Second edition

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298 Other major syndromes
and rocking from side to side; furthermore, if attempts are
made to restrain the patient, these are generally met with
some resistance. In a conversion grand mal seizure, some
patients may bite their lips, but the tongue is generally
spared; furthermore, it is very rare to see urinary incontinence
during a conversion seizure. After the event one typically
does not see any confusion, nor does one find a
positive Babinski sign. Conversion complex partial seizures
are more difficult to diagnose given, as discussed in Section
7.3, the extraordinary range of symptomatology seen in
true complex partial seizures. In general, however, as the
behavior becomes more complex and the episode lasts
longer, well past 5 minutes, the greater the likelihood is
that the event represents a conversion seizure. Laboratory
testing, including video–EEG and serum prolactin, neuron-specific
enolase and CPK levels, may be required to
confirm the diagnostic impression, and these are discussed
further in Section 7.3.
Other conversion symptoms, of course, are possible, and
these include aphonia, anosmia, nystgmus, convergence
spasm, and ageusia.
Demonstrating a ‘violation’ may at times require considerable
ingenuity on the part of the examining physician,
and in all cases requires a thorough and detailed neurologic
examination coupled with a firm grasp of the anatomy and
physiology of the nervous system. Whether or not investigation
beyond the clinical examination is required, for
example with MR scanning, evoked potentials or EEGs, is a
question that should be decided on a case-by case basis.
Certainly, if the ‘violation’ is questionable, such investigation
should be considered.
Although conversion disorder may occur in isolation,
most patients have other disorders (Binzer et al. 1997),
most commonly either a depression or a personality disorder
of the histrionic, passive–aggressive, borderline, or
antisocial types. Another feature often said to occur in
association with conversion symptoms is ‘la belle indifference’,
that is to say a casual indifference to symptoms, such
as blindness or hemianesthesia, which would normally
provoke considerable alarm. Unfortunately, this is not a
reliable symptom, as it may either be absent or seen in
other disorders (Stone et al. 2006). Furthermore, it may be
confused with anosognosia.
COURSE
Conversion disorder may pursue either an episodic or
chronic course (Mace and Trimble 1996). In episodic cases,
recovery is seen typically in a matter of weeks or months; this
favorable turn of events is more likely in younger patients,
those of good intelligence, and in cases wherein the onset is
acute, and occurs shortly after a major emotional stress. In
those who do recover, however, recurrences are common in
the following years; when recurrences do occur, the symptoms
may or may not be the same. Chronicity may be anticipated
when initial symptoms persist much beyond
6 months.
ETIOLOGY
The experience of patients with conversion symptoms is
quite remarkable. Although it may be clear to the examining
physician that the symptoms are, in some sense or other,
‘produced’ by the patient, the patient is not aware of doing
so: for the patient, the symptom simply appeared, and did so
not on the basis of any motivation or intention that the
patient was aware of. Various theories have been proposed to
explain this. Some invoke the concept of dissociation or suggest
an association with hypnotic phenomena, whereas others
involve unconscious motivations. For example, in
explaining of conversion paralysis, say, of the right arm, one
might speculate that the patient experienced a number of
events unconsciously, including anger and a desire to strike
out, guilt at entertaining such a notion and a sense of shame
at not acting decisively. Here, the ‘paralysis’ of the arm serves
two purposes: it effectively prevents the patient from hurting
anyone, thus avoiding guilt, but also provides a ready excuse
why decisive action cannot be taken, thus avoiding shame.
Although such theories have a strong intuitive appeal, there is
not, as yet, compelling evidence in their support.
Imaging studies have provided some interesting results.
SPECT scanning has revealed decreased activity in the striatum
and thalamus contralateral to conversion paralysis,
with this asymmetry resolving with remission of the paralysis
(Vuilleumier et al. 2001). Positron emission tomography
(PET) scanning has revealed underactivation of the motor
cortex contralateral to conversion paralysis when patients
are requested to move the limb, with associated increased
activation of the orbitofrontal and anterior cingulate cortex
(Marshall et al. 1997), and, in a similar vein, functional MR
scanning revealed decreased activity in the sensory cortex
contralateral to conversion anesthesia (Ghaffar et al. 2006).
Finally, in one study, MR scanning revealed slight atrophy
of both striata and the right thalamus in patients with conversion
disorder (Atmaca et al. 2006).
Overall, it may be prudent to say that the appearance of
conversion symptoms involves dysfunction of the corticostriato-thalamic
circuitry, which, in some as yet unknown
fashion, is associated with behavior whose motivation is
unknown to the patient.
DIFFERENTIAL DIAGNOSIS
The most important differential to make, of course, is
between conversion symptoms and ‘true’ symptoms that
are, in fact, occurring on the basis of central or peripheral
nervous system disease. In this regard, it must be borne in
mind that, despite thorough investigation, a small minority
of patients who receive the diagnosis of conversion disorder
will, on follow-up, be found to have lesions missed during
the initial evaluation (Binzer and Kullgren 1998; Moene
et al. 2000). Consequently, the importance of a detailed and
thorough examination, coupled with appropriate imaging
and laboratory testing, cannot be overemphasized.
Conversion symptoms may occur not only in conversion
disorder, but also in Briquet’s syndrome and schizophrenia.