Somatoform Disorder not Otherwise Specified
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.
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.