Pathological Laughter, Multiple Sclerosis, Behavioural Abnormality

Posterior Fossa Lesion Load and Pathological Laughing and Crying in Multiple Sclerosis

BACKGROUND

Pathological laughing and crying (PLC) encompasses episodes of involuntary laughing, crying, or both that are contextually incongruous with the individual's subjective mood. Despite a 10% to 46% prevalence in people with multiple sclerosis (MS) and reduced quality of life, localization of neuroanatomical lesions associated with PLC remains poorly delineated.

METHODS

The relationship between posterior fossa lesions and PLC in people with MS was examined using a retrospective medical record review of people with MS (2012-2016) who had completed the Center for Neurologic Study-Liability Scale (CNS-LS) and had undergone 1.5-T magnetic resonance imaging within 6 months of each other.

RESULTS

Medical record review identified 80 potential cases, with 77 included. Brainstem and cerebellar lesions were counted, measured, and compared between people with MS who had positive results on the CNS-LS (scores ≥17, n = 22) with those who had negative results on the CNS-LS (scores ≤16, n = 55). Initial χ2 analysis showed no significant difference in lesion numbers in people with MS without (CNS-LS score ≤16) versus with (CNS-LS score ≥17) PLC. When analyzing only people with MS without evidence of depression, a significant inverse relationship was identified such that fewer posterior fossa lesions on automated magnetic resonance imaging was associated with the presence of PLC.

CONCLUSIONS

Posterior fossa lesion load is not indicative of which individuals could develop PLC. Further investigations to delineate the primary source of PLC symptoms would aid in diagnosis and treatment of this condition.

The epidemiology and pathophysiology of pseudobulbar affect and its association with neurodegeneration

Pseudobulbar affect is a disorder resulting from neurologic damage manifesting as sudden, stereotyped affective outbursts that are not reflective of internal emotion. A literature review was completed to examine the current understanding of the epidemiology, characterization, diagnosis, pathophysiology, and treatment of pseudobulbar affect. This review revealed that it is common in neurodegenerative disorders but is poorly recognized, placing significant impacts on patients and their families. The disorder appears to result from a disruption of the cortico-limbic-subcortical-thalamic-pontocerebellar network involved in emotional expression and regulation with resulting disruptions of neurotransmitter systems. Effective treatment is available with agents such as selective serotonin reuptake inhibitors and dextromethorphan combined with quinidine, but further well-designed comparative studies are needed. Advances in technology such as neuroimaging may enhance knowledge about the pathophysiology of this disorder, and help guide future interventions.