as examples pseudocyesis, disorders involving hypochondriacal complaints but of less than 6 months’ duration, and disorders involving unexplained physical complaints such as fatigue or body weak-ness not due to another mental disorder and again of less than 6 months’ duration. This last syndrome would seem to resemble neurasthenia of short duration, a syndrome with a long historical tradition.

Inclusion of pseudocyesis deserves special mention. With the restriction of conversion in DSM-IV to include only symp-toms affecting voluntary motor and sensory function, pseudo-cyesis was excluded from the conversion disorder definition. In a sense, it is placed in the somatoform disorder NOS category for lack of a more appropriate place. Pseudocyesis is a reasonably discrete syndrome for which specific criteria as listed in DSM-IV can be delineated. However, given its rarity, it is not listed as a specified somatoform disorder.

Diagnosis and Differential Diagnosis

As a residual category, somatoform disorder NOS is to be diag-nosed after all other possibilities are excluded (see Figure 54.1). After it is determined that a syndrome with somatoform symp-toms is not attributable to a nonsomatoform psychiatric disor-der and does not meet criteria for any of the specific somatoform disorders (including, on the symptom-focused side, pain, con-version and somatization disorders and, on the preoccupation-focused side, hypochondriasis or body dysmorphic disorder), the two diagnostic possibilities that remain are undifferentiated somatoform disorder and somatoform disorder NOS. Except in the case of pseudocyesis, these two are differentiated on the basis of whether the disturbance is of 6 months’ duration. If symptoms last more than 6 months, undifferentiated somatoform disorder is diagnosed; if less than 6 months, somatoform disorder NOS.