Pathological Laughing and Crying Is Associated with Posterior Fossa Lesions in Multiple Sclerosis

Background: Pathological laughing and crying (PLC) is defined as episodes of involuntary laughing, crying, or both, that are contextually inappropriate or incongruous with the individual’s subjective mood state. PLC is known to occur in persons with MS (PwMS). Localization of neuroanatomical lesions associated with PLC remains poorly delineated.

Objectives: To examine the relationship between lesions in the posterior fossa and PLC in PwMS.

Methods: This retrospective chart review from the London (ON) MS Clinic identified PwMS between 2012 and 2016 who had completed the Center for Neurologic Study-Liability Scale (CNS-LS) and had an MRI for clinical reasons on the same 1.5T MRI machine within six months of each other. Brainstem and cerebellar lesions were counted and measured. Chi-square analysis was used to compare the number of posterior fossa lesions (brainstem and cerebellum) in PwMS who were positive on the CNS-LS (scores of ≥ 17) with those who were negative on the CNS-LS (scores 0-16). Next, the same analysis was performed when the sample was restricted to PwMS without depressive symptoms (Hospital Anxiety and Depression Scale, Depressive subscore (HADS-D) < 8) due to the confounding effect of depression on CNS-LS scores.

Results: Of the charts reviewed, 80 potential cases were identified with an MRI and CNS-LS within six months of each other. Three cases were excluded, due to CIS diagnosis (n=2) or no HADS-D scores (n=1). The mean age of the cohort was 39.3 (± 11.0) years, the majority were women (51, 66.2%), and the mean years since diagnosis was 5.3 (± 7.3). Most of the cohort had a relapsing form of MS (66, 85.7), the median EDSS was 2.0 (0.0-6.5) and 37 (48.1%) were on a disease modifying therapy. The mean CNS-LS score was 13.9 (± 5.0), with 22 (28.6%) in the positive range for PLC symptoms. On MRI, 42 (54.5%) had lesions in the posterior fossa, ranging from 0 to 35 (brainstem 0-10, cerebellum 0-12). The number of lesions was not significantly different in PwMS without PLC (CNS-LS ≤ 16) compared to PwMS with PLC (CNS-LS ≥ 17) (X2 (11, N=77) = 12.903, p = 0.3). When the analysis was restricted to PwMS without evidence of depression (HADS-D < 8), there was a significant difference (X2 (9, N=57) = 17.882, p = 0.037).

Conclusions: In PwMS, the number of posterior fossa lesions on MRI is associated with the presence of PLC. Further studies into the relationship between these lesions and PLC symptoms are needed.