This form of disordered emotional expression, characterized by outbursts of involuntary, uncontrollable, and stereotyped laughing or crying, has been recognized since the late nineteenth century. Numerous references to these conditions (the Zwangslachen and Zwangsweinen noted by German neurologists and the rire et pleurer spasmodiques described by the French) can be found in the writings of Oppenheim, von Monakow, and Wilson (see Wilson for historical references). The term emotional incontinence applied by psychiatrists may be accurate but is a bit pejorative. Forced laughing or crying always has a pathologic basis in the brain, either diffuse or focal. There have been reports of spasmodic laughter following unilateral striatocapsular infarction (Ceccaldi et al) and occasional cases after unilateral pontine infarction or arteriovenous malformation, but these were not verified. It may occur with degenerative and vascular diseases of the brain (Table 24-2), but often the diffuse nature of the underlying disease precludes useful topographic analysis and clinicoanatomic correlation.
The best examples of pathologic laughing and crying are provided by multiple lacunar vascular disease and by amyotrophic lateral sclerosis, multiple sclerosis, and progressive supranuclear palsy, in each case the lesions being distributed bilaterally and generally involving the corticobulbar motor system. The condition also occurs with the more widespread lesions of hypoxic–ischemic encephalopathy, Binswanger ischemic encephalopathy, cerebral trauma, infiltrative gliomas of the frontal lobe or pons, and infectious and noninfectious encephalitides. Another important presentation is the Foix-Marie-Chavany syndrome, in which there is a sudden hemiplegia from a stroke that is engrafted upon a preexistent (and often clinically silent) lesion in the opposite hemisphere; this sets the stage for the pathologic displays of emotionality. In this state, there is sometimes a striking incongruity between the loss of voluntary movements of muscles innervated by the motor nuclei of the lower pons and medulla (inability to forcefully close the eyes, elevate and retract the corners of the mouth, open and close the mouth, chew, swallow, phonate, articulate, and move the tongue) and the preservation of reflexive movements of the same muscles in yawning, coughing, throat clearing, and spasmodic laughing or crying. This is the motor syndrome of pseudobulbar palsy for which reason the term pseudobulbar affective state has been applied to the emotional disorder.
On the slightest provocation and sometimes for no apparent reason, the patient is thrown into a stereotyped spasm of laughter that may last for moments or up to many minutes, to the point of exhaustion. Or, far more often, the opposite happens—the mere mention of the patient’s family or the sight of the doctor provokes an uncontrollable spasm of crying that resembles a caricature of crying itself. The severity of the emotional display and the ease with which it is provoked does not correspond with the severity of the pseudobulbar motor paralysis or with an exaggeration of the facial and masseter (“jaw jerk”) tendon reflexes. In some patients with forced crying and laughing, there is little or no detectable weakness of facial and bulbar muscles; in others, forced laughing and crying are lacking despite a severe upper motor neuron weakness of these muscles. In certain diseases, such as progressive supranuclear palsy and central pontine myelinolysis, of which pseudobulbar palsy is a frequent manifestation, forced laughing and crying are less dramatic or absent. Consequently, the pathologic emotional state cannot be equated with pseudobulbar palsy even though the two frequently occur together.