Pseudobulbar Affect: A Network Disorder Linking Emotion, Neurobiology, and Therapeutics.

Pseudobulbar affect (PBA), historically described as emotional incontinence, is a neurologic syndrome characterized by sudden, involuntary episodes of laughing or crying that are disproportionate to context and incongruent with mood. Once viewed as a minor behavioral complication of brain injury, it is now understood as a network-level disorder of emotional expression, arising from disinhibition of the brainstem faciovocal apparatus rather than from alterations in emotional experience. This narrative review synthesizes 39 peer-reviewed studies, examining the historical origins, pathophysiology, clinical recognition, and treatment of PBA across neurologic diseases. Classical descriptions by Magnus, Bechterew, and Wilson anticipated contemporary findings, that disruption of cortico-limbic-pontocerebellar circuits, together with neurotransmitter imbalance in serotonergic and glutamatergic pathways, underlie these episodes. Modern neuroimaging and electrophysiologic evidence demonstrate that structural and functional connectivity loss within this network leads to dysregulation of affective output, or emotional dysmetria. Validated instruments, such as the Center for Neurologic Study-Lability Scale (CNS-LS), improve recognition, while pharmacologic therapies, including selective serotonin reuptake inhibitors (SSRIs) and dextromethorphan/quinidine (DM/Q), restore inhibitory balance. Conceptualizing PBA as a disorder of expressive control rather than affective tone reframes it as a treatable manifestation of network dysfunction. Future directions include biomarker development, cerebellar-targeted neuromodulation, and integration of standardized screening into neurologic care.