Resume : Patients with
pathological laughter and crying (PLC) are
subject to relatively uncontrollable episodes of
laughter, crying or both. The episodes occur
either without an apparent triggering stimulus
or following a stimulus that would not have led
the subject to laugh or cry prior to the onset
of the condition. PLC is a disorder of emotional
expression rather than a primary disturbance of
feelings, and is thus distinct from mood
disorders in which laughter and crying are
associated with feelings of happiness or
sadness. The traditional and currently accepted
view is that PLC is due to the damage of
pathways that arise in the motor areas of the
cerebral cortex and descend to the brainstem to
inhibit a putative centre for laughter and
crying. In that view, the lesions 'disinhibit'
or 'release' the laughter and crying centre.
The neuroanatomical findings in a recently
studied patient with PLC, along with new
knowledge on the neurobiology of emotion and
feeling, gave us an opportunity to revisit the
traditional view and propose an alternative.
Here we suggest that the critical PLC lesions
occur in the cerebro-ponto-cerebellar
pathways and that, as a consequence, the
cerebellar structures that automatically adjust
the execution of laughter or crying to the
cognitive and situational context of a potential
stimulus, operate on the basis of incomplete
information about that context, resulting in
inadequate and even chaotic behaviour.
Sander, K. and H. Scheich (2001). "Auditory
perception of laughing and crying activates
human amygdala regardless of attentional
state." Brain Res Cogn Brain Res 12(2):
181-98.
Adequate behavioral responses to socially
relevant stimuli are often impaired after
lesions of the amygdala. Such lesions concern
especially the recognition of facial and
sometimes of vocal expression of emotions. Using
low-noise functional magnetic resonance imaging
(fMRI), we investigated in which way the
amygdala, auditory cortex and insula are
involved in the processing of affective
nonverbal vocalizations (Laughing and Crying) in
healthy humans. The same samples of male and
female Laughing and Crying were presented in
different experimental conditions: Simply
listening to the stimuli, self-induction of the
corresponding emotions while listening, and
detection of artificial pitch shifts in the same
stimuli. All conditions activated the amygdala
similarly and bilaterally, whereby the amount of
activation was larger in the right amygdala. The
auditory cortex was more strongly activated by
Laughing than by Crying with a slight
right-hemisphere advantage for Laughing, both
likely due to acoustic stimulus features. The
insula was bilaterally activated in all
conditions. The mean signal intensity change
with stimulation was much larger in the amygdala
than in auditory cortex and insula. The amygdala
results seem to be in accordance with the
right-hemisphere hypothesis of emotion
processing which may not be applicable as
strongly to the level of auditory cortex or
insula.
Feinstein, A., P. O'Connor, et al. (1999).
"Pathological laughing and crying in multiple
sclerosis: a preliminary report suggesting a
role for the prefrontal cortex." Mult Scler
5(2): 69-73.
As part of a wide ranging study investigating
the prevalence, demographic and disease related
characteristics of pathological laughing and
crying (PLC) in multiple sclerosis (MS), a
putative role for the prefrontal cortex was also
explored. Eleven multiple sclerosis (MS)
patients with carefully defined PLC were
compared to a control group of 13 MS patients
without PLC on various cognitive indices known
to be sensitive to frontal lobe dysfunction.
Although the two groups did not differ with
respect to age, sex, physical disability,
disease course, duration of MS, years of
education, premorbid IQ, and depression, the PLC
group performed more poorly on the Stroop test
and a measure of verbal fluency. They also
showed a trend to make more total errors on the
Wisconsin Card Sort Test. The relevance of these
findings to the pathogenesis of PLC is
discussed, in particular whether the syndrome
is, in part, mediated by dysfunction of the
prefrontal cortex.
Gondim Fde, A., B. J. Parks, et al. (2001).
"Fou rire prodromique as the presentation of
pontine ischaemia secondary to vertebrobasilar
stenosis." J Neurol Neurosurg Psychiatry
71(6): 802-4.
"Fou rire prodromique" (prodrome of crazy
laughter) is a rare form of pathological
laughter of uncertain pathophysiology. A patient
is presented with pathological laughter as the
first manifestation of pontine ischaemia due to
vertebrobasilar stenosis. A 65 year old man
developed uncontrollable and unemotional
laughter for almost an hour followed by
transient right facial-brachial paresis. He had
fluctuation of laughter, right facial brachial
paresis, and occasional crying. Magnetic
resonance imaging, magnetic resonance angiogram
(MRA), and an angiogram showed small left
pontine and cerebellar infarcts, left vertebral
artery occlusion, and right vertebral and
basilar artery stenosis. His condition
deteriorated to bilateral brain stem infarction
and he died. Necropsy confirmed the extensive
brain stem infarction. Pathological laughter can
be the very first presenting manifestation of
ischaemia of the ventrotegmental junction of the
upper pons. It is hypothesised that the
pathological laughter in this patient was
secondary to ischaemic ephaptic stimulation of
the descending corticopontine/ bulbar pathways.
McCullagh, S., M. Moore, et al. (1999).
"Pathological laughing and crying in amyotrophic
lateral sclerosis: an association with
prefrontal cognitive dysfunction." J Neurol
Sci 169(1-2): 43-8.
Pathological laughing and crying (PLC)
frequently occurs in amyotrophic lateral
sclerosis (ALS). The etiology of the syndrome is
unclear, but frontal-subcortical circuits are
implicated, given their known association with
mood and affect regulation. Ten ALS patients
with PLC, eight patients without, and ten
healthy controls were compared on a number of
psychometric measures. Three indices of
prefrontal cortical function were given: the
Wisconsin Card Sort Test (WCST), the novel
'Gambling task' and a measure of olfactory
discrimination. Global cognitive ability,
psychiatric symptoms, and illness variables were
also examined. No significant between-groups
differences emerged with respect to global
cognitive ability, mood, olfaction, and
performance on the Gambling task. On the WCST,
however, patients with PLC made significantly
more total errors than the other two groups, and
showed a strong trend in a similar direction for
perseverative errors. A discriminant function
analysis revealed that the WCST variable 'total
errors' correctly predicted the presence or
absence of pathological affect in 75% of cases.
Thus, PLC appears to be associated with
impairment in the functional integrity of the
prefrontal cortex. Although this was not found
for all prefrontal measures, further
investigation of this area appears warranted.
